Few political and intellectual partnerships can rival that of Karl Marx and Friedrich Engels. They not only famously coauthored The Communist Manifesto in 1848, both taking part in the social revolutions of that year, but also two earlier works — The Holy Family in 1845 and The German Ideology in 1846.

In the late 1870s, when the two scientific socialists were finally able to live in close proximity and to confer with each other every day, they would often pace up and down in Marx’s study, each on their own side of the room, boring grooves in the floor as they turned on their heels, while discussing their various ideas, plans, and projects.

They frequently read to each other passages from their works in progress. Engels read the entire manuscript of his Anti-Dühring (to which Marx contributed a chapter) to Marx before its publication. Marx wrote an introduction to Engels’s Socialism: Utopian and Scientific. After Marx’s death in 1883, Engels prepared volumes two and three of Capital for publication from the drafts his friend had left behind. If Engels, as he was the first to admit, stood in Marx’s shadow, he was nevertheless an intellectual and political giant in his own right.

Yet for decades academics have suggested that Engels downgraded and distorted Marx’s thought. As political scientist John L. Stanley critically observed in his posthumous Mainlining Marx in 2002, attempts to separate Marx from Engels — beyond the obvious fact that they were two different individuals with differing interests and talents — have more and more taken the form of disassociating Engels, viewed as the source of all that is reprehensible in Marxism, from Marx, viewed as the epitome of the civilized man of letters, and not himself a Marxist.

Almost forty-two years ago, on December 12, 1974, I attended a lecture by David McLellan on “Karl Marx: The Vicissitudes of a Reputation,” at the Evergreen State College in Olympia, Washington. The year before McLellan had published Karl Marx: His Life and Thought, which I had studied closely. But McLellan’s message that day, in a nutshell, was that Karl Marx was not Frederich Engels. To discover the authentic Marx, it was necessary to separate Marx’s wheat from Engels’s chaff. It was Engels, McLellan contended, who had introduced positivism into Marxism, pointing to the Second and Third Internationals, and eventually to Stalinism. A few years later, McLellan was to put some of these criticisms into his short biography, Friedrich Engels.

This was my first introduction to the anti-Engels outlook that emerged as a defining characteristic of the Western academic left, and which was closely connected to the rise of “Western Marxism” as a distinct philosophical tradition — in opposition to what was sometimes called official or Soviet Marxism. Western Marxism, in this sense, had as its principal axiom the rejection of Engels’s dialectics of nature, or “merely objective dialectics,” as Georg Lukács called it.

For most Western Marxists the dialectic was an identical-subject object relation: we could understand the world to the extent to which we had made it. Such a critical view constituted a welcome rejection of the crude positivism that had infected much of Marxism, and that had been rationalized in official Soviet ideology. Yet it also had the effect of pushing Marxism in a more idealist direction, leading to the abandonment of the long tradition of seeing historical materialism as related not just to the humanities and social science — and of course politics — but also to materialist natural science.

Disparaging Engels became a popular pastime among left academics, with some figures, like political theorist Terrell Carver, constructing whole careers on this basis. One common maneuver was to use Engels as the device for extracting Marx from Marxism. As Carver wrote in 1984: “Karl Marx denied that he was a Marxist. Friedrich Engels repeated Marx’s comment but failed to take his point. Indeed, it is now evident that Engels was the first Marxist, and it is increasingly accepted that he in some way invented Marxism.” For Carver, Engels not only committed the cardinal sin of inventing Marxism, but also committed numerous other sins, such as promoting quasi-Hegelianism, materialism, positivism, and dialectics — all of which were said to be “miles away from Marx’s painstaking eclecticism.”

The very idea that Marx had “a methodology” was attributed to Engels, and hence declared false. Removed from his association with Engels and stripped of all determinate content, Marx was easily made acceptable to the status quo, as a kind of intellectual forerunner. As Carver recently put it, with no apparent sense of irony, “Marx was a liberal thinker.”

But most criticisms of Engels have been directed at his alleged scientism in Anti-Dühring and his unfinished Dialectics of Nature. McLellan in his Engels biography stated that the latter’s interest in natural science “made him emphasize a materialist conception of nature rather than of history.” He was accused of bringing “the concept of matter” into Marxism, which was “entirely foreign to Marx’s work.” His main mistake was in attempting to develop an objective dialectics that abandoned “the subjective side of the dialectic,” and that led to “the gradual assimilation of Marx’s views to a scientific world outlook.”

“It is not surprising,” McLellan charged, “that, with the consolidation of the Soviet regime, the vulgarizations of Engels should have become the main philosophical content of Soviet textbooks.” Just as Marx was increasingly presented as the refined intellectual, Engels was seen more and more as the coarse popularizer. Engels has thus served in the academic discourse on Marxism as a convenient whipping boy.

