The argument from commitment is a second-order predicate argument that supports a value with a fact (2 pre VF).
ANALYSIS OF AN EXAMPLE
We are the guardians of the galaxy, because you said it yourself
The arguer states in the conclusion that something is the case and supports this claim by stating that the addressee has said it herself. Since the argument fits the form q is true, because q is Z, it can be identified as a second-order predicate argument. In this specific case, q is instantiated by ‘that we are the guardians of the galaxy’ and Z by ‘was said by yourself’.
That we are the guardians of the galaxy (q) is true, because that we are the guardians of the galaxy (q) was said by yourself (Z)
Second-order predicate arguments are further differentiated by identifying the types of statement in the conclusion and the premise. In this case, the former is a statement of (logical) value and the latter a statement of fact, which means that we are dealing with a second-order predicate argument supporting a value with a fact (2 pre VF).
The trivial name of second-order predicate arguments is derived from the characterization of the relationship between the predicates ‘true’ and Z. In this example, the fact that the addressee said something herself renders her committed to the truth of the proposition. We can therefore call such an argument an ‘argument from commitment’.