Final answer:
The argument presented is an example of modus tollens, a valid logical form, which correctly deduces that Patsy did not pass the bar exam from the information given that she is not a lawyer.
Step-by-step explanation:
The statement "Patsy is a lawyer only if Patsy passed the bar exam" sets up a condition where passing the bar exam is necessary to be a lawyer. If Patsy is not a lawyer, we can deduce, using modus tollens, that she must not have passed the bar exam. Modus tollens is a valid form of argument where the denial of the consequent (being a lawyer) logically leads to the denial of the antecedent (passing the bar exam). The assertion fulfills the modus tollens form, which can be described with the logical form: If P, then Q. Not Q. Therefore, not P.
This is distinct from modus ponens, which affirms the antecedent to infer the consequent is true; affirming the consequent, an invalid form of argument that wrongly infers the truth of the antecedent from the consequent; and denying the antecedent, another invalid form that incorrectly infers the falsity of the consequent from the falsity of the antecedent.