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The late Georgian period saw the birth of the semi-detached house, planned systematically, as a suburban compromise between the terraced houses of the city and the detached "villas" further out, where land was cheaper. There had been occasional examples in town centres going back to medieval times. Most early suburban examples are large, and in what are now the outer fringes of Central London, but were then in areas being built up for the first time. Blackheath, Chalk Farm and St John's Wood are among the areas contesting being the original home of the semi. Sir John Summerson gave primacy to the Eyre Estate of St John's Wood. A plan for this exists dated 1794, where "the whole development consists of pairs of semi-detached houses, So far as I know, this is the first recorded scheme of the kind". In fact the French Wars put an end to this scheme, but when the development was finally built it retained the semi-detached form, "a revolution of striking significance and far-reaching effect".
Until the Church Building Act of 1818, the period saw relatively few churches built in Britain, which was already well-supplied, although in the later years of the period the demand for Non-conformist and Roman Catholic places of worship greatly increased. Anglican churches that were built were designed internally to allow maximum audibility, and visibility, for preaching, so the main nave was generally wider and shorter than in medieval plans, and often there were no side-aisles. Galleries were common in new churches. Especially in country parishes, the external appearance generally retained the familiar signifiers of a Gothic church, with a tower or spire, a large west front with one or more doors, and very large windows along the nave, but all with any ornament drawn from the classical vocabulary. Where funds permitted, a classical temple portico with columns and a pediment might be used at the west front. Decoration inside was very limited, but churches filled up with monuments to the prosperous.
Public buildings generally varied between the extremes of plain boxes with grid windows and Italian Late Renaissance palaces, depending on budget. Somerset House in London, designed by Sir William Chambers in 1776 for government offices, was as magnificent as any country house, though never quite finished, as funds ran out. Barracks and other less prestigious buildings could be as functional as the mills and factories that were growing increasingly large by the end of the period. But as the period came to an end many commercial projects were becoming sufficiently large, and well-funded, to become "architectural in intention", rather than having their design left to the lesser class of "surveyors".
Georgian architecture was widely disseminated in the English colonies during the Georgian era. American buildings of the Georgian period were very often constructed of wood with clapboards; even columns were made of timber, framed up, and turned on an over-sized lathe. At the start of the period the difficulties of obtaining and transporting brick or stone made them a common alternative only in the larger cities, or where they were obtainable locally. Dartmouth College, Harvard University, and the College of William and Mary, offer leading examples of Georgian architecture in the Americas.
Unlike the Baroque style that it replaced, which was mostly used for palaces and churches, and had little representation in the British colonies, simpler Georgian styles were widely used by the upper and middle classes. Perhaps the best remaining house is the pristine Hammond-Harwood House (1774) in Annapolis, Maryland, designed by the colonial architect William Buckland and modelled on the Villa Pisani at Montagnana, Italy as depicted in Andrea Palladio's I quattro libri dell'architettura ("Four Books of Architecture").
After about 1840, Georgian conventions were slowly abandoned as a number of revival styles, including Gothic Revival, that had originated in the Georgian period, developed and contested in Victorian architecture, and in the case of Gothic became better researched, and closer to their originals. Neoclassical architecture remained popular, and was the opponent of Gothic in the Battle of the Styles of the early Victorian period. In the United States the Federalist Style contained many elements of Georgian style, but incorporated revolutionary symbols.
In the early decades of the twentieth century when there was a growing nostalgia for its sense of order, the style was revived and adapted and in the United States came to be known as the Colonial Revival. In Canada the United Empire Loyalists embraced Georgian architecture as a sign of their fealty to Britain, and the Georgian style was dominant in the country for most of the first half of the 19th century. The Grange, for example, a manor built in Toronto, was built in 1817. In Montreal, English born architect John Ostell worked on a significant number of remarkable constructions in the Georgian style such as the Old Montreal Custom House and the Grand séminaire de Montréal.
The revived Georgian style that emerged in Britain at the beginning of the 20th century is usually referred to as Neo-Georgian; the work of Edwin Lutyens includes many examples. Versions of the Neo-Georgian style were commonly used in Britain for certain types of urban architecture until the late 1950s, Bradshaw Gass & Hope's Police Headquarters in Salford of 1958 being a good example. In both the United States and Britain, the Georgian style is still employed by architects like Quinlan Terry Julian Bicknell and Fairfax and Sammons for private residences.
The Republic of Liberia, beginning as a settlement of the American Colonization Society (ACS), declared its independence on July 26, 1847. The United States did not recognize Liberia's independence until during the American Civil War on February 5, 1862. Between January 7, 1822 and the American Civil War, more than 15,000 freed and free-born Black Americans from United States and 3,198 Afro-Caribbeans relocated to the settlement. The Black American settlers carried their culture with them to Liberia. The Liberian constitution and flag were modeled after the United States. In January 3, 1848 Joseph Jenkins Roberts, a wealthy free-born Black American from Virginia who settled in Liberia, was elected as Liberia's first president after the people proclaimed independence.
Longstanding political tensions from the 27 year rule of William Tubman resulted in a military coup in 1980 that overthrew the leadership soon after his death, marking the beginning of political instability. Five years of military rule by the People's Redemption Council and five years of civilian rule by the National Democratic Party of Liberia were followed by the First and Second Liberian Civil Wars. These resulted in the deaths and displacement of more than half a million people and devastated Liberia's economy. A peace agreement in 2003 led to democratic elections in 2005. Recovery proceeds but about 85% of the population live below the international poverty line.
This influx was compounded by the decline of the Western Sudanic Mali Empire in 1375 and the Songhai Empire in 1591. Additionally, as inland regions underwent desertification, inhabitants moved to the wetter coast. These new inhabitants brought skills such as cotton spinning, cloth weaving, iron smelting, rice and sorghum cultivation, and social and political institutions from the Mali and Songhai empires. Shortly after the Mane conquered the region, the Vai people of the former Mali Empire immigrated into the Grand Cape Mount region. The ethnic Kru opposed the influx of Vai, forming an alliance with the Mane to stop further influx of Vai.[citation needed]
In the United States, there was a movement to resettle American free blacks and freed slaves in Africa. The American Colonization Society was founded in 1816 in Washington, DC for this purpose, by a group of prominent politicians and slaveholders. But its membership grew to include mostly people who supported abolition of slavery. Slaveholders wanted to get free people of color out of the South, where they were thought to threaten the stability of the slave societies. Some abolitionists collaborated on relocation of free blacks, as they were discouraged by discrimination against them in the North and believed they would never be accepted in the larger society. Most African Americans, who were native-born by this time, wanted to improve conditions in the United States rather than emigrate. Leading activists in the North strongly opposed the ACS, but some free blacks were ready to try a different environment.
In 1822, the American Colonization Society began sending African-American volunteers to the Pepper Coast to establish a colony for freed African Americans. By 1867, the ACS (and state-related chapters) had assisted in the migration of more than 13,000 African Americans to Liberia. These free African Americans and their descendants married within their community and came to identify as Americo-Liberians. Many were of mixed race and educated in American culture; they did not identify with the indigenous natives of the tribes they encountered. They intermarried largely within the colonial community, developing an ethnic group that had a cultural tradition infused with American notions of political republicanism and Protestant Christianity.
