The following work is by no means the fruit of any "inner urge". On the contrary.
When three years ago Herr Dühring, as an adept and at the same time a reformer of socialism, suddenly issued his challenge to his age, friends in Germany repeatedly urged on me their desire that I should subject this new socialist theory to a critical examination in the central organ of the Social Democratic Party, at that time the Volksstaat. They thought this absolutely necessary if the occasion for sectarian divisions and confusions were not once again to arise within the Party, which was still so young and had but just achieved definite unity.  They were in a better position than I was to judge the situation in Germany, and I was therefore duty bound to accept their view. Moreover, it became apparent that the new convert was being welcomed by a section of the socialist press with a warmth which it is true was only extended to Herr Dühring's good will, but which at the same time also indicated that in this section of the Party press there existed the good will, precisely on account of Herr Dühring's good will, to take also, without examination, Herr Dühring's doctrine into the bargain.  There were, besides, people who were already preparing to spread this doctrine in a popularised form among the workers.  And finally Herr Dühring and his little sect were using all the arts of advertisement and intrigue to force the Volksstaat to take a definite stand in relation to the new doctrine which had come forward with such mighty pretensions. 
Nevertheless it was a year before I could make up my mind to neglect other work and get my teeth into this sour apple. It was the kind of apple that, once bitten into, had to be completely devoured; and it was not only very sour, but also very large. The new socialist theory was presented as the ultimate practical fruit of a new philosophical system. It was therefore necessary to examine it in the context of this system, and in doing so to examine the system itself; it was necessary to follow Herr Dühring into that vast territory in which he dealt with all things under the sun and with some others as well. That was the origin of a series of articles which appeared in the Leipzig VorwÃ¤rts, the successor of the Volksstaat, from the beginning of 1877 onwards and are here presented as a connected whole.
It was thus the nature of the object itself which forced the criticism to go into such detail as is entirely out of proportion to the scientific content of this object, that is to say, of Dühring's writings. But there are also two other considerations which may excuse this length of treatment. On the one hand it gave me, in connection with the very diverse subjects to be touched on here, the opportunity of setting forth in a positive form my views on controversial issues which are today of quite general scientific or practical interest. This has been done in every single chapter, and although this work cannot in any way aim at presenting another system as an alternative to Herr Dühring's "system", yet it is to be hoped that the reader will not fail to observe the connection inherent in the various views which I have advanced. I have already had proof enough that in this respect my work has not been entirely fruitless.
On the other hand, the "system-creating" Herr Dühring is by no means an isolated phenomenon in contemporary Germany. For some time now in Germany systems of cosmogony, of philosophy of nature in general, of politics, of economics, etc., have been springing up by the dozen overnight, like mushrooms. The most insignificant doctor philosophiae and even a student will not go in for anything less than a complete "system". Just as in the modern state it is presumed that every citizen is competent to pass judgment on all the issues on which he is called to vote; and just as in economics it is assumed that every consumer is a connoisseur of all the commodities which he has occasion to buy for his maintenance -- so similar assumptions are now to be made in science. Freedom of science is taken to mean that people write on every subject which they have not studied, and put this forward as the only strictly scientific method. Herr Dühring, however, is one of the most characteristic types of this bumptious pseudo-science which in Germany nowadays is forcing its way to the front everywhere and is drowning everything with its resounding -- sublime nonsense. Sublime nonsense in poetry, in philosophy, in politics, in economics, in historiography, sublime nonsense in the lecture room and on the platform, sublime nonsense everywhere; sublime nonsense which lays claim to a superiority and depth of thought distinguishing it from the simple, commonplace nonsense of other nations; sublime nonsense, the most characteristic mass product of Germany's intellectual industry -- cheap but bad -- just like other German-made goods, only that unfortunately it was not exhibited along with them at Philadelphia.  Even German socialism has lately, particularly since Herr Dühring's good example, gone in for a considerable amount of sublime nonsense, producing various persons who give themselves airs about "science", of which they "really never learnt a word".  This is an infantile disease which marks, and is inseparable from, the incipient conversion of the German student to Social Democracy, but which our workers with their remarkably healthy nature will undoubtedly overcome.
It was not my fault that I had to follow Herr Dühring into realms where at best I can only claim to be a dilettante. In such cases I have for the most part limited myself to putting forward the correct, undisputed facts in opposition to my adversary's false or distorted assertions. This applies to jurisprudence and in some instances also to natural science. In other cases it has been a question of general views connected with the theory of natural science -- that is, a field where even the professional natural scientist is compelled to pass beyond his own speciality and encroach on neighbouring territory -- territory on which he is therefore, as Herr Virchow has admitted, just as much a "semi-initiate" a as any one of us. I hope that in respect of minor inexactitudes and clumsiness of expression, I shall be granted the same indulgence as is shown to one another in this domain.
