A Short History of Modern Philosophy: From Descartes to Wittgenstein, Second Edition (13 page)

Locke and the theory of ideas

However, in order to understand the philosophical significance of empiricism, and the true nature of its opposition to the philosophies of Descartes, Spinoza and Leibniz, we must consider its mature expression in the arguments of Locke. There had been a reaction to the empiricism of Hobbes. In Cambridge an anti-empiricist school had been founded (known as the Cambridge Platonists, and including such men as Ralph Cudworth (1617-1688) and Henry More (1614-1687)). This school upheld many of the traditional claims made on behalf of metaphysics; however, it took its authority from the speculative metaphysics of Plato, rather than from the methodological rationalism of Descartes. It was of little lasting significance, and the publication of Locke’s
Essay,
which followed closely on that of Newton’s
Principia,
gave such complete expression to the new empiricist spirit, that it could not but eclipse the opposing efforts of these lesser writers.

John Locke (1632-1704) was a student of Christ Church, Oxford, a lawyer and a medical practitioner. Becoming embroiled, through a position as tutor in the household of the first Earl of Shaftesbury, in the political controversies of his day, he spent part of his life exiled in Holland. There he awaited that ‘glorious revolution’ which was to place William of Orange on the throne of England and vindicate the ideal of legitimacy defended in Locke’s own political writings. These political writings I shall discuss in chapter 14; what is of immediate concern is the change wrought in philosophy by Locke’s highly ambitious and influential theory of knowledge, contained in the
Essay Concerning Human Understanding
published in 1689.

The
Essay
is the fruit of a lifetime’s interest in philosophy and the foundations of natural science. It is a vast, disorganised and repetitious work, written in a sinuous style, full of hidden subtleties and difficult to grasp in its totality. The arguments are directly opposed to many of the most important tenets of Cartesian rationalism. Yet the language of the book is through and through influenced by Descartes and can be read, from one point of view, as an extended critical reflection on the crucial term ‘idea’, which Locke took from Descartes with the intention of freeing it from its rationalist connotations. Ideas are the immediate objects of the understanding:

every man being conscious to himself that he thinks; and that which his mind is applied about whilst thinking being the ideas that are there, it is past doubt that men have in their minds several ideas,— such as those expressed by the words whiteness, hardness, sweetness, thinking, motion, man, elephant, army, drunkenness, and others.

And the first thing to note about ideas, according to Locke, is that they all, without exception, come to us from experience.

Innate ideas

Hence there are no innate ideas or principles. In making this claim, Locke is explicitly going against Descartes, who had argued that the principles of rational argument, and ideas like those of God, thought and extension which we perceive clearly and distinctly and which provide the rational foundations of our knowledge, are innate, implanted in us by God without the help of any sensory experience. On the contrary, Locke argued, the mind of the infant is a blank slate—a
tabula rasa
— until experience imprints it with the ideas that are necessary for thinking. We have no awareness of either ideas or rational principles, until we have begun to exercise the mind in the attempt to understand experience. Nothing is innate to the mind, apart from the faculties whereby we acquire knowledge.

One of Leibniz’s intentions, in his
New Essays on the Human Understanding,
was to mount a defence of innate ideas against Locke’s attack on them. Spinoza admitted—what can scarcely be denied—that the laws of logic and mathematics, and the concept of metaphysics, are not part of an infant’s new-born consciousness. But the issue, he believed, cannot be settled by such an observation. We possess innate ideas and innate knowledge in a
virtual
manner. The mind should be compared, Spinoza suggested, to a block of marble, veined in such a way that a figure of Hercules emerges, just as soon as it is struck with a hammer. In like manner, the impact of experience creates the ideas to which our minds are by nature predisposed, since they are the preconditions of thinking.

The controversy between the defenders and attackers of innate ideas was long-drawn-out and bewildering. It might seem to be of parochial interest now, but in fact this is not so, for two reasons. First, because it has been revived in recent times on account of Chomsky’s work in linguistics; secondly, because beneath the bluster of this quarrel lies concealed a more serious dispute over the status of
a priori
truths. The first of those reasons concerns us little. Those linguists who argue that there must be innate concepts if language acquisition is to be possible, do no more than repeat an old fallacy adequately exposed by Locke himself. They confuse the possession of a concept with the power to acquire it. As Locke points out, it is trivial to assert the existence of innate ideas if we mean only that the child is born with the
power
to acquire those ideas which are later displayed in him. For how could it be otherwise?

But this brings us to the second and more important reason for taking an interest in the controversy. At first sight it seems rather odd that philosophers, from Descartes to Hume, should have spent so much of their labours disputing over a point of little consequence. For what does it matter, philosophically speaking, whether we choose to believe with Locke that the mind of the infant is a
tabula rasa
awaiting the inscription of experience, or with Leibniz, that this board comes to us, as it were, already lined and ruled, with markings the significance of which has yet to be discerned? In what way is our view of human knowledge, or of reality, changed by these theories? To see the dispute in its modern significance we must, as always with early empiricist philosophers, rephrase a theory that is expressed genetically (in terms of the ‘history’ of the acquisition of a concept) as a theory concerning the nature of a concept, however that concept is in fact acquired. We will then see that Locke and Leibniz were arguing over whether there are concepts which are
a priori,
in a sense later to be made precise by Kant. Locke wishes to show that everything that we understand (every idea) we understand
in virtue of
its connection with experience. The content of every idea is revealed by tracing it back to experience. (Whether or not it has its
origin
in experience is another question, and one that is irrelevant to epistemology.) Leibniz had many philosophical interests to urge against that assertion, as well as against its mistaken formulation in genetic terms. In particular he wished to defend the premise of rationalism, that there are ideas whose content can be revealed by no experience, but by reason alone. Moreover we can generate from that content a system of truths whereby we know the universe as it really is, and not as it appears to our fallible organs of sensation. Into that knowledge we may then fit our experience, as best we can. But it is not experience which tells us what we mean.

