Assault is a general intent crime even though it requires a specific mental state. The distinction was made because this offense too often is associated with intoxication. However, assault with intent to murder is a specific intent crime. If the intent to murder is negated by intoxication or mental illness, then a defendant is found guilty of only assault. Arson is a general intent crime, so it also cannot be negated by intoxication.
Murder is a specific intent crime despite there being no further act required.
Defendants lacking the specific intent required for murder are found guilty of manslaughter. The distinction between murder and manslaughter developed to prevent individuals who killed another in a drunken brawl from receiving an automatic death penalty. Intoxication itself is no excuse for committing a crime. Since ancient times debate has existed as to whether intoxication should be partially excusing or whether it should increase the gravity of the crime. Saint Thomas Aquinas believed that intoxication should be partially excusing.