Passions can be contrary to reason only in so far as they are accompanied with some judgment or opinion.

Two ways a passion may be called unreasonable:

1. The passion is founded on the supposition of the existence of objects which really do not exist.
2. When in exerting any passion in action, we choose means insufficient for the designed end, and deceive ourselves in our judgment of causes and effects.

"In short, a passion must be accompanied by some false judgment in order to its being unreasonable; and even then 'tis not the passion, properly speaking, which is unreasonable, but the judgment."