Start with the fact that needs explaining. We routinely criticise emotions, and not merely as unpleasant. We tell someone their anger is disproportionate, that their guilt is unearned, that their fear is irrational. These are not complaints about a sensation's intensity — they are claims that the emotion gets something wrong. Any adequate theory has to account for that.
Feeling theories struggle here. William James proposed the striking inversion that we do not tremble because we are afraid but are afraid because we tremble — the emotion just is the perception of bodily changes triggered by a situation. This captures something real: emotions do have a distinctive bodily character, and stripped of it, "fear" seems to name something else. But if an emotion is only a sensation, it is hard to see how it could be mistaken. Sensations are not the kind of thing that can be wrong about anything.
Judgement theories solve that directly. To fear something is, on this view, to judge that it is dangerous; to be angry is to judge that one has been wronged. Now the criticism makes sense — a fear is irrational when the danger judgement is false. This was essentially the Stoic position, and it has a striking practical consequence: if emotions are judgements, then changing what you believe changes what you feel, which is why Stoicism treats the work as cognitive rather than as suppression.
The problem is that judgement theories seem too intellectual. You can fear flying while sincerely believing it safe — and that is not simply a contradiction, it is an extremely common condition. The theory has to say either that you secretly believe flying is dangerous, which seems false, or that you are irrational in a stronger sense than the case warrants.
Perceptual theories are the most popular contemporary response. Emotions present the world as having evaluative features — as dangerous, offensive, unjust — much as vision presents it as having colours. This explains the phobia case elegantly, because perception is famously resistant to belief: knowing that two lines in an optical illusion are equal does not make them look equal. Your fear presents the flight as threatening; your belief says otherwise; the conflict is exactly what we observe.
Are emotions rational?Not the obstacle they are taken for.
The inherited picture sets reason against emotion, with emotion as interference. Philosophy has largely abandoned it. If emotions carry evaluations, they are a source of information — often faster and more reliable than deliberate reasoning, particularly about social situations and danger. Someone with no fear is not more rational; they are missing data.
This also reframes what it means to cultivate character. If emotions are evaluations, they can be educated rather than merely controlled. Aristotle's account of virtue depends on this: the virtuous person does not restrain inappropriate feelings but comes to feel appropriately — the right emotion, toward the right object, to the right degree. That is a demanding standard, and it is only coherent if a feeling can be correct in the first place.
It is worth marking a common misreading here. Stoicism is routinely described as recommending emotional suppression. What the Stoics actually held is that emotions follow from judgements, so the work happens at the level of what you believe about a situation. Someone who has genuinely stopped believing that reputation matters has nothing left to suppress.