FACTOID #53: If you thought Antarctica was inhospitable, think again - its land area is only ninety-eight percent ice. Reassuringly, the other 2% is categorised as "barren rock".
Socialism can refer to a political doctrine, an economic theory, a vision of an ideal society, or a description of an actually existing society.
In its broadest sense, socialism is a belief that human society can and should be organised along social lines - that is, for the benefit of all, rather than for the profit of a few, which it argued had been the case hitherto.
However: "By majority consent of both socialists and non-socialists, National Socialism (Nazism) and kindred movements are not considered to be socialist." (Salvadori) Despite Salvadori's statement, some right-wing groups (which wish to discredit socialism) do refer to Nazism as being socialist.
The inequity of inequality: egalitarian instincts and evolutionary psychology.
Evolutionary Psychology is a recent activity which brings psychology into the mainstream of biology, focused around the integrated study of "instincts" which are interpreted in cognitive terms as domain-specific, information-processing modules which have evolved to detect relevant stimuli in the external and internal environment and respond with adaptive behaviours (Hirschfield and Gelman, 1994; Charlton, 1995).
So, social democrats accept that inequality is inevitable (or even desirable) in modern society, but may passionately believe that current levels of inequality are excessive, that their magnitude ought to be reduced, and that such reduction would effect a qualitative transformation in equity and increase the sum of human gratification.