Either sally is dating sturdley or sally is dating vernon. but sally isn't dating sturdley, because sally won't date anyone with a tattoo, and sturdley has a large tattoo of a drunken rat on his right forearm. so, sally is dating vernon. this argument is

This is valid, as the premise does mention Vernon. Since deductive reasoning can be either valid or invalid; but, inductive reasoning is neither valid or invalid, it leaves a deductive reasoning.

This argument is an example of deductive reasoning.

Explanation:

Deductive reasoning is a process of information analysis that leads us to a conclusion. That way you use deduction to find the end result.

This type of reasoning is characterized by the act of arriving at a new truth, starting from the principle of already known truths. That is, according to the reasoning deduct we come to a true conclusion because we know principles that are true and that made us come to that conclusion.

An example of this can be seen in the question above, where we came to the conclusion that Sally dates Vernon, because we know that Sally doesn't date people with tattoos and Sturdley has a big tattoo on his right forearm.