Are we creatures who learn new things? Or does human mental development consist of awakening structures of thought? A view has gained ground - 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 holds too for much of the specific knowledge and understanding expressed in language. When the first human evolved from apes (it is claimed), her biological inheritance comprised not just a distinctive anatomy but a rich structure of cognition. This book examines the various arguments for instinctive knowledge, with the author arguing 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, Sampson contends, by taking language acquisition to be a case of Popperian learning. In this way, we are not born know-alls; we are born knowing nothing but able to learn anything and this is why we can find ways to think and talk about a world that goes on changing.