The Americo-Liberian settlers did not identify with the indigenous peoples they encountered, especially those in communities of the more isolated "bush." They knew nothing of their cultures, languages or animist religion. Encounters with tribal Africans in the bush often developed as violent confrontations. The colonial settlements were raided by the Kru and Grebo people from their inland chiefdoms. Because of feeling set apart and superior by their culture and education to the indigenous peoples, the Americo-Liberians developed as a small elite that held on to political power. It excluded the indigenous tribesmen from birthright citizenship in their own lands until 1904, in a repetition of the United States' treatment of Native Americans. Because of the cultural gap between the groups and assumption of superiority of western culture, the Americo-Liberians envisioned creating a western-style state to which the tribesmen should assimilate. They encouraged religious organizations to set up missions and schools to educate the indigenous peoples.
On April 12, 1980, a military coup led by Master Sergeant Samuel Doe of the Krahn ethnic group overthrew and killed President William R. Tolbert, Jr.. Doe and the other plotters later executed a majority of Tolbert's cabinet and other Americo-Liberian government officials and True Whig Party members. The coup leaders formed the People's Redemption Council (PRC) to govern the country. A strategic Cold War ally of the West, Doe received significant financial backing from the United States while critics condemned the PRC for corruption and political repression.
The rebels soon split into various factions fighting one another. The Economic Community Monitoring Group under the Economic Community of West African States organized a military task force to intervene in the crisis. From 1989 to 1996 one of Africa's bloodiest civil wars ensued, claiming the lives of more than 200,000 Liberians and displacing a million others into refugee camps in neighboring countries. A peace deal between warring parties was reached in 1995, leading to Taylor's election as president in 1997.
In March 2003, a second rebel group, Movement for Democracy in Liberia, began launching attacks against Taylor from the southeast. Peace talks between the factions began in Accra in June of that year, and Taylor was indicted by the Special Court for Sierra Leone for crimes against humanity that same month. By July 2003, the rebels had launched an assault on Monrovia. Under heavy pressure from the international community and the domestic Women of Liberia Mass Action for Peace movement, Taylor resigned in August 2003 and went into exile in Nigeria.
The subsequent 2005 elections were internationally regarded as the most free and fair in Liberian history. Ellen Johnson Sirleaf, a Harvard-trained economist and former Minister of Finance, was elected as the first female president in Africa. Upon her inauguration, Sirleaf requested the extradition of Taylor from Nigeria and transferred him to the SCSL for trial in The Hague. In 2006, the government established a Truth and Reconciliation Commission to address the causes and crimes of the civil war.
Liberia is divided into fifteen counties, which, in turn, are subdivided into a total of 90 districts and further subdivided into clans. The oldest counties are Grand Bassa and Montserrado, both founded in 1839 prior to Liberian independence. Gbarpolu is the newest county, created in 2001. Nimba is the largest of the counties in size at 11,551 km2 (4,460 sq mi), while Montserrado is the smallest at 1,909 km2 (737 sq mi). Montserrado is also the most populous county with 1,144,806 residents as of the 2008 census.
The Legislature is composed of the Senate and the House of Representatives. The House, led by a speaker, has 73 members apportioned among the 15 counties on the basis of the national census, with each county receiving a minimum of two members. Each House member represents an electoral district within a county as drawn by the National Elections Commission and is elected by a plurality of the popular vote of their district into a six-year term. The Senate is made up of two senators from each county for a total of 30 senators. Senators serve nine-year terms and are elected at-large by a plurality of the popular vote. The vice president serves as the President of the Senate, with a President pro tempore serving in their absence.
Liberia's highest judicial authority is the Supreme Court, made up of five members and headed by the Chief Justice of Liberia. Members are nominated to the court by the president and are confirmed by the Senate, serving until the age of 70. The judiciary is further divided into circuit and speciality courts, magistrate courts and justices of the peace. The judicial system is a blend of common law, based on Anglo-American law, and customary law. An informal system of traditional courts still exists within the rural areas of the country, with trial by ordeal remaining common despite being officially outlawed.
Liberia scored a 3.3 on a scale from 10 (highly clean) to 0 (highly corrupt) on the 2010 Corruption Perceptions Index. This gave it a ranking 87th of 178 countries worldwide and 11th of 47 in Sub-Saharan Africa. This score represented a significant improvement since 2007, when the country scored 2.1 and ranked 150th of 180 countries. When seeking attention of a selection of service[clarification needed] providers, 89% of Liberians had to pay a bribe, the highest national percentage in the world according to the organization's 2010 Global Corruption Barometer.
The Central Bank of Liberia is responsible for printing and maintaining the Liberian dollar, which is the primary form of currency in Liberia. Liberia is one of the world's poorest countries, with a formal employment rate of 15%. GDP per capita peaked in 1980 at US$496, when it was comparable to Egypt's (at the time). In 2011, the country's nominal GDP was US$1.154 billion, while nominal GDP per capita stood at US$297, the third-lowest in the world. Historically, the Liberian economy has depended heavily on foreign aid, foreign direct investment and exports of natural resources such as iron ore, rubber and timber.
Following a peak in growth in 1979, the Liberian economy began a steady decline due to economic mismanagement following the 1980 coup. This decline was accelerated by the outbreak of civil war in 1989; GDP was reduced by an estimated 90% between 1989 and 1995, one of the fastest declines in history. Upon the end of the war in 2003, GDP growth began to accelerate, reaching 9.4% in 2007. The global financial crisis slowed GDP growth to 4.6% in 2009, though a strengthening agricultural sector led by rubber and timber exports increased growth to 5.1% in 2010 and an expected 7.3% in 2011, making the economy one of the 20 fastest growing in the world.
In 2003, additional UN sanctions were placed on Liberian timber exports, which had risen from US$5 million in 1997 to over US$100 million in 2002 and were believed to be funding rebels in Sierra Leone. These sanctions were lifted in 2006. Due in large part to foreign aid and investment inflow following the end of the war, Liberia maintains a large account deficit, which peaked at nearly 60% in 2008. Liberia gained observer status with the World Trade Organization in 2010 and is in the process of acquiring full member status.
Liberia has the highest ratio of foreign direct investment to GDP in the world, with US$16 billion in investment since 2006. Following the inauguration of the Sirleaf administration in 2006, Liberia signed several multibillion-dollar concession agreements in the iron ore and palm oil industries with numerous multinational corporations, including BHP Billiton, ArcelorMittal, and Sime Darby. Especially palm oil companies like Sime Darby (Malaysia) and Golden Veroleum (USA) are being accused by critics of the destruction of livelihoods and the displacement of local communities, enabled through government concessions. The Firestone Tire and Rubber Company has operated the world's largest rubber plantation in Liberia since 1926.
The Kpelle comprise more than 20% of the population and are the largest ethnic group in Liberia, residing mostly in Bong County and adjacent areas in central Liberia. Americo-Liberians, who are descendants of African American and West Indian, mostly Barbadian settlers, make up 2.5%. Congo people, descendants of repatriated Congo and Afro-Caribbean slaves who arrived in 1825, make up an estimated 2.5%. These latter two groups established political control in the 19th century which they kept well into the 20th century.
Numerous immigrants have come as merchants and become a major part of the business community, including Lebanese, Indians, and other West African nationals. There is a high percentage of interracial marriage between ethnic Liberians and the Lebanese, resulting in a significant mixed-race population especially in and around Monrovia. A small minority of Liberians of European descent reside in the country.[better source needed] The Liberian constitution restricts citizenship to people of Black African descent.
