Many thanks to "http://swift.eng.ox.ac.uk/jdr/locke.html", the source of this page.
In 1675, Locke left England to live in France, where he became familiar with the
doctrines of Rene Descartes and his critics. He returned to England in 1679 while
Shaftesbury was in power and pressing to secure the exclusion of James, duke of York (the
future King James II) from the succession to the throne. Shaftesbury was later tried for
treason, and although he was acquitted, he fled to Holland. Because he was closely allied
with Shaftesbury, Locke also fled to Holland in 1683; he lived there until the overthrow
(1688) of James II.
In 1689, Locke returned to England in the party escorting the princess of Orange, who
was to be crowned Queen Mary II of England. In 1691, Locke retired to Oates in Essex, the
household of Sir Francis and Lady Masham. During his years at Oates, Locke wrote and
edited, and received many influential visitors, including Sir Isaac Newton. He continued
to exercise political influence. His friendships with prominent government officers and
scholars made him one of the most influential men of the 17th century.
Locke’s Essay Concerning Human Understanding (1690) is one of the classical
documents of British empirical philosophy. The essay had its origin in a series of
discussions with friends that led Locke to the conclusion that the principal subject of
philosophy had to be the extent of the mind’s ability to know. He set out "to
examine our abilities and to see what objects our understandings were or were not fitted
to deal with." The Essay is a principal statement of empiricism, and, broadly
speaking, was an effort to formulate a view of knowledge consistent with the findings of
Newtonian science.
Locke began the Essay with a critique of the rationalistic idea that the mind is
equipped with innate ideas, ideas that do not arise from experience. He then turned to the
elaboration of his own empiricism: "Let us suppose the mind to be, as we say, white
paper, void of all characters, without any ideas; how comes this to be furnished? . . .
whence has it all the materials of reason and knowledge? To this I answer, in a word, from
experience." What experience provides is ideas, which Locke defined as "the
object of the understanding when a man thinks."
He held that ideas come from two sources: sensation, which provides ideas about the
external world, and reflection, or introspection, which provides the ideas of the internal
workings of the mind. Locke’s view that experience produces ideas, which are the
immediate objects of thought, led him to adopt a causal or representative view of human
knowledge. In perception, according to this view, people are not directly aware of
physical objects. Rather, they are directly aware of the ideas that objects
"cause" in them and that "represent" the objects in their
consciousness. A similar view of perception was presented by earlier thinkers such as
Galileo and Descartes. Locke’s view raised the question of the extent to which ideas
are like the objects that cause them. His answer was that only some qualities of objects
are like ideas.
He held that primary qualities of objects, or the mathematically determinable qualities
of an object, such as shape, motion, weight, and number, exist in the world, and that
ideas copy them. Secondary qualities, those which arise from the senses, do not exist in
objects as they exist in ideas. According to Locke, secondary qualities, such as taste,
"are nothing in the objects themselves but powers to produce ideas in use by their
primary qualities." Thus, when an object is perceived, a person’s ideas of its
shape and weight represent qualities to be found in the object itself. Color and taste,
however, are not copies of anything in the object.
One conclusion of Locke’s theory is that genuine knowledge cannot be found in
natural science, because the real essences of physical objects that science studies cannot
be known. It would appear that genuine certainty can be achieved only through mathematics.
Locke’s view of knowledge anticipated developments by later philosophers and
exercised an important influence on the subsequent course of philosophical thought.
Locke’s considerable importance in political thought is better known. As the first
systematic theorist of the philosophy of liberalism, Locke exercised enormous influence in
both England and America. In his Two Treatises of Government (1690), Locke set forth the
view that the state exists to preserve the natural rights of its citizens. When
governments fail in that task, citizens have the right and sometimes the duty to withdraw
their support and even to rebel. Locke opposed Thomas Hobbes’s view that the original
state of nature was "nasty, brutish, and short," and that individuals through a
social contract surrendered for the sake of self-preservation their rights to a supreme
sovereign who was the source of all morality and law. Locke maintained that the state of
nature was a happy and tolerant one, that the social contract preserved the preexistent
natural rights of the individual to life, liberty, and property, and that the enjoyment of
private rights the pursuit of happiness led, in civil society, to the common good.
Locke’s notion of government was a limited one: the checks and balances among branches of government (later reflected in the US Constitution) and true representation in the legislature would maintain limited government and individual liberties. A Letter Concerning Toleration (1689) expressed Locke’s view that, within certain limits, no one should dictate the form of another’s religion. Other important works include The Reasonableness of Christianity (1695), in which Locke expressed his ideas on religion, and Some Thoughts Concerning Education (1693).