Locke's father, who was also named John Locke, was a country lawyer and clerk to the Justices of the Peace in Chew Magna, who had served as a captain of cavalry for the Parliamentarian forces during the early part of the English Civil War. His mother, Agnes Keene, was a tanner's daughter and reputed to be very beautiful. Both parents were Puritans.Locke was born on 29 August 1632, in a small thatched cottage by the church in Wrington, Somerset, about twelve miles from Bristol. He was baptized the same day. Soon after Locke's birth, the family moved to the market town of Pensford, about seven miles south of Bristol, where Locke grew up in a rural Tudor house in Belluton.

In 1647, Locke was sent to the prestigious Westminster School in London under the sponsorship of Alexander Popham, a member of Parliament and former commander of the younger Locke's father. After completing his studies there, he was admitted to Christ Church, Oxford. The dean of the college at the time was John Owen, vice-chancellor of the university. Although a capable student, Locke was irritated by the undergraduate curriculum of the time. He found the works of modern philosophers, such as René Descartes, more interesting than the classical material taught at the university. Through his friend Richard Lower, whom he knew from the Westminster School, Locke was introduced to medicine and the experimental philosophy being pursued at other universities and in the English Royal Society, of which he eventually became a member.

Locke was awarded a bachelor's degree in 1656 and a master's degree in 1658. He obtained a bachelor of medicine in 1674, having studied medicine extensively during his time at Oxford and worked with such noted scientists and thinkers as Robert Boyle, Thomas Willis, Robert Hooke and Richard Lower. In 1666, he met Lord Anthony Ashley Cooper, 1st Earl of Shaftesbury, who had come to Oxford seeking treatment for a liver infection. Cooper was impressed with Locke and persuaded him to become part of his retinue.

Locke had been looking for a career and in 1667 moved into Shaftesbury's home at Exeter House in London, to serve as Lord Ashley's personal physician. In London, Locke resumed his medical studies under the tutelage of Thomas Sydenham. Sydenham had a major effect on Locke's natural philosophical thinking an effect that would become evident in the An Essay Concerning Human Understanding.

Locke's medical knowledge was put to the test when Shaftesbury's liver infection became life-threatening. Locke coordinated the advice of several physicians and was probably instrumental in persuading Shaftesbury to undergo an operation (then life-threatening itself) to remove the cyst. Shaftesbury survived and prospered, crediting Locke with saving his life.

It was in Shaftesbury's household, during 1671, that the meeting took place, described in the Epistle to the reader of the Essay, which was the genesis of what would later become the Essay. Two extant Drafts still survive from this period. It was also during this time that Locke served as Secretary of the Board of Trade and Plantations and Secretary to the Lords and Proprietors of the Carolinas, helping to shape his ideas on international trade and economics.Shaftesbury, as a founder of the Whig movement, exerted great influence on Locke's political ideas. Locke became involved in politics when Shaftesbury became Lord Chancellor in 1672. Following Shaftesbury's fall from favour in 1675, Locke spent some time travelling across France. He returned to England in 1679 when Shaftesbury's political fortunes took a brief positive turn. Around this time, most likely at Shaftesbury's prompting, Locke composed the bulk of the Two Treatises of Government. While it was once thought that Locke wrote the Treatises to defend the Glorious Revolution of 1688, recent scholarship has shown that the work was composed well before this date, however, and it is now viewed as a more general argument against Absolute monarchy (particularly as espoused by Robert Filmer and Thomas Hobbes) and for individual consent as the basis of political legitimacy. Though Locke was associated with the influential Whigs, his ideas about natural rights and government are today considered quite revolutionary for that period in English history.

However, Locke fled to the Netherlands in 1683, under strong suspicion of involvement in the Rye House Plot, although there is little evidence to suggest that he was directly involved in the scheme. In the Netherlands, Locke had time to return to his writing, spending a great deal of time re-working the Essay and composing the Letter on Toleration. Locke did not return home until after the Glorious Revolution. Locke accompanied William of Orange's wife back to England in 1688. The bulk of Locke's publishing took place upon his return from exile his aforementioned Essay Concerning Human Understanding, the Two Treatises of Civil Government and A Letter Concerning Toleration all appearing in quick succession.

