 As is everywhere the case in philosophy, there is disagreement here: for a critique of the doctrine that mathematical truth is an irrevocably use-relative notion, see (Koellner 2009b), and for a retort, see (Warren 2015). Some react to mathematical pluralism by taking it one step further still, and argue that also all inconsistent mathematical theories should be regarded as true (in a relativised sense). Moreover, some mathematical theories that are trivial in the sense of being inconsistent, are commonly taken to be just as valuable as many venerable consistent ones: “Historically, there are three [to the author’s knowledge] mathematical theories which had a profound impact on mathematics and logic, and were found to be trivial. There are Cantor’s naive set theory, Frege’s formal theory of logic and the first version of Church’s formal theory of mathematical logic. All three had profound reprecussions on subsequent mathematics” (Friend 2013, p. 294).