Aggression is a polyvalent, equivocal and elusive concept. J. M. G. va
n der Dennen (1980) has listed 106 more or less different definitions
of aggression and related concepts such as agonistic behavior and viol
ence. Aggression has been variously conceptualized. Controversies reig
n over many questions, e.g. whether aggression is an unitary construct
or a multifactorial one, whether to include or exclude violence, etc.
In psychology, G. V. Caprara (1992, 1994) represents a change from th
e unitary conception of aggression towards the specifying one includin
g tolerance towards violence. A most representative survey concerning
main theories of human aggression, violence, and the predominant role
of threat perception and fear in all kinds and forms of human aggressi
on and violence are presented in many studies and books by J. M. G. va
n der Dennen.