In the philosophy of
So-called "type" identity theory asserts that each type of mental event, such as pain, is identical to some type of event in the brain, such as the firing of c-fibres. In response to objections based on the assumed "multiple realizability" of mental states, "token" identity theory makes the weaker claim that each token of a mental event, such as a particular pain, is identical to some token of a brain event of some type. See also {{link=mind-body problem">mind-body problem .