The predominant school of thought holds that the markets are irrationally acting—and crashing—in response to the news.
It would be better to spend rationally now than irrationally in the heat of an election year.
We seem to now be in a period when people who are irrationally afraid of others are far outnumbered by those who are not.
late 15c., "not endowed with reason" (of beats, etc.); earlier (of quantities) "inexpressible in ordinary numbers" (late 14c.); from Latin irrationalis "without reason," from assimilated form of in- "not, opposite of" (see in- (1)) + rationalis "reason" (see rational). Meaning "illogical, absurd" is attested from 1640s. Related: Irrationally.
irrational ir·ra·tion·al (ĭ-rāsh'ə-nəl)
Not rational; marked by a lack of accord with reason or sound judgment.