by Morton Hunt
Everyone must not hope to be a Boyle or Sydenham; and in an age that produces such masters as the great Huygenius, and the incomparable Mr. Newton…it is ambition enough to be employed as an under laborer in clearing the ground a little, and removing some of the rubbish that lies in the way to knowledge.40
In his case, such modesty was as unwarranted as it was becoming.
Locke died in 1704, at the beginning of a century in which the exact sciences advanced by leaps and bounds. Among its notable strides was the work of Galvani in physiology, Volta in electricity, Dalton in atomic theory, Euler and Lagrange in mathematics, Herschel and Laplace in astronomy, Linnaeus in botany, Jenner in preventive medicine, and, later, of Cavendish, Priestley, and Rutherford in discovering, respectively, hydrogen, oxygen, and nitrogen.
Psychology made no similar bounds forward, and would not until the emergence of experimentalism in the nineteenth century. For the most part, the eighteenth-century protopsychologists were either rationalistnativists in the Cartesian tradition or empiricist-associationists in the Hobbist-Lockean tradition. Still, some of them did advance each of these basic theories in ways that affected the future of psychology. It is worth meeting them briefly and glancing at their contributions.
Berkeley
The theory for which the philosopher and protopsychologist George Berkeley (1685–1753) is famous always amuses undergraduates in history of philosophy courses and gives professors the opportunity to quote Cicero: “There is nothing so absurd but some philosopher has said it.” Berkeley’s philosophy was absurd, but many remember it; his psychology was sound, but nearly everyone has forgotten it.
His place in history rests almost entirely on three books he wrote before he was twenty-eight. For the rest, his life is of little interest. He was born in Ireland, studied philosophy at Trinity College, Dublin, earned a doctorate and was ordained a deacon of the Anglican Church at twenty-four, traveled and preached for some years, and spent the rest of his life as Bishop of Cloyne in County Cork, Ireland.
Berkeley was inspired to write his first noteworthy book, An Essay Towards a New Theory of Vision (1709), by a brief passage in Locke that asked whether a man born blind, who later gains vision, would be able by sight alone to tell a cube from a sphere. Locke thought not; Berkeley agreed, but was stimulated to study the problem further, basing his analysis on associationist psychology. Sight alone, he said, gives the newborn no idea of distance, shape, size, or relative position. It is by means of repeated experiences—touch, reaching, walking—that the child learns to make spatial judgments. We associate the visual clues of distance, size, and shape with what we have learned through the other senses.
The thesis is sound, and a genuine contribution to perception theory. Moreover, his breaking down the seemingly simple experience of depth perception into more basic experiences anticipated or perhaps even led to the “molecular” approach of later psychology—the effort to analyze all experiences into their simplest components.
But if Berkeley was realistic in his psychology of perception, he was unworldly in the philosophic theory for which he is famous. Philosophy had long created problems for psychologists; Berkeley’s psychology created a problem that would stump philosophers. It started when, as a youth of twenty-one, he decided that materialistic Newtonian science was endangering religion; he told himself in a diary that if he could only do away with the doctrine of matter, the “monstrous schemes” of “every wretched sect of atheists” would collapse.41
For a twenty-one-year-old to dream of doing away with the worldwide belief that matter exists—and to publish a book at twenty-five, The Principles of Human Knowledge (1710), expounding that dream—sounds ludicrous, if not insane. (His third important work, published in 1713, was a dialogue restating the argument.) But Berkeley was simply following through to its ultimate conclusion Locke’s distinction between primary and secondary qualities. If all knowledge comes from our perceptions, we know nothing of the external world except them; but they are only secondary qualities. How do we know that the matter or substance in which primary qualities are said to reside really exists? In dreams, we see trees, houses, mountains vividly, but they are only illusions; why should we suppose our waking perceptions are better evidence that anything real exists? In Berkeley’s words:
But though it were possible that solid, figured, movable substances may exist without the mind, corresponding to the ideas we have of bodies, yet how is it possible for us to know this? Either we must know it by sense or by reason. As for our senses, by them we have only the knowledge of our sensations… [As for reason,] what reason can induce us to believe the existence of bodies without the mind from what we perceive? … It is possible we might be affected with all the ideas we have now, though there were no bodies existing without, resembling them. 42
What exists, as far as we can know, is only what we perceive. Esse est percipi: to be perceived is to be. What is not perceived may as well not exist, for all the difference it makes to us (a doctrine that will reappear in modern times as phenomenological psychology, an offbeat by-product of existentialism).
