In this case Shame is to Guilt what Sociology is to Psychology; that is, the bigger, more social version of the smaller individual experience. Shame also suggests moral decrepitude whereas guilt suggests either error in judgment or some form of misdeed. The latter also highlights etiquette over ethics, i.e., focusing on behavior rather than principle, though in reality, it may impossible to totally separate the two. Shame seems to use poor self-esteem to amplify the effect of guilt. Others emphasize social feedback as one crucial factor in differentiating guilt and shame. Here is a quote from someone who sees the distinction in another light, altogether.
“Shame is closely related to guilt, but there is a key qualitative difference. No audience is needed for feelings of guilt, no one else need know, for the guilty person is his own judge. Not so for shame. The humiliation of shame requires disapproval or ridicule by others. If no one ever learns of a misdeed there will be no shame, but there still might be guilt. Of course, there may be both. The distinction between shame and guilt is very important, since these two emotions may tear a person in opposite directions. The wish to relieve guilt may motivate a confession, but the wish to avoid the humiliation of shame may prevent it.”–Paul Ekman
Guilt can result from errors committed by normal or healthy people; whereas, shame results from personal or group intrapersonal deficit, possibly also because of a faulty act, but not necessarily. For example, original sin is the result of birth status, not deed. However, there can be shame just as much in individuals. Members of Alcoholics Anonymous will frequently tout shame as their core personality experience when attending “AA” meetings. They frequently talk of always recovering, never being recovered because they are internally flawed, in this case by “character defects.” This is shame experienced individually, even though brought to the surface by a group. In short, shame seems to add the dimension of personal grieving for the loss of a bigger, deeper ideal (flaws in the sense of self or integration of aspects of self); whereas, guilt usually is more specific to action, not state (but again, not always).
Additionally, the social consequences of “getting caught” are seen as more important than the individual feelings or experiences of the agent. The Latin word for guilt is culpa, a word sometimes seen in law literature, for instance in mea culpa meaning “my fault (guilt),” again, referring to the smaller, not the larger experience.
Lastly, an individual has to believe the actions caused by the ingroup were unjustifiable, indefensible and unforgivable. If an individual can justify the actions of the ingroup, this will lessen collective guilt. Only when an individual views the ingroup actions as reprehensible will that individual feel collective guilt.
“Where all are guilty, no one is; confessions of collective guilt are the best possible safeguard against the discovery of culprits, and the very magnitude of the crime the best excuse for doing nothing.”–Hanna Arendt
Collective guilt is not only a result of feeling empathy for the outgroup, it can also be caused by self-conscious emotion that stems from questioning of the morality of the ingroup. The opposite is also true. If the actions of the ingroup are just, particularly if paired with equally reprehensible actions of the outgroup, then no collective guilt occurs, despite the possibly egregious acts the former perpetrates upon the latter. Witness the actions of so many righteous “warriors of religion” during the four, maybe five Crusades (depending upon which source is consulted). And, don’t forget what the Nazis did during the Holocaust, etc. (An indirect term sometimes used to express guilt is “denazification;” meaning, to rid the influence of the Nazis.) In each case thousands, even millions of lives were lost in the name of some higher value “exclusively owned” by the perpetrators.