In 2010, the literacy rate of Liberia was estimated at 60.8% (64.8% for males and 56.8% for females). In some areas primary and secondary education is free and compulsory from the ages of 6 to 16, though enforcement of attendance is lax. In other areas children are required to pay a tuition fee to attend school. On average, children attain 10 years of education (11 for boys and 8 for girls). The country's education sector is hampered by inadequate schools and supplies, as well as a lack of qualified teachers.
Hospitals in Liberia include the John F. Kennedy Medical Center in Monrovia and several others. Life expectancy in Liberia is estimated to be 57.4 years in 2012. With a fertility rate of 5.9 births per woman, the maternal mortality rate stood at 990 per 100,000 births in 2010. A number of highly communicable diseases are widespread, including tuberculosis, diarrheal diseases and malaria. In 2007, the HIV infection rates stood at 2% of the population aged 15–49 whereas the incidence of tuberculosis was 420 per 100,000 people in 2008. Approximately 58.2% – 66% of women are estimated to have undergone female genital mutilation.
Liberia has a long, rich history in textile arts and quilting, as the settlers brought with them their sewing and quilting skills. Liberia hosted National Fairs in 1857 and 1858 in which prizes were awarded for various needle arts. One of the most well-known Liberian quilters was Martha Ann Ricks, who presented a quilt featuring the famed Liberian coffee tree to Queen Victoria in 1892. When President Ellen Johnson Sirleaf moved into the Executive Mansion, she reportedly had a Liberian-made quilt installed in her presidential office.
Beginning in the late 1910s and early 1920s, Whitehead gradually turned his attention from mathematics to philosophy of science, and finally to metaphysics. He developed a comprehensive metaphysical system which radically departed from most of western philosophy. Whitehead argued that reality consists of processes rather than material objects, and that processes are best defined by their relations with other processes, thus rejecting the theory that reality is fundamentally constructed by bits of matter that exist independently of one another. Today Whitehead's philosophical works – particularly Process and Reality – are regarded as the foundational texts of process philosophy.
Alfred North Whitehead was born in Ramsgate, Kent, England, in 1861. His father, Alfred Whitehead, was a minister and schoolmaster of Chatham House Academy, a successful school for boys established by Thomas Whitehead, Alfred North's grandfather. Whitehead himself recalled both of them as being very successful schoolmasters, but that his grandfather was the more extraordinary man. Whitehead's mother was Maria Sarah Whitehead, formerly Maria Sarah Buckmaster. Whitehead was apparently not particularly close with his mother, as he never mentioned her in any of his writings, and there is evidence that Whitehead's wife, Evelyn, had a low opinion of her.
In 1918 Whitehead's academic responsibilities began to seriously expand as he accepted a number of high administrative positions within the University of London system, of which Imperial College London was a member at the time. He was elected Dean of the Faculty of Science at the University of London in late 1918 (a post he held for four years), a member of the University of London's Senate in 1919, and chairman of the Senate's Academic (leadership) Council in 1920, a post which he held until he departed for America in 1924. Whitehead was able to exert his newfound influence to successfully lobby for a new history of science department, help establish a Bachelor of Science degree (previously only Bachelor of Arts degrees had been offered), and make the school more accessible to less wealthy students.
The two volume biography of Whitehead by Victor Lowe is the most definitive presentation of the life of Whitehead. However, many details of Whitehead's life remain obscure because he left no Nachlass; his family carried out his instructions that all of his papers be destroyed after his death. Additionally, Whitehead was known for his "almost fanatical belief in the right to privacy", and for writing very few personal letters of the kind that would help to gain insight on his life. This led to Lowe himself remarking on the first page of Whitehead's biography, "No professional biographer in his right mind would touch him."
In addition to numerous articles on mathematics, Whitehead wrote three major books on the subject: A Treatise on Universal Algebra (1898), Principia Mathematica (co-written with Bertrand Russell and published in three volumes between 1910 and 1913), and An Introduction to Mathematics (1911). The former two books were aimed exclusively at professional mathematicians, while the latter book was intended for a larger audience, covering the history of mathematics and its philosophical foundations. Principia Mathematica in particular is regarded as one of the most important works in mathematical logic of the 20th century.
At the time structures such as Lie algebras and hyperbolic quaternions drew attention to the need to expand algebraic structures beyond the associatively multiplicative class. In a review Alexander Macfarlane wrote: "The main idea of the work is not unification of the several methods, nor generalization of ordinary algebra so as to include them, but rather the comparative study of their several structures." In a separate review, G. B. Mathews wrote, "It possesses a unity of design which is really remarkable, considering the variety of its themes."
Whitehead and Russell had thought originally that Principia Mathematica would take a year to complete; it ended up taking them ten years. To add insult to injury, when it came time for publication, the three-volume work was so massive (more than 2,000 pages) and its audience so narrow (professional mathematicians) that it was initially published at a loss of 600 pounds, 300 of which was paid by Cambridge University Press, 200 by the Royal Society of London, and 50 apiece by Whitehead and Russell themselves. Despite the initial loss, today there is likely no major academic library in the world which does not hold a copy of Principia Mathematica.
The ultimate substantive legacy of Principia Mathematica is mixed. It is generally accepted that Kurt Gödel's incompleteness theorem of 1931 definitively demonstrated that for any set of axioms and inference rules proposed to encapsulate mathematics, there would in fact be some truths of mathematics which could not be deduced from them, and hence that Principia Mathematica could never achieve its aims. However, Gödel could not have come to this conclusion without Whitehead and Russell's book. In this way, Principia Mathematica's legacy might be described as its key role in disproving the possibility of achieving its own stated goals. But beyond this somewhat ironic legacy, the book popularized modern mathematical logic and drew important connections between logic, epistemology, and metaphysics.
Whitehead's most complete work on education is the 1929 book The Aims of Education and Other Essays, which collected numerous essays and addresses by Whitehead on the subject published between 1912 and 1927. The essay from which Aims of Education derived its name was delivered as an address in 1916 when Whitehead was president of the London Branch of the Mathematical Association. In it, he cautioned against the teaching of what he called "inert ideas" – ideas that are disconnected scraps of information, with no application to real life or culture. He opined that "education with inert ideas is not only useless: it is, above all things, harmful."
Rather than teach small parts of a large number of subjects, Whitehead advocated teaching a relatively few important concepts that the student could organically link to many different areas of knowledge, discovering their application in actual life. For Whitehead, education should be the exact opposite of the multidisciplinary, value-free school model – it should be transdisciplinary, and laden with values and general principles that provide students with a bedrock of wisdom and help them to make connections between areas of knowledge that are usually regarded as separate.
Whitehead did not begin his career as a philosopher. In fact, he never had any formal training in philosophy beyond his undergraduate education. Early in his life he showed great interest in and respect for philosophy and metaphysics, but it is evident that he considered himself a rank amateur. In one letter to his friend and former student Bertrand Russell, after discussing whether science aimed to be explanatory or merely descriptive, he wrote: "This further question lands us in the ocean of metaphysic, onto which my profound ignorance of that science forbids me to enter." Ironically, in later life Whitehead would become one of the 20th century's foremost metaphysicians.
Whitehead was unimpressed by this objection. In the notes of one his students for a 1927 class, Whitehead was quoted as saying: "Every scientific man in order to preserve his reputation has to say he dislikes metaphysics. What he means is he dislikes having his metaphysics criticized." In Whitehead's view, scientists and philosophers make metaphysical assumptions about how the universe works all the time, but such assumptions are not easily seen precisely because they remain unexamined and unquestioned. While Whitehead acknowledged that "philosophers can never hope finally to formulate these metaphysical first principles," he argued that people need to continually re-imagine their basic assumptions about how the universe works if philosophy and science are to make any real progress, even if that progress remains permanently asymptotic. For this reason Whitehead regarded metaphysical investigations as essential to both good science and good philosophy.
