far beyond those which Marx specified[?]. So there are tendencies and counter-tendencies operating simultaneously, and no particular empirical result necessarily and always follows from them[?]. Labor theory of value Steve Keen argues that if you assume the labor theory of value is wrong, then this obviates the bulk of the critique. Keen suggests that the TRPF was based on the idea that only labor can create new value (following the labor theory of value), and that there was a tendency over time for ratio of capital to labor (in value terms) to rise. However, if surplus can be produced by all production inputs, then he believes there is no reason why an increase in the ratio of capital to labor inputs should cause the overall rate of surplus to decline. Eugen Böhm von Bawerk and his critic Ladislaus Bortkiewicz (himself influenced by Vladimir Karpovich Dmitriev) claimed that Marx's argument about the distribution of profits from newly produced surplus value is mathematically faulty. This gave rise to a lengthy academic controversy. Critics claimed that Marx failed to reconcile the law of value with the reality of the distribution of capital and profits, a problem that had already preoccupied David Ricardo – who himself inherited the problem from Adam Smith, yet failed to solve it. Marx was already aware of this theoretical problem when he wrote The Poverty of Philosophy (1847). It gets a mention again in the Grundrisse (1858). At the end of chapter 1 of his A Contribution to the Critique of Political Economy (1859), he referred to it, and announced his intention to solve it. In Theories of Surplus Value (1862–1863), he discusses the problem very clearly. His first attempt at a solution occurs in a letter to Engels, dated 2 August 1862. In Capital, Volume I (1867) he noted that "many intermediate terms" were still needed in his progressing narrative, to arrive at the answer. Engels suggested, that Marx had indeed solved the problem in the posthumously published Capital, Volume III, but critics alleged Marx never delivered a credible or definitive solution. Specifically, critics claimed that Marx failed to prove that average labour requirements are the real regulator of product-prices within capitalist production, since Marx failed to demonstrate what exactly the causal or quantitative connection was between the two. As a corollary, Marx's theory of the TRPF was undermined as well, since it was based on a necessary