The Story of Psychology (15 page)

At Oxford he studied philosophy, admired Descartes’ writings, but was attracted by experimental science. Staying on at Oxford for a while as a don, he met and worked with the great chemist Robert Boyle and with the eminent medical scientist Thomas Sydenham. This induced him to study medicine, and in 1667 he became personal physician and general adviser to Anthony Ashley Cooper—soon to become the first Earl of Shaftesbury—with whom he remained connected for some years. From then on Locke was involved in politics, and during the reign of William and Mary he held various government posts.

His portrait shows a long-featured and serious face, and we hear that he was, indeed, uncommonly orderly, controlled, parsimonious, and abstemious. But he was also a sociable man, had many good friends, and
loved children. Although he never married—neither did Descartes, Spinoza, Hobbes, and a number of other seventeenth-century philosophers, a phenomenon worthy of a dissertation—he had a love affair during his Oxford years which, he said, “robbed me of the use of my reason.” When the affair ended, his reason returned; philosophy and psychology were the richer for his never again suffering such a loss.

Of Locke’s many works, the one that concerns us is his
Essay Concerning Human Understanding.
In 1670, he and a handful of friends met informally in his quarters at Exeter House (Shaftesbury’s home) to discuss the view of a number of Platonists at Cambridge that our ideas of God and morality are innate. Locke tells of that meeting in the “Epistle to the Reader” prefacing the
Essay:

Locke guessed that one sheet of paper would be enough to contain the list he would offer, at the next meeting, of the mental processes that the mind itself is capable of understanding. As it turned out, he spent nearly twenty years at the task and filled hundreds of pages with his observations and conclusions.

The
Essay
, which he worked on in England and in exile, in peacetime and during the Glorious Revolution of 1688, was finally published in 1690; it immediately made him famous. It went through four editions in fourteen years, was the topic of drawing room conversation, and altered the course of British philosophy and psychology. It also made him infamous. His rejection of innate ideas and his insistence that the soul was unknowable aroused the wrath of Platonists and of divines who, already displeased with his advocacy of toleration, vociferously attacked him for playing into the hands of atheists. Time handed down the verdict: the
Essay
became part of the mainstream of modern thought; the writings of his attackers ended up on the trash pile of history.

What made Locke’s
Essay
historic was his explanation of how we acquire knowledge; the rest of it does not concern us. He set about exploring, differently from his predecessors, how the mind comes by knowledge. First, unlike Descartes and Hobbes, and despite his medical training, he chose not to speculate about the “motions of our spirits, or alteration of our bodies” by which we have sensations, perceptions, or thoughts.
³²
Either he realized that physiology was still in a primitive state or that psychological processes can be studied at a macro level, ignoring the micro level, as one can study wave mechanics without considering the movements of the molecules making up the waves.

Nor did he rely on formal deductive reasoning, as had Descartes and Spinoza. Instead, he used as nearly empirical an approach as was then available by examining his own experiences and those of others, including children of different ages, asking himself what events take place, and in what sequence, that result in knowledge. He also conducted at least one famous experiment. After putting one hand in a basin of hot water and the other in a basin of cold water, he moved both to a basin of tepid water, which felt cold to one hand and hot to the other. This demonstrated that despite the objective nature of the cause of a perception, our perception of it is subjective and not a replica of the object’s qualities.
³³

Locke’s first piece of business in the
Essay
is to attack the doctrine of innate ideas. To Descartes’ argument that the idea of God must be innate, since we do not experience Him directly, Locke replies that it cannot be innate, because some peoples have been found who have no such idea. He suggests a pious—but empirical—alternative: we derive our idea of God from “the visible marks of extraordinary wisdom and power…in all the works of creation.”
³⁴
Nor can there be innate principles of right and wrong; history shows so wide a range of moral judgments that they must be socially acquired. Even if some ideas are universal, they are not innate if some other explanation can be found. And it can. He will show “whence the understanding may get all the ideas it has” and, as evidence, “I shall appeal to every one’s own observation and experience.”
³⁵

He then states the great primal doctrine of empirical psychology: “Let us then suppose the mind [at birth] to be, as we say, white paper, void of all characters, without any ideas. How comes it to be furnished?…I answer, in one word, from
experience.
In that, all our knowledge is founded, and from that it ultimately derives itself.”
³⁶
(It is often said that
Locke spoke of the newborn’s mind as a tabula rasa, but he did not use that term; it was Aquinas’s translation of a phrase in Aristotle.)