Perhaps foremost among what Whitehead considered faulty metaphysical assumptions was the Cartesian idea that reality is fundamentally constructed of bits of matter that exist totally independently of one another, which he rejected in favor of an event-based or "process" ontology in which events are primary and are fundamentally interrelated and dependent on one another. He also argued that the most basic elements of reality can all be regarded as experiential, indeed that everything is constituted by its experience. He used the term "experience" very broadly, so that even inanimate processes such as electron collisions are said to manifest some degree of experience. In this, he went against Descartes' separation of two different kinds of real existence, either exclusively material or else exclusively mental. Whitehead referred to his metaphysical system as "philosophy of organism", but it would become known more widely as "process philosophy."
This is not to say that Whitehead's thought was widely accepted or even well-understood. His philosophical work is generally considered to be among the most difficult to understand in all of the western canon. Even professional philosophers struggled to follow Whitehead's writings. One famous story illustrating the level of difficulty of Whitehead's philosophy centers around the delivery of Whitehead's Gifford lectures in 1927–28 – following Arthur Eddington's lectures of the year previous – which Whitehead would later publish as Process and Reality:
However, Mathews' frustration with Whitehead's books did not negatively affect his interest. In fact, there were numerous philosophers and theologians at Chicago's Divinity School that perceived the importance of what Whitehead was doing without fully grasping all of the details and implications. In 1927 they invited one of America's only Whitehead experts – Henry Nelson Wieman – to Chicago to give a lecture explaining Whitehead's thought. Wieman's lecture was so brilliant that he was promptly hired to the faculty and taught there for twenty years, and for at least thirty years afterward Chicago's Divinity School was closely associated with Whitehead's thought.
Wieman's words proved prophetic. Though Process and Reality has been called "arguably the most impressive single metaphysical text of the twentieth century," it has been little-read and little-understood, partly because it demands – as Isabelle Stengers puts it – "that its readers accept the adventure of the questions that will separate them from every consensus." Whitehead questioned western philosophy's most dearly held assumptions about how the universe works, but in doing so he managed to anticipate a number of 21st century scientific and philosophical problems and provide novel solutions.
In Whitehead's view, then, concepts such as "quality", "matter", and "form" are problematic. These "classical" concepts fail to adequately account for change, and overlook the active and experiential nature of the most basic elements of the world. They are useful abstractions, but are not the world's basic building blocks. What is ordinarily conceived of as a single person, for instance, is philosophically described as a continuum of overlapping events. After all, people change all the time, if only because they have aged by another second and had some further experience. These occasions of experience are logically distinct, but are progressively connected in what Whitehead calls a "society" of events. By assuming that enduring objects are the most real and fundamental things in the universe, materialists have mistaken the abstract for the concrete (what Whitehead calls the "fallacy of misplaced concreteness").
To put it another way, a thing or person is often seen as having a "defining essence" or a "core identity" that is unchanging, and describes what the thing or person really is. In this way of thinking, things and people are seen as fundamentally the same through time, with any changes being qualitative and secondary to their core identity (e.g. "Mark's hair has turned gray as he has gotten older, but he is still the same person"). But in Whitehead's cosmology, the only fundamentally existent things are discrete "occasions of experience" that overlap one another in time and space, and jointly make up the enduring person or thing. On the other hand, what ordinary thinking often regards as "the essence of a thing" or "the identity/core of a person" is an abstract generalization of what is regarded as that person or thing's most important or salient features across time. Identities do not define people, people define identities. Everything changes from moment to moment, and to think of anything as having an "enduring essence" misses the fact that "all things flow", though it is often a useful way of speaking.
Whitehead pointed to the limitations of language as one of the main culprits in maintaining a materialistic way of thinking, and acknowledged that it may be difficult to ever wholly move past such ideas in everyday speech. After all, each moment of each person's life can hardly be given a different proper name, and it is easy and convenient to think of people and objects as remaining fundamentally the same things, rather than constantly keeping in mind that each thing is a different thing from what it was a moment ago. Yet the limitations of everyday living and everyday speech should not prevent people from realizing that "material substances" or "essences" are a convenient generalized description of a continuum of particular, concrete processes. No one questions that a ten-year-old person is quite different by the time he or she turns thirty years old, and in many ways is not the same person at all; Whitehead points out that it is not philosophically or ontologically sound to think that a person is the same from one second to the next.
A second problem with materialism is that it obscures the importance of relations. It sees every object as distinct and discrete from all other objects. Each object is simply an inert clump of matter that is only externally related to other things. The idea of matter as primary makes people think of objects as being fundamentally separate in time and space, and not necessarily related to anything. But in Whitehead's view, relations take a primary role, perhaps even more important than the relata themselves. A student taking notes in one of Whitehead's fall 1924 classes wrote that:
In fact, Whitehead describes any entity as in some sense nothing more and nothing less than the sum of its relations to other entities – its synthesis of and reaction to the world around it. A real thing is just that which forces the rest of the universe to in some way conform to it; that is to say, if theoretically a thing made strictly no difference to any other entity (i.e. it was not related to any other entity), it could not be said to really exist. Relations are not secondary to what a thing is, they are what the thing is.
It must be emphasized, however, that an entity is not merely a sum of its relations, but also a valuation of them and reaction to them. For Whitehead, creativity is the absolute principle of existence, and every entity (whether it is a human being, a tree, or an electron) has some degree of novelty in how it responds to other entities, and is not fully determined by causal or mechanistic laws. Of course, most entities do not have consciousness. As a human being's actions cannot always be predicted, the same can be said of where a tree's roots will grow, or how an electron will move, or whether it will rain tomorrow. Moreover, inability to predict an electron's movement (for instance) is not due to faulty understanding or inadequate technology; rather, the fundamental creativity/freedom of all entities means that there will always remain phenomena that are unpredictable.
Since Whitehead's metaphysics described a universe in which all entities experience, he needed a new way of describing perception that was not limited to living, self-conscious beings. The term he coined was "prehension", which comes from the Latin prehensio, meaning "to seize." The term is meant to indicate a kind of perception that can be conscious or unconscious, applying to people as well as electrons. It is also intended to make clear Whitehead's rejection of the theory of representative perception, in which the mind only has private ideas about other entities. For Whitehead, the term "prehension" indicates that the perceiver actually incorporates aspects of the perceived thing into itself. In this way, entities are constituted by their perceptions and relations, rather than being independent of them. Further, Whitehead regards perception as occurring in two modes, causal efficacy (or "physical prehension") and presentational immediacy (or "conceptual prehension").
Whitehead describes causal efficacy as "the experience dominating the primitive living organisms, which have a sense for the fate from which they have emerged, and the fate towards which they go." It is, in other words, the sense of causal relations between entities, a feeling of being influenced and affected by the surrounding environment, unmediated by the senses. Presentational immediacy, on the other hand, is what is usually referred to as "pure sense perception", unmediated by any causal or symbolic interpretation, even unconscious interpretation. In other words, it is pure appearance, which may or may not be delusive (e.g. mistaking an image in a mirror for "the real thing").
