As if reading my mind

...or reading the blog comments, John Quiggin reposts a quick meditation on how 'rational' has been stripped of meaning and should be discarded in favor of more directly descriptive terminology:

In keeping with the idea of this regular feature, I thought about providing a definition that would clarify the issues surrounding this word and the reasons it causes so much confusion. In reflecting on the problem, however, I’ve come to the conclusion that the word ‘rational’ has no meaning that cannot better be conveyed by some alternative term and that the best advice is probably to avoid it altogether.


Rather than taking sides in this dispute, I will offer the following purely mathematical claim. Given any data on any observed set of problems involving the selection of one or more choices from a set of alternatives, the observed choices can be represented as the maximisation of an appropriately specified function. To give an easy example, satisficing can be represented (rationalised) as optimising, taking calculation costs into account, or alternatively as a combination of set-valued maximisation with a selection rule based on the order in which alternatives are presented.

If this claim is accepted, it’s evident that the definition of rational choices as those that maximise an objective function is empty, since all choices satisfy this criterion.


Most uses of the term rational and the opposed ‘irrational’ involve some confused mix of the following connotations

1. reasonable as opposed to emotional

2. calculating as opposed to intuitive

3. self-interested as opposed to altruistic

4. materialistic as opposed to non-materialistic

5. logically consistent as opposed to inconsistent


More generally, the problem with debates involving the word ‘rationality’ is that people tend to shift from one meaning to another, sometimes deliberately and sometimes without realising what they are doing. Given the entrenched nature of all five uses listed above, and the tangled relationships between them, it’s impossible to specify a ‘right’ meaning. The best option is probably to avoid the word altogether, and to use the specific terms I’ve suggested as appropriate to its various components.

Hear, hear. In the comments to this post, John Emerson clearly explains a concept I've been fumbling around in my excoriation of Rationalism:

Just using rationality in a value-neutral, purely descriptive way would greatly reduce the harm the word does. “Rational” is normally a buzz-word—science is rational, scientists are rational, some historical actors are rational (or at least, much more so than others), and it is assumed that if everyone were more rational, the world would be a better place.

It isn’t hard to find cases when rationality is harmful, either because it’s predatory or because the assignment of costs and benefits leaves out important considerations. Rationality is a way of choosing actions, but also a way of framing justifications or proposals, and if rationality is too high on your queue of justifications, you will probably end up justifying harmful behavior in cases in which one aspect of a situation has been adequately formulated, whereas spokespersons concerned with other aspects of the situation are still speaking “pre-rationally”. External costs is an example; the human cost of economic progress is another.

It has been noted that certain sorts of sociopaths are fully rational. This is especially so if you lump traditional moral taboos in the “emotional” category, so that the taboo on torturing children is on the same formal footing as the taboo on eating shrimp.


An odd feature of this is that evpsych people explain that even our most irrational gut feelings are rational from the point of view of genes. This is another case of expanding the concept of rationality beyond its possible meaningful uses.

All of which reminds me of Mises' position on rationality & human action:

Human action is necessarily always rational. The term "rational action" is therefore pleonastic and must be rejected as such. When applied to the ultimate ends of action, the terms rational and irrational are inappropriate and meaningless. The ultimate end of action is always the satisfaction of some desires of the acting man. Since nobody is in a position to substitute his own value judgments for those of the acting individual, it is vain to pass judgment on other people's aims and volitions. No man is qualified to declare what would make another man happier or less discontented. The critic either tells us what he believes he would aim at if he were in the place of his fellow; or, in dictatorial arrogance blithely disposing of his fellow's will and aspirations, declares what condition of this other man would better suit himself, the critic.


When applied to the means chosen for the attainment of ends, the terms rational and irrational imply a judgment about the expediency and adequacy of the procedure employed. The critic approves or disapproves of the method from the point of view of whether or not it is best suited to attain the end in question. It is a fact that human reason is not infallible and that man very often errs in selecting and applying means. An action unsuited to the end sought falls short of expectation. It is contrary to purpose, but it is rational, i.e., the outcome of a reasonable--although faulty--deliberation and an attempt--although an ineffectual attempt--to attain a definite goal. The doctors who a hundred years ago employed certain methods for the treatment of cancer which our contemporary doctors reject were--from the point of view of present-day pathology--badly instructed and therefore inefficient. But they did not act irrationally; they did their best. It is probable that in a hundred years more doctors will have more efficient methods at hand for the treatment of this disease. They will be more efficient but not more rational than our physicians.

The opposite of action is not irrational behavior, but a reactive response to stimuli on the part of the bodily organs and instincts which cannot be controlled by the volition of the person concerned.

Now, it is too late in the evening/early in the morning for me to come up with a pithy or witty conclusion, so I will leave it all as it is for the gentle reader to digest, except perhaps to quote the future Dread Pirate Roberts:

"That word you keep using. I don't think it means what you think it means."

