 In dealing with counterfactual hypotheses of indirect proofs mentioned above, Averroes and Thomas Aquinas made use of the idea of abstract possibilities which did not imply the idea of alternative domains. The possibilities of a thing can be dealt with at various levels which correspond to Porphyrian predicables. Something which is possible for a thing as a member of a genus can be impossible for it as a member of a species. The same holds of it as a member of a species and an individuated thing. Thus humans can fly because there are other animals which can fly. These abstract possibilities are impossible in the sense that they cannot be actualized. Buridan heavily criticized this approach from the point of view of his modal theory. He argued that if a counterfactual state of affairs is possible, it can be coherently imagined as actual. If something cannot be treated in this way, calling it possible is based on conceptual confusion. (See Knuuttila and Kukkonen 2011.) While Scotus, Buridan and many others understood the basic level of possibility in terms of semantic consistency, Ockham wanted to preserve the link to the notion of power in his modal considerations, thinking that necessity is actuality plus immutability, the past and the present are necessary, and Scotus was wrong in assuming that things could be different from how they are at the very moment of their actuality (Normore 2016). 