Abstract

In the traditional logic of the syllogism, Aristotelian logic, there are four kinds of syllogisms, Darapti, Felapton, Bramantip, and Fesapo, that are often said to be invalid in modern logic. Elementary logic students may even simply be told that they really are invalid. This is, of course, a distortion; but it is instructive to consider why this has happened and why it is that the syllogisms are considered invalid.