Berkeley was no fool; he acknowledged in the Preface to his Principles that some passages in it, taken by themselves, might seem to have “absurd consequences.” And scoffers have accused him of claiming that there is no real world whatever and that all existence is only in our imagination—that a tree exists when we see it but ceases to when we look away. Berkeley, however, rescued the universe by recourse to God, the Permanent Perceiver, Who sees all things all the time. There may be no material world, but the universe of His perceptions is steady and enduring; even when we do not see a thing, He does, and it therefore does not cease to exist when we cease looking at it. The twentieth-century British theologian Father Ronald Knox admirably summed up Berkeley’s view in a famous limerick:
There was a young man who said “God
Must think it exceedingly odd
If he finds that this tree
Continues to be
When there’s no one about in the Quad.”*
Berkeley’s theory created a problem for both psychologists and philosophers, who found it unanswerable on its own terms. Many years later Boswell asked Dr. Johnson, as they were strolling one August day in 1763, how he would refute Berkeley’s theory. Johnson kicked a large stone forcefully and rebounded from it, saying, “I refute it thus.” He should have known better; Berkeley could have replied that the solidarity and mass of the stone and Johnson’s rebounding from it were only perceptions put into his head by God and no proof that any material thing caused them.
There are subtler and better replies to Berkeley than Johnson’s, but none simpler or saner than Hume’s: Berkeley’s arguments, he said, “admit of no answer and produce no conviction.”
Hume
But David Hume (1711–1776) himself created a difficult problem for both philosophers and psychologists in his psychological writing. First, let us meet this brightest star of the Scottish Enlightenment.
In Scotland, as elsewhere in the Western world, the Enlightenment was the prevalent eighteenth-century philosophic movement, characterized by reliance on science and reason, the questioning of traditional religion, and the belief in universal human progress. In childhood, Hume was, on two counts, an unlikely prospect to become a luminary of that movement. He was born in Edinburgh of a well-to-do Presbyterian family and indoctrinated in childhood with Calvinist theology. As a boy he seemed dull (his own mother said he was “a fine, good-natured crater but uncommon weak-minded”), but the dullness was probably a misimpression created by his stolidity and tendency toward overweight; he was bright enough to enter the University of Edinburgh at twelve. As for his Calvinism, at fifteen he was avidly reading the philosophy of his time and by eighteen had become a convert to it, later commenting that “he never had entertained any belief in religion since he began to read Locke and Clarke.”*
Hume, the second son in his family, inherited only a trifling portion. He theref
ore studied law, but so loathed it that he had a breakdown. He found a stint in a merchant’s office equally intolerable. At twenty-three he decided to eke out an existence as a philosopher and moved to France to live cheaply. He settled at La Flèche (where Descartes had studied), and, though not enrolled at the college, talked the Jesuits into letting him use its library. In only two years he wrote his two-volume Treatise of Human Nature: An Attempt to Introduce the Experimental (Newtonian) Method of Reasoning into Moral Subjects (1738), the work in which he first set forth his psychology.
He expected it to make him famous but was bitterly disappointed when it attracted almost no notice. (Rewritten, later, in simpler form, it did better.) Forced to earn a living, he briefly tutored a young nobleman, then became secretary to General James St. Clair, in which post he earned a good salary, wore a scarlet uniform, ate well, and grew stout. A visitor described him as having a broad fat face “without any expression other than that of imbecility” and a body better suited to an alderman than a refined philosopher. Again appearances were deceptive; fairly soon Hume had saved enough to devote himself to writing, and the works of his mature years in politics, economics, philosophy, history, and religion brought him the fame he sought. In France he was, though vast in girth, the darling of the salonières and much admired by Voltaire and Diderot; in London his home became a salon where Adam Smith and other liberal thinkers regularly met for stimulating conversation.
Friends and acquaintances considered him wise, amiable, moderate in controversy, and tolerant; he said the same of himself, adding that he was “a man of great moderation in all my passions.” (At twenty-three he had made a young woman pregnant, and at thirty-seven wooed a married countess on his knees, without success. These episodes aside, he seems to have been remarkably moderate in at least one passion.) Though he denounced Spinoza as an atheist, he was himself a doubter to the end. When Boswell asked him, as he lay dying of cancer of the bowel, if he did not now believe in another life, Hume replied that it was “a most unreasonable fancy.” He was, all in all, a true man of the Enlightenment.
Hume’s main purpose in writing the Treatise was to develop a moral philosophy based on “the science of man,” meaning psychology. He therefore undertook to construct a theory of the human passions and our ideas of them, and this necessitated his knowing where our ideas come from. He approached the matter as a true empiricist: “As the science of man is the only solid foundation for the other sciences, so the only solid foundation we can give to this science itself must be laid on experience and observation.”43
Accordingly, while he made ample and critical use of the work of others, he relied in considerable part on introspective observation of his own mind. As a thoroughgoing empiricist, he peremptorily dismissed all questions about the nature of the incorporeal soul—the thinking “I” that had seemed so significant to Descartes—declaring that the nature of soul was an “unintelligible question” not even worth discussing. His own view of the conscious thinking self, based on a scrutiny of his own thought processes, was that the mind was made up entirely of perceptions:
When I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure…I may venture to affirm the same of the rest of mankind, that they are nothing but a bundle or collection of different perceptions.44
Hume distinguished between “impressions” (his word for sensations or perceptions) and “ideas” (the same experiences, but in the absence of the object, as in memories, reflections, and dreams). Like Locke, he said that these simple elements are the components of which complex and abstract ideas are formed. But how? Here he went far beyond Locke. There must be a “uniting principle,” which, he hypothesized, takes three forms: “The qualities, from which this association arises, and by which the mind is, after this manner, conveyed from one idea to another, are three, viz. resemblance, contiguity in time and place, and cause and effect. ”45
The association or combining of ideas by means of these three characteristics seemed to Hume the fundamental principle of the mind and as central to its operations as gravitation to the motions of the stars; he even called association “a kind of attraction” that causes ideas to cohere. He thus made much more of association than had Locke, who relied on it chiefly to explain abnormal connections among ideas but not mental processes in general.
