What we have shown is that arguments may have valid and invalid argument forms. But an argument is valid if any of its argument forms are valid. Thus we may only draw provisional conclusions regarding the invalidity of an argument, since it is theoretically possible that an argument has a form which is valid. For the purposes of this class, however, if the counterexample method is carefully followed and the logical form of an argument is identified as invalid, we will assume that the argument has no valid form and is thus, invalid. No capitalists are philanthropists.
All philanthropists are altruists.
So, no capitalists are altruists. So, no A are C. Next, construct a counterexample. No apples are oranges. All oranges are fruit. So, no apples are fruit.