The obsession with TRPF among the new left is really bizarre. Marx had an actually very theoretically developed theory of crisis stemming from overproduction. He also listed 6 countervailing tendencies to the TRPF that make it anything but a theory of acute crisis. The problem of the modern left in large part can be displayed as the inability to intercede in depression and recession politics with a relevant economic theory of crisis, which the TRPF is not. The TRPF is important, but operating at a completely different level than is relevant when developing a cogent theory that can be used for agitation.
Read Michael Roberts blog or his book, ya ding dong. Nearly all crises of capitalism are because of overproduction. There are counter tendencies to the rate of profit falling but nothing can stop its secular decline over the last 150 years of industrial capitalism. Really good analysis done by him here. Its also a tendency and not a law because it has counter tendencies that can temporarily boost profit, wording Marx chose carefully. But still describes secular decline over many decades.
It was theoretical for Marx but has been born out empirically. No other economic theory explains capitalist crises, for example Keynsianism was proven wrong by the 70s stagflation - a contradiction in Keynes theory that we could even have inflation and stagnation. The Chicago neolibs were disproven by the continued decline of profit following the 2009 crash. Only 1 theory explains why capitalism has crises, why these are inevitable, and what to do about it - and its Marxism, capitalist overproduction, and the tendency for the rate of profit to fall as laid out by Marx.
There is no other theory or remedy for capitalist crises but trpf and socialism.
Marx never even dealt with the TRPF in any work published while he was living. And it was only dealt with very shortly in his 3rd volume of Capital which was really a cobbled together collection of shoddy and disparate notes. But very importantly, Marx never links any theory of crisis to the TRPF. Michael Roberts has this bizarre outsized influence in the current left, because he asserts that Marx's theory of crisis extends from the TRPF and he has the receipts to prove the TRPF exists and therefore he's somehow rescued Marx, who was never in any need of it.
Marx's actual theory of capitalist overproduction and crisis can only account for the TRPF after interest bearing capital and credit have been taken into account.
"in a general crisis of overproduction the contradiction is not between the different kinds of productive capital, but between industrial and loan capital; between capital as it is directly involved in the production process and capital as it appears as money independently (relativement) outside that process.”
Yet the TRPF posits a theory of crisis that has no need to even consider money or credit. Which is something that Marx NEVER argued for. He recognized that a systemic theory of crisis must follow from an analysis of credit and loan capital.
This was not accomplished before his death, so in reality his systematic treatment of crisis was never completed, but we do have very effective and cogent existing arguments made by Marx and Engels about overproduction and it's very apparent and visible contradictions, which are more informative to the nature of class struggle than any egg headed treatment of the TRPF.
Also, the TRPF is a called a law so I'm seriously questioning the extent of your research on this. Marx calls it the "Law of the Tendency of the Rate of Profit to Fall." And his treatment of it is completely jumbled and not very powerfully descriptive. Many contend he was on the verge of abandoning all together (if he hadn't already.) Considering how central everyone seems to think the TRPF is, you'd think he would have dedicated a lot more time and ink to its investigation.
Ultimately, overproduction and TRPF both come from the same idea. Either you cut costs and end up lowering the demand for products, which ruins your profits, or you keep producing too much, which you can't sell. Either way, Capitalist greed eventually means that you don't fully go from C to M'.
The end result in either case is a crisis of overproduction, but in the post-1980 world of austerity, people are more used to the idea of "cost cutting causing a demand collapse" than "too much shit made and no market for it".
A "crisis of overproduction" doesn't make sense to modern people who have no understanding outside of mainstream economics because we have a solution to that - just have the government buy up the surplus and print money! TRPF is a more concrete way to say "this system is doomed".
True, it's different now than when Marx and Engels wrote their theory of crises. Back then it was basically a perfect 10 year cycle that only stopped as monopolies began acting as a countervailing force to the anarchy of production.
Those create new problems (namely financial imperialism and stagnation), that eventually lead to a return of regular crises. Kinda like holding your finger over a hose.
I think the dominance of the speculative market is creating an even more rapid cycle of crises.
