In his writings, did Marx only seek to explain the social and economic transformation precipitated by the rise of capitalism as well as offer some forecast for the future or did he actively also agitate for class struggle? In other words, was he only theoretical or did he advocate and encourage revolution and proactive ideological activism? Or was strategy of lesser importance in his writings?
Yet another way to ask is, was Marx a marxist?
The quotee, 'One thing is certain, it is that I am not a Marxist', has for its context Marx's and Engels' vexation with two French revolutionaries : Jules Guesde (1845-1922) and Paul Lafargue (1842-1911).
Marx and Engels ... did not wholly agree with the actions and utterances of their French disciples [Guesde and Lafargue] .. Guesde was too eager to realize big results in his own lifetime. He had inherited "the Parisian superstition of bandying about the word revolution." While Engels disapproved of Guesde's "absurd purism," of the rigidity of his doctrine and of his desire, à la Bakunin, to dominate all organizations, Marx reproached Lafargue for continuing "to multiply useless incidents" and for talking too loosely. "I find," wrote Marx to Engels, "that he is too much like an oracle." In his activity, Marx said, Lafargue was "the last, earnest disciple of Bakunin." The theories and tactics of the French leaders were so at variance with those of Marx and Engels that the two observers in London questioned the derivation of the Guesdist doctrine. "It is true," wrote Engels to Bernstein, "that the so-called 'Marxism' in France is quite a special product." And after reflecting on the French version of his teachings Marx was reported to have said to Lafargue: "One thing is certain, it is that I am not a Marxist." (Samuel Bernstein, 'Jules Guesde, Pioneer of Marxism in France', Science & Society, Vol. 4, No. 1 (Winter, 1940), pp. 29-56: 51-2.)
For the credentials of the quote, see E. Bernstein, Die Briefe von Engels an Bernstein (Berlin, 1925), p.34 f.
Marx made this comment because he saw his followers, some at least, as solidifying his ideas and arguments into a set, finished body of doctrine. No matter how dogmatic he could be, Marx was an inquirer, or saw himself as such, who had obtained crucial insights into the nature of capitalism and the direction of history but who never supposed that his work was a finished job. He never got past the first volume of Capital, meant to be a multi-volumed work. Marx's ideas and arguments were, as far as he was concerned, work in progress even of he had achieved (to his own mind) significant progress.
There is also the point that Marx resented what he regarded as the idiosyncratic and only partially comprehending use of his ideas and arguments by groups that chose to use his name.
The idea that he had produced a comprehensive account of politics, history, economics, philosophy and society rather than penetrating, coherent and vitally illuminating insights into them struck him as absurd.
There is no clear answer to this question for a number of reasons:
We must remember that Karl Marx spent his entire life in Western Europe-(i.e. Germany, England); to the best of my knowledge, I don't believe Karl Marx ever ventured beyond the European continent. While he was a Foreign Affairs Correspondent during his earlier years, he appears to have been totally situated in Europe.
It is important to bring this up because Marx, in many ways, was a product of his European environment. His critiques on Capitalism and seeming advocacy for a "Workers" Revolution, would have only been applicable to the industrialized countries of Northern and Western Europe during his lifetime-(the United States and Canada, as possible exceptions). If Marx was a sincere Revolutionary-(and it's unclear when looking at his biography), then his hopes for the radical dismantling of Capitalism and ushering in of the Communist Utopia, would have only occurred on Northern and Western European soil-(Again, North America, being the possible lone exception).
When Karl Marx wrote his "Communist Manifesto" and "Das Capital", the Russian Empire was still governed by the Tsars and China was still governed by its centuries old Dynasties-(I believe the British Empire conquered part of China after Karl Marx passed away). My GUESS is that the very Eurocentric Karl Marx, would have probably raised his eyebrows with shock and perplexity when seeing The Bolshevik and Cultural Revolutions had he lived in the 20th century. For Marx, the evolution of Communism was to occur and (hopefully succeed), within the Industrialized European (and possibly) North American West. Karl Marx's romanticized Proletariat class, were largely city and townsfolk from Europe (and probably North America). However, rural villagers and peasants from Unindustrialized, Non-Western countries, were not central to Karl Marx's Eurocentric vision of a Communist Utopia-(and yet, there were certain rural, unindustrialized countries, with a large peasantry, who ushered in Communist revolutions and Civil Wars throughout the world during the 20th century).
So the answer to your question is twofold. Yes, I believe that if Marx's vision of Communism had succeeded in Northern Europe (and possibly North America), I believe he would have proudly identified himself as a "Marxist". However, if Marx had lived during the 20th century and seen Communist revolutions in Russia, China, Vietnam and Cuba, he probably would have stated-(once again)...."I am not a Marxist."
