What should be our estimate of the place of John Locke in the history of philosophy and of his influence on succeeding generations of thinkers? What impact has his work had upon society at large and has it been on balance a beneficial one? Big questions like these are tempting to ask and to try to answer, but it would be an illusion to suppose that they can be settled definitively and in a wholly objective fashion. Each succeeding age fashions its own intellectual heroes, often more in order to vindicate its own prejudices than in dispassionate recognition of the true achievements of the individual thinkers who are selected for this purpose. Unsurprisingly, then, the reputation of past philosophers has often been subject to large swings of fashion from one age to the next. David Hume, for example, is now widely admired by academic philosophers, not least because the sceptical, atheistic and naturalistic tendencies of his thought are in tune with recent and current philosophical and scientific attitudes. It is probably true to say that Hume’s stock amongst academic philosophers is at present still somewhat higher than Locke’s, although I sense that the balance is now shifting. But it was not always so and at various times in the past Hume’s philosophy was very much out of fashion. Locke, however, has never really been out of fashion in this way and it is interesting to speculate as to why this should be so.
A significant fact, I think, is that Locke never aspired, as Hume and many other philosophers both major and minor have done, to be admired as a clever or ingenious or strikingly original thinker.
Consequently, those philosophers who especially value such intellectual qualities are often inclined to dismiss Locke as a worthy but essentially mediocre figure in the history of their subject. But Locke’s real greatness as a philosopher lies not least in his unswerving determination to pursue the truth to the best of his ability, irrespective of whether the results of his inquiries should lead him to endorse or reject fashionable claims. As a result, some of the claims that he does advance may seem either tediously obvious or hopelessly mistaken to the fashionable thinkers of any particular generation. A symptom of his solid worth, however, is that the fashionable thinkers of different generations typically select different Lockean doctrines for criticism as being either tediously obvious or hopelessly mistaken – depending, of course, upon their own predilections. Consequently, their verdicts undermine each other. A doctrine cannot easily be both tediously obvious and hopelessly mistaken.
The serious philosophers of each succeeding age find that in revisiting Locke’s greatest works they discover a vast storehouse of important insights into matters of profound importance for a proper understanding of our own condition and of the world we inhabit. Since I am better equipped to speak for the philosophers of the present rather than of any previous generation, I shall briefly illustrate this fact by citing some prominent examples of philosophical issues whose modern treatment still owes much to Locke.
In the philosophy of perception, for instance, Locke’s account of the distinction between primary qualities – such as shape and size – and secondary qualities – such as colour and taste – still provides the starting-point for most present-day discussion (see, for example, McGinn 1983). In the philosophy of language and the philosophy of science, his distinction between ‘real’ and ‘nominal’ essences informs current views of the meaning of so-called natural kind terms – terms denoting naturally occurring types of substances or biological organisms, such as ‘gold’ and ‘tiger’ (see Putnam 1975). In metaphysics, it was Locke who laid the foundation of recent debates about the persistence of objects over time and the nature of personal identity (see, for example, Parfit 1984 and Wiggins 2001), for he was the first philosopher to see clearly that before we can say whether something existing at one time and place is or is not identical with something existing at another time and place, we must first determine what sort or kind of thing it is whose identity is in question (see Lowe 1989).
Other important examples of the continuing impact of Locke’s thought may be found in the philosophy of action and moral theory. There has recently been a revival of volitionism – the view, favoured by Locke, that voluntary actions are initiated by an ‘act of will’ on the part of the agent (see, for example, Ginet 1990 and McCann 1998). This, together with renewed attention to the perennial problem of free will and moral responsibility – another major concern of Locke’s – has led to increasing engagement with Locke’s views by modern philosophers working in these areas (see Yaffe 2000). The same may be said regarding Locke’s distinctively liberal-minded political philosophy. Revitalized scholarly interest in this has been connected with a resurgence of Locke’s idea that political obligation is founded on an agreement or ‘compact’ between those who submit themselves to government – an agreement freely entered into by and equally binding upon all parties to it, including those into whose hands governmental authority is entrusted. The highly influential work of the American political philosophers John Rawls and Robert Nozick in the last three decades of the twentieth century cannot be adequately understood without an appreciation of its Lockean resonances (see Rawls 1972 and Nozick 1974).
