“I conceive reason as an attitude whose principle it is to conform thought, feeling, and action to objective values. Objective values are established by the everyday experience of external facts on the one hand, and of inner, psychological facts on the other. Such experiences, however, could not represent objective “values” if they were valued as such by the subject, for that would already amount to an act of reason. The rational attitude which permits us to declare objective values as valid at all is not the work of the individual subject, but the product of human history.”
He went on to explain that reason is “…nothing other than the expression of man’s adaptability to average occurrences, which have gradually become deposited in firmly established complexes of ideas that constitute our objective values. Thus the laws of reason are the laws that designate and govern the average…“
Jung defined irrational “not as denoting something contrary to reason, but something beyond reason, something therefore, not grounded on reason. Elementary facts come into this category; the fact, for example that the earth has a moon, that chlorine is an element, that water reaches its greatest density at four degrees centigrade, etc… The irrational is an existential factor which, though it may be pushed further and further out of sight by an increasingly elaborate rational explanation, finally makes the explanation so complicated that it passes our powers of comprehension…
“A completely rational explanation of an object that actually exists (not one that is merely posited) is a Utopian ideal. Only an object that is posited can be completely explained on rational grounds, since it does not contain anything beyond what has been posited by rational thinking. Empirical science, too, posits objects that are confined within rational bounds, because by deliberately excluding the accidental it does not consider the actual object as a whole, but only that part of it which has been singled out for rational observation.”
So far, the range of experience falling under the category of irrational and accidental includes all elementary facts of existence, known or not: given properties of the world and how we perceive them. It also includes all objects to the extent they’re unique and individual, as well as all chance events occurring in the relations between individual “objects.” It includes the unconscious psyche, which by definition is unknown and so unlimited. Aspects of these irrational factors have been “singled out for rational observation” as Jung noted; yet they remain, in fact and basis, irrational.
Excerpt from: Jung’s Definitions of Rational and Irrational