Home > Uncategorized > Krugman and Mankiw on loanable funds — so wrong, so wrong

Krugman and Mankiw on loanable funds — so wrong, so wrong

from Lars Syll

slide_6A couple of years ago — in a debate with James Galbraith and Willem Buiter — Paul Krugman made it perfectly clear that he was a strong believer of the ‘loanable funds’ theory.

Unfortunately, this is not an exception among ‘New Keynesian’ economists.

Neglecting anything resembling a real-world finance system, Greg Mankiw — in his intermediate textbook Macroeconomics — more or less equates finance to the neoclassical thought-construction of a ‘market for loanable funds.’

On the subject of financial crises, he admits that

perhaps we should view speculative excess and its ramifications as an inherent feature of market economies … but preventing them entirely may be too much to ask given our current knowledge.

This is, of course, self-evident for all of us who understand that genuine uncertainty makes any such hopes totally unfounded. But it’s rather odd to read this in a book that bases its models on assumptions of rational expectations, representative actors and dynamically stochastic general equilibrium – assumptions that convey the view that markets – give or take a few rigidities and menu costs – are efficient! For being one of many neoclassical economists so proud of their consistent models, Mankiw here certainly is flagrantly inconsistent! 

And as if being afraid that all the talk of financial crises might weaken the student’s faith in the financial system, Mankiw, in his concluding remarks, has to add a more Panglossian warning that we

should not lose sight of the great benefits that the system brings … By bringing together those who want to save and those who want to invest, the financial system promotes economic growth and overall prosperity


Finance has its own dimension, and if taken seriously, its effect on an analysis must modify the whole theoretical system and not just be added as an unsystematic appendage. Finance is fundamental to our understanding of modern economies, and acting like the baker’s apprentice who, having forgotten to add yeast to the dough, throws it into the oven afterwards, simply isn’t enough.

I may be too bold, but I’m willing to take the risk, and so recommend Krugman and Mankiw to make the following addition to their reading lists …

Fallacy 2

Urging or providing incentives for individuals to try to save more is said to stimulate investment and economic growth.

Saving does not create “loanable funds” out of thin air. There is no presumption that the additional bank balance of the saver will increase the ability of his bank to extend credit by more than the credit supplying ability of the vendor’s bank will be reduced. If anything, the vendor is more likely to be active in equities markets or to use credit enhanced by the sale to invest in his business, than a saver responding to inducements such as IRA’s, exemption or deferral of taxes on pension fund accruals, and the like, so that the net effect of the saving inducement is to reduce the overall extension of bank loans. Attempted saving, with corresponding reduction in spending, does nothing to enhance the willingness of banks and other lenders to finance adequately promising investment projects. With unemployed resources available, saving is neither a prerequisite nor a stimulus to, but a consequence of capital formation, as the income generated by capital formation provides a source of additional savings.

Fallacy 3

Government borrowing is supposed to “crowd out” private investment.

The current reality is that on the contrary, the expenditure of the borrowed funds (unlike the expenditure of tax revenues) will generate added disposable income, enhance the demand for the products of private industry, and make private investment more profitable. As long as there are plenty of idle resources lying around, and monetary authorities behave sensibly, (instead of trying to counter the supposedly inflationary effect of the deficit) those with a prospect for profitable investment can be enabled to obtain financing. Under these circumstances, each additional dollar of deficit will in the medium long run induce two or more additional dollars of private investment. The capital created is an increment to someone’s wealth and ipso facto someone’s saving. “Supply creates its own demand” fails as soon as some of the income generated by the supply is saved, but investment does create its own saving, and more. Any crowding out that may occur is the result, not of underlying economic reality, but of inappropriate restrictive reactions on the part of a monetary authority in response to the deficit.

William Vickrey Fifteen Fatal Fallacies of Financial Fundamentalism

  1. August 18, 2017 at 9:23 pm

    “Fallacy 2

    Urging or providing incentives for individuals to try to save more is said to stimulate investment and economic growth.”

    More to the point, individuals here are a bad logical category. If you could induce people making under $100k a year to save more and these savings fueled an increase in consumption down the road, then that would help the economy. The only tool people seem to have for doing that these days is to put billions of dollars in the hands of billionaires and hope that consumers having more money to spend somehow magically comes out of the wash.

    “Fallacy 3

    Government borrowing is supposed to “crowd out” private investment.”

    The real Worse Than Failure here is that tax cuts on the rich and other programs promoting increased concentration of wealth have pushed interest rates and other ROIs steadily toward zero since the 1980s. The “I”s in ROIs clearly do not need to be stimulated to have a healthy economy. To be fair, the included response hinted in that direction, but…

  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s