Just as I was completing this preface I received a publishers' notice, composed by Herr Dühring, of a new "authoritative" work of Herr Dühring's: Neue Grundgesetze zur rationellen Physik und Chemie. Conscious as I am of the inadequacy of my knowledge of physics and chemistry, I nevertheless believe that I know my Herr Dühring, and therefore, without having seen the work itself, think that I am entitled to say in advance that the laws of physics and chemistry put forward in it will be worthy to take their place, by their erroneousness or platitudinousness, among the laws of economics, world schematism, etc., which were discovered earlier by Herr Dühring and are examined in this book of mine; and also that the rhigometer, or instrument constructed by Herr Dühring for measuring extremely low temperatures, will serve as a measure not of temperatures either high or low, but simply and solely of the ignorant arrogance of Herr Dühring.
London, June 11, 1878
I had not expected that a new edition of this book would have to be published. The subject matter of its criticism is now practically forgotten; the work itself was not only available to many thousands of readers in the form of a series of articles published in the Leipzig VorwÃ¤rts in 1877 and 1878, but also appeared in its entirety as a separate book, of which a large edition was printed. How then can anyone still be interested in what I had to say about Herr Dühring years ago?
I think that I owe this in the first place to the fact that this book, as in general almost all my works that were still current at the time, was prohibited within the German Empire immediately after the Anti-Socialist Law  was promulgated. To anyone whose brain has not been ossified by the hereditary bureaucratic prejudices of the countries of the Holy Alliance,  the effect of this measure must have been self-evident: a doubled and trebled sale of the prohibited books, and the exposure of the impotence of the gentlemen in Berlin who issue prohibitions and are unable to enforce them. Indeed the kindness of the Imperial Government has brought me more new editions of my minor works than I could really cope with; I have had no time to make a proper revision of the text, and in most cases have been obliged simply to allow it to be reprinted as it stood.
But there was also another factor. The "system" of Herr Dühring which is criticised in this book ranges over a very wide theoretical domain; and I was compelled to follow him wherever he went and to oppose my conceptions to his. As a result, my negative criticism became positive, the polemic was transformed into a more or less connected exposition of the dialectical method and of the communist world outlook championed by Marx and myself -- an exposition covering a fairly comprehensive range of subjects. After its first presentation to the world in Marx's Misére de la philosophie and in the Communist Manifesto, this mode of outlook of ours, having passed through an incubation period of fully twenty years before the publication of Capital, has been more and more rapidly extending its influence among ever widening circles, and now finds recognition and support far beyond the boundaries of Europe, in every country which contains on the one hand proletarians and on the other undaunted scientific theoreticians. It seems therefore that there is a public whose interest in the subject is great enough for them to take into the bargain the polemic against the Dühring tenets merely for the sake of the positive conceptions developed alongside this polemic, in spite of the fact that the latter has now largely lost its point.
I must note in passing that inasmuch as the mode of outlook expounded in this book was founded and developed in far greater measure by Marx, and only to an insignificant degree by myself, it was self-understood between us that this exposition of mine should not be issued without his knowledge. I read the whole manuscript to him before it was printed, and the tenth chapter of the part on economics ("From Kritische Geschichte") was written by Marx  but unfortunately had to be shortened somewhat by me for purely external reasons. As a matter of fact, we had always been accustomed to help each other out in special subjects.
With the exception of one chapter, the present new edition is an unaltered reprint of the former edition. For one thing, I had no time for a thoroughgoing revision, although there was much in the presentation that I should have liked to alter. Besides I am under the obligation to prepare for the press the manuscripts which Marx has left, and this is much more important than anything else. Then again, my conscience rebels against making any alterations. The book is a polemic, and I think that I owe it to my adversary not to improve anything in my work when he is unable to improve his. I could only claim the right to make a rejoinder to Herr Dühring's reply. But I have not read, and will not read, unless there is some special reason to do so, what Herr Dühring has written concerning my attack ; in point of theory I have :finished with him. Besides, I must observe the rules of decency in literary warfare all the more strictly in his regard because of the despicable injustice that has since been done to him by the University of Berlin. It is true that the University has not gone unpunished. A university which so abases itself as to deprive Herr Dühring, in circumstances which are well known, of his academic freedom  must not be surprised to find Herr Schweninger forced on it in circumstances which are equally well known.
