Another common fallacy is mixing up the sufficient and necessary conditions of an implication "$\Rightarrow$". Given two propositions $p$ and $q$, this fallacy takes the following form:
$$\begin{array}{rll} p\Rightarrow q&\text{premise}&\text{e.g. Any square is a rectangle.}\\ \hline q\Rightarrow p&\text{conclusion}&\text{e.g. Therefore, any rectangle is a square.}\\ \end{array} $$
Proofs: 1
Chapters: 1
Lemmas: 2
Proofs: 3 4 5