In philosophy, an accident is a property that its bearer has contingently—that is, a property which its bearer could have failed to have (without having failed to exist), had things been different.

Accidental properties are defined by contrast with essential properties—properties which their bearer could not fail to have without failing to exist (or failing to exist as what it is). Thus, for example, the high value of gold in the jewelry market is an accident of gold: if humans did not exist, or did not make jewelry, or found gold ugly, then gold would not have a high value in the jewelry market, but it would still be gold. Being metallic, on the other hand, is an essential property of gold: any substance that were non-metallic, whatever it might be, would not be gold.

See also: essence, modal logic