According to what might be described as ‘humanist’ approaches to epistemology, the fundamental task of epistemology is to investigate the nature, scope and origins of human knowledge. Evidently, what we can know depends upon the nature of our cognitive faculties, including our senses and our understanding. Since there may be significant differences between human cognitive faculties and those of other beings, it would seem that an investigation of the nature, scope and origins of human knowledge must therefore concern itself, in the first instance, with uncovering the structure and operations of the human cognitive apparatus. The most influential versions of humanism in epistemology have also been inclined to insist both that it is contingent that our cognitive faculties are as they are, and that an investigation of these faculties must be largely empirical. An empirical investigation is to be understood, very roughly, as one which relies upon observation and experiment, and to describe such an investigation as naturalistic is to draw attention to the fact that it is presupposed by humanism that the faculties being investigated are a part of the natural world, the world of space, time and causal law.

Locke's Essay and Hume's Treatise are arguably the most distinguished examples of works whose approaches to epistemology are, in these terms, ‘humanist’. To begin with, the Essay is An Essay Concerning Human Understanding, and the Treatise is A Treatise of Human Nature.