The only chapter in which I have allowed myself some additional elucidation is the second of Part III, "Theoretical". This chapter deals simply and solely with the exposition of a pivotal point in the mode of outlook for which I stand, and my adversary cannot therefore complain if I attempt to state it in a more popular form and to make it more coherent. And there was in fact an extraneous reason for doing this. I had revised three chapters of the book (the first chapter of the Introduction and the first and second of Part III) for my friend Lafargue with a view to their translation into French  and publication as a separate pamphlet and after the French edition had served as the basis for Italian and Polish editions, a German edition was issued by me under the title: Die Entwicklung des Sozialismus von der Utopie zur Wissenschaft. This ran through three editions within a few months, and also appeared in Russian  and Danish translations. In all these editions it was only the chapter in question which had been amplified, and it would have been pedantic, in the new edition of the original work, to have tied myself down to its original text instead of the later text which had become known internationally.
Whatever else I should have liked to alter relates in the main to two points. First, to the history of primitive society, the key to which was provided by Morgan only in 1877. But as I have since then had the opportunity, in my work: Der Ursprung der Familie, des Privateigenthums und des Stoats (Zurich, 1884) to work up the material which in the meantime had become available to me, a reference to this later work meets the case. The second point concerns the section dealing with theoretical natural science. There is much that is clumsy in my exposition and much of it could be expressed today in a clearer and more definite form. I have not allowed myself the right to improve this section, and for that very reason am under an obligation to criticise myself here instead.
Marx and I were pretty well the only people to rescue conscious dialectics from German idealist philosophy and apply it in the materialist conception of nature and history. But a knowledge of mathematics and natural science is essential to a conception of nature which is dialectical and at the same time materialist. Marx was well versed in mathematics, but we could keep up with natural science only piecemeal, intermittently and sporadically. For this reason, when I retired from business and transferred my home to London,  thus enabling myself to give the necessary time to it, I went through as complete as possible a "moulting", as Liebig calls it,  in mathematics and the natural sciences, and spent the best part of eight years on it. I was right in the middle of this "moulting" process when it happened that I had to occupy myself with Herr Dühring's so-called natural philosophy. It was therefore only too natural that in dealing with this subject I was sometimes unable to find the correct technical expression, and in general moved with considerable clumsiness in the field of theoretical natural science. On the other hand, my lack of assurance in this field, which I had not yet overcome, made me cautious, and I cannot be charged with real blunders in relation to the facts known at that time or with incorrect presentation of recognised theories. In this connection there was only one unrecognised genius of a mathematician a who complained in a letter to Marx  that I had made a wanton attack upon the honour of [the square root of minus one].
It goes without saying that my recapitulation of mathematics and the natural sciences was undertaken in order to convince myself also in detail -- of what in general I was not in doubt -- that in nature, amid the welter of innumerable changes, the same dialectical laws of motion force their way through as those which in history govern the apparent fortuitousness of events; the same laws which similarly form the thread running through the history of the development of human thought and gradually rise to consciousness in thinking man; the laws which Hegel first developed in all-embracing but mystic form, and which we made it one of our aims to strip of this mystic form and to bring clearly before the mind in their complete simplicity and universality. It goes without saying that the old philosophy of nature -- in spite of its real value and the many fruitful seeds it contained *1 -- was unable to satisfy us. As is more fully brought out in this book, natural philosophy, particularly in the Hegelian form, erred because it did not concede to nature any development in time, any "succession", but only "co-existence". This was on the one hand grounded in the Hegelian system itself, which ascribed historical evolution only to the "spirit", but on the other hand was also due to the whole state of the natural sciences in that period. In this Hegel fell far behind Kant, whose nebular theory had already indicated the origin of the solar system,' and whose discovery of the retardation of the earth's rotation by the tides also had proclaimed the doom of that system. And finally, to me there could be no question of building the laws of dialectics into nature, but of discovering them in it and evolving them from it.
But to do this systematically and in each separate department, is a gigantic task. Not only is the domain to be mastered almost boundless; natural science in this entire domain is itself undergoing such a mighty process of being revolutionised that even people who can devote the whole of their spare time to it can hardly keep pace. Since Karl Marx's death, however, my time has been requisitioned for more urgent duties, and I have therefore been compelled to lay aside my work. For the present I must content myself with the indications given in this book, and must wait to find some later opportunity to put together and publish the results which I have arrived at, perhaps in conjunction with the extremely important mathematical manuscripts left by Marx. 
