While Robert Weiss offers us a reductionistic view of human behavior centering on emotion, Peter Straton counters with a reductionistic view of human behavior centering on rational thinking.  Each looks through their respective, limited lens.  For a more complete view of human behavior, good and bad, I'd suggest reading Robert M. Sapolsky's (Stanford Professor) book "Behave:  The Biology of Humans at Our Best and Worst."  In that 717 page tome Sapolsky outlines and then elaborates on myriad contributors to behavior and illuminates a complexity that easily eclipses Weiss' and Straton's narrow views, and still does not claim to be exhaustive.