Justin Weinberg at Daily Nous riffs off my post, Ideas Behind Their Time , to ask for philosophical examples . He nominates Gettier problems –i.e. counterexamples to the idea that knowledge is simply “justified true belief” as a possibility. The classic Gettier paper is from 1963. Wikipedia notes that the Indian philosopher Dharmottara has some clear examples c770 AD but as an element within the Western tradition the idea does seem behind its time. I would nominate the following as philosophical ideas behind their time: Hume’s is/ought distinction: the idea that you cannot derive a normative conclusion from factual premises. Hume’s problem of induction: past regularities do not rationally guarantee future regularities. Rawls’s Veil of Ignorance:  the principles of justice should be derived without knowing one’s own particularities of class, race, gender and so forth. Seems obvious as an idea.…