This controversy was not to become clear until Kant formulated his theory of synthetic
a priori
truth. However, to understand Locke’s intention we need only recognise that he was not putting forward a psychological hypothesis. He was proposing, rather, an empiricist theory of understanding. According to this theory all communication depends upon the common significance of words. This significance can be identified only by referring to the experiences which lead us to apply or revoke the words whose significance we seek to explain. That way of putting it is not Locke’s, and indeed it conflicts with Locke’s own formulation, according to which ‘ideas’ are private mental particulars, and accessible only through the words that denote them. Nevertheless it is the most plausible thesis contained in Locke’s discussion of innate ideas. It is also a thesis that caused him to deny the possibility of rationalist metaphysics by denying all significance to the words that such a metaphysics would be compelled to employ.

This is not to say that Locke was wholly clear about the extent to which he rejected rationalism. He took over in modified form the Cartesian notion of ‘intuition’, arguing that I do have intuitive knowledge of certain truths (including the truth that I exist), and contrasting this intuitive knowledge with the ‘demonstrative’ knowledge of mathematics. He also argued that we have ‘demonstrative’ knowledge of God. It might therefore be thought that Locke was disposed, like the rationalists, to accept at least in part the idea that the ultimate truth about the world can be derived from the exercise of reason alone. It turns out, however, that this is not so. His demonstration of the existence of God has a purely contingent (if intuitive) premise, namely, that I exist. It concedes to rationalism only the principle which it employs to advance from that premise. This principle (for which Locke offers no argument and which stands out as peculiarly isolated from the rest of his thought) is the following: ‘everything which has a beginning has a cause.’ In other words, Locke’s demonstration of the existence of God is a form of the ‘cosmological’ argument. And this does not lead him to reject the fundamental principles of empiricism. Moreover he held that ‘demonstration’, including all mathematics, provides no new knowledge of the world. It speaks only of the relations among ideas. That theory of mathematical truth finds further elaboration in the philosophy of Hume, and is the ancestor of the modern empiricist doctrine that necessary truths are ‘tautologous’ or ‘verbal’ (see chapter 19).

The theory of ideas

There are two forms of experience through which ideas are acquired— sensation and reflection. Ideas of sensation come to us through the senses—through seeing, hearing, touching, tasting and smelling things. Ideas of reflection come to us through the activity of the mind as it observes its inner processes. Since the soul does not think until the senses have furnished it with ideas, sensation has a primary importance in delivering our theory of the real world.

Locke follows Descartes in distinguishing the understanding from the will—the first being the passive power of the mind to receive ideas, the second the active power of the mind to affirm or act on them. But he seems to treat sensations (including visual and other forms of sensory perception) as a distinct kind of mental event—one from which we may
receive
ideas, but which is not itself a kind of idea. Locke’s ideas are really
concepts
; and although he sometimes writes of them as though they were images, he clearly distinguishes them from complete thoughts or propositions. Ideas are of the following kinds.

Simple and complex.
A simple idea is one like the idea of redness, which cannot be analysed into its components. It is ‘not in the power of thought to make or erase’ these simple ideas, which come to us through sensation or reflection. All ideas that are not simple are complex; and if you can define
a
in terms of
b, c, d,
etc., then the idea of
a
is composed of the ideas of
b, c, d.
He writes of ideas as a kind of mental object, which can be pushed around in the mind and combined and separated just as physical objects might be. This picture of the mind survives in other British empiricists, and is one cause of the antiquated feel to their arguments.

Ideas of one sense, of more than one sense, of reflection, and of both sense and reflection.
The idea of greenness is derived from one sense, the visual. The idea of solidity corresponds to both visual and tactile experiences. The idea of imagination comes from inner awareness of the operations of the mind. The idea of action derives from all those sources working together.

Ideas of, modes, substances and relations.
A mode is a property, a substance the bearer of properties. Locke means two things by ‘substance’: the individual, for example John Smith; and the basic
kind,
such as gold or water. Both individuals and kinds are bearers of properties, and both endure through time. Modes are simple or complex, and a complex mode may also be ‘mixed’, when its idea is put together from ideas derived from different sources. ‘Table’ signifies a mixed mode, whose idea is unified by ‘an act of the mind’.

Finally there are
abstract
ideas, which deserve a section to themselves.

Abstract ideas

Locke, in common with other empiricists, felt called upon to explain our ability to form general notions. This ability is exercised in every application of a predicate and therefore in almost every thought. He was well aware that, if all ideas derive from experience, they ought, in the first instance, to reflect the particular features of the experiences from which they stem. How then can any of our thoughts become general in its nature, when experience itself is irremediably particular?

We form complex ideas either by bringing together separate ideas into a composite whole (and among such composite wholes are all our ideas of relation), or else by separating ideas in such a way as to generate what is common to all of them. This second process Locke called abstraction, regarding it as of considerable importance in the genesis of human knowledge. Locke thought that abstraction enabled him to explain, without departing from the theory of ideas, our ability to use general terms. ‘Words’, he wrote, ‘become general by being made the sign of general ideas’, and these general ideas are derived from particular ideas (or ideas of particular things) by a process of abstraction. The theory is roughly as follows: I have many ideas of particular men, some tall, some short; some fat, some thin; some intelligent, some stupid; some white, some black. All the respects in which these ideas might differ, while yet remaining ideas of men, cancel each other out in the composite idea formed by their agglomeration. What remains is an ‘abstract’ idea which contains only those features which are in common to all the instances. These features are the defining properties of manhood, the idea of which is abstract, because, being incomplete, it can identify no particular thing.