Rational choice theorists argue that thisis simply the result of social conditioning and isin any case quite arbitrary

if people are so self-centered, how is itpossible for society to exist at all?

The second element is that a rational[individual] has the capacity to allocate his [orher] scarce resources in such a way that[he/she] succeeds in maximizing utility. Thethird element is that the [individual] isself-regarding [selfish]. His/her motivation willalways be that his[or her] wellbeing is served.

instrumentalrationality

First, from all possible (andrelevant) action alternatives those alternativesare selected which are feasible. Second, fromthis set of alternatives the preferred one ischosen.