John Locke

In the late 1660s, Locke medically attended Lord Ashley, First Earl of Shaftesbury, and later lord chancellor of England. Their friendship and lifelong association drew Locke into political affairs. He attended Shaftesbury as physician and adviser, and in this latter capacity Locke drafted The Fundamental Constitutions of Carolina and served as secretary to the Board of Trade. In 1676 Locke went to France for his health. An inheritance from his father made him financially independent, and he remained in Montpellier for three years.

Locke rejoined Shaftesbury's service, and joined the earl when he fled to Holland. He remained in exile from 1683 to 1689, and during these years he was deprived of his studentship by express order of Charles III. Most of his important writings were composed during this period. After the Glorious Revolution of 1689 Locke returned to England and later served with distinction as a commissioner of trade until 1700. He spent his retirement at Oates in Essex as the guest of the Mashams. Lady Masham was the daughter of Ralph Cudworth, the philosopher. Locke died there on October 28, 1704.

Locke, by virtue of his temperament and mode of existence, was a man of great circumspection. None of his major writings was published until he was nearly 60. In 1690 he brought out his major works: Two Treatises and the Essay Concerning Human Understanding. But the four books of the Essay were the culmination of 20 years of intellectual labor. He relates that, together with a few friends, probably in 1670, a discussion arose concerning the basis of morality and religion. The aim of this work is “to inquire into the origin, certainty, and extent of human knowledge, together with the grounds of belief, opinion, and agreement.”

The procedure employed is what he called the “historical, plain method,” which consists of observations derived from external sensations and the internal processes of reflection or introspection. Locke combined external observation with internal reflection, and said that people are not born with ideas or beliefs, but develop them through experiences and ideas. This new psychological definition of experience as sensation and reflection shifted the focus of philosophy from being based on analyzing reality to exploring the mind. The new perspective was Locke's major contribution, and it dominated European thought for at least two centuries. Locke also left an unclear definition of idea, which led to much discussion. Nonetheless the intention of the Essay was positive in that Locke wished to establish the dependence of all human knowledge upon everyday experience or sensation.

Locke devotes the first two books of the Essay to developing a deceptively simple theory of knowledge. Knowing originates in external and internal sources of sensation and reflection. The conclusion drawn in the Essay is that knowledge is relational; that is, it consists in the perception “of the agreement or disagreement among ideas.” The third book of the Essay deals with words, and it is a pioneer contribution to the philosophy of language.

The final section of the Essay deals with the extent, types, and divisions of knowledge. This work seems to have been written earlier than the others, and many of its conclusions are qualified by preceding material. With the exception of the self and God, all knowledge of existing things is dependent upon sensation. According to Locke's commonsense attitude, the severe restrictions placed upon knowledge merely reflect that man's mental capacity is suitable for his nature and condition.

In short, Locke can be credited with contributing not only to modern cognitive psychology, but even to all modern science. His emphasis on the study of the mind's cognitive functions of sensing and perceiving stretched beyond philosophy and theory to influence future research and progress.