Locke was not an atheist, but in arguing that religious diversity shows that the concept of God is not innate (ibid., Book I, Chapter 3), he opens the door to a kind of relativism. He argues specifically that the dogma of received opinions is counter to the search for truth and further that doctrine is used to subjugate the individual and their freedom to think. Based on these premises, Locke argues that “all ideas come from sensation or reflection” (ibid., Book 2, Chapter I, p. 2). Thence it follows that different people have different ideas based on different experiences (ibid., Book 2, Chapter I, p. 7), and that thinking is developed through the experience of the quantity and quality of ideas (ibid., Book 2, Chapter I, p. 24). Our thinking, therefore, is the sum of our experience.

Locke further argues (ibid., Book 2, Chapter 8, p. 7) that perceptions are mental phenomena distinct from the external objects they represent, and that complex ideas can be built up only in small steps consisting of ideas of which we can be certain. In this respect, much of the natural sciences remains speculative, as our knowledge of the constituent materials and “powers” of complex objects is simply beyond observation. Expressing extreme scepticism about objectivity, he argues that the effect of relations between complex bodies can be observed, but our confidence that we derive knowledge from this is necessarily very tentative. It follows that there is no such thing as privileged insight: all insights are valid and knowledge is gained through personal synthesis of the conflicting views of others. Thus, as Howard points out: “a great deal of humility will be needed in determining who is more nearly right about anything” (Howard, 2000, p. 151).

Hume (1711-1776)

Locke made a great leap in philosophy with his elevation of sense experience. Hume’s An Enquiry Concerning Human Understanding is an explicit attempt to find a middle path between an obscure and arcane abstract metaphysics and the everyday, unstructured, natural philosophy of “taste and sentiment”. Hume (2006) stated that he would be “happy, if we can unite the boundaries of the different species of philosophy, by reconciling profound enquiry with clearness, and truth with novelty” (ibid., p. IO)! In so doing he explores the implications of empiricism, highlighting issues which lay the ground for the work of Kant and twentieth century pragmatists.

Hume retains much of Locke’s empiricism. Yet he moves the focus of the discussion from Locke’s emphasis on that of which we can be rationally certain, to the issues of cause and effect in the real world and, perhaps, what we might do about it. What Hume describes as ‘true metaphysics’ – based on experience and observation – is, in essence therefore, empirical enquiry. He rejects with conviction the certainty of divine truths and of the possibility of extending knowledge through reason alone. He argues that if rationality were sufficient, our concepts would be perfectly formed from the outset, whereas in fact they are developed and refined by experience and observation (ibid., p. 3I). Not only does he consider this approach more practical and more accurate, but also more consistent: he argues that Descartes’ sceptical rationalism is inherently inconsistent in that it must doubt its own foundation and method (ibid., p. 116).