|—n , pl -ties|
|1.||the state or quality of being rational or logical|
|2.||the possession or utilization of reason or logic|
|3.||a reasonable or logical opinion|
|4.||economics the assumption that an individual will compare all possible combinations of goods and their prices when making purchases|
in philosophy, the faculty or process of drawing logical inferences. The term "reason" is also used in several other, narrower senses. Reason is in opposition to sensation, perception, feeling, desire, as the faculty (the existence of which is denied by empiricists) by which fundamental truths are intuitively apprehended. These fundamental truths are the causes or "reasons" of all derivative facts. According to the German philosopher Immanuel Kant, reason is the power of synthesizing into unity, by means of comprehensive principles, the concepts that are provided by the intellect. That reason which gives a priori principles Kant calls "pure reason," as distinguished from the "practical reason," which is specially concerned with the performance of actions. In formal logic the drawing of inferences (frequently called "ratiocination," from Latin ratiocinari, "to use the reasoning faculty") is classified from Aristotle on as deductive (from generals to particulars) and inductive (from particulars to generals).
Learn more about rationality with a free trial on Britannica.com.