Modus Tollens, means “method of denial” in Latin, is a form of #202206101739 in which the conclusion is a denial. It takes the following form:
$$ \begin{align} &\text{If } p \text{ then } q \\ &\sim q \\ \therefore \ &\sim p\end{align} $$
Note the similarity with the contrapositive of the 202205062055. Therefore, we can know that Modus Tollens is logically equivalent to 202206101747.
We can prove the validity of it by contradiction. Suppose we are analysing the following #202205062050:
- If Zeus is human, then Zeus is mortal
- Zeus is not mortal
From the above premises, if Zeus were human, then by (1) he would be mortal. However, by (2) he is not mortal. Therefore, he cannot be human.