NB: This applies to me equally. :)

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Brian's original posts in

Brian's original posts in the Gerin Oil thread attacked *Rationalism*, not rationality.

Admittedly, there is some ambiguity there.

Here's some definitions of Rationalism:
"A movement in the 18 th century Protestantism which abandoned the idea of Biblical inerrancy and adopted the belief that the Bible can be analyzed as a historical document. Some Rationalists assert that the existence of some form of deity can be proven by reason. Others see Rationalism and Atheism as synonyms."


"A branch of philosophy where truth is determined by reason."


"Any philosophy magnifying the role played by unaided reason, in the acquisition and justification of knowledge. . . "

and from Wikipedia:

"Rationalism, also known as the rationalist movement, is a philosophical doctrine that asserts that the truth should be determined by reason and factual analysis, rather than faith, dogma or religious teaching. ..."

By disparaging Rationalism, I can only assume that the disparager is opposed to using reason in the pursuit of truth, which definitely explains their religious tendencies.


You're irrational.

You're irrational.

In the comments to this

In the comments to this post, John Emerson clearly explains a concept...

I wouldn't say that. I really have no idea what point he's trying to make.

And I'm pretty sure it was Montoya who said that.

Nmg, I am aware of the

Nmg, I am aware of the Rationalist movement. As I remember it the story goes .. blah, blah, blah, Newton's laws, blah, blah, blah, errors by Marx, blah, blah, blah, disprovent by Bertrand Russel.. blah, blah, blah, disproven by Godel.

I however do not think that being rational rationally leads to social engineering.

I don't think Brian was being so specific either. Seemed he was using the Rationalist movement to discredit rationality. Seems you've come to the same conclusion about his motives.

Brandon- Yes, but Montoya is


Yes, but Montoya is at least highly hinted at becoming the next Dread Pirate Roberts since he's out of the revenge game. :)

I posted a trackback but it

I posted a trackback but it didn't go through. In any case I have commented extensively here.

Attempted Assasination of

Attempted Assasination of the Word "Rational"
In the Gerin Oil comments I was getting the distinct feeling that Mr. Doss was confused as to the meaning of the word rational when used by us rationalists. I didn?t however want to get into long discussion at that point. Now that he has declared war...

I think “rational” is a

I think “rational” is a useful word. Here is what I understand one of its meanings to be.

Rationality consists of recognizing the possibility of error in our beliefs and actions, then using every method available and commensurate with the situation to reduce such error.

Brian, great post. I've

Brian, great post. I've always been unsure about the "correct" notion of rationality. I use Mises' definition, but it clashes with, say, an Objectivist's notion of rationality, or many other views of what makes action rational. I have always figured that concepts like "unreasonable" and "short-sighted" and "logical" should be stated by themselves and not assumed under the mantle of rationality. Not to say that this is correct way, but it's my understanding.

So of couse when countering someone's opinion that a given action is irrational, I have employed the Mises understanding of the term only to find weirdly confused reaction. "What," they seem to imply with their bewilderment, "is the point of a concept of rationality if I can't use it to judge someone else's actions?" I say, that's the point... judge them some other way if you must.

Stefan beat me to it ;)

Stefan beat me to it ;)

I use the term "rationality

I use the term "rationality fallacy" to describe the error of "mainstream" economists who persist in identifying rationality with wealth maximization. Closely related are so-called libertarian paternalists, about whom I've written here, here, here, here, and here. The bottom line is that the use of "rationality" is a signal that the person who uses it is about to prescribe the behavior of others.

I was nodding my head until

I was nodding my head until this:

"Human action is necessarily always rational."

That's a classic Mises howler. Talk about defining a word to the point where it's meaningless! There'd be no sense in ever using the word "rational" if we define it this way, but fortunately nobody but hardline Misesians uses it this way (and even they don't in their everyday lives). Quiggin is right, though, that it's a problematic word due to the very different multiple meanings it's loaded with. I would arrange them this way, though:

1. Choice of ends. Some values are more conducive to a person's well-being than others.
2. Choice of means. Some courses of action are more likely to achieve one's values than others.
3. Systematic consistency in one's choices of means and ends. Ceteris paribus, you can't want to eat lots of ice cream and not gain any weight, and you don't accumulate a retirement nestegg by spending like a drunken sailor.
4. Consideration and weighing of the possible future consequences of one's actions, as opposed to acting impulsively.
5. Critical attitude, i.e. a willingness to reconsider and alter one's choices and beliefs in the light of new information.

Meaning (1) might be better called "wisdom," (2) might be called "efficacy," and (3) could perhaps be simply called "consistency." But I think (4) and (5) together coincide most closely with the most common colloquial uses of the word "rational", and there really is no better word for them that I can think of. (Though there is a good word for their opposite: sphexishness.)