In higher organisms (like people), these two modes of perception combine into what Whitehead terms "symbolic reference", which links appearance with causation in a process that is so automatic that both people and animals have difficulty refraining from it. By way of illustration, Whitehead uses the example of a person's encounter with a chair. An ordinary person looks up, sees a colored shape, and immediately infers that it is a chair. However, an artist, Whitehead supposes, "might not have jumped to the notion of a chair", but instead "might have stopped at the mere contemplation of a beautiful color and a beautiful shape." This is not the normal human reaction; most people place objects in categories by habit and instinct, without even thinking about it. Moreover, animals do the same thing. Using the same example, Whitehead points out that a dog "would have acted immediately on the hypothesis of a chair and would have jumped onto it by way of using it as such." In this way symbolic reference is a fusion of pure sense perceptions on the one hand and causal relations on the other, and that it is in fact the causal relationships that dominate the more basic mentality (as the dog illustrates), while it is the sense perceptions which indicate a higher grade mentality (as the artist illustrates).
Whitehead makes the startling observation that "life is comparatively deficient in survival value." If humans can only exist for about a hundred years, and rocks for eight hundred million, then one is forced to ask why complex organisms ever evolved in the first place; as Whitehead humorously notes, "they certainly did not appear because they were better at that game than the rocks around them." He then observes that the mark of higher forms of life is that they are actively engaged in modifying their environment, an activity which he theorizes is directed toward the three-fold goal of living, living well, and living better. In other words, Whitehead sees life as directed toward the purpose of increasing its own satisfaction. Without such a goal, he sees the rise of life as totally unintelligible.
Whitehead's idea of God differs from traditional monotheistic notions. Perhaps his most famous and pointed criticism of the Christian conception of God is that "the Church gave unto God the attributes which belonged exclusively to Caesar." Here Whitehead is criticizing Christianity for defining God as primarily a divine king who imposes his will on the world, and whose most important attribute is power. As opposed to the most widely accepted forms of Christianity, Whitehead emphasized an idea of God that he called "the brief Galilean vision of humility":
It should be emphasized, however, that for Whitehead God is not necessarily tied to religion. Rather than springing primarily from religious faith, Whitehead saw God as necessary for his metaphysical system. His system required that an order exist among possibilities, an order that allowed for novelty in the world and provided an aim to all entities. Whitehead posited that these ordered potentials exist in what he called the primordial nature of God. However, Whitehead was also interested in religious experience. This led him to reflect more intensively on what he saw as the second nature of God, the consequent nature. Whitehead's conception of God as a "dipolar" entity has called for fresh theological thinking.
God's consequent nature, on the other hand, is anything but unchanging – it is God's reception of the world's activity. As Whitehead puts it, "[God] saves the world as it passes into the immediacy of his own life. It is the judgment of a tenderness which loses nothing that can be saved." In other words, God saves and cherishes all experiences forever, and those experiences go on to change the way God interacts with the world. In this way, God is really changed by what happens in the world and the wider universe, lending the actions of finite creatures an eternal significance.
Whitehead thus sees God and the world as fulfilling one another. He sees entities in the world as fluent and changing things that yearn for a permanence which only God can provide by taking them into God's self, thereafter changing God and affecting the rest of the universe throughout time. On the other hand, he sees God as permanent but as deficient in actuality and change: alone, God is merely eternally unrealized possibilities, and requires the world to actualize them. God gives creatures permanence, while the creatures give God actuality and change. Here it is worthwhile to quote Whitehead at length:
For Whitehead the core of religion was individual. While he acknowledged that individuals cannot ever be fully separated from their society, he argued that life is an internal fact for its own sake before it is an external fact relating to others. His most famous remark on religion is that "religion is what the individual does with his own solitariness ... and if you are never solitary, you are never religious." Whitehead saw religion as a system of general truths that transformed a person's character. He took special care to note that while religion is often a good influence, it is not necessarily good – an idea which he called a "dangerous delusion" (e.g., a religion might encourage the violent extermination of a rival religion's adherents).
However, while Whitehead saw religion as beginning in solitariness, he also saw religion as necessarily expanding beyond the individual. In keeping with his process metaphysics in which relations are primary, he wrote that religion necessitates the realization of "the value of the objective world which is a community derivative from the interrelations of its component individuals." In other words, the universe is a community which makes itself whole through the relatedness of each individual entity to all the others – meaning and value do not exist for the individual alone, but only in the context of the universal community. Whitehead writes further that each entity "can find no such value till it has merged its individual claim with that of the objective universe. Religion is world-loyalty. The spirit at once surrenders itself to this universal claim and appropriates it for itself." In this way the individual and universal/social aspects of religion are mutually dependent.
Whitehead also described religion more technically as "an ultimate craving to infuse into the insistent particularity of emotion that non-temporal generality which primarily belongs to conceptual thought alone." In other words, religion takes deeply felt emotions and contextualizes them within a system of general truths about the world, helping people to identify their wider meaning and significance. For Whitehead, religion served as a kind of bridge between philosophy and the emotions and purposes of a particular society. It is the task of religion to make philosophy applicable to the everyday lives of ordinary people.
Isabelle Stengers wrote that "Whiteheadians are recruited among both philosophers and theologians, and the palette has been enriched by practitioners from the most diverse horizons, from ecology to feminism, practices that unite political struggle and spirituality with the sciences of education." Indeed, in recent decades attention to Whitehead's work has become more widespread, with interest extending to intellectuals in Europe and China, and coming from such diverse fields as ecology, physics, biology, education, economics, and psychology. One of the first theologians to attempt to interact with Whitehead's thought was the future Archbishop of Canterbury, William Temple. In Temple's Gifford Lectures of 1932-1934 (subsequently published as "Nature, Man and God"), Whitehead is one of a number of philosophers of the emergent evolution approach Temple interacts with. However, it was not until the 1970s and 1980s that Whitehead's thought drew much attention outside of a small group of philosophers and theologians, primarily Americans, and even today he is not considered especially influential outside of relatively specialized circles.
Early followers of Whitehead were found primarily at the University of Chicago's Divinity School, where Henry Nelson Wieman initiated an interest in Whitehead's work that would last for about thirty years. Professors such as Wieman, Charles Hartshorne, Bernard Loomer, Bernard Meland, and Daniel Day Williams made Whitehead's philosophy arguably the most important intellectual thread running through the Divinity School. They taught generations of Whitehead scholars, the most notable of which is John B. Cobb, Jr.
But while Claremont remains the most concentrated hub of Whiteheadian activity, the place where Whitehead's thought currently seems to be growing the most quickly is in China. In order to address the challenges of modernization and industrialization, China has begun to blend traditions of Taoism, Buddhism, and Confucianism with Whitehead's "constructive post-modern" philosophy in order to create an "ecological civilization." To date, the Chinese government has encouraged the building of twenty-three university-based centers for the study of Whitehead's philosophy, and books by process philosophers John Cobb and David Ray Griffin are becoming required reading for Chinese graduate students. Cobb has attributed China's interest in process philosophy partly to Whitehead's stress on the mutual interdependence of humanity and nature, as well as his emphasis on an educational system that includes the teaching of values rather than simply bare facts.
Overall, however, Whitehead's influence is very difficult to characterize. In English-speaking countries, his primary works are little-studied outside of Claremont and a select number of liberal graduate-level theology and philosophy programs. Outside of these circles his influence is relatively small and diffuse, and has tended to come chiefly through the work of his students and admirers rather than Whitehead himself. For instance, Whitehead was a teacher and long-time friend and collaborator of Bertrand Russell, and he also taught and supervised the dissertation of Willard Van Orman Quine, both of whom are important figures in analytic philosophy – the dominant strain of philosophy in English-speaking countries in the 20th century. Whitehead has also had high-profile admirers in the continental tradition, such as French post-structuralist philosopher Gilles Deleuze, who once dryly remarked of Whitehead that "he stands provisionally as the last great Anglo-American philosopher before Wittgenstein's disciples spread their misty confusion, sufficiency, and terror." French sociologist and anthropologist Bruno Latour even went so far as to call Whitehead "the greatest philosopher of the 20th century."
Deleuze's and Latour's opinions, however, are minority ones, as Whitehead has not been recognized as particularly influential within the most dominant philosophical schools. It is impossible to say exactly why Whitehead's influence has not been more widespread, but it may be partly due to his metaphysical ideas seeming somewhat counter-intuitive (such as his assertion that matter is an abstraction), or his inclusion of theistic elements in his philosophy, or the perception of metaphysics itself as passé, or simply the sheer difficulty and density of his prose.
Historically Whitehead's work has been most influential in the field of American progressive theology. The most important early proponent of Whitehead's thought in a theological context was Charles Hartshorne, who spent a semester at Harvard as Whitehead's teaching assistant in 1925, and is widely credited with developing Whitehead's process philosophy into a full-blown process theology. Other notable process theologians include John B. Cobb, Jr., David Ray Griffin, Marjorie Hewitt Suchocki, C. Robert Mesle, Roland Faber, and Catherine Keller.
Process theology typically stresses God's relational nature. Rather than seeing God as impassive or emotionless, process theologians view God as "the fellow sufferer who understands", and as the being who is supremely affected by temporal events. Hartshorne points out that people would not praise a human ruler who was unaffected by either the joys or sorrows of his followers – so why would this be a praise-worthy quality in God? Instead, as the being who is most affected by the world, God is the being who can most appropriately respond to the world. However, process theology has been formulated in a wide variety of ways. C. Robert Mesle, for instance, advocates a "process naturalism", i.e. a process theology without God.
In fact, process theology is difficult to define because process theologians are so diverse and transdisciplinary in their views and interests. John B. Cobb, Jr. is a process theologian who has also written books on biology and economics. Roland Faber and Catherine Keller integrate Whitehead with poststructuralist, postcolonialist, and feminist theory. Charles Birch was both a theologian and a geneticist. Franklin I. Gamwell writes on theology and political theory. In Syntheism - Creating God in The Internet Age, futurologists Alexander Bard and Jan Söderqvist repeatedly credit Whitehead for the process theology they see rising out of the participatory culture expected to dominate the digital era.
One philosophical school which has historically had a close relationship with process philosophy is American pragmatism. Whitehead himself thought highly of William James and John Dewey, and acknowledged his indebtedness to them in the preface to Process and Reality. Charles Hartshorne (along with Paul Weiss) edited the collected papers of Charles Sanders Peirce, one of the founders of pragmatism. Noted neopragmatist Richard Rorty was in turn a student of Hartshorne. Today, Nicholas Rescher is one example of a philosopher who advocates both process philosophy and pragmatism.
In physics, Whitehead's thought has had some influence. He articulated a view that might perhaps be regarded as dual to Einstein's general relativity, see Whitehead's theory of gravitation. It has been severely criticized. Yutaka Tanaka, who suggests that the gravitational constant disagrees with experimental findings, proposes that Einstein's work does not actually refute Whitehead's formulation. Whitehead's view has now been rendered obsolete, with the discovery of gravitational waves. They are phenonena observed locally that largely violate the kind of local flatness of space that Whitehead assumes. Consequently, Whitehead's cosmology must be regarded as a local approximation, and his assumption of a uniform spatio-temporal geometry, Minkowskian in particular, as an often-locally-adequate approximation. An exact replacement of Whitehead's cosmology would need to admit a Riemannian geometry. Also, although Whitehead himself gave only secondary consideration to quantum theory, his metaphysics of processes has proved attractive to some physicists in that field. Henry Stapp and David Bohm are among those whose work has been influenced by Whitehead.
This work has been pioneered by John B. Cobb, Jr., whose book Is It Too Late? A Theology of Ecology (1971) was the first single-authored book in environmental ethics. Cobb also co-authored a book with economist Herman Daly entitled For the Common Good: Redirecting the Economy toward Community, the Environment, and a Sustainable Future (1989), which applied Whitehead's thought to economics, and received the Grawemeyer Award for Ideas Improving World Order. Cobb followed this with a second book, Sustaining the Common Good: A Christian Perspective on the Global Economy (1994), which aimed to challenge "economists' zealous faith in the great god of growth."
Another model is the FEELS model developed by Xie Bangxiu and deployed successfully in China. "FEELS" stands for five things in curriculum and education: Flexible-goals, Engaged-learner, Embodied-knowledge, Learning-through-interactions, and Supportive-teacher. It is used for understanding and evaluating educational curriculum under the assumption that the purpose of education is to "help a person become whole." This work is in part the product of cooperation between Chinese government organizations and the Institute for the Postmodern Development of China.
Whitehead has had some influence on philosophy of business administration and organizational theory. This has led in part to a focus on identifying and investigating the effect of temporal events (as opposed to static things) within organizations through an “organization studies” discourse that accommodates a variety of 'weak' and 'strong' process perspectives from a number of philosophers. One of the leading figures having an explicitly Whiteheadian and panexperientialist stance towards management is Mark Dibben, who works in what he calls "applied process thought" to articulate a philosophy of management and business administration as part of a wider examination of the social sciences through the lens of process metaphysics. For Dibben, this allows "a comprehensive exploration of life as perpetually active experiencing, as opposed to occasional – and thoroughly passive – happening." Dibben has published two books on applied process thought, Applied Process Thought I: Initial Explorations in Theory and Research (2008), and Applied Process Thought II: Following a Trail Ablaze (2009), as well as other papers in this vein in the fields of philosophy of management and business ethics.
Margaret Stout and Carrie M. Staton have also written recently on the mutual influence of Whitehead and Mary Parker Follett, a pioneer in the fields of organizational theory and organizational behavior. Stout and Staton see both Whitehead and Follett as sharing an ontology that "understands becoming as a relational process; difference as being related, yet unique; and the purpose of becoming as harmonizing difference." This connection is further analyzed by Stout and Jeannine M. Love in Integrative Process: Follettian Thinking from Ontology to Administration
Antibiotics revolutionized medicine in the 20th century, and have together with vaccination led to the near eradication of diseases such as tuberculosis in the developed world. Their effectiveness and easy access led to overuse, especially in livestock raising, prompting bacteria to develop resistance. This has led to widespread problems with antimicrobial and antibiotic resistance, so much as to prompt the World Health Organization to classify antimicrobial resistance as a "serious threat [that] is no longer a prediction for the future, it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country".
In empirical therapy, a patient has proven or suspected infection, but the responsible microorganism is not yet unidentified. While the microorgainsim is being identified the doctor will usually administer the best choice of antibiotic that will be most active against the likely cause of infection usually a broad spectrum antibiotic. Empirical therapy is usually initiated before the doctor knows the exact identification of microorgansim causing the infection as the identification process make take several days in the laboratory.
