I remember seeing mention someplace of one or more studies concluding that one’s views of their (intentional use of ‘their’ as the genderless singular pronoun) abilities is more accurate when they are depressed. Depression is an emotion that supports accurate cognition of one’s abilities. (It attunes one to the actual state of one’s abilities, to use Heidegger’s word.) At the same time, it tends to suppress or dampen down any action or initiative.
Conversely, one has a less accurate cognition of one’s abilities when they are happy/joyful/exuberantly optimistic. The actual state of one’s abilities then gets covered up, hidden to some extent. At the same time, one’s initiative, the likelihood of their taking action of some sort, increases.
So each of these emotions falls someplace on two spectrums: the cognition/suppression-of-cognition spectrum, and the spurring-of-action/suppressing-or-dampening-of-action spectrum.
One of the more frustrating discussions I’ve ever had was on the question whether (at least in the case of human beings) cognition requires the emotions. This discussion was with an otherwise highly intelligent person (I am looking at you, Lijoy) who kept insisting, as if this refuted my argument, that being in an emotional state would lead him to make bad decisions by preventing him from seeing things as they are. He could see things as they actually were, he said, only when he is in a calm state of mind.
But of course calm is an emotion — one says, after all, that they feel calm. Calm is the emotion that best attunes one to what the situation is with regard to what matters to one. It also dampens one’s eagerness to take some action right now, this moment, without thinking, so that one moves, not impulsively, not with blind rashness, but deliberately.
The emotions form the basis of cognition by opening up to one this or that aspect of the world or of one’s self — but this doesn’t prevent the emotions from also closing these things from view. The emotions form the basis of action by motivating one to do this or that (for example, start up a company in a wild burst of entrepreneurial optimism) — but that is not to say they do not also suppress, slow down, or dampen the likelihood of action. Each emotion falls someplace on the opening-up/hiding-from-view spectrum and someplace on the motivating-action/suppressing-action spectrum.