Nor should we forget epistemology, the central concern of Locke’s greatest work, the Essay Concerning Human Understanding. One very important unifying element in Locke’s thought is his relatively modest conception of the scope of human knowledge – especially in matters of metaphysics – which he combines with a conviction that we may nevertheless establish with certainty the truth of at least some principles of mathematics and morality. Such certainty, according to Locke, is entirely the product of reason and intuition and is in no way indicative of the innateness of the principles in question. Indeed, he emphatically repudiates the doctrine of innate ideas and principles as both unfounded and pernicious, as no doubt it was in the hands of many of his seventeenth-century contemporaries. This combination of views is in considerable measure responsible for Locke’s endorsement of toleration in matters of religious belief and his insistence that legitimate civil government rests upon the freely given consent of the governed. For if, as Locke supposes, all human beings have very similar but strictly limited cognitive capacities and each of us demonstrably has a duty to exercise those capacities to the best of our ability in judging what to believe or not to believe, rather than relying blindly on authority or tradition, then none of us is justified in forcing our religious beliefs upon others or in presuming to judge for others where their true political interests lie (see Wolterstorff 1996).
Incidentally, Locke’s repudiation of the doctrine of innate ideas, while it does align him with much present-day thinking in epistemology, places him in opposition to some recent views in linguistics and psychology, notably those that see evidence for the doctrine in our language-learning capacities (see Chomsky 1988) and some of those that emphasize the evolutionary roots of human psychology (see Cummins and Allen [eds] 1998). However, these modern trends in favour of innatism – or ‘nativism’, as it is often now called – have by no means gone unopposed (see Cowie 1999) and at the very least we can say that Locke’s contribution to the debate between innatism and empiricism still provides a startingpoint for much current discussion of the issues at stake. In any case, we should not forget that Locke wrote long before Charles Darwin developed the modern theory of evolution through natural selection and hence at a time at which innate ideas and principles could only be supposed to have a divine origin, enabling their advocates to claim an unchallengeable status for them as representing God’s own ordinances. The kind of innatism that modern theoretical linguists and evolutionary psychologists argue for is quite different and they fully embrace an empiricist methodology in their own scientific work. It is hard to say how Locke himself would have regarded their position, so far removed is it from the innatism of his seventeenth-century contemporaries (for further discussion, see Lowe 1995, pp. 27–33).
Although Locke has never really been out of fashion, there have been times at which he has been set up as something of a straw man whose doctrines – for instance, concerning abstract general ideas, the workings of language, and volitions or acts of will – have been caricatured simply to provide an easy target for opposing views. Thankfully, this sort of cavalier treatment is now largely a thing of the past and Locke’s reputation as a serious and important philosopher is probably higher at present than it has been at any time since the eighteenth century. This should not be particularly surprising, because Locke’s approach to philosophical questions is, in many ways, in keeping with that of the current age. His respect for empirical science and his naturalistic view of the powers of the human mind exemplify this harmony. Recall here that Locke cast himself in the role of an ‘under-labourer’ to the great scientists of his day, such as Isaac Newton and Robert Boyle (see Chapter 2 above). Indeed, although Locke deferred to Newton and Boyle in matters concerning physical science, he himself may be said to be the father – or at least the grandfather – of modern empirical psychology. His distrust of words put him out of favour when it was fashionable, during the middle of the twentieth century, to approach philosophical questions almost exclusively through the medium of language. But it sits much more comfortably with many modern views of the development of the human mind and its cognitive capacities – setting aside the issue concerning innatism mentioned earlier. Thus, it is no longer possible to dismiss as naive and wrong-headed Locke’s assumption of the priority of thought over language. Even his views about abstract general ideas, once strongly ridiculed, now find an echo in some modern psychological accounts of our ability to categorize and classify objects of perception (see Keil 1989).
In sum, if I were pressed to identify, in just a few sentences, those aspects of Locke’s work that have had the most lasting influence on philosophy and the intellectual world in general, this is what I would say. Locke was a pivotal figure in the history of philosophy, helping to forge a naturalistic conception of the human mind and its powers and thereby opening the way to the development of the modern science of empirical psychology. At the same time, he helped to engender the modern division of labour between philosophy – understood as centrally involving a critical inquiry into our own conceptual structures and pretensions to knowledge – and empirical science, seen as underwritten by systematic experimentation and the impartial observation of nature. He also stands out, of course, as the foremost champion of individual liberty in the political sphere and of toleration in matters of religious belief. In all of these respects, Locke’s philosophy has been a major force for enlightenment and freedom in human affairs and hence, in my estimation, a major force for good.