Why should we model two-person random interactions in everyday human activity? If
we had to how would we model such interactions? This thesis tries to understand how
individuals will behave in 2-person everyday interactions as such interactions comprise
a substantial part of our everyday lives. It starts to answers these questions by reviewing
Adam Smith’s concepts of selfishness (self-interest) and altruism (benevolence) in his
books, An Inquiry into the Nature and Causes of the Wealth of Nations (1776) and The
Theory of Moral Sentiments (1790) to put this research into context. This literature
review is extended to strong reciprocity that develops on the ideas of selfishness and
altruism and explains how punishment can impact such behaviour. Game theory and
complex system are used to develop the 2-person random interaction model (2PRIM) in
order to explain the evolutionary dynamics of selfishness, altruism and strong
reciprocity within such interactions. Previous two-person models have not simulated
random interactions with strong reciprocity. Results show that selfishness increases
rapidly in such interactions and punishment has little or no impact in such situations.
However, an increase in the return on selfishness, common or public good or cost of
competition in 2PRIM can have a similar impact as strong reciprocity in such two-person
random interactions.