[Waddell reviews The Instincts of the Herd in Peace and War, and deems it an outstanding examination of society's primary influences.]

Wilfred Trotter, 1872-1939, was one of the foremost surgeons of his time and for many years an outstanding figure in British medicine. He was a humanist of great intellectual power, widely admired for his clinical wisdom and surgical craftsmanship and his inspiring gifts as a teacher. He devoted considerable attention to social psychology to which he made an original and valuable contribution by The Instincts of the Herd in Peace and War.

The book is a collection of essays written between 1905 and 1919. The early essays were published in The Sociological Review in 1908-9, and the whole series was published in book form in 1919. It has had a very considerable vogue and influence and has become a classic in the literature of psychology. The Oxford University Press has now published a definitive library edition. A number of errors in the text of the original edition have been corrected, a detailed index has been provided, and an appendix sets out the history of the manuscript and a number of passages in it which were omitted by Trotter from its printed form.

As the author says, “the chief purpose of the book was to expound the conception that psychology is a science useful in actual affairs.” It was his aim to offer an explanatory and guiding light on the tragic and irrational events that preceded and continued through the first world war. He was thus concerned with social events and, in particular, with national morale in war and peace.

Trotter's thesis is that the social nature of human organisation has the same foundation as that of the gregarious animals and insects namely, the herd instinct. Man's gregarious nature had long been recognised but Trotter was the first to proclaim its basic importance and to attribute it to the herd instinct.

He observes that the attempts to explain man's behaviour by the prompting of such obvious instincts as self preservation, nutrition and sex failed because “man, in spite of his obvious duty to the contrary, would continue so often not to preserve himself, not to nourish himself and to prove resistant to the blandishments of sex.” He suggests that behaviour would be more adequately explained by the additional supposition of a herd or social instinct which would appear chiefly as modifying towards group ends, the individualism of the other instincts “and leading to new combinations in which the primitive instinctual impulse was unrecognisable as such.”

Trotter then asks if there are biological reasons for ascribing the herd instinct to man. He compares the characteristics of human society with that of animals and insects whose gregariousness is manifested by an instinctual pattern of behaviour. He notes the evolutionary significance of the fact that the transition from the solitary to the social organism modified the nature of the unit upon which natural selection acted unchecked. The individual was thus enabled to acquire specialised qualities which would have involved his extinction had he been a vulnerable solitary unit. Such a transition would be preserved by inherited social traits. Trotter concludes that, from the biological point of view, the probability of the herd instinct being a primitive and fundamental quality in man is considerable.

The bulk of the essays is given up to an examination of aspects of social behaviour and a number of then current events to see if they can be aptly explained in terms of a herd instinct and so confirm the biological probability. Trotter outlines man's more obvious gregarious characteristics as follows:

1. He is intolerant or fearful of solitude, physical or mental. From this springs his religious needs and feelings, and his conservatism or resistiveness to new ideas the acceptance of which would isolate him, even briefly, from other members of the herd. Herd is used to mean any social group which shows solidarity such as one's country, class, club, political party, etc.

2. He is more sensitive to the voice of the herd than to any other influence. This characteristic the author terms “suggestibility”. Because of it opinions bearing the stamp of authority or herd approval are accepted even though contrary to experience and reason. Suggestibility does not denote a preference for the irrational, but for herd opinion whether rational or not.

3. He is subject to the passions of the pack in his mob violence and the passions of the herd in his panics.

4. He is remarkably susceptible to leadership and here his gregarious qualities result in the acceptance of leaders for reasons mainly unconnected with their fitness for rational guidance of the destinies of the group.

5. His relations with his fellows are dependant upon the recognition of him as a member of the herd.

Man differs from other gregarious species because of his large mental capacity and consequent wide freedom of response to instinctive impulses. Mental capacity in no way limits the impulsive power of instinct, but by providing an infinite number of channels in which the impulse is free to flow, may actually prevent the impulse from obtaining the goal of its normal object. This does not impair the potential impulsive strength of the instinct. Nor does the apparent rationality of an action mean that it is not due to instinctive impulsion. Trotter believes that man's intellect with its capacity for purpose as distinct from and additional to desire, introduces a factor virtually new to the biological series.

He notes that in the society of the bee two leading characteristics are evident “—an elaborate and exact specialisation of the individual and a perfect absorption of the interests of the individual in those of the hive.” He claims that “this combination of specialisation and moral homogeneity should be evident in human society if it is taking advantage of its biological resources.”

Trotter believes that man's gregarious qualities contain the seeds of the destruction of his civilisation unless understood and directed into fields which enable him to make the most of his biological possibilities. Rational statecraft should be based on such an understanding.

The author freely admits that his method is speculative. For his work he makes two claims, that it indicates useful and necessary lines of enquiry, and that his conclusions have some use in the conduct of affairs.

In his essay of 1919 he is able to point out that in that of 1915 he deduced that the morale of England and Germany was founded on different social factors and that German morale depended on leadership and would collapse if not nourished on attack and success, and that it would not support fighting on German soil. This analysis was borne out by the course of the war. English morale he said was based on social homogeneity, not on leadership, and as a practical measure for improving it he advocated abolition of privilege and class barriers. No such policies were then adopted, but by the time of the second world war, the lesson had been learnt and morale was supported by the promise and execution of widespread social reforms.

In modern psychology the word instinct is regarded as apt only to describe the unlearned, and often complex, action patterns of animals and insects due to inheritance. Such morale depended on leadership and action patterns are rare in adult human beings. But there are many human actions motivated by unlearned and inherited motives or trends such as the sex motive or the social motive. Trotter uses the word in the first sense and also as meaning an inherited motive or trend. The modern usage is a refinement of language which does not affect the structure of his argument.

The interest of this book is by no means historical only. There is as yet no general agreement as to whether man's social characteristics are the result of an inherited trend or of social learning. The role of instinct has not yet been satisfactorily charted, many psychologists holding that instincts do not survive in their original form but tend to fuse with one another, and that behaviour cannot adequately be accounted for in terms of primitive instincts. This book is a brilliant and persuasive exposition of the theory that instincts in their primitive form have a constant and decisive effect on human conduct and that man's social solidarity is the result of the gregarious instinct.

It is also noteworthy for an interesting analysis of English and German national characteristics, its theory of conflict in the individual between the dictates of the social and the other instincts, and its perceptive and stimulating comment on the many irrational aspects of human society. In the light of what is now known, Trotter is guilty of some over-simplification, but this criticism goes to detail rather than to the basis of his argument.