PART 1 
GENERAL PRINCIPLES OF COLLECTIVE 
PSYCHOLOGY 
CHAPTER II 
THE MENTAL LIFE OF THE CROWD 
IT is a notorious fact that, when a number of men think and feel 
and act together, the mental operations and the actions of each 
member of the group are apt to be very different from those he would 
achieve if he faced the situation as an isolated individual. Hence, 
though we may know each member of a group so intimately that 
we can, with some confidence, foretell his actions under given 
circumstances, we cannot foretell the behaviour of the group from 
our knowledge of the individuals alone. If we would understand and 
be able to predict the behaviour of the group, we must study the 
way in which the mental processes of its members are modified 
in virtue of their membership. That is to say, we must study the 
interactions between the members of the group and also those 
between the group as a whole and each member. We must examine 
also the forms of group organisation and their influence upon the 
life of the group. 
Groups differ greatly from one another in respect of the kind and 
degree of organisation they possess. In the simplest case the group 
has no organisation. In some cases the relations of the constituent 
individuals to one another and to the whole group are not in any 
way determined or fixed by previous events: such a group constitutes 
merely a mob. In other groups the individuals have certain deter- 
minate relations to one another which have arisen in one or more 
of three ways: 
(1) Certain relations may have been established between the 
individuals, before they came together to form a group; for 
example, a parish council or a political meeting may be formed 
by persons belonging to various definitely recognised classes, and 
their previously recognised relations will continue to play a part in