So far, so good. But Hume, though convinced that he had found the fundamental scientific law of the mind, proceeded to undercut the very foundation of the sciences by his interpretation of one of the three forces of association, namely, cause and effect. He did not, as is sometimes claimed, say there is no such thing as cause and effect; he did say, however, that we cannot experience causality directly and therefore cannot know what it is or even prove that it exists. We know only that certain events seem always, or almost always, to be followed by certain others, and we therefore infer that the first causes the second. But this is only expectation based on the association of the two events:
The idea of cause and effect is derived from experience, which informs us that such particular objects, in all past instances, have been constantly conjoined with each other… All our reasonings concerning causes and effects are derived from nothing but custom.46
Causality is only a habit of mind. We do not and cannot experience or perceive it in any fundamental sense; we know only that when one thing happens, the other happens. To predict that this will always be so is to commit a fallacy; we can only infer that when A next occurs, B will probably follow.
Hume concluded that we believe in causality and in the reality of the external world not because we really know that they exist but because the skeptical view that he has set forth is too hard to live with:
It is impossible, upon any system, to defend either our understanding or our senses…As the skeptical doubt arises naturally from a profound and intense reflection on those subjects, it always increases the further we carry our reflections, whether in opposition or conformity to it. Carelessness and inattention alone can afford us any remedy. For this reason I rely entirely upon them, and take it for granted, whatever may be the reader’s opinion at this present moment, that an hour hence he will be persuaded there is both an external and internal world.47
Hume’s devastating assault on the concept of causality is of great importance in the history of science, and nowhere more so than in psychology, which, struggling to become a science, was seeking to discover the laws of mental causation. Some psychologists in Hume’s time, and many later on, would therefore maintain that psychology cannot yield causal explanations and should attempt to deal only in correlations— the probabilities that two things will continue to occur together or in sequence. Ironically, the empiricism and associationism that Hume meant to be the foundation of his system of morals lives on; his system of morals, a gentle utilitarianism, is quite forgotten.
The Empiricist-Associationist School
Empiricist-associationist psychology disposed of some of the intractable problems in the theory of mind-body dualism and innate ideas, but in all sciences a new theory that answers old questions usually raises new and different ones. The new psychological theory not only led to subjectivism and cast doubt on the validity of causal explanations but, by reducing the major mental processes to perception and association, was able to say nothing illuminating about such high-level mental phenomena as consciousness, reasoning, speech, unconscious thought, problem solving, and creativity. It would, in fact, eventually prove most useful, in somewhat different form, as a theory of animal psychology.
Its simplistic explanation of how the mind forms abstract ideas worked well enough for concepts derived from perceptions, such as equality, but was unconvincing about those with no perceptual basis, such as virtue, soul, nonbeing, possibility, necessity, or the nondimensionality of a point in geometry.
Furthermore, except for Hobbes’s atomistic conjecture about nervous impulses, the ne
w theory ignored the physiology of mental phenomena and could say nothing explanatory about reflexive reactions, let alone all those high-level automatic responses which make up much of everyday human behavior.
From Locke’s time on, a series of empiricist-associationists, mostly in Great Britain, sought to solve some of these problems, but with only minor success, if any. Nonetheless, some of their work represents courageous venturing into the unknown; if they crossed no uncharted oceans, some of them at least mapped a few miles of alien coastline.
David Hartley (1705–1757) was one of the latter. A scholarly physician, he was inspired by Locke’s work to write at length about associationism in his Observations on Man (1749). Although he added nothing original, his treatment of the subject was organized and systematic, and thereby, says the great historian of psychology, Edwin G. Boring, turned it into a “school.”48
In addition, Hartley, as a doctor, was sharply aware of Locke’s omission of physiology; he sought to present a more holistic psychology by discussing each phenomenon first in mental terms and then in physiological ones. An admirable effort; unfortunately, in the mid-eighteenth century the neurophysiology he offered was largely imaginary. From Newtonian physics he derived the idea that external vibrations in matter must cause corresponding vibrations of infinitesimal particles within the nerves. These vibrations produced miniature counterparts or “vibratiuncles… the physiological counterpart of ideas,”49 a pure figment of his imagination, yet a little closer to the truth than Descartes’ theory of hollow nerves and animal spirits. It did, furthermore, keep an interest alive among associationists in the physical substrate of mental events.