Antibiotics are screened for any negative effects on humans or other mammals before approval for clinical use, and are usually considered safe and most are well tolerated. However, some antibiotics have been associated with a range of adverse side effects. Side-effects range from mild to very serious depending on the antibiotics used, the microbial organisms targeted, and the individual patient. Side effects may reflect the pharmacological or toxicological properties of the antibiotic or may involve hypersensitivity reactions or anaphylaxis. Safety profiles of newer drugs are often not as well established as for those that have a long history of use. Adverse effects range from fever and nausea to major allergic reactions, including photodermatitis and anaphylaxis. Common side-effects include diarrhea, resulting from disruption of the species composition in the intestinal flora, resulting, for example, in overgrowth of pathogenic bacteria, such as Clostridium difficile. Antibacterials can also affect the vaginal flora, and may lead to overgrowth of yeast species of the genus Candida in the vulvo-vaginal area. Additional side-effects can result from interaction with other drugs, such as elevated risk of tendon damage from administration of a quinolone antibiotic with a systemic corticosteroid. Some scientists have hypothesized that the indiscriminate use of antibiotics alter the host microbiota and this has been associated with chronic disease.
Exposure to antibiotics early in life is associated with increased body mass in humans and mouse models. Early life is a critical period for the establishment of the intestinal microbiota and for metabolic development. Mice exposed to subtherapeutic antibiotic treatment (STAT)– with either penicillin, vancomycin, penicillin and vancomycin, or chlortetracycline had altered composition of the gut microbiota as well as its metabolic capabilities. Moreover, research have shown that mice given low-dose penicillin (1 μg/g body weight) around birth and throughout the weaning process had an increased body mass and fat mass, accelerated growth, and increased hepatic expression of genes involved in adipogenesis, compared to controlled mice. In addition, penicillin in combination with a high-fat diet increased fasting insulin levels in mice. However, it is unclear whether or not antibiotics cause obesity in humans. Studies have found a correlation between early exposure of antibiotics (<6 months) and increased body mass (at 10 and 20 months). Another study found that the type of antibiotic exposure was also significant with the highest risk of being overweight in those given macrolides compared to penicillin and cephalosporin. Therefore, there is correlation between antibiotic exposure in early life and obesity in humans, but whether or not there is a causal relationship remains unclear. Although there is a correlation between antibiotic use in early life and obesity, the effect of antibiotics on obesity in humans needs to be weighed against the beneficial effects of clinically indicated treatment with antibiotics in infancy.
The majority of studies indicate antibiotics do interfere with contraceptive pills, such as clinical studies that suggest the failure rate of contraceptive pills caused by antibiotics is very low (about 1%). In cases where antibacterials have been suggested to affect the efficiency of birth control pills, such as for the broad-spectrum antibacterial rifampicin, these cases may be due to an increase in the activities of hepatic liver enzymes' causing increased breakdown of the pill's active ingredients. Effects on the intestinal flora, which might result in reduced absorption of estrogens in the colon, have also been suggested, but such suggestions have been inconclusive and controversial. Clinicians have recommended that extra contraceptive measures be applied during therapies using antibacterials that are suspected to interact with oral contraceptives.
Interactions between alcohol and certain antibiotics may occur and may cause side-effects and decreased effectiveness of antibiotic therapy. While moderate alcohol consumption is unlikely to interfere with many common antibiotics, there are specific types of antibiotics with which alcohol consumption may cause serious side-effects. Therefore, potential risks of side-effects and effectiveness depend on the type of antibiotic administered. Despite the lack of a categorical counterindication, the belief that alcohol and antibiotics should never be mixed is widespread.
The successful outcome of antimicrobial therapy with antibacterial compounds depends on several factors. These include host defense mechanisms, the location of infection, and the pharmacokinetic and pharmacodynamic properties of the antibacterial. A bactericidal activity of antibacterials may depend on the bacterial growth phase, and it often requires ongoing metabolic activity and division of bacterial cells. These findings are based on laboratory studies, and in clinical settings have also been shown to eliminate bacterial infection. Since the activity of antibacterials depends frequently on its concentration, in vitro characterization of antibacterial activity commonly includes the determination of the minimum inhibitory concentration and minimum bactericidal concentration of an antibacterial. To predict clinical outcome, the antimicrobial activity of an antibacterial is usually combined with its pharmacokinetic profile, and several pharmacological parameters are used as markers of drug efficacy.
Antibacterial antibiotics are commonly classified based on their mechanism of action, chemical structure, or spectrum of activity. Most target bacterial functions or growth processes. Those that target the bacterial cell wall (penicillins and cephalosporins) or the cell membrane (polymyxins), or interfere with essential bacterial enzymes (rifamycins, lipiarmycins, quinolones, and sulfonamides) have bactericidal activities. Those that target protein synthesis (macrolides, lincosamides and tetracyclines) are usually bacteriostatic (with the exception of bactericidal aminoglycosides). Further categorization is based on their target specificity. "Narrow-spectrum" antibacterial antibiotics target specific types of bacteria, such as Gram-negative or Gram-positive bacteria, whereas broad-spectrum antibiotics affect a wide range of bacteria. Following a 40-year hiatus in discovering new classes of antibacterial compounds, four new classes of antibacterial antibiotics have been brought into clinical use in the late 2000s and early 2010s: cyclic lipopeptides (such as daptomycin), glycylcyclines (such as tigecycline), oxazolidinones (such as linezolid), and lipiarmycins (such as fidaxomicin).
With advances in medicinal chemistry, most modern antibacterials are semisynthetic modifications of various natural compounds. These include, for example, the beta-lactam antibiotics, which include the penicillins (produced by fungi in the genus Penicillium), the cephalosporins, and the carbapenems. Compounds that are still isolated from living organisms are the aminoglycosides, whereas other antibacterials—for example, the sulfonamides, the quinolones, and the oxazolidinones—are produced solely by chemical synthesis. Many antibacterial compounds are relatively small molecules with a molecular weight of less than 2000 atomic mass units.[citation needed]
The emergence of resistance of bacteria to antibiotics is a common phenomenon. Emergence of resistance often reflects evolutionary processes that take place during antibiotic therapy. The antibiotic treatment may select for bacterial strains with physiologically or genetically enhanced capacity to survive high doses of antibiotics. Under certain conditions, it may result in preferential growth of resistant bacteria, while growth of susceptible bacteria is inhibited by the drug. For example, antibacterial selection for strains having previously acquired antibacterial-resistance genes was demonstrated in 1943 by the Luria–Delbrück experiment. Antibiotics such as penicillin and erythromycin, which used to have a high efficacy against many bacterial species and strains, have become less effective, due to the increased resistance of many bacterial strains.
Several molecular mechanisms of antibacterial resistance exist. Intrinsic antibacterial resistance may be part of the genetic makeup of bacterial strains. For example, an antibiotic target may be absent from the bacterial genome. Acquired resistance results from a mutation in the bacterial chromosome or the acquisition of extra-chromosomal DNA. Antibacterial-producing bacteria have evolved resistance mechanisms that have been shown to be similar to, and may have been transferred to, antibacterial-resistant strains. The spread of antibacterial resistance often occurs through vertical transmission of mutations during growth and by genetic recombination of DNA by horizontal genetic exchange. For instance, antibacterial resistance genes can be exchanged between different bacterial strains or species via plasmids that carry these resistance genes. Plasmids that carry several different resistance genes can confer resistance to multiple antibacterials. Cross-resistance to several antibacterials may also occur when a resistance mechanism encoded by a single gene conveys resistance to more than one antibacterial compound.
