  On the other hand, he directly supports plurallism by arguing that for each area of research, there is (or there could be) a plurality of correct theories. His reasoning goes as follows. All theories are grounded on logic because logic is necessary for reasoning about both the data used by those theories and the theories themselves. And, if there is, not just one, but a plurality of correct logics, there is (or there could be) a plurality of correct theories which spring from all those different, but all equally acceptable, ways of reasoning as well (cf. 1997, 61–74). From this, a plurality of actual worlds follows if we accept two enthymematic assumptions. The first one is that any correct logic, in virtue of its being correct, properly describes an actual world. If so, if there is more than one correct logic, there is more than one actual world too. The second assumption, then, is that there are many correct logics. This idea was not shared by Sylvan’s contemporaries but one that he came to defend late in his career, claiming (1997, xix) “that not merely is there a plurality of logics, but there is also [a plurality] of correct logics”. The idea is elaborated on in Sylvan (1997, ch. 4) and is now widely discussed in the literature (see, for instance, Beall and Restall 2000; Russell 2008; Weber 2017b). Sylvan claims that phenomenological data seems to support plurallism as well (cf. 1997, 118–133).