Rational is an adjective which means in accordance with logic, sensible, reasonable, having the ability to reason. Rational connotes the absence of emotion when addressing a problem or argument and relying only on facts and logic. The adverb form is rationally and the noun forms are rationalness and more commonly, rationality. The verb form is rationalize, related forms are rationalizes, rationalized, rationalizing, rationalization. Rationalize may sometimes mean an attempt to justify one’s actions or ideas, even if these justifications are not true or accurate. Rational as an adjective comes to us in the late fourteenth century from the Latin rationalis, meaning of or belonging to reason, reasonable.
Rationale is a noun which means a set of arguments or reasons which form a logical basis for one’s beliefs or actions. Rationale enters the English language in the 1650s, meaning an exposition of principles, from the Late Latin rationale, of reason.
Examples
Insisting he wants a “more rational” debate, Turnbull says everything is on the table. (The Guardian)
There’s nothing wrong with entertainment, but it is not a substitute for sober, rational analysis. (Newsweek)
Despite his eloquent public appearances as a good-willed, jovial and rational champion of peace, he is the prime mover of see-saw diplomacy. (The Jerusalem Post)
The rationale for selecting these countries was that all of them have made recent commitments to financial inclusion, all reflecting political, economic, and geographic diversity. (The Dhaka Tribune)
DAP questions rationale behind burning of effigies (The Malaysian Insider)
Trying to fend off a hostile takeover attempt by Mylan, Ireland-based Perrigo Co. released a letter Thursday sent to Mylan executive chairman Robert Coury blasting his rationale for merging the two drug companies. (The Pittsburgh Post-Gazette)