  David Hume (1711–76) is the first figure in this narrative who can properly be attached to the Enlightenment, though this term means very different things in Scotland, in France and in Germany. Hume held that reason cannot command or move the human will. Since morals clearly do have an influence on actions and affections, ‘it follows that they cannot be derived from reason; and that because reason alone, as we have already proved, can never have any such influence’ (Treatise III.1). For Hume an action, or sentiment, or character, is virtuous or vicious ‘because its view causes a pleasure or uneasiness of a particular kind’ (Ibid., III.2). The denial of motive power to reason is part of his general skepticism. He accepted from Locke the principle that our knowledge is restricted to sense impressions from experience and logically necessary relations of ideas in advance of experience (in Latin, a priori). From this principle he derived more radical conclusions than Locke had done. For example, we cannot know about causation or the soul. The only thing we can know about morals is that we get pleasure from the thought of some things and pain from the thought of others. Since the idea of morality implies something universal, there must be some sentiment of sympathy or (he later says) humanity, which is common to all human beings, and which ‘recommends the same object to general approbation’ (Enquiry Concerning the Principles of Morals, IX. I. 221). Hume thought we could get conventional moral conclusions from these moral sentiments, which nature has fortunately given us. He was also skeptical about any attempt to derive conclusions containing ‘ought’ from premises containing only ‘is’, though scholars debate about the scope of the premises he is talking about here. Probably he included premises about God's will or nature or action. This does not mean he was arguing against the existence of God. He thought (like Calvin) that we cannot rely on rational proofs of God's existence, even though humans have what Calvin called a sense of the divine and Human called ‘true religion’. But Hume never identified himself as an atheist, though he had opportunity in the atheist circles he frequented in Paris, and his Dialogues on Natural Religion end with the sentiment that ‘to be a philosophical skeptic is, in a man of letters, the first and most essential step towards being a sound, believing Christian’ (Dialogues, part XII, penultimate paragraph). Some scholars take this remark (like similar statements in Hobbes) as purely ironic, but this goes beyond the evidence.