\$$\def\cat#1{{\mathcal{#1}}}\$$
Check that monoidal categories generalize monoidal preorders: a monoidal preorder is a
monoidal category \$$(\cat{P},I,\otimes)\$$ where, for every \$$p,q\in\cat{P}\$$, the
set \$$\cat{P}(p,q)\$$ has at most one element.