Rationalism is, most generally, the philosophical view that beings such as humans are able to acquire knowledge because certain innate categories or knowledge exists in the being's mind.

This is different from empiricism in that rationalists would argue that experience of the world alone can not inform a mind without first having some degree of knowledge about how to sort or relate experiences of reality.

Rationalists tend towards the idea that what is prior to experience or "a priori" (Latin for "prior to") is the most critical to coming to an understanding of the world in which a being exists.

The rationalist may argue that, for example, our idea of certain very basic features of reality, such as causation, can not be learned and therefore must be innate to the being's mind in question.

The empiricist would hold that the idea of causation, rather than being innate, comes from observation of cause and effect relationships or happenings in the world that is observed.

The rationalist can take various forms in that they may be of the beleif that certain knowledge is innate, that certain concepts are innate, or that ways of categorizing empirical knowledge are innate- or any mix of these views.

The rationalist view is that the mind, before experiencing the world, has primarily important features that, without, experience of the world would not make sense or even be possible.

A skeptical philosopher may argue that both rationalists and empiricists make claims without absolute or complete knowledge of these claims and how they can be known or even tested. How, for example, can we know that a baby is afraid of heights without exposing the infant to a high place?

And, once exposed to a high shelf, for example, how can we know whether it was an innate knowledge of heights or the experience of being high up that caused, perhaps, the baby's fear?

Rationalists look inward towards the mind and the reality of the concepts of mathematics and geometry as areas of human knowledge that can not possibly have come from observation of it, they would argue, because nowhere in empirical reality do we find numbers and pure geometry.

Only from within are we able to conjure number and form and we apply these concepts to the things we encounter in our daily lives or in our human developmental phases.

Reason itself, for example, can be found nowhere in the reality that humans experience except for in their minds.

Using deductive or inductive reasoning (if induction can be called reason at all) is not something that can easily be seen as being encountered in the world of the senses but rather in the inner world of the mind.

The faculty humans have, and perhaps other beings have, for logical deducation, for instance, does not appear to be something that can be gained from observing the details of objects or environments.