Locke's close friend Lady Masham invited him to join her at the Mashams' country house in Essex. Although his time there was marked by variable health from asthma attacks, he nevertheless became an intellectual hero of the Whigs. During this period he discussed matters with such figures as John Dryden and Isaac Newton.

He died in 28 October 1704, and is buried in the churchyard of the village of High Laver, east of Harlow in Essex, where he had lived in the household of Sir Francis Masham since 1691. Locke never married nor had children.

Events that happened during Locke's lifetime include the English Restoration, the Great Plague of London and the Great Fire of London. He did not quite see the Act of Union of 1707, though the thrones of England and Scotland were held in personal union throughout his lifetime. Constitutional monarchy and parliamentary democracy were in their infancy during Locke's time.

Locke exercised a profound influence on political philosophy, in particular on modern liberalism. Michael Zuckert has argued that Locke launched liberalism by tempering Hobbesian absolutism and clearly separating the realms of Church and State. He had a strong influence on Voltaire who called him "le sage Locke". His arguments concerning liberty and the social contract later influenced the written works of Alexander Hamilton, James Madison, Thomas Jefferson, and other Founding Fathers of the United States. In fact, one passage from the Second Treatise is reproduced verbatim in the Declaration of Independence, the reference to a "long train of abuses." Such was Locke's influence that Thomas Jefferson wrote: "Bacon, Locke and Newton ... I consider them as the three greatest men that have ever lived, without any exception, and as having laid the foundation of those superstructures which have been raised in the Physical and Moral sciences". Today, most contemporary libertarians claim Locke as an influence.

But Locke's influence may have been even more profound in the realm of epistemology. Locke redefined subjectivity, or self, and intellectual historians such as Charles Taylor and Jerrold Seigel argue that Locke's Essay Concerning Human Understanding (1690) marks the beginning of the modern Western conception of the self.

Theories of religious tolerance

Locke, writing his Letters Concerning Toleration (1689—92) in the aftermath of the European wars of religion, formulated a classic reasoning for religious tolerance. Three arguments are central: (1) Earthly judges, the state in particular, and human beings generally, cannot dependably evaluate the truth-claims of competing religious standpoints; (2) Even if they could, enforcing a single "true religion" would not have the desired effect, because belief cannot be compelled by violence; (3) Coercing religious uniformity would lead to more social disorder than allowing diversity.

Constitution of Carolina

Appraisals of Locke have often been tied to appraisals of liberalism in general, and also to appraisals of the United States. Detractors note that (in 1671) he was a major investor in the English slave-trade through the Royal African Company, as well as through his participation in drafting the Fundamental Constitution of the Carolinas while Shaftesbury's secretary, which established a feudal aristocracy and gave a master absolute power over his slaves. For example, Martin Cohen notes that as a secretary to the Council of Trade and Plantations (1673—4) and a member of the Board of Trade (1696—1700) Locke was, in fact, "one of just half a dozen men who created and supervised both the colonies and their iniquitous systems of servitude". Some see his statements on unenclosed property as having been intended to justify the displacement of the Native Americans. Because of his opposition to aristocracy and slavery in his major writings, he is accused of hypocrisy and racism, or of caring only for the liberty of English capitalists.

Theory of value and property

Locke uses the word property in both broad and narrow senses. In a broad sense, it covers a wide range of human interests and aspirations; more narrowly, it refers to material goods. He argues that property is a natural right and it is derived from labour.

Locke believed that ownership of property is created by the application of labour. In addition, property precedes government and government cannot "dispose of the estates of the subjects arbitrarily." Karl Marx later critiqued Locke's theory of property in his social theory.

