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 coldI don't want to be coldIf I close the window I will not be cold... Therefore, I will close the window All that is required for an action to be rational is that if one believes action X (which can be done) implies Y, and that Y is desirable, he or she does X. The action would likewise be avoided were Y undesirable. Such arguments are
logically valid but not necessarily
logically sound. For example, the premise "If I close the window I will not be cold..." may in fact be incorrect. As making formally sound argument is
generally considered difficult, the "soundness" or "strength" of such premises will often rest on
induction,
statistics, and simplified
heuristical models.
