A Latin phrase, properly cui bono est, fuit, etc., meaning ‘To whom [is or was it] for a benefit?’ i.e., ‘Who profits (or has profited) by it?’ attributed by Cicero to a certain Lucius Cassius (Pro Roscio Amer. xxx): popularly but erroneously taken in English to mean ‘To what use or good purpose?’; hence, sometimes subst. The question of the practical advantage of anything; practical utility as a principle.
1604. Bp. Andrewes, Serm., E j b (T.). For, what of all this? what good? cui bono?
1621–51. Burton, Anat. Mel., I. ii. IV. vii. (1676), 102/2. To build an house without pins, make a rope of sand, to what end? cui bono?
1836. J. F. Davis, Chinese, II. 260 (Stanford). The Chinese always estimate such matters by their intermediate and apparent cui bono.
1847. De Quincey, Secr. Soc., i. Wks. 1890, VII. 178. The point on which our irreconcilability was greatest respected the cui bono (the ultimate purpose) of this alleged conspiracy.
b. adj. or attrib. Of or relating to the question cui bono?; sometimes = utilitarian.
a. 1734. North, Exam., I. iii. § 130 (1740), 207. All which Matters … amount … to a Dæmonstration of the Sort I may term cui bono.
1791. Boswell, Johnson (1848), 690/2. Dr. Shaw … used to say, ‘I hate a cui bono man.’
1873. H. Spencer, Stud. Sociol., iii. 69. Are there any who utter the cui bono criticism?
c. vb. To put the question cui bono? in regard to (anything); to question the utility of.
1837. Lytton, E. Maltrav., VIII. i. An ambition, which seemed … to cui bono the objects of worldly distinction.
