The term rationalize refers to any situations in which a person's action is described with reference to some supporting reason or cause. The term “legitimate” refers to one criterion by which rationalizations are selected from the many possible explanations for action. Justifications or rationalizations are selected primarily when they are acceptable explanations in a given social context. This means they fit with the facts as known according to the rules of behavior generally followed.

Rationalizing is not a tool for penetration of reality but a post-factum attempt to harmonize one's own wishes with existing reality.

Rationalization may be defined as self-deception by reasoning.

So convenient a thing it is to be a reasonable creature, since it enables one to find or make a reason for everything one has a mind to do

Reasoning is a robust source of hope and confidence in a world darkened by murky deeds – past and present. It is not hard to see why this is so. Even when we find something immediately upsetting, we can question that response and ask whether it is an appropriate reaction and whether we should really be guided by it. Reasoning can be concerned with the right way of viewing and treating other people, other cultures, other claims, and with examining different grounds for respect and tolerance.

The use of reason is to justify the obscure desires that move our conduct, impulses, passions, prejudices and follies, and also our fears.

So convenient a thing to be a reasonable creature, since it enables one to find or make a reason for every thing one has a mind to do.

Reason … contradicts the established order of men and things on behalf of existing societal forces that reveal the irrational character of this order — for “rational” is a mode of thought and action which is geared to reduce ignorance, destruction, brutality, and oppression.

In the subjectivist view, when ‘reason’ is used to connote a thing or idea rather than an act, it refers exclusively to the relation of such an object or concept to a purpose, not to the object or concept itself. It means that the thing or the idea is good for something else. There is no reasonable aim as such, and to discuss the superiority of one aim over another in terms of reason becomes meaningless. From the subjective approach, such a discussion is possible only if both aims serve a third and higher one, that is, if they are means, not ends.

In most cases, to be reasonable means not to be obstinate, which in turn points to conformity with reality as it is. The principle of adjustment is taken for granted. When the idea of reason was conceived, it was intended to achieve more than the mere regulation of the relation between means and ends: it was regarded as the instrument for understanding the ends, for determining them.

The rehabilitation of reason is urgent because it is only through the proper use of reason that we can find our way out of the quagmires in which many big issues of our time have become stuck. Without a clear sense of what it means for one point of view to be more reasonable than another, it seems that the position one adopts is ultimately based on nothing more than personal opinion or preference.

The evidence of science and history is that humans are only ever partly and intermittently rational, but for modern humanists the solution is simple: human beings must in future be more reasonable. These enthusiasts for reason have not noticed that the idea that humans may one day be more rational requires a greater leap of faith than anything in religion. Since it requires a miraculous breach in the order of things, the idea that Jesus returned from the dead is not as contrary to reason as the notion that human beings will in future be different from how they have always been.

Reason, when it is refined into logic, has something to offer but only in terms of itself and depends for its effect and use on the nature of the premise. That useful argument as to how many angels can stand on the point of a needle would turn into nothing without the concept of angels. I took a further step into my new world. I formulated what I had felt against a mass of reasonable evidence and saw that to explain the near infinite mysteries of life by scholastic Darwinism, by the doctrine of natural selection, was like looking at a sunset and saying "Someone has struck a match". As for Freud, the reductionism of his system made me remember the refrain out of Marianna in Moated Grande — "He cometh not, she said, she said I am aweary aweary, O God that I were dead!". This was my mind, not his, and I had a right to it....
We question free will, doubt it, dismiss it, experience it. We declare our own triviality on a small speck of dirt circling a small star at the rim of one countless galaxies and ignore the heroic insolence of the declaration. We have diminished the world of God and man in a universe ablaze with all the glories that contradict that diminution. Of man and God. We have come to it, have we not? I believe in God; and you may think to yourselves — here is a man who has left a procession and gone off by himself only to end with another gasfilled image he towns round with him at the end of the rope. You would be right of course. I suffer those varying levels or intensities of belief which are, it seems, the human condition. Despite the letters I still get from people who believe me to be still alive and who are deceived by the air of confident authority that seems to stand behind that first book, Lord of the Flies, nevertheless like everyone else I have had to rely on memories of moments, bet on what once seemed a certainty but may now be an outsider, remember in faith what I cannot recreate.

We cannot reason ourselves out of our basic irrationality. All we can do is learn the art of being irrational in a reasonable way.