Yet the advance of theoretical natural science may possibly make my work to a great extent or even altogether superfluous. For the revolution which is being forced on theoretical natural science by the mere need to set in order the purely empirical discoveries great masses of which have been piled up, is of such a kind that it must bring the dialectical character of natural processes more and more to the consciousness even of those empiricists who are most opposed to it. The old rigid antagonisms, the sharp, impassable dividing lines are more and more disappearing. Since even the last "true" gases have been liquefied, and since it has been proved that a body can be brought into a condition in which the liquid and the gaseous forms are indistinguishable, the aggregate states have lost the last relics of their former absolute character.  With the thesis of the kinetic theory of gases, that in perfect gases at equal temperatures the squares of the speeds with which the individual gas molecules move are in inverse ratio to their molecular weights heat also takes its place directly among the forms of motion which can be immediately measured as such. Whereas only ten years ago the great basic law of motion, then recently discovered, was as yet conceived merely as a law of the conservation of energy, as the mere expression of the indestructibility and uncreatability of motion, that is, merely in its quantitative aspect, this narrow negative conception is being more and more supplanted by the positive idea of the transformation of energy, in which for the first time the qualitative content of the process comes into its own, and the last vestige of an extramundane creator is obliterated. That the quantity of motion (so-called energy) remains unaltered when it is transformed from kinetic energy (so-called mechanical force) into electricity, heat, potential energy, etc., and vice versa, no longer needs to be preached as something new; it serves as the already secured basis for the now much more pregnant investigation into the very process of transformation, the great basic process, knowledge of which comprises all knowledge of nature. And since biology has been pursued in the light of the theory of evolution, one rigid boundary line of classification after another has been swept away in the domain of organic nature. The almost unclassifiable intermediate links are growing daily more numerous, closer investigation throws organisms out of one class into another, and distinguishing characteristics which almost became articles of faith are losing their absolute validity; we now have mammals that lay eggs, and, if the report is confirmed, also birds that walk on all fours. Years ago Virchow was compelled, following on the discovery of the cell, to dissolve the unity of the individual animal being into a federation of cell-states -- thus acting more progressively rather than scientifically and dialectically  -- and now the conception of animal (therefore also human) individuality is becoming far more complex owing to the discovery of the white blood corpuscles which creep about amoeba-like within the bodies of the higher animals. It is however precisely the polar antagonisms put forward as irreconcilable and insoluble, the forcibly fixed lines of demarcation and class distinctions, which have given modern theoretical natural science its restricted, metaphysical character. The recognition that these antagonisms and distinctions, though to be found in nature, are only of relative validity, and that on the other hand their imagined rigidity and absolute validity have been introduced into nature only by our reflective minds -- this recognition is the kernel of the dialectical conception of nature. It is possible to arrive at this recognition because the accumulating facts of natural science compel us to do so; but one arrives at it more easily if one approaches the dialectical character of these facts equipped with an understanding of the laws of dialectical thought. In any case natural science has now advanced so far that it can no longer escape dialectical generalisation. However it will make this process easier for itself if it does not lose sight of the fact that the results in which its experiences are summarised are concepts, that the art of working with concepts is not inborn and also is not given with ordinary everyday consciousness, but requires real thought, and that this thought similarly has a long empirical history, not more and not less than empirical natural science. Only by learning to assimilate the results of the development of philosophy during the past two and a half thousand years will it rid itself on the one hand of any natural philosophy standing apart from it, outside it and above it, and on the other hand also of its own limited method of thought, which is its inheritance from English empiricism.
London, September 23, 1885
The following new edition is a reprint of the former, except for a few very unimportant stylistic changes. It is only in one chapter -- the tenth of Part II: "From Kritische Geschichte" that I have allowed myself to make substantial additions, on the following grounds.
As already stated in the preface to the second edition, this chapter was in all essentials the work of Marx. I was forced to make considerable cuts in Marx's manuscript, which in its first wording had been intended as an article for a journal; and I had to cut precisely those parts of it in which the critique of Dühring's propositions was overshadowed by Marx's own revelations from the history of economics. But this is just the section of the manuscript which is even today of the greatest and most permanent interest. I consider myself under an obligation to give in as full and faithful a form as possible the passages in which Marx assigns to people like Petty, North, Locke and Hume their appropriate place in the genesis of classical political economy; and even more his explanation of Quesnay's economic Tableau, which has remained an insoluble riddle of the sphinx to all modern political economy. On the other hand, wherever the thread of the argument makes this possible, I have omitted passages which refer exclusively to Herr Dühring's writings.
For the rest I may well be perfectly satisfied with the degree to which, since the previous edition of this book was issued, the views maintained in it have penetrated into the social consciousness of scientific circles and of the working class in every civilised country of the world.
London May 23, 1894