This question arises infrequently probably because it is assumed to be an “obvious” response to certain events. Is it obvious? I do not believe so.
Those who have attempted to answer the question have not done so. Instead they have simply described emotional events associated with grief (Kubler Ross). That does not advance causality.
In posing the question, the unique behavioural features of grief need to be considered. The first is that grief is almost universal to humans. In that tiny minority who do not express grief, there is a parallel lack of other emotions, as in Autism, which demonstrates that grief has a neurological basis, by this association. The expression of grief is striking in its universal behaviour pattern. This is why it can be divided, with consistency, into a number of emotional subsets. These are remarkably consistent.
Grief does not appear to be quantitative although it is strongly qualitative. It does not seem that grief can be “multiplied” by the number of stimulants to grief. The intensity of grief is, however, varied by the degree of proximity of the grieving individual to the source of the grief, and the period of association between the two. Another interesting factor is that the more an individual has contributed to society, the more widespread the grief, albeit with less intensity.
It is proposed that for the conglomerate of individuals comprising the social unit of human society, grief plays an exact parallel with pain in a single individual.
Like pain the purpose of grief is to avoid future injury and death. Therefore the enhanced and intense emotions of grief will focus on, identify and demonstrate the causes that danger. One of the strongest emotions of the grieving individual is questioning the cause of death, injury or loss. The first question usually asked after being informed of a death, is “what was the cause?” and then “When was the death?” which allows the death to be put into the context prevailing at that moment.
This is so consistent as to be almost universal. Exactly in parallel with that, a painful injury to the individual is instantly associated with a search for the cause of the pain, (and emphasises a strategy to prevent future injury.)
Therefore at individual level, the object of pain is to instil precaution in relation to an external source of threat. With grief, an exactly similar emotion emphasises to a social group an enquiry into circumstances which could cause death, injury or loss. It is a warning mechanism and one which causes the group nearest the object of the grief to intensely consider the context in which damage to that sector of society might have occurred and that it should be avoided in the future.
To put it crudely, the dead individual can feel no pain and hence can learn no lesson from the cause of death. Society, on the other hand, needs to focus on that cause of death, and feels grief in order to protect itself from a similar future event.