Explanations of the changes occurring in behavior and mental processes that result from being in the world. Theories of learning present accounts of these changes by describing both the resources newborn children bring with them into the world and the principles that explain how these congenital factors participate in the creation of experience. An examination of the various theories of learning reveals obvious differences in how learning is explained. The greatest of these differences among theories of learning is accounted for by the role assigned to the a priori. Since there are three conceptions of the a priori at work, theories of learning can be classified by means of three major categories. Within each category there will be differences, but those differences will not be as great as the differences among categories.