In philosophy rationality and reason are the key methods we use to treat the data we gather through empiricism, which stands for the experiences, the observations which our senses are used to collect.

A logical argument is sometimes described as rational if it is logically valid. However, rationality is a much broader term than logic, as it includes "uncertain but sensible" arguments based on probability, expectation, personal experience and the like, whereas logic deals principally with provable facts and demonstrably valid relations between them. For example, ad hominem arguments are logically unsound, but in many cases they may be rational. A simple philosophical definition of rationality refers to one's use of a "practical syllogism". For example,

I am cold

If I close the window I will not be cold

Therefore, I close the window

We should note that standard form practical syllogisms follow a very specific format and are always valid if constructed correctly though they are not necessarily sound. There are several notable implications of such a definition. First, rationality is objective - it exists only when a valid practical syllogism is used. Second, a choice is either rational or it is not - there is no gradation since there is no gradation between valid and invalid arguments. Third, rationality only applies to actions - i.e. shutting the window is a rational thing to do if you are cold (assuming it is cold outside). Evidence bears on belief but not on rationality. All that is required for an action to be rational is that you believe that X and that that if X then Y so you do Y. Arguments about belief are couched in the terms valid and sound - logically you must believe something if the argument supporting it is sound. In some cases, such as religious belief, the argument may be valid but its soundness cannot be known for the truth of its premises cannot be known.

In economics, sociology, and political science, a decision or situation is often called rational if it is in some sense optimal, and individuals or organizations are often called rational if they tend to act somehow optimally in pursuit of their goals. Thus one speaks, for example, of a rational allocation of resources, or of a rational corporate strategy. In this concept of "rationality", the individual's goals or motives are taken for granted and not made subject to criticism, ethical or otherwise. Thus rationality simply refers to the success of goal attainment, whatever those goals may be. Sometimes, in this context, rationality is equated with behavior that is self-interested to the point of being selfish. Sometimes rationality implies having complete knowledge about all the details of a given situation. It might be said that because the goals are not important in definition of rationality, it really only demands logical consistency in choice making. See rational choice theory.

Debates arise in these three fields about whether or not people or organizations are "really" rational, as well as whether it make sense to model them as such in formal models. Some have argued that a kind of bounded rationality makes more sense for such models. Others think that any kind of rationality along the lines of rational choice theory is a useless concept for understanding human behavior; the term homo economicus (economic man: the imaginary logically consistent but immoral being assumed in economic models) was coined largely in honor of this view.

Sociologist Max Weber's writing can be interpreted as suggesting an increasing irrationality of rationality.

Rationality is a central principle in artificial intelligence, where a rational agent is specifically defined as an agent which always chooses the action which maximises its expected performance, given all of the knowledge it currently possesses.

Use of the term rational

In a number of kinds of speech, "rational" may also denote a hodge-podge of generally positive attributes, including:

• reasonable: "having sound judgement" (Webster's)
• reasonable: "not extreme or excessive" (Webster's)
• justifiable on the basis of reason (as opposed to tradition or emotional grounds). (logical)
• not foolish
• sane
• good

Commonly used contrasts may include:

• rational vs. emotional
• rational vs. creative
• rational vs. spiritual
• reason vs. divine truth

See also

• Bounded rationality
• Irrationality
• Perfect rationality
• Principle of rationality
• Rational choice theory
• Rational number
• Satisficing
• Rational pricing

External links and references

• Reason and Rationality, by Richard Samuels, Stephen Stich, Luc Faucher, examines the broad field of reason and rationality from the descriptive, normative, and evaluative points of view
• Stanford Encyclopedia of Philosophy entry on Historicist Theories of Rationality
• Legal Reasoning After Post-Modern Critiques of Reason, by Peter Suber
• Spohn, W. (2002). The Many Facets of the Theory of Rationality. Croatian Journal of Philosophy 2: 247-262.

Rationalism

Rationalität | Racionalidad | Rationalité | Racional | Rasjonalitet | Rationaalisuus