This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Locke opens his Essay Concerning Human Understanding by attacking a view he takes to be widespread and false: that certain ideas and principles are innate, stamped into the mind from birth, needing no experience to be known. His alternative image is now so familiar it barely reads as an argument: the mind at birth is a blank sheet, a tabula rasa, with no writing on it at all, and everything a person ever comes to know is written there afterward by experience, and by experience alone. Locke divides that experience into two sources. Sensation supplies ideas of the external world, colors, sounds, tastes, arriving through the senses. Reflection supplies ideas of the mind's own operations, thinking, doubting, believing, reasoning, noticed by attending to what the mind does with the materials sensation hands it. Every complex idea a person holds, however abstract or refined it seems, Locke insists can be traced back, link by link, to some combination of simple ideas that ultimately came from one of these two sources; nothing is built in beforehand, waiting to be recognized rather than learned. This is Empiricism's founding wager, and it is a genuinely testable sounding claim in a way rationalist innatism sometimes is not: find a substantive idea with no traceable root in sensation or reflection, and the blank slate has a hole in it. Locke's own confidence that no such idea exists is what makes his empiricism a program rather than a mood, an actual commitment about where every piece of human knowledge, without exception, comes from.