The meaning of humanitas is dogged by a controversy that troubled the ancients. The antiquarian Aulus Gellius, writing in the second half of the second century AD, puts it as follows:
Correct Latin speakers do not give humanitas the meaning that it is commonly thought to have, namely what the Greeks call philanthropia, which is a sort of correctness and goodwill towards all men. Latin purists give humanitas approximately the force of the Greek paideia, which we know as education and training in the liberal arts. Those who pursue these goals are essentially human, for the cultivation of this kind of knowledge and training has been given to man alone, therefore it is called humanitas.
(Cell. NA 13.17.1)
Gellius has confused cause and effect. Paideia, training and education, is as important to humanitas as it was to philanthropia. It promotes a mindset, a behavioural pattern that distinguishes civilised man from savages and beasts, a pattern that predisposes him against committing acts of brutality. But paideia itself is not that mindset. That role is (largely) filled by philanthropia/humanitas. It can no doubt be claimed that Gellius' idea still enjoys some currency, for a liberal education is still said to be 'in the humanities'. But modern lexicographers do not hesitate to credit humanitas with similar values to those credited to philanthropia. According to the Oxford Latin Dictionary, humanitas covers 'human nature or character; the quality distinguishing civilised man from savages or beasts; civilisation, culture; humane character, kindness,