Marx’s Law of the Tendency of the Profit Rate to Fall: A Re-Examination

Marx’s law of the tendency of the profit rate to fall, formulated in Capital Volume III, is central to his critique of capital. A logical re-examination defends his core claim — that rising capital composition (reflecting mechanization and productivity growth) coexisting with a constant rate of surplus value necessarily yields a declining general profit rate. The claim holds when real wages rise proportionally with labor productivity — a historical possibility contingent on working-class organized strength. Not only Marx’s law holds under constant exploitation, but it extends to more general conditions: even when exploitation rises, profit rates fall if capital composition growth outpaces exploitation growth (assuming stable variable-capital turnover). Turnover slowdowns exert additional downward pressure. These relations highlight the law as expressing the tendency of capital to revolutionize the productive forces of labor while subordinating them to surplus valorization imperatives. An Appendix presents the mathematical formalization as well as an illustrative decomposition of global profit-rate trends using macroeconomic data. While not an empirical test, the illustrative exercise demonstrates the law’s analytical value for interpreting historical profitability tendencies. The analysis reaffirms the internal coherence of Marx’s proposition against criticisms questioning its foundational logic.