The strange fact is that every mental state has a reason. It's not really a failure of logic. Rather it's what you put into it; to use the computer parlance "garbage in garbage out".

Even the extreme schizophrenic or retarded individual uses logic. It's just that their premises are faulty. To fear white rabbits is irrational but then it leads to calculated measures in the mad/foolish person to avoid white rabbits.

So, what people describe as irrational may not be actually irrational in the sense of a failure to apply the principles of logic. One could even say that it is a matter of conformity. The irrational person doesn't wish to conform to the majority in terms of what he/she puts into his logical apparatus.

I guess we could say that there is no such thing as an irrational person. Just different.

it really is hopelessly circular — Posty McPostface

I thought so too. But then, how does one define Rationality? A dictionary definition is "the quality of being based on or in accordance with reason or logic." Reason is defined (second meaning) "the power of the mind to think, understand, and form judgments by a process of logic." Logic is defined as "reasoning conducted or assessed according to strict principles of validity". So, "irrationality" is thought that lacks reason, logic; or reasoning conducted without testing it against the strict principles of validity". And so on.

Is there a rational, reasoned, logical kernel that is irreducible? Once one has identified that kernel, one can determine whether something is irrational?

In order to assess the rationality of an act or a thought, one would have to know what was loaded into the logical reasoning process. Example: Mary is 68 and has terminal cancer. She will be able to live independently for a few months, then will deteriorate rapidly. She decides to spend all of her cash reserves doing whatever she feels like doing at the time. (This is a radical change from her previous practice.) Her friends think she is being irrational. "What if you don't die after all? What if you experience a spontaneous remission? Then you will be broke." is Mary being irrational? She knows she is going to die; she wants to enjoy life in a way she has never experienced before. This is her last chance. I'd say she is being rational.

What Mary is doing would be irrational for her healthy friends to do. They haven't been diagnosed with any disease. They will probably live for quite a few years yet. For healthy 68 year olds to just spend all of their cash in a few months would be irrational, because they will probably need their cash to maintain themselves.

I guess we could say that there is no such thing as an irrational person. Just different. — TheMadFool

No -- that is way too loose, too relativist.

No -- that is way too loose, too relativist. — Bitter Crank

There's method in madness. In some religions the fool/mad person is an enlightened being.

I honestly got teary reading about Mary...

Irrationality is as essential to rationality, as night is essential to day.

All rationality begins its life as irrational. Theory, genius, iconoclasm, all represent the maturation of the irrational into the rational. Nature matures out of the irrational randomness of mutation and the subsequent application of natural selection.

Human rationality matures out of and is equally dependent upon the randomness of irrational thought.

Irrationality therefore is the fountainhead of creativity and rationality its temporal limitation.
M

Human rationality matures out of and is equally dependent upon the randomness of irrational thought. — Marcus de Brun

Well, then there's really no way to deny or affirm this. It seems like a metaphysical statement.

Irrationality therefore is the fountainhead of creativity and rationality its temporal limitation. — Marcus de Brun

Yes, possible.

I feel logic is about conformity - with nature and with yellow rest of society.

Imagine a game. As all games come we have rules to abide by. All is well until someone decides to break the rules and then pandemonium. It's interesting that rule breaking is most often seen in children - The most creative and inquisitive phase of all humans.

[reply="TheMadFool;196150"

But for the rule breakers there would be no rules, and but for the rules there would be no game.

The philosopher is the Antichrist.

M

Maybe 'transrational' is a better word than irrational in some cases. Going by Richard Dawkins use of the word rational, religious people might be 'transrational'.

I honestly got teary reading about Mary... — Posty McPostface

Mary was an off-the-cuff creation. Her non-existent situation was a quick and dirty way to show how the loading in a logical process could support seemingly irrational decisions from someone else's POV.

