Saturday, January 14, 2012

Debt, generations, savings, and economic categorization or the "Borges Problem"

I didn't comment much on the great debt debate, stirred up a Krugman post called Debt Is (Mostly) Money We Owe to Ourselves, but followed it quite closely.

Nick Rowe taught me (here, here, here, and here), and Bob Murphy clarified (here, here, here, here, here, here, here, and here), that present generations can indeed take resources from future generations via debt issuance.

I also learnt via Daniel Kuehn here and here that if you use a very unintuitive definition of "generations", than this is not the case. Basically, you can swap the meanings of terms to argue your way out of a tight spot.

My comment is from a Murphy post:
I’ve learnt that the method by which one aggregates individuals into groups, and the labels that one attaches to such groups, can have an important influence on a debate’s ability to reach resolution. If people are aggregating differently, and using non-standard words for their categories, then the debate will degenerate into shouting matches.
In a comment on a post called Why "saving" should be abolished, Nick describes this as the Borges Problem, which I rather like. Says Nick,
Let me first do one general response:
 There are lots of different ways we can divide up the world into categories see Borges on "animals"
 Which would be the most useful way to divide up income, and define saving?
 Which of these 3 definitions of desired saving is the most useful?
Nick later on:
Notice also that the recent debate about the burden of the debt was also an example of the "Borges Problem". Do we divide the future up into time periods or into cohorts? We get very different results depending on how we categorise the world. And sometimes the categories we use are chosen by someone long ago who had a totally different purpose and/or a totally different theory to ours. Our way of seeing the world gets distorted by the dead hand of historical ways of seeing.
Yes! I did notice that. It caused me a lot of confusion. Nick also notes that the solution is to choose the most useful categorization out of all possible options, and proceeds to advocate a different category to which we should attach the word "savings". Interesting stuff. I'm not sure how Nick proposes we solve for "usefulness" though. Isn't the fact that almost everyone uses the same term for a given categorization a good enough claim for usefulness?

Here's another Rowe comment on Kuehn's blog which is relevant:
Put it another way: there's more than one way to aggregate. We shouldn't let our theories of what is happening in the world be determined by the choices made by long-dead National Income Accountants.
Anyways, in my comment on Nick's savings post, I proposed a more useful (at least to me) Borgian response to the categorization problem. Instead of categorizing the world on the basis of flows, categorize it as a series of balance sheets, or stocks. The result is that consumption, investment, and savings are all attached to entirely different bins (and more intuitive ones, to me at least) than in a world composed in terms of flows:
Nick, I agree with you that the conversation on debt was mainly about categorizations and the lack of standardized terms associated with categorizations. That made it very frustrating to follow.
So I am all in favor of standardizing terms, as you advocate in this post. 
I noticed you originally introduced C and I as flows and A and M as stocks. Then when you brought in the individual's economy, you introduced not a stock of antique furniture, but a flow of antiques, and not a stock of money, but a flow of money. Presumably you did this to preserve stock flow consistency.
The idea of a flow of antiques or money is very unintuitive to me. Why not go the other way? Not flows of consumption and investment, but stocks? Thus you have and individual's goods C, I, A, and M, which are all stocks. Sum them all up and you have S (the noun form of S, not the verb). This S can rise or fall. As a solution to the Borgian categorization problem, this configuration makes more intuitive sense to me.
And later:
N: "but if we think of income as a flow, then thinking of C and I as stocks is going to create problems."
 Me: You start out with the C and I that you have produced in your stock of assets, hold this C and I until you find someone who'll exchange for them with the M they have in their stock of assets. Now they are holding C and I and you are holding M. So here income isn't a flow, it's just a trade, an instantaneous swap of assets held in a portfolio.
 How much of economics is taken up by definitional debates and confusion? You'd think there would be a universal set of definitions for economic terms somewhere so these issues don't pop up. When I read William Hutt's books I'm always pleased because he uses his first chapter to explicitly define every term he'll be using.
and once more *phew*:
N: "Will those trades all take place in an instant, with some buying and some selling a stock of antiques? Or will those trades happen slowly over time, as people buy or sell a flow of antiques, and slowly get back to their long run desired stocks? That depends. If antiques are a small part of your wealth, and the market is frictionless with all antiques identical and so zero search costs (obviously not, for antiques). Each person would instantly buy or sell a stock of antiques to get back to his personal desired stock. Otherwise, there will be a flow of trades. If antiques are a large fraction of your wealth, you may only buy and sell slowly, in a flow."
 me: Ok, thinking in a world with stocks, (an infinite series of balance sheets), trades still happen in an instant, even if you introduce search costs. You hold the antique on your balance sheet until you don't. The antique is in your hand up until the moment it enters the hand of the buyer.
 Introducing frictions means that someone can have the intention of selling that antique and will need to incur costs to search out someone to trade. But it doesn't mean the process must be a conceptualized as a flow. Rather, the intention of selling an antique just moves the antique to a different part of an individual's balance sheet. It continues to lie in the asset column of their balance sheet, but is moved from long-term assets to current or liquid assets. Introducing search costs means that instead of an interval of two balance sheets before a swap occurring, the interval is some number larger than two.
My rough final thoughts are that thinking in terms of stocks, not flows, introduces a number of important categories that flow-based economics ignores because it is focused on flows. The most important of these is a stock of non-durable consumption goods. In flow-based economics, it's always been odd to me that factories produce, and we instantaneously use up, consumption goods.

A stock based world also is terribly confusing way to go about things, because the word savings in a flow-based world is attached to a different category than that which it is attached to in a stock based world, much like how in the Great Debt debate the word "our children" can be attached to either a period of time or a cohort.


  1. You need to read some Wynne Godley. He already did the work to create a stock-flow consistent matrix of accounts which makes thinking about these very issues much, much easier.

  2. Mike, I'm looking more for something like in this post:

    I'm looking for a certain set of categorizations. I don't think Godley has the ones I want.