[In the following essay, Struik assesses and praises Engels' contributions and achievements in the philosophy of science. Struik's assessment focuses on Engels' Dialectics of Nature which, the critic explains, examines the “fundamental dialectical laws which govern the universe as well as the inquiring mind.”]

Outstanding among the thinkers of past generations are a few whose thought was so penetrating, whose vision so clear, that study of their works gives guidance to those who try to understand the principles underlying contemporary science. Leibnitz was one of them, and Hegel, despite all his vagaries, was another. Friedrich Engels belongs to this group of brilliant men.

Engels is always remembered, in the first instance, as the collaborator of Marx, and it is true that he had the advantage of constant stimulation by the greatest thinker of the nineteenth century. It is also true that Engels always considered himself the Number Two of the team. This tends to obscure the great merits of Engels himself as a thinker as well as a man of action. It is still necessary to stress the fact that Engels, in his own name, was a thinker of the very first rank, whose ideas are bound to influence not only world politics, but also the philosophy of science for many generations to come.

It is perhaps unfortunate that Engels never presented the world with a magnum opus, a fundamental treatise like Marx's Capital or Spinoza's Ethics. His ideas, even more than those of Leibnitz, were scattered in polemical books, in essays, in letters and in epigrammatical notes. Much of his fundamental work was only published in recent years, in his Dialectics of Nature. Many scientists and philosophers, caught in the common prejudice against working class materialism, have not yet taken notice of Engels' contributions, despite the appeals of scientists like Bernal, Haldane, Vavilov or Komazov.

How can we characterize Engels' work on the understanding of modern and past scientific trends? We can repeat Engels himself and explain that it consists in the search for the fundamental dialectical laws which govern the universe as well as the inquiring mind. Many people are suspicious of such explanation, since they are told that dialectics is a form of sophistry and that, after all, Engels took some laws of nature and squeezed them into a straitjacket of antiquated Hegelian formalism. It requires little study to see how ill this formulation fits the lively, alert and penetrating analysis to which Engels subjected the results of past and contemporary science. Let any one interested in understanding Engels read only the thirty-four pages of his Introduction to the Dialectics of Nature, and he will see how far Engels was from squeezing any facts into straitjackets. His efforts were rather concentrated on rescuing many a petrified notion from the straitjacket into which academic pedantry was wont to squeeze it. Dialectics, as Engels understood it, was liberation, not enslavement.

As a matter of fact, what else can be expected from such a humane being as Friedrich Engels was, alive to all important events in the world from England to China, a leader of the labor movement, a political analyst of the very first order, an economist with considerable business experience, a former soldier who kept abreast of all new military developments, a linguist who read Russian to understand agrarian conditions and Persian to enjoy the luxurious poetry of Hafiz? Marx used to worry about Engels' adventurous escapades on fox-hunts. When Engels, during the last years of his life, took to the study of natural science, he tackled this field not only in the best traditions of German scholarship, but also with the background of a man of the world in the best and noblest sense.

When, therefore, Engels undertook to formulate the general laws of nature and society as well as those of thought, and selected for this purpose the language of Hegel, he had good reason for it. The reason was that no better terminology had been invented, and, as far as I know, there is no substitute even now. Rather than reformulate these laws, we had better try to understand their meaning. Then we have treasure trove indeed.

The first law is that of the transformation of quantity into quality and vice versa. This means essentially that in nature as well as in society, in a manner fixed for each individual case, qualitative changes occur by the quantitative addition or subtraction of matter or energy, or both. What appears to one man as a change in quality, as for instance the difference in the properties of chloride and bromide, appears to the other as the difference of electrons in their atoms, in this case seventeen, and thirty-five respectively. And where another man may see only a difference in number, as in the pounds of weight on the camel's back, for the camel it may mean the difference between a healthy or an injured spine. Engels, who liked to trace the pertinence of the fundamental laws in all directions, quoted Napoleon as one of his authorities:

“Two Mamelukes were undoubtedly more than a match for three Frenchmen, 300 Frenchmen could generally beat 300 Mamelukes, and 1,000 Frenchmen invariably defeated 1,500 Mamelukes.”

Engels often illustrated the meaning of the fundamental laws of extremely simple examples, especially in his Anti-Duehring, which was written for the general public. This has occasionally disappointed sophisticated readers. Such an abstract and far-fetched way of saying that ten bushes make a copse, and 5,000 make a jungle! What escaped these good people is the universality of the law, which holds for bushes and beans and Mamelukes as well as for electrons and fibres and solar systems. Nobody who reads the recently published report on atomic energy by Prof. Henry D. Smyth can fail to see how profoundly quantitative difference, and very simple quantitative difference at that, affect the qualitative differentiation of matter. This fundamental character of Engels' law gives us the general confidence that quantitative analysis and synthesis may also bring the solution to riddles still unsolved, such as the further development of nuclear physics and the transformation of elements, the creation of new biological species, or the synthesis of living matter itself.

[Quantitative differences need not always be expressable in their simplest form, that is, in integer numbers. The difference between electricity and magnetism, for example, is reflected in a more complicated quantitative relationship. The late Prof. G. D. Birkhoff, however, has shown how subtle esthetic differences can already be based on very simple quantitative differences.]

But even if we grant all this, some critics have said, what is the use of this law anyhow? Does it teach us how a new biological or chemical process can be performed in a specific case? The answer, of course, is a decided no. No general principle can replace the patient work at desk or in laboratory. The more general the principle, the less it proclaims about a concrete application. The principles of evolution, or of transformation of energy, also establish guidance in research without prescribing the precise course of events. Yet there are few persons who deny their fundamental importance. Engels' fundamental principle is even more general than the principles of evolution or energy. It deserves to be tested, to be analyzed, rather than rejected. The present generation of scientists is, as a matter of fact, no longer in the mood of some of the old time positivists, who rejected the value of philosophical guidance for the benefit of science. Engels' formulation deserves serious study, and is beginning to get it.

