Rational

Rational (pronounced rash-nl (U) or rash-uh-nl (non-U))

(1) Agreeable to reason; reasonable; sensible.

(2) Having or exercising reason, sound judgment, or good sense.

(3) Of a person or their personal characteristics, being in or characterized by full possession of one's reason; sane; lucid; healthy or balanced intellectually; exhibiting reasonableness.

(4) Endowed with the faculty of reason; capable of reasoning.

(5) Of or relating to, or constituting reasoning powers.

(6) Proceeding or derived from reason or based on reasoning.

(7) Logically sound; not self-contradictory or otherwise absurd

(8) In mathematics, capable of being expressed exactly by a ratio of two integers or (of a function) capable of being expressed exactly by a ratio of two polynomials.

(9) In chemistry, expressing the type, structure, relations, and reactions of a compound; graphic; said of formulae.

(10) In physics, expressing a physical object.

(11) In the philosophy of science, based on scientific knowledge or theory rather than practical observation.

(12) The breastplate worn by Israelite high priests (historic references only).

1350-1400: From the Old French rationel & rational, from the Middle English racional, from the Late Latin ratiōnālis (of or belonging to reason, rational, reasonable; having a ratio), the construct being ratiōn (stem of ratiō (reason; calculation)) + -ālis.  The –alis suffix was from the primitive Indo-European -li-, which later dissimilated into an early version of –āris and there may be some relationship with hel- (to grow); -ālis (neuter -āle) was the third-declension two-termination suffix and was suffixed to (1) nouns or numerals creating adjectives of relationship and (2) adjectives creating adjectives with an intensified meaning.  The suffix -ālis was added (usually, but not exclusively) to a noun or numeral to form an adjective of relationship to that noun. When suffixed to an existing adjective, the effect was to intensify the adjectival meaning, and often to narrow the semantic field.  If the root word ends in -l or -lis, -āris is generally used instead although because of parallel or subsequent evolutions, both have sometimes been applied (eg līneālis & līneāris).  The use to describe the breastplate worn by Israelite high priests was from the Old French rational, from the Medieval Latin ratiōnāle (a pontifical stole, a pallium, an ornament worn over the chasuble), neuter of the Latin rationalis (rational).  The spelling rationall is obsolete.  Rational is a noun & adjective, rationalizing is a noun & verb, rationalize & rationalized are verbs, rationalism , rationalness & rationalizer are nouns and rationally is an adverb; the noun plural is rationals.  The rarely used adjective hyperrational means literally “extremely rational” and can be used positively or neutrally but it’s applied also negatively, usually as a critique of “economic rationality”.

Rational & irrational numbers illustrated by Math Monks.

In something of a departure from the usual practice in English, “antirational”, “nonrational” & “irrational” (there are hyphenated forms of both) are not necessarily synonymous.  Antirational describes something or someone who is or acts in a way contrary to the rational while arational (often in the form arationality) is a technical term used in philosophy in the sense of “not within the domain of what can be understood or analyzed by reason; not rational, outside the competence of the rules of reason” an applied to matters of faith (religious & secular).  Nonrational (used usually in the hyphenated form) is literally simply the antonym of rational (in most senses) but now appears most often in the language of economics where it’s used of decisions made by actors (individual, collective & corporate) which are contrary to economic self-interest.  Irrational can be used as another antonym but it’s also a “loaded” adjective which carries an association with madness (now called mental illness) while in mathematics (especially the mysterious world of number theory) it’s the specific antonym of the “ration number” and means a “real number unable to be written as the ratio of two integers”, a concept dating from the 1560s.

