ABSTRACT
A deductive inference is valid just when the conclusion follows logically from its premisses; and the conclusion follows just when there is no possible situation in which the premisses are true but the conclusion is not. So, on the face of it, accepting A and B logically commits me to Z. Why, then, must I accept Z if I accept A and B? Lewis Carroll argued that, even though I accept A and B, I am not obliged to accept Z without first granting
But what obliges me then to accept Z? I am not obliged to do so until I have granted
But then I am not obliged to grant Z until I have granted
And so on ad infinitum. But this means we are never going to be obliged to accept the validity of any inference.
