Full Idea
If all truths were necessary truths, there would be no occasion for different tenses in the verbs by which they are expressed.
Gist of Idea
The existence of tensed verbs shows that not all truths are necessary truths
Source
Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5)
Book Reference
Reid,Thomas: 'Inquiry and Essays', ed/tr. Beanblossom /K.Lehrer [Hackett 1983], p.266
A Reaction
This really is like modern linguistic analysis. Of course the tensed verbs might only indicate times when the universal necessities have been noticed by speakers. …But then the noticing would be contingent!