There isn't a lot of philosophical (or even psychological) work on schadenfreude -- the pleasure people sometimes feel at witnessing or hearing about (but not personally causing) the suffering of others. But the most prominent analyses treat it as a type of pleasure one feels seeing someone get their comeuppance. John Portman calls schadenfreude "an emotional corollary of justice" (2000, p. 197*). Aaron Ben-Ze'ev suggests that a typical feature is that the sufferer deserves the misfortune (1992, p. 41). Frans de Waal suggests that schadenfreude "derives from a sense of fairness" (1996, p. 85).
We could define schadenfreude as involving just deserts, for the sake of philosophical analysis. But doing so misses, we think, central cases that should be within the term's scope and which give it its uncomfortable moral coloring.
Consider that staple of "America's Funniest Videos", the groin shot:
It doesn't seem that these are instances of justice delivered. We are laughing at -- seemingly enjoying -- pain, indifferent to whether it is deserved. If we stipulate that schadenfreude requires desert, we would need a different name for this interesting phenomenon. But rather than do that, let's acknowledge that there are at least two different types of schadenfreude: just-deserts schadenfreude, when the bad guy finally gets what's coming to him, and the comic schadenfreude of America's Funniest Videos and FailBlog. Comic schadenfreude seems to require not justice but rather a kind of absurdity involving pain as an integral component. And unlike the schadenfreude of just deserts, where pleasure can sometimes be found when inexpiable wrongdoing is met with severe pain, comic schadenfreude might require that the injury (or pain) not be too serious.
Still another species of the genus seems to involve neither comic absurdity nor justice: the schadenfreude of grace.
Sweet it is, when on the great sea the winds are buffeting the waters, to gaze from the land on another's great struggles; not because it is pleasure or joy that any one should be distressed, but because it is sweet to perceive from what misfortune you yourself are free. Sweet is it too, to behold great contests of war in full array over the plains, when you have no part in the danger (On the Nature of Things, Book II.1ff., Bailey trans.).And Hobbes:
from what passion proceedeth it, that men take pleasure to behold from the shore the danger of them that are at sea in a tempest, or in fight, or from a safe castle to behold two armies charge one another in the field? It is certainly in the whole sum joy, else men would never flock to such a spectacle. Nevertheless there is in it both joy and grief. For as there is a novelty and remembrance of own security present, which is delight; so is there also pity, which is grief. But the delight is so far predominant, that men usually are content in such a case to be spectators of the misery of their friends (Human Nature, IX.19).
Evidently, people throughout the ages have found great pleasure standing atop the bluff in a storm, watching sailors below die on the rocks. Lucretius and Hobbes suggest, plausibly we think, that for many viewers an important part of the the pleasure derives from how salient another’s suffering makes your own safety by comparison. Similarly, perhaps, reading a history of war and genocide can put into perspective one's own complaints about the erroneous telephone bill and the journal rejections.
Indeed, the very fact that the suffering of the others is undeserved lends the schadenfreude of grace its particular bittersweet flavor. If the sailors or soldiers were fools or villains then it's maybe just harsh justice to see them die from their bad choices, and we have something closer to the schadenfreude of just deserts; but if they did nothing wrong or foolish and it could just as easily have been you, then it's both more a shame for them (the bitter) and also more vividly pleasing how lucky you yourself are (the sweet): There but for undeserved grace go I.
The schadenfreude of just deserts, comic schadenfreude, and the schadenfreude of grace do not exhaust the list of schadenfreudes, we think. There are at least two more: the schadenfreude of envy, and pathological forms of erotic schadenfreude (not to be confused with consensual play-acting sadism). We also suspect that these different types of schadenfreude can sometimes merge into a single complex emotion.
Probably no unified analysis of the psychological mechanisms suffices to cover all types, and they differ substantially in what they reveal about the moral character of the person who is moved by them. Comeuppance is only the start of it.
* Though comeuppance seems to be Portman's take-home message, his overall view is nuanced and anticipates some of the points of this post.