Locke says there are two sources of the mind’s “ideas” (the word he uses to refer to everything from perceptions to abstract concepts). They are
sensation
and
reflection
(the mind’s own operations on whatever it has acquired; in his words, “all the different actings of our own minds”).

Our sense organs transmit sensations to the mind; these he calls “simple ideas.” From them the mind gradually forms “ideas of reflection” (its recognition of its own ability to perceive, to think, to will, to distinguish between things, to compare, and so on). From the interaction of these two classes of ideas arise all others, including the most complex and abstruse.

Locke goes on at great length to show how this is all that is needed to account for the most remote and difficult concepts. (He apologizes for his prolixity, but says, “I am now too lazy, or too busy, to make it shorter.”) He explains how the mind contemplates simple ideas and puts them together to make complex ones; sees similarities and differences between simple and complex ideas; and uses the recognition of differences to construct still more complex ideas. We derive abstract ideas such as whiteness, for instance, by noticing a quality common to certain different things (a sail, a bone, milk) and consciously excluding their differences. In similar fashion we eventually form abstract ideas such as infinity, identity and diversity, truth and falsity.

All this seems soundly put together and watertight, but there was one serious leak in the system. It was the ancient philosophic problem concerning sense perception: How can we know that what we sense is a true representation of what exists outside the mind? Locke sees no reason to doubt that we have true knowledge of the world around us. He does say, like Descartes, that God would not mislead us, but his comments have the sound not so much of piety as of common sense:

In two respects, however, his discussion of perception created problems for later psychologists. (Locke did not distinguish between sensation
and perception; the differentiation would not be made for nearly two centuries.)

First, he accepted the distinction, as old as Aquinas and maintained by Descartes, Galileo, and Newton, between “primary” qualities and “secondary” qualities of the objects we perceive. Primary qualities are “inseparable” from their objects, no matter how much they may change; they produce in us the simple ideas of solidity, extension, figure, motion or rest, and number. “Take a grain of wheat,” Locke says, “divide it in two parts; each part still has solidity, extension, figure, and mobility.” Secondary qualities, such as color, sound, taste, and smell, do not exist in the objects in the form that we perceive them but are sensations that the object’s primary qualities cause in us. A violet is not violet in the dark; it is violet only when it causes a sensation of that color in us. Or so Locke reasoned.

Second, if our ideas are all derived from our perceptions, we know what we perceive but not the reality underlying them—nor even that any reality exists. Similarly, we never know the substance that is mind; we know only our experiences of our ideas. Reasonable Locke is undaunted:

But this simple reassurance would not convince certain other philosophers and psychologists. They would try, and fail, to find a way to prove either that our knowledge of the world is accurate or that anything exists other than our perceptions.

Locke was vague about the nature of mind. Because of his own belief or perhaps in order not to be heretical, he said it was a substance but insisted that we cannot know it any more than we can know the substance behind the qualities we perceive in objects. In fact, in a celebrated passage of the
Essay
he gingerly suggests that it is as possible to imagine that mind is matter as that it is a different kind of substance:

This infuriated the orthodox, who accused Locke of secretly being a materialist and of endangering all of Christian theology. Locke’s psychology survived their attack, and Christianity survived the Lockean threat.

Locke, justly famous for all the foregoing, is often undeservedly credited with being the prime theorist of associationism. It is true that he coined the phrase “association of ideas”; Hobbes and earlier thinkers who discussed the phenomenon did not use that term. But the chapter in which Locke treats of association was an afterthought, an addendum to the fourth edition of the
Essay;
he had developed his entire system without the concept of association.

He does, to be sure, say that we combine simple ideas to form complex ones, and notes that repetition and pleasure play a part in forming such combinations. But he says nothing about the laws of association and does not treat the topic as one of broad relevance. His interest in it is limited to the unreasonable connections or trains of thought found in certain kinds of illnesses and in some bizarre phenomena of everyday life. He tells of a friend who had a surgical operation (no anesthetic yet existed) and who, though grateful to the surgeon, could never bear to look at him afterward, so powerful was the association of the surgeon’s face with pain. He also tells of a man who learned complicated dance steps in a room that had a trunk in it, and later was able to dance well only in a room in which there was a similar trunk.

Yet if Locke’s treatment of the association of ideas was limited, it stimulated others to work out the ways in which such connections and sequences of ideas are formed in the mind. Eventually, behaviorism would reduce all mental life to associations, and even after psychology escaped from the domination of behaviorism, association would remain one of its principal themes. Locke’s thinking was clouded by leftover metaphysics and traces of theology, but he moved psychology away from philosophy and in the direction of science. He wrote with becoming modesty of the contribution he hoped the
Essay
would make: