Murder is classified by humans as a subset of killing according to their cultural attitudes and the political climate. In nature, killing is an intrinsic and essential element of its self-recycling process, but for humans, killing is enmeshed with a complex and socially biased range of evaluations. The classifications of types of killing such as 'harvesting', 'slaughtering', 'euthanasia', 'revenge', 'murder', 'manslaughter', 'cleansing' and so on, can be quite different from one culture to another, and from one dominant political force to another. Opposing intercultural attitudes confound even further the ways in which 'assassinations', 'war casualties', 'executions', 'co-lateral damage' and 'ethnic purges' are to be evaluated.

Murder is the socially internal classification of a killing which is legally disapproved of by the controlling authority and which generally carries a severe retribution. The controlling authority of a society usually classifies a killing as that of murder when the act was deemed to be performed as a means of facilitating the self-interest of one or more individuals. Within a society therefore, killings motivated by robbery, inheritance, revenge, reward, pleasure, etc, are usually classified as murder, but would not necessarily be so considered if they were perpetrated on individuals of another society in a war setting. Murder is an in-house happening between individuals with a minimum of socio-political implications. No culture ever classifies as murder the killing of sacrifices, gladiators, battle enemies, espionage agents, deserters, or the promoters of treason.

Murder is an on-going social reality. It is often an aggressive killing performed as a supposed solution to a problem and has been practised by humans from palaeontological times... for a more diverse and creative range of problem-solving motives than that displayed by other species. It is seemingly enjoyed vicariously or by active participation by a significant proportion of any population... as evidenced by the numerous public executions and blood sports that have been organized thruout history... so that it is widely simulated as entertainment in television and films. By this means, the extensive promotion of methods, the suggestion of suitable motives, the range of precautions needed to avoid detection and the ready availability of reality-distorting drugs, is proving to be quite successful in ensuring that any individual or group contemplating such an acts is fully informed and up to date.

One of the few cases where a killing for self-benefit ought not be classified as murder... nor even be subject to any form of retribution... is when it is committed in self-defence from an unprovoked attack. It is impossible for any intended victim to divine the intentions, abilities, strength, or mental condition of the individual or individuals that are initiating an unprovoked assault. Such events usually occur so unexpectedly, that there is neither time to fully evaluate the situation nor the expectation of any assistance whatsoever from police authorities or the advice of sophisticated legal advocates. Any aspiring aggressive murderers do not usually anticipate being killed themselves by their intended victim, yet they should expect nothing less. Any misfortune that is implicated in an attempt to murder... whether that be some form of delusional state or not... must attach to the perpetrator and not the intended victim. The practice of providing support and sympathy for the perpetrator at the expense of the victim is a grotesque perversion. In cases where provocation is a factor, no laws could ever devise adequate simplifications to account for the complexities of human stupidity and circumstances. Any socially sanctioned response will have to be evaluated on a case by case basis, with the implications carefully weighted and influenced by a pragmatic and secular altruism.