Political theory

Locke's political theory was founded on social contract theory. Unlike Thomas Hobbes, Locke believed that human nature is characterized by reason and tolerance. Like Hobbes, Locke believed that human nature allowed men to be selfish. This is apparent with the introduction of currency. In a natural state all people were equal and independent, and everyone had a natural right to defend his “Life, health, Liberty, or Possessions", basis for the phrase in the American Declaration of Independence; "Life, liberty, and the pursuit of happiness".

Like Hobbes, Locke assumed that the sole right to defend in the state of nature was not enough, so people established a civil society to resolve conflicts in a civil way with help from government in a state of society. However, Locke never refers to Hobbes by name and may instead have been responding to other writers of the day. Locke also advocated governmental separation of powers and believed that revolution is not only a right but an obligation in some circumstances. These ideas would come to have profound influence on the Constitution of the United States and its Declaration of Independence.

Limits to accumulation

Labour creates property, but it also does contain limits to its accumulation: man’s capacity to produce and man’s capacity to consume. According to Locke, unused property is waste and an offense against nature. However, with the introduction of “durable” goods, men could exchange their excessive perishable goods for goods that would last longer and thus not offend the natural law. The introduction of money marks the culmination of this process. Money makes possible the unlimited accumulation of property without causing waste through spoilage. He also includes gold or silver as money because they may be “hoarded up without injury to anyone,” since they do not spoil or decay in the hands of the possessor. The introduction of money eliminates the limits of accumulation. Locke stresses that inequality has come about by tacit agreement on the use of money, not by the social contract establishing civil society or the law of land regulating property. Locke is aware of a problem posed by unlimited accumulation but does not consider it his task. He just implies that government would function to moderate the conflict between the unlimited accumulation of property and a more nearly equal distribution of wealth and does not say which principles that government should apply to solve this problem. However, not all elements of his thought form a consistent whole. For example, labour theory of value of the Two Treatises of Government stands side by side with the demand-and-supply theory developed in a letter he wrote titled Some Considerations on the Consequences of the Lowering of Interest and the Raising of the Value of Money. Moreover, Locke anchors property in labour but in the end upholds the unlimited accumulation of wealth.

On price theory

Locke’s general theory of value and price is a supply and demand theory, which was set out in a letter to a Member of Parliament in 1691, titled Some Considerations on the Consequences of the Lowering of Interest and the Raising of the Value of Money. Supply is quantity and demand is rent. “The price of any commodity rises or falls by the proportion of the number of buyer and sellers.” and “that which regulates the price... [of goods] is nothing else but their quantity in proportion to their rent.” The quantity theory of money forms a special case of this general theory. His idea is based on “money answers all things” (Ecclesiastes) or “rent of money is always sufficient, or more than enough,” and “varies very little” Regardless of whether the demand for money is unlimited or constant, Locke concludes that as far as money is concerned, the demand is exclusively regulated by its quantity. He also investigates the determinants of demand and supply. For supply, goods in general are considered valuable because they can be exchanged, consumed and they must be scarce. For demand, goods are in demand because they yield a flow of income. Locke develops an early theory of capitalization, such as land, which has value because “by its constant production of saleable commodities it brings in a certain yearly income.” Demand for money is almost the same as demand for goods or land; it depends on whether money is wanted as medium of exchange or as loanable funds. For medium of exchange “money is capable by exchange to procure us the necessaries or conveniences of life.” For loanable funds, “it comes to be of the same nature with land by yielding a certain yearly income or interest.”

Monetary thoughts

Locke distinguishes two functions of money, as a "counter" to measure value, and as a "pledge" to lay claim to goods. He believes that silver and gold, as opposed to paper money, are the appropriate currency for international transactions. Silver and gold, he says, are treated to have equal value by all of humanity and can thus be treated as a pledge by anyone, while the value of paper money is only valid under the government which issues it.

Locke argues that a country should seek a favourable balance of trade, lest it fall behind other countries and suffer a loss in its trade. Since the world money stock grows constantly, a country must constantly seek to enlarge its own stock. Locke develops his theory of foreign exchanges, in addition to commodity movements, there are also movements in country stock of money, and movements of capital determine exchange rates. The latter is less significant and less volatile than commodity movements. As for a country’s money stock, if it is large relative to that of other countries, it will cause the country’s exchange to rise above par, as an export balance would do.

