 Note that if a logic implements the cancellation view of negation, it will also be paraconsistent because the ex contradictione quodlibet principle, (A ∧ ∼A) ⊢ B, will not be valid. (The idea of ex contradictione nihil sequitur is discussed in Wagner 1991.) According to the Routleys, a connection between the subtraction account of negation and Aristotle’s thesis AT′ then arises as follows (Routley and Routley 1985, p. 205):