Here is a real, non-teary situation: Two years ago dentists at the U of MN told me my teeth had reached a state of wearing down, cracking, and repair where nothing more could be done with them through normal dentistry. The best course they could recommend was either false teeth or a "mouth rebuild" where the bite is redesigned and all the teeth are crowned (a 2 year project). I decided to spend a lot of money (from my POV) on the rebuild.

I made a rational gamble: IF I lived another 10 to 15 years (reaching 79 to 84 years), I would certainly appreciate the benefit of being able to chew on any food effectively and have absurdly attractive teeth. If I die in the next couple of years... well, tough luck, but the expenditure will definitely not matter at that point. Plus, I knew many people who are unhappy with their false teeth.

There is always soup. :)

Some irrationality is rational. For example, fear of death.

One is not dead yet, so it would be irrational to be fearful of death.
But one will eventually be dead one day, so it is rational to be fearful of upcoming death.

This type of irrationality is a human condition as temporal being.

It is more specifically described as an action or opinion given through inadequate use of reason, or through emotional distress or cognitive deficiency. — Wikipedia

Ignore the first sentence and move on to the second.

Is it circular to say rationality is pragmatic reasoning that aspires to some high ideal - some sense of optimality and certainty - and that then the irrational is a very substandard adherence to that?

So being irrational is trying to be rational and failing for some reason.

One way to fail is a lack of information. The other way is a faulty habit of conception. So pragmatically, things can go wrong when we don’t have a good enough theory of a phenomenon. And they can go wrong if we don’t make the right evidential measurements. The ideas and the impressions have to be in synch in some optimal way.

Schizophrenics suffer mainly from faulty measurement. They are trying to construct rational beliefs about a world, but they are getting wrong information at a sensory and affective level.

Ordinary folk then suffer mainly from faulty conception - which leads on to working off the wrong kind of evidence. Their irrationality is down to habits of thought that might accept, for instance, coincidences as some kind of miracle.

So rationality is that tango between theory and measurement. Our ideas are clear and good when they have a crisp logical structure - one that imposes a definite counterfactuality on our impressions. We can know yes or no because a proper question is getting put.

But there is something else. The reasoning has to be serving some purpose. The theory must have an aim.

So irrationality also tends to be ascribed to purposes that seem idiosyncratic or subjective. To be rational is to go with the “objective” view of the collective social reality. You don’t get to invent your own private world - unless you are an artist or poet. In which case, it is that irrationality which is now socially approved.

And the big secret is that artists and poets need to be switched on, atuned to the cultural zeitgeist in cunningly rational fashion. Their irrationality is a disguise to a large extent (although, because this is “unbelievable”, folk will scour for evidence of all the creative minds that were “actually crazy dudes” in the culturally require sense).

True, and I like soup, but I also like chewy foods like raw vegetables, meat, raw apples, nuts, good bread with tough crusts... all that stuff. Plus, We could not evolve to make, eat, and like soup until we had developed the technology of pots and kettles, which was late in the game.

So, it was definitely a rational choice to trade cash for teeth. Plus, I now have these natural looking lithium dislocate anterior teeth and gold posterior teeth. Unfortunately, I am way beyond the age where people in bars admire one's teeth. People my age with nice teeth are a weird oddity.

Some irrationality is rational. For example, fear of death. — Corvus

It is rational to fear the details of approaching death, which can be quite ghastly. Once you're dead, we are beyond caring whether we believe in an afterlife with the gods or an afterlife with worms and plant roots.

IF people "fear death" it is because they have been taught (deliberately or inadvertently) that death is the ultimate horror. Hell is one of the levers with which this instruction is carried out. Shame shame shame. I just don't believe that fearing death intensely is at all natural.

"I have no fear of death. I just don't want to be there when it happens." Woody Allen.

If a definition of irrational is required it might look something like;

Irrational thinking is when thinking is not in accordance with the natural order of the world.

Someone thinking they can be in Berlin and then be in London 1 minute later is being irrational.
Someone thinking they can be in Berlin and then be in London 1 day later is being rational.

Being rational is when thinking is congruent with the order of the world.