He also prepares estimates of the cash requirements for different economic groups (landholders, labourers and brokers). In each group the cash requirements are closely related to the length of the pay period. He argues the brokers — middlemen — whose activities enlarge the monetary circuit and whose profits eat into the earnings of labourers and landholders, had a negative influence on both one's personal and the public economy that they supposedly contributed to.

The self

Locke defines the self as "that conscious thinking thing, (whatever substance, made up of whether spiritual, or material, simple, or compounded, it matters not) which is sensible, or conscious of pleasure and pain, capable of happiness or misery, and so is concerned for itself, as far as that consciousness extends". He does not, however, ignore "substance", writing that "the body too goes to the making the man." The Lockean self is therefore a self-aware and self-reflective consciousness that is fixed in a body.

In his Essay, Locke explains the gradual unfolding of this conscious mind. Arguing against both the Augustinian view of man as originally sinful and the Cartesian position, which holds that man innately knows basic logical propositions, Locke posits an "empty" mind, a tabula rasa, which is shaped by experience; sensations and reflection being the two sources of all our ideas.

John Locke's formulation of tabula rasa in An Essay Concerning Human Understanding was influenced by a 17th century Latin translation Philosophus Autodidactus (published by Edward Pococke) of the Arabic philosophical novel Hayy ibn Yaqzan by the 12th century Andalusian-Islamic philosopher and novelist Ibn Tufail (known as "Abubacer" or "Ebn Tophail" in the West). Ibn Tufail demonstrated the theory of tabula rasa as a thought experiment through his Arabic philosophical novel novel Hayy ibn Yaqzan in which he depicted the development of the mind of a feral child "from a tabula rasa to that of an adult, in complete isolation from society" on a desert island, through experience alone.

Locke's Some Thoughts Concerning Education is an outline on how to educate this mind: he expresses the belief that education maketh the man, or, more fundamentally, that the mind is an "empty cabinet", with the statement, "I think I may say that of all the men we meet with, nine parts of ten are what they are, good or evil, useful or not, by their education."

Locke also wrote that "the little and almost insensible impressions on our tender infancies have very important and lasting consequences." He argued that the "associations of ideas" that one makes when young are more important than those made later because they are the foundation of the self: they are, put differently, what first mark the tabula rasa. In his Essay, in which is introduced both of these concepts, Locke warns against, for example, letting "a foolish maid" convince a child that "goblins and sprites" are associated with the night for "darkness shall ever afterwards bring with it those frightful ideas, and they shall be so joined, that he can no more bear the one than the other."

"Associationism", as this theory would come to be called, exerted a powerful influence over eighteenth-century thought, particularly educational theory, as nearly every educational writer warned parents not to allow their children to develop negative associations. It also led to the development of psychology and other new disciplines with David Hartley's attempt to discover a biological mechanism for associationism in his Observations on Man (1749).

• (1689) A Letter Concerning Toleration
• (1690) A Second Letter Concerning Toleration
• (1692) A Third Letter for Toleration
• (1689) Two Treatises of Government
• (1690) An Essay Concerning Human Understanding
• (1693) Some Thoughts Concerning Education
• (1695) The Reasonableness of Christianity, as Delivered in the Scriptures
• (1695) A Vindication of the Reasonableness of Christianity

Major unpublished or posthumous manuscripts

• (1660) First Tract of Government (or the English Tract)
• (c.1662) Second Tract of Government (or the Latin Tract)
• (1664) Questions Concerning the Law of Nature (definitive Latin text, with facing accurate English trans. in Robert Horwitz et al., eds., John Locke, Questions Concerning the Law of Nature, Ithaca: Cornell University Press, 1990).
• (1667) Essay Concerning Toleration
• (1706) Of the Conduct of the Understanding
• (1707) A Paraphrase and Notes on the Epistles of St. Paul