Yet Engels had his admirers, as well. The first real sign of a reversal in his fading fortunes within contemporary Marxist theory arose with historian E. P. Thompson’s The Poverty of Theory in 1978, which was primarily directed against the structuralist Marxism of Louis Althusser. Here Thompson defended historical materialism against an abstract and hypostatized theory divorced from any historical subject and from all empirical reference points. In the process, he valiantly — and in what I have always seen as one of the high points in late twentieth-century English letters — stood up for that “old duffer Frederick Engels,” who had been the target of so much of Althusser’s criticism.

On this basis, Thompson made a case for a kind of dialectical empiricism — what he admired most in Engels — as essential to a historical-materialist analysis. A few years later, Marxian economist Paul Sweezy’s Four Lectures on Marxism began by boldly reasserting the importance of Engels’s approach to dialectics and his critique of mechanistic and reductionist views.

But the real shift that was to restore Engels’s reputation as a major classical Marxist theorist alongside Marx was to emanate not from historians and political economists, but from natural scientists. In 1975 Stephen Jay Gould, writing in Natural History, openly celebrated Engels’s theory of human evolution, which had emphasized the role of labor, describing it as the most advanced conception of human evolutionary development in the Victorian age — one which had anticipated the anthropological discovery in the twentieth century of Australopithecus africanus.

A few years later, in 1983, Gould extended his argument in the New York Review of Books, pointing out that all theories of human evolution were theories of “gene-culture coevolution,” and that “the best nineteenth-century case for gene-culture coevolution was made by Friedrich Engels in his remarkable essay of 1876 (posthumously published in The Dialectics of Nature), ‘The part played by labor in the transition from ape to man.’”

That same year, medical sociologist and MD Howard Waitzkin devoted much of his landmark The Second Sickness to Engels’s pioneering role as a social epidemiologist, showing how the twenty-four-year-old Engels, while writing The Condition of the Working Class in England in 1844, had explored the etiology of disease in ways that prefigured later discoveries within public health. Two years after this, in 1985, Richard Lewontin and Richard Levins came out with their now classic The Dialectical Biologist, with its pointed dedication: “To Frederick Engels, who got it wrong a lot of the time but who got it right where it counted.”

The 1980s were to see the birth of an ecosocialist tradition within Marxism. In first-stage ecosocialism, represented by the pioneering work of Ted Benton, Marx and Engels were criticized for not having taken Malthusian natural limits seriously enough. However by the late 1990s the debates that ensued had given rise to a second-stage ecosocialism, beginning with Paul Burkett’s Marx and Nature in 1999, which sought to explore the materialist and ecological elements to be found within the classical foundations of historical materialism itself.

These efforts focused initially on Marx, but also took into account Engels’s ecological contributions. This was reinforced by the new MEGA (Marx-Engels Gesamtausgabe) project, in which Marx and Engels’s natural-scientific notebooks began to be published for the first time. The result has been a revolution in the understanding of the classical Marxian tradition, much of it resonating with a new, radical ecological praxis evolving out of today’s epochal crisis (both economic and ecological).

The growing recognition of Engels’s contributions to science along with the rise of ecological Marxism have sparked a renewed interest in Engels’s Dialectics of Nature and his other writings related to natural science. Much of my own research since 2000 has focused on the relation of Engels — and others influenced by him — to the formation of an ecological dialectic. Nor am I alone in this respect. Political economist and ecological Marxist Elmar Altvater recently published a book in German addressing Engels’s Dialectics of Nature.

The case for the indispensability of Engels for the critique of capitalism in our time is rooted in his famous thesis in Anti-Dühring that “Nature is the proof of dialectics.” This was often derided within Western Marxist philosophy. Nevertheless, Engels’s thesis, reflecting his own deep dialectical and ecological analysis, would have to be rendered in today’s parlance: Ecology is the proof of dialectics — a proposition the significance of which few would now be prepared to deny. Viewed in this way, it is easy to see why Engels has assumed such an important place in contemporary ecosocialist discussions. Works in ecological Marxism commonly quote as leitmotif his famous words of warning in The Dialectics of Nature:

Let us not, however, flatter ourselves overmuch on account of our human victories over nature. For each such victory nature takes its revenge on us. Each victory, it is true, in the first place brings about the results we expected, but in the second and third places it has quite different, unforeseen effects which only too often cancel out the first . . . Thus at every step we are reminded that we by no means rule over nature like a conqueror over a foreign people, like someone standing outside nature — but that we, with flesh, blood, and brain, belong to nature, and exist in its midst, and that all our mastery of it consists in the fact that we have the advantage over all other creatures of being able to learn its laws and apply them correctly.

For Engels, as for Marx, the key to socialism was the rational regulation of the metabolism of humanity and nature, in such a way as to promote the fullest possible human potential, while safeguarding the needs of future generations. No wonder, then, that we are seeing, in the twenty-first century, the return of Engels, who, along with Marx, continues to inform the struggles and inspire the hopes that define our own crisis-ridden, and necessarily revolutionary time.