After a mere mention of the polemic against innate ideas, Locke explained his own belief that all human thought originates in the simple ideas of sensation and reflection.
by John Locke Locke prefaced his masterwork with a rhetorically understated “Epistle to the Reader.” His awareness of the need for a systematic investigation of the human understanding first arose in the context of a friendly but unproductive discussion of other issues.The testimony of our senses, together with a natural inclination to seek pleasure and avoid pain, guides much of our daily conduct even though sensitive knowledge cannot offer demonstrative certainty about the existence of an external world.[Essay IV xi 8-10] It would be foolish indeed to refuse to eat simply because God has not granted us speculative certainty regarding the nutritional efficacy of food.With respect to each significant area of human knowledge, we must ask ourselves: where does it come from, how reliable is it, and how broadly does it extend?[Essay I i 1-2] The last of these questions is arguably most to the point.[Essay I i 5] The pursuit of happiness—the genuine business of human life, on Locke’s view—demands only that religion, morality, and science be established to a degree that permits practical progress.Even with respect to such vital matters, Locke supposed, our knowledge is often limited.Then he outlined the account of our formation of crucial complex ideas, including those of substances, mixed modes, and relations. 365-378] Noting his own belated discovery of the vital importance of language, Locke offered a basic statement of his own theory of language, with special attention to the relation between general terms and abstract ideas.Drawing the distinction between civil and philosophical uses of language, he pointed out that difficulties in communication result both from the natural imperfections of language and from its deliberate misuse. 378-388] Finally, Locke defined knowledge and distinguished its several types, each of which is subject to strict limitations.Our intellectual energy would be most efficiently employed were we to avoid intractable disputes over matters beyond our ken and rely instead upon our “Satisfaction in a quiet and secure Possession of Truths, that most concern’d us.” [Essay I i 7] In ordinary life, we know what we need to know, and expecting more than that would only lead us to despair.After all, Locke argued, we do have what we need most.