Are we creatures who learn new things? Or does human mental development consist of awakening instinctive structures of thought? A view has gained ground - powerfully advocated, for example, by Steven Pinker's book The Language Instinct - that language in much of its detail is hard-wired in our genes. Others add that this also holds true for much of the specific knowledge and understanding expressed in language. When the first human Eve evoleved from pre-human apes (it is claimed), her biological inheritance comprised not just a distinctive anatomy but a rich structure of cognition. Despite the impressive roll of converts which these ideas have gained, there is no good reason to believe them. The arguments of PInker and others depend on earlier and more technical contributions, by writers such as Noam Chomsky. Many readers take these foundations on trust, not realizing how weak they are. This book examines the various arguments for instinctive knowledge, and finds that each one rests on false premises or embodies a logical fallacy. A different picture of learning is suggested by Karl Popper's account of knowledge growing through 'conjectures and refutations'. The facts of human language are best explained by taking language acquisition to be a case of Popperian learning. Eve was not born a know-all. She was born knowing nothing, but able to learn anything. That is why we can find ways to think and talk about a world that goes on changing today.