Financial instability and debt deflation

Most of Steve Keen's recent work focuses on modeling Hyman Minsky's financial instability hypothesis and Irving Fisher's debt deflation.^[4][5] The hypothesis predicts that an overly large private debt to GDP ratio can cause deflation and depression. Here, the falling of the price level results in a continually rising real quantity of outstanding debt. Moreover, the continued deleveraging of outstanding debts increases the rate of deflation. Thus, debt and deflation act on and react to one another, resulting in a debt-deflation spiral. The outcome is a depression.
Debunking Economics

Keen's full-range critique of neoclassical economics is contained in his book Debunking Economics.^[6] Keen presents a wide variety of critiques on neoclassical economic theory. He argues they show neoclassical assumptions which are fundamentally flawed. Keen claims several neoclassical assumptions are empirically unsupported (that is, they are unsupported by observable and repeatable phenomena) nor are they desirable for society at large (that is, they do not necessarily produce either efficiency or equity for the majority). He argues economists' overall conclusions are very sensitive to small changes in these assumptions.

Keen has attempted to counter Karl Marx's theory (in his view Marx's pre-1857 view, specifically) from a post-Keynesian perspective, by arguing machines can add more product-value over their operational lifetime than the total value of depreciation charged "during those asset lives".

For example, the total value of sausages produced by a sausage machine over its useful life might be greater than the value of the machine. Depreciation, he implies, was the weak point in Marx's social accounting system all along. Keen argues all factors of production can add new value to outputs. However he gives credit to Marx for contributing to the "financial instability hypothesis" of Hyman Minsky.^{[7][full citation needed]}

Keen's book closes with a survey of various schools of heterodox economics, concluding "None of these is at present strong enough or complete enough to declare itself a contender for the title of 'the' economic theory of the 21st century." However, he argues neoclassical economics is a degenerative research program, not generating new knowledge. It primarily grows a belt of protective auxiliary hypotheses to shield its core beliefs from critique. There is an accompanying website which provides more detailed mathematical expositions.