 The deepest reason for IF logic, as Hintikka saw it, is that the relations of dependence and independence between quantifiers are the only way of expressing relations of dependence and independence between variables on the first-order level (Hintikka 1996: 34–35, 73–74; 2002a: 404–405; 2006a: 71, 515). To understand this remark properly, recall that relations of quantifier (in)dependence are semantic relations, but syntactically expressed. More precisely, in IF logic the (in)dependence relations are syntactically expressed by the interplay of two factors: syntactic scope and the independence indicator ‘/’. In a given sentence, an existential quantifier \(\exists x\), say, depends on precisely those universal quantifiers within whose scope \(\exists x\) lies, but of which \(\exists x\) is not marked as independent using the slash sign. What Hintikka means when he speaks of (in)dependence relations between variables, are functional dependencies between quantities in a model. The kinetic energy of a material body depends on its mass and its speed, but does not depend on the particular material body being considered. This fact can be expressed in IF logic by the sentence