today includes studies of processes within individuals, where relations
with neurophysiology are being established;
studies of the behavior of individuals in isolation or when interacting
with machines; and studies of individuals in groups. Research has been
concerned primarily with questions of causation and development, therein
differing from research on behavior carried out by biologists, who have
been interested also in questions of the biological function and evolution
Most of the psychological research relevant to war has been concerned
not with the causes of war as such but with its conduct for instance,
with the selection of military personnel, the behavior of soldiers in
and out of battle, the maintenance of morale, the performance of human
operators in charge of war machines, and the design of such machines
to optimize performance. Developments in psychology permitted increased
sophistication in the selection of personnel in World War II, especially
in officer selection; and the increasing complexity of war machines
requires designs compatible with human capabilities, so that considerable
psychological research has been devoted to such topics as the vigilance
of radar operators and other aspects of human performance. For these
purposes psychology has employed both experimental approaches in appropriately
controlled but contrived situations, and "field" data from real-life
situations. Such studies have had strictly specified practical objectives,
but they have had some impact on psychological theorizing: there have
been, for instance, notable advances in control theory stemming from
military research, and in theories of habituation and memory from the
work on human performance.
Since the monumental studies of war summarized by Quincy Wright
(1965), considerable efforts have been made to establish links between
psychology and other disciplines. In forging those links, psychologists
have become increasingly interested in principlesdrawn from
biology, but are rightly distrustful of analogies between the
behavior of particular animal species and particular human practices:
there are so many animal species, and so many human cultures, that analogies
to back up any thesis are always available. The resemblances of conflicts
between ant colonies and international war are entirely superficial,
and even the inter-group conflicts of chimpanzees lack all the defining
features (see below) of international war
More importantly, the last fifty years have seen intense efforts to
link advances in endocrine and neurophysiology with individual functioning
(e.g., Damasio, 1994),
to relate the behavior of individuals to their social situation and
group membership (Turner et
al., 1994), and to incorporate the insights of sociology and anthropology
on the role of culture (Hinde, 1987,1997).
It is with such issues that this essay is primarily concerned, because
they throw light not on the causes of particular wars, but on how it
is that individuals are prepared to accept the horrors of war.
A linguistic point is first necessary. In everyday speech we speak of
one individual behaving aggressively to another, and we use exactly
the same words when speaking of two nations, each with a population
of many million individuals. The factors that increase the likelihood
of aggression between individuals are not the same as those that increase
the likelihood of war between states; the processes are quite dissimilar.
Again, some ascribe the propensity to harm other individuals to assertiveness
and even associate it with creativity (Lorenz, 1966;
1991). This is simply wrong: an assertive salesman does not hit
his clients, and the motivational bases of assertiveness have little
in common with those of aggressiveness, though they may contribute to
aggressive acts. To say that, without man's aggressive capabilities,
"humans would never have been able to build cathedrals, fight disease,
or devise scientific theories" (Mansfield,
1991) is absurd.
To anticipate the argument made here, in order to understand any aspect
of human social behavior it is necessary both to distinguish successive
levels of complexity physiological/psychological processes within
individuals, individual behavior, interactions, relationships, groups,
and societies and to come to terms with the relations between
them. Each of these levels affects and is affected by those adjacent
to it, and each also affects and is affected by the socio-cultural structure
of beliefs, norms, values, and institutions with their constituent roles.
Thus, in the present context, an aggressive interaction between two
individuals, group aggression, and the societal phenomena of war can
be described in similar words, but they differ in many respects. For
instance, group aggression may involve individual aggressive propensities
but also issues of group dynamics irrelevant to the behavior of individuals;
and war involves issues of group dynamics but must be seen also as an
institution with its constituent roles. This paper therefore discusses
three examples of aggression to illustrate the continuum from individual
aggression through group, religious, and ethnic conflicts to international
order to discuss
these three paradigmatic cases of individual aggression, intergroup
aggression, and international war, a digression explicating both the
distinctions between successive levels of social complexity and the
relations between them is first necessary.
The first two levels are the province of individual psychology/physiology
processes within individuals (which could, of course, be further
subdivided into intracellular, cellular, organic, and so on) and individual
Moving to social psychology, an interaction is defined as involving
at least two individuals and lasting only a brief span of time. During
an interaction the behavior of each individual is influenced by his/her
own goals and by the norms and values held, by perceptions of those
of the other, and by the context. Each participant seeks to understand
the goals and strategies of the other and to realize his/her own so
far as possible.
In terms of the behavior involved, a relationship involves a
series of interactions between two individuals, each interaction being
influenced by past ones and, often, by expectations of further interactions
in the future. Thus a brief conversation between two strangers would
constitute an interaction, but next time they met they would be influenced
by the first interaction, and start to have a relationship. Of course,
behavior is not all: relationships continue in the absence of interactions
and involve wishes, emotions, judgments, and so on.
Each relationship is usually nested within a network of other relationships.
These may constitute a psychological group, namely one whose
members define themselves and are defined as a group and see themselves
as interdependent, and whose interactions are mediated, at least to
some extent, by rules and norms more or less characteristic of the group
An individual may belong to several groups. A collection of groups whose
membership may or may not overlap, but whose members recognize the groups
as constituents in a larger unit, constitute a society. Group
processes may operate to augment the cohesiveness of the society.
Three points about these levels of complexity must be emphasized.
each level has properties that are not relevant to the level below.
Thus a relationship may involve one or many types of interaction
a property not relevant at the interaction level. And a group may
be structureless, centrifocal, hierarchical, and so on properties
not relevant to the relationships within it.
we tend to use different explanatory concepts at each level. We might
see nationalism as a factor in aggression at the societal level, sibling
rivalry at the relationship level, and acquisitiveness at the individual
each level affects and is affected by the others. For instance, a
relationship is affected both by its constituent interactions and,
since A's relationship with B is affected by B's relationship with
C, by the group in which it is embedded. And the nature of a group
is affected by the relationships of the individuals within it and
by the society of which it forms part. Here it is also necessary to
bring in an anthropological/ sociological perspective, for each level
affects and is affected by the socio-cultural structure that
is, by the values, norms, institutions, and so on accepted
by the individuals concerned, and by the relations between those values.
Thus a norm of group loyalty affects the behavior of its members,
and the behavior of the individuals affects the group norm.
The relations between these levels can be seen as dialectical, in
the sense that new "truth" is continually emerging from their reciprocal
interaction. The successive levels of complexity, including that of
the individual, must be regarded not as entities but as processes
in continuous creation, maintenance, or degradation mediated by internal
factors and by the dialectical relations with other levels (Hinde, 1997).
We shall return to these dialectical relations between levels repeatedly
in later sections. In the meantime, it will be apparent that their
importance for understanding the phenomena of war depends on the precise
question being asked. Analyses of the causes of war in political,
economic, or historical terms are likely to focus on the dialectics
between societies and their socio-cultural structures. Understanding
the causes and course of a particular war would involve also reference
to group processes and to the relationships of and interactions between
the leaders on each side, as well as to the behavior of individuals.
The following sections, therefore, consider some of the factors involved
in individual and group aggression before considering how each contributes
to institutionalized war.