The adjective rational emerged in the mid-1400s and was was a variant of the late fourteenth century racional (“pertaining to or springing from reason” and of persons “endowed with reason; having the power of reasoning”, from the Old French racionel and directly from the Latin rationalis (of or belonging to reason, reasonable) from ratio (genitive rationis) (reckoning, calculation, reason).  By the 1560s it was picked up in mathematics to mean “expressible in finite terms” before becoming more precisely defined.  The meaning “conformable to the precepts of practical reason” dates from the 1630s.  The adverb rationally was from the same source as ratio and ration; the sense in rational is aligned with that in the related noun reason which got deformed in French.  The noun rationality by the 1620s was used in the sense of “quality of having reason” and by mid-century that had extended to “fact of being agreeable to reason”, from the French rationalité and directly from the Late Latin rationalitas (reasonableness, rationality (the source also for the Spanish racionalidad and the Italian razionalita), from the Latin rationalis (of or belonging to reason, reasonable).  As late as the early fifteenth century racionabilite (the faculty of reason) was in Middle English, from the Latin rationabilitas.

Rational AG's iCombi Pro range: Gas or Electric.

By the 1820s, the noun rationalization was in use in the sense of “a rendering rational, act of subjection to rational tests or principles”, the specific modern sense in psychology in reference to subconscious (to justify behavior to make it seem rational or socially acceptable) adopted by the profession early in the twentieth century.  The verb rationalize (explain in a rational way, make conformable to reason) dates from the mid eighteenth century although the sense familiar in psychology (to give an explanation that conceals true motives) came into use only in the 1920s on the notion of “cause to appear reasonable or socially acceptable” although decades earlier it had been used with the intransitive sense of “think for oneself, employ one's reason as the supreme test”.  The use in psychology endured but “rationalize” also came into use in applied economics with the meaning “to reorganize an industry or other commercial concern to eliminate wasteful processes”.  That seems to have come from US use although the first recorded entry was the Oxford English Dictionary’s (OED) supplementary edition in 1927.  In this context, it became a “vogue word” of the inter-war years of both sides of the Atlantic although it fell from favour after 1945 as the vogue shifted to “integrate”, “tailor”, “streamline” and that favourite of 1970s management consultants: the “agonizing reappraisal”.  However, in the 1980s & 1990s, “rationalize” gained a new popularity in economics and (especially) the boom industry of financial journalism, presumably because the “economic rationalists” coalesced during the Reagan-Thatcher era as the dominant faction in political economy.

Many have their own favourite aspect of Sigmund Freud’s (1856-1939) theories but one concept which infuses mush of his work is the tussle in the human psyche between the rational and irrational.  Freud’s structural model consisted of the three major components: id, ego & superego, the elements interacting and conflicting to shape behavior and personality.  The id was the primitive & instinctual part containing sexual and aggressive drives; operating on the pleasure principle, it seeks seeking immediate gratification and pleasure.  Present even before birth, it’s the source of our most basic desires and in its purest processes is wholly irrational, focused on wants and not the consequences of actions.

Concept of the id, ego & superego by the Psych-Mental Health Hub.

The rational was introduced by the ego, something which developed from the id and was the rational, decision-making part of the mind which balanced the demands of the id and the constraints of reality.  As Freud noted, implicit in this interaction was that the ego repressed the id which obviously was desirable because that’s what enables a civilized society to function but the price to be paid was what he called “surplus repression”.  That was a central idea in Freud's later psychoanalytic theory, exploring the consequences of the repression of innate, instinctual drives beyond that which was necessary for the functioning of society and the individual: the rational took its pound of flesh.  Discussed in Civilization and its Discontents (1930), “primary repression” was essential to allow the individual to adapt to societal norms and function in a civilized society while “surplus repression” was the operation of these forces beyond what is required for that adaptation.  Freud identified this as a source of psychological distress and neurosis.

Lindsay Lohan’s early century lifestyle made her a popular choice as a case-study for students in Psychology 101 classes studying the interaction of the rational and irrational process in the mind.  Most undergraduates probably enjoyed writing these essays more than had they been asked to analyse Richard Nixon (1913-1994; US president 1969-1974), America’s other great exemplar of the struggle.

It was the ego which mediated between the id, the superego, and the external world, making possible realistic and socially acceptable decisions, essentially by making individuals consider the consequences of their actions.  The superego developed last and built a construct of the morality, ethical standards & values internalized from parents, the education system, society and cultural norms; operating on the “morality principle”, the superego one of the “nurture” parts of the “nature vs nurture” equation which would for decades be such an important part of research in psychology.