Similar considerations can be applied to Engels' two other fundamental laws. The second of them is known as the interpenetration of opposites. Though Engels did not explain its meaning as carefully as he did with the first law, the principle is sufficiently clear. In the first place it expresses the fact that every thing or conception is meaningless without its opposite. This is sometimes trivial, as in man—no man, or warm—cold, but there are many cases where the study of opposites and their relation gives fundamental results as in the case of positive and negative electricity, attraction and repulsion, or the two magnetic poles. Engels' treatment of the relation of force and its manifestation, one as the active, the other as the passive side of motion, is quite modern, and in sharp contrast to the metaphysical approach common in his day, which treated force as having independent existence. This last example illustrates, moreover, that there is more to the law than mere relation of opposites. It establishes the fact that there are no rigid lines of separation in nature or society, that things that seem to be opposites will turn out to be different aspects of the same thing. The term “opposites” has to be understood in a broader sense than in classical logic, so that heredity and adaptation appear in their mutual relation, dominating in endless variety the development of living matter from protozoa to human beings. The main advances in scientific work have always been in the discovery of relations between categories which seem contrasted at the time of their discovery, between such categories as immutability and change, causality and statistics, life and death. Engels' analysis of the deep connections between casual and statistical relations, based on a materialist interpretation of certain places of Hegel's logic, belongs to the best work written on the subject.

The third law of dialectics is the negation of the negation, which in its abstract formulation seems to be one of the most sterile dicta concerning nature and society. What does it help us when, we pass from plus a to minus a, and from minus a back to plus a, or when we change water into ice and ice back to water? The word negation, moreover, seems something only applicable to specific human statements. Yet Hegel claimed this principle as the cornerstone of his whole system and Engels' formulation seems to bear it out. It is necessary to understand this conception of “negation” in a new and wider, objective sense, for which another term is difficult to find. Engels illustrated his interpretation by his famous example of the barley seed “negating” itself into a plant, and the plant “negating” itself into many seeds. In this way we find in the law of the negation of negation an outline of the process of creation, describing how new processes arise from previous ones. Almost every process in nature has the tendency to develop opposite processes to stop it, and in this process of stopping new and often more comprehensive processes develop. The evolution of living matter from elementary organisms to mammals follows such a route, and so does the formation of mountain ranges as well as the growth of an individual being. Even the evolution of matter itself, as we now begin to understand it, follows similar dialectical processes. Modern physics and chemistry has grown strong in the discovery of such chains of “contradictions” negating each other, as in the contrast of Newton's corpuscular theory of light versus Huygens' undulatory theory, at present “negated” in the quantum theory of light.

Let us allow ourselves another quotation.

“There are two principles that have been the cornerstone of modern physics. The first, that matter can be neither created nor destroyed but only altered in form, has led to the principal known as the law of conservation of matter. The second, that energy can be neither created nor destroyed but only altered in form, has ever since been the plague of inventors of perpetual-motion machines; it is known as the law of conservation of energy.”

“These two principles have constantly guided and disciplined the development and application of science. For all purposes they were unaltered and separate until some five years ago. For most practical purposes they still are so, but it is known that they are, in fact, two phases of a single principle, for we have discovered that energy may sometimes be converted into matter and matter into energy.”

This sounds like a typical quotation from Engels' Dialectics of Nature till we realize that “some five years ago” must be 1940. The quotation is taken from Professor Smyth's new book on atomic energy. The conversion of matter into energy has been observed in the nuclear fission of uranium, which releases an enormous amount of energy. This release of nuclear energy is dialectics of nature with a vengeance. In such events Engels used to speak of “cases which would have pleased old Hegel.” Modern science follows a direction which would have pleased “old” Engels.

By means of these detailed investigations of the science of his time and their interpretation as aspects of three general laws, Engels helped to accomplish still another task, the modernization of materialism. Every generation, from the Greeks till the present, has had its own interpretation of materialism and its principal tenets that ultimate reality is matter in motion and that both are uncreatable, that is, are their own final cause. Engels saw clearly that materialism on the basis of the old mechanics of Newton and Laplace was constantly becoming more untenable, and that the nineteenth-century materialists in their attempts to defend it only succeeded in crude vulgarization. He showed the way in which the ancient principles of the Ionian philosophers had to be elaborated in order to account for the revolutionary scientific discoveries of a new age. This enabled him, not only to sketch a unified presentation of the modern scientific method, but to look deeper into the nature of things than even many contemporary scientists.

Every reader of Engels' essays on the dialectics of nature must be struck by the masterful way in which he applied his method to the understanding of the past. The historian of science can find instruction and inspiration, and doubtless often challenge, in every page which Engels devoted to a discussion of men and systems of former days. This modern outlook is the more striking if we compare his writings to those of some outstanding historians of science of the middle of the nineteenth century, with a Whewell, a Libri, a De Morgan. Even compared with a modern author like Dampier his vision is remarkably fresh. Our young and exciting history of technology seems to move along the trails which Engels blazed, even without conscious reference to him. Both history of science and of technology can only profit by a serious study of the “Old General” of the labor movement.

We can therefore recommend the study of Engels' essays to philosophers, scientists and historians alike. The man whose work in the social field has contributed so much to the successes of the Soviet Union and with this to the one of the most fundamental phenomena of modern times deserves the full attention of all thinking men, indeed.