Why did John Locke believe that infants do not possess innate ideas?

In his Essay Concerning Human Understanding, John Locke rejected the doctrine of innate ideas—the belief that certain truths are imprinted on the mind at creation—by arguing that an idea cannot be considered to be "in the mind" unless one is conscious of it.12

Locke contended that infants provide clear evidence against the existence of innate knowledge, as they possess no conception of God, moral principles, or logical and mathematical truths. To claim that such ideas are present in an infant's mind, despite a total lack of awareness, is an unwarranted assumption used only to defend a flawed philosophical position.12

Instead, Locke proposed that the mind begins as a tabula rasa, or "white paper," and that all materials of reason and knowledge are derived from experience. He identified two sources for these ideas: sense experience and reflection, which is the mind's awareness of its own operations.312