An argument is valid if, and only if the conclusion of the argument is true under all interpretations under which the premises are true. In contrast to most modern incarnations of this definition, I take truth (or rather satisfaction) to be a primitive notion. Interpretations are understood as substitution instances. In contrast to Tarski's typed approach, the notion of logical validity is applicable to the language in which it is formulated. In contrast to the usual model-theoretic definition of logical validity, my account features an intended interpretation. Moreover, for every model of the language, there is a substitutional interpretation, that is, a substitutional instance plus a specification of the values of the free variables of the substitution instances.