The truth table for the material conditional P -> Q expresses a mathematical ordering relation among the truth values for P and Q; that is, it is
- reflexive: (P -> P),
- antisymmetric: ( P -> Q) and (Q -> P) if and only if (P <-> Q), and
- transitive: If P -> Q and Q -> R then P -> R). This is the simplest example of an ordering relation.
When true, it signifies that Q is not less true than P, or Q is at least as true as P. This applies to the truth values only. Any other relationships among the two statements is ignored.
In terms of deductive reasoning, this assures that if P -> Q is true, and we assume that P is true, drawing the conclusion that Q is true does not introduce an error that was not present in the initial assumptions. If P -> Q is true but P is false, Q may be either true (more true than P), or equally false, and we cannot conclude anything about its truth value.