 The first formula is often called Aristotle’s Thesis. If this non-theorem of classical logic is found plausible, then the second principle, AT′, would seem to enjoy the same degree of plausibility. Indeed, also AT′ is sometimes referred to as Aristotle’s Thesis, for example in Routley 1978, Mortensen 1984, Routley and Routley 1985, and Ferguson 2016. As McCall (1975, p. 435) explains,