 Väänänen (2014: 181) applied sort logic to Foundations of Mathematics. He proposed the notion of truth in a structure \(\mathcal{A}\) characterizable in sort logic, making a new distinction between general truth \(\models \varphi\) and specific truth in those structures. Whenever general truth is reduced to specific truth, we can use the calculus to prove the satisfiability of a formula. Under certain constraints, any class of structures closed under isomorphism is definable in sort logic (see Kennedy &amp; Väänänen 2021, Theorem 19). Thus, Väänänen argues that sort logic is an “alternative way of looking at mathematics”, where, unlike set theory, “definition rather than construction is the focus” (2014: 185). It is also an interesting tool for studying Logicality and model classes (Kennedy &amp; Väänänen 2021).