Antibacterial-resistant strains and species, sometimes referred to as "superbugs", now contribute to the emergence of diseases that were for a while well controlled. For example, emergent bacterial strains causing tuberculosis (TB) that are resistant to previously effective antibacterial treatments pose many therapeutic challenges. Every year, nearly half a million new cases of multidrug-resistant tuberculosis (MDR-TB) are estimated to occur worldwide. For example, NDM-1 is a newly identified enzyme conveying bacterial resistance to a broad range of beta-lactam antibacterials. The United Kingdom's Health Protection Agency has stated that "most isolates with NDM-1 enzyme are resistant to all standard intravenous antibiotics for treatment of severe infections."
Inappropriate antibiotic treatment and overuse of antibiotics have contributed to the emergence of antibiotic-resistant bacteria. Self prescription of antibiotics is an example of misuse. Many antibiotics are frequently prescribed to treat symptoms or diseases that do not respond to antibiotics or that are likely to resolve without treatment. Also, incorrect or suboptimal antibiotics are prescribed for certain bacterial infections. The overuse of antibiotics, like penicillin and erythromycin, has been associated with emerging antibiotic resistance since the 1950s. Widespread usage of antibiotics in hospitals has also been associated with increases in bacterial strains and species that no longer respond to treatment with the most common antibiotics.
Common forms of antibiotic misuse include excessive use of prophylactic antibiotics in travelers and failure of medical professionals to prescribe the correct dosage of antibiotics on the basis of the patient's weight and history of prior use. Other forms of misuse include failure to take the entire prescribed course of the antibiotic, incorrect dosage and administration, or failure to rest for sufficient recovery. Inappropriate antibiotic treatment, for example, is their prescription to treat viral infections such as the common cold. One study on respiratory tract infections found "physicians were more likely to prescribe antibiotics to patients who appeared to expect them". Multifactorial interventions aimed at both physicians and patients can reduce inappropriate prescription of antibiotics.
Several organizations concerned with antimicrobial resistance are lobbying to eliminate the unnecessary use of antibiotics. The issues of misuse and overuse of antibiotics have been addressed by the formation of the US Interagency Task Force on Antimicrobial Resistance. This task force aims to actively address antimicrobial resistance, and is coordinated by the US Centers for Disease Control and Prevention, the Food and Drug Administration (FDA), and the National Institutes of Health (NIH), as well as other US agencies. An NGO campaign group is Keep Antibiotics Working. In France, an "Antibiotics are not automatic" government campaign started in 2002 and led to a marked reduction of unnecessary antibiotic prescriptions, especially in children.
The emergence of antibiotic resistance has prompted restrictions on their use in the UK in 1970 (Swann report 1969), and the EU has banned the use of antibiotics as growth-promotional agents since 2003. Moreover, several organizations (e.g., The American Society for Microbiology (ASM), American Public Health Association (APHA) and the American Medical Association (AMA)) have called for restrictions on antibiotic use in food animal production and an end to all nontherapeutic uses.[citation needed] However, commonly there are delays in regulatory and legislative actions to limit the use of antibiotics, attributable partly to resistance against such regulation by industries using or selling antibiotics, and to the time required for research to test causal links between their use and resistance to them. Two federal bills (S.742 and H.R. 2562) aimed at phasing out nontherapeutic use of antibiotics in US food animals were proposed, but have not passed. These bills were endorsed by public health and medical organizations, including the American Holistic Nurses' Association, the American Medical Association, and the American Public Health Association (APHA).
There has been extensive use of antibiotics in animal husbandry. In the United States, the question of emergence of antibiotic-resistant bacterial strains due to use of antibiotics in livestock was raised by the US Food and Drug Administration (FDA) in 1977. In March 2012, the United States District Court for the Southern District of New York, ruling in an action brought by the Natural Resources Defense Council and others, ordered the FDA to revoke approvals for the use of antibiotics in livestock, which violated FDA regulations.
Before the early 20th century, treatments for infections were based primarily on medicinal folklore. Mixtures with antimicrobial properties that were used in treatments of infections were described over 2000 years ago. Many ancient cultures, including the ancient Egyptians and ancient Greeks, used specially selected mold and plant materials and extracts to treat infections. More recent observations made in the laboratory of antibiosis between microorganisms led to the discovery of natural antibacterials produced by microorganisms. Louis Pasteur observed, "if we could intervene in the antagonism observed between some bacteria, it would offer perhaps the greatest hopes for therapeutics". The term 'antibiosis', meaning "against life", was introduced by the French bacteriologist Jean Paul Vuillemin as a descriptive name of the phenomenon exhibited by these early antibacterial drugs. Antibiosis was first described in 1877 in bacteria when Louis Pasteur and Robert Koch observed that an airborne bacillus could inhibit the growth of Bacillus anthracis. These drugs were later renamed antibiotics by Selman Waksman, an American microbiologist, in 1942. Synthetic antibiotic chemotherapy as a science and development of antibacterials began in Germany with Paul Ehrlich in the late 1880s. Ehrlich noted certain dyes would color human, animal, or bacterial cells, whereas others did not. He then proposed the idea that it might be possible to create chemicals that would act as a selective drug that would bind to and kill bacteria without harming the human host. After screening hundreds of dyes against various organisms, in 1907, he discovered a medicinally useful drug, the synthetic antibacterial salvarsan now called arsphenamine.
The effects of some types of mold on infection had been noticed many times over the course of history (see: History of penicillin). In 1928, Alexander Fleming noticed the same effect in a Petri dish, where a number of disease-causing bacteria were killed by a fungus of the genus Penicillium. Fleming postulated that the effect is mediated by an antibacterial compound he named penicillin, and that its antibacterial properties could be exploited for chemotherapy. He initially characterized some of its biological properties, and attempted to use a crude preparation to treat some infections, but he was unable to pursue its further development without the aid of trained chemists.
The first sulfonamide and first commercially available antibacterial, Prontosil, was developed by a research team led by Gerhard Domagk in 1932 at the Bayer Laboratories of the IG Farben conglomerate in Germany. Domagk received the 1939 Nobel Prize for Medicine for his efforts. Prontosil had a relatively broad effect against Gram-positive cocci, but not against enterobacteria. Research was stimulated apace by its success. The discovery and development of this sulfonamide drug opened the era of antibacterials.
In 1939, coinciding with the start of World War II, Rene Dubos reported the discovery of the first naturally derived antibiotic, tyrothricin, a compound of 20% gramicidin and 80% tyrocidine, from B. brevis. It was one of the first commercially manufactured antibiotics universally and was very effective in treating wounds and ulcers during World War II. Gramicidin, however, could not be used systemically because of toxicity. Tyrocidine also proved too toxic for systemic usage. Research results obtained during that period were not shared between the Axis and the Allied powers during the war.
Florey and Chain succeeded in purifying the first penicillin, penicillin G, in 1942, but it did not become widely available outside the Allied military before 1945. Later, Norman Heatley developed the back extraction technique for efficiently purifying penicillin in bulk. The chemical structure of penicillin was determined by Dorothy Crowfoot Hodgkin in 1945. Purified penicillin displayed potent antibacterial activity against a wide range of bacteria and had low toxicity in humans. Furthermore, its activity was not inhibited by biological constituents such as pus, unlike the synthetic sulfonamides. The discovery of such a powerful antibiotic was unprecedented, and the development of penicillin led to renewed interest in the search for antibiotic compounds with similar efficacy and safety. For their successful development of penicillin, which Fleming had accidentally discovered but could not develop himself, as a therapeutic drug, Ernst Chain and Howard Florey shared the 1945 Nobel Prize in Medicine with Fleming. Florey credited Dubos with pioneering the approach of deliberately and systematically searching for antibacterial compounds, which had led to the discovery of gramicidin and had revived Florey's research in penicillin.

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