Did Marx Have Second Thoughts about the Law of the Falling Rate of Profit? An Archival Rejection of Heinrich's Arguments

In this paper, I investigate archivally Michael Heinrich's arguments for the existence of a crucial theoretical shift in Marx's thought during the 1870s centered around his supposed doubts about the validity of the law of the falling rate of profit. Heinrich's arguments have been grouped into six clusters and discussed deploying the material contained in collections of published and unpublished writing of Karl Marx and Friedrich Engels, such as MECW and especially MEGA, whose second section includes all manuscripts related to Capital. This investigation concludes that the manuscripts and letters that Heinrich invokes to support his arguments do not substantiate any uncertainty on Marx's part about the validity of the law of the falling rate of profit nor a shift of his opinion during the 1870s towards the primacy of capitalist circulation, and especially credit, for explaining economic crisis.