Sunday, November 23, 2008

"We should define "deflation" using economists' theory plus the philosophers' Principle of Charity "

I'm going to talk about Nick Rowe's post on Deflation, but first I need to talk about an old friend, and I mean a very old friend, called the Principle Of Charity.

So as not to bore people, I'm going to give a very cursory description of my position.

The Principle Of Charity, from my point of view, follows from Quine's Indeterminacy Of Translation. The Principle Of Charity can be used to explain how we can come to understand a foreign language. My basic problem with this whole mode of explanation is that the problem only exists if you are a Behaviorist, which Quine was. Davidson, more or less, works out of Quine's system. From my point of view, there's no Indeterminacy Of Translation, and no need for the Principle Of Charity. However, it does seem to have become synonomous with giving people the benefit of the doubt, assuming that they're rational.

Now, to Deflation.

"Some prices are falling, some are falling quickly, and some are still rising. Whether we've got deflation, and how much deflation we've got, depends on what you include in the index, with what weights, and over what time period. Do we include asset prices for example? It depends on how you define the word. Now you can define "deflation" to mean anything you want, but some definitions might be more useful than others."

This does seem to be the case. There is no clear definition of deflation.

"We fear deflation because aggregate demand for newly-produced domestic goods and services depends on the real rate of interest. The real rate of interest is the nominal rate minus expected inflation, and since deflation is just negative inflation, the real rate of interest is the nominal rate plus expected deflation. We fear deflation because deflation causes expected deflation, which raises the real rate of interest, which lowers aggregate demand, which causes excess supply and a recession, which causes deflation to increase. If we are close to the lower bound on nominal interest rates, this is something we ought to fear."

Essentially, we fear deflation for the same reason we fear a too high rate of inflation, i.e., it distorts the market in ways we don't like. Since most people, like William Gross, believe that capitalism works best with a little inflation, deflation is not a good thing in general.

"So right now, the best definition of "deflation" is the definition which maximises the truth-value of the sentence: "Aggregate demand for newly-produced domestic goods and services depends on nominal interest rates plus expected deflation". In other words, we should choose a definition of deflation which would provide the best fit in an estimated aggregate demand equation. We should define "deflation" using economists' theory plus the philosophers' Principle of Charity

http://en.wikipedia.org/wiki/Principle_of_charity

Let's see how this meta-definition works."

Fine. Lead on.

"If the price of antique furniture is falling, does that count as deflation? No, because even though people would postpone buying antique furniture if they expect prices to fall, this has no effect on current output and employment, because nobody produces antique furniture. (OK, the services of antique dealers might take a hit.)"

Okay. The decline in prices in some goods is not deflation.

"If the price of houses is falling, does that count as deflation? Yes, if it's new house prices that are falling, because people will postpone buying a new house if they expect new house prices to fall, which will reduce the demand for newly-produced houses. But old house prices (pre-owned?) don't matter, for the same reason that antique furniture prices don't matter."

Namely, they're already built. New houses need to be built, so to the extent that the demand for them declines, employment will decline, as will business profits. I think that's it.

"If the price of gasoline is falling, does that count as deflation? To the extent that people postpone buying gas if they expect falling gas prices, and to the extent that gasoline is domestically-produced, the answer is yes. But if the intertemporal elasticity of demand for gas is zero the answer is no. And if the gasoline is all imported (and if we hold the exchange rate constant), the answer is again no."

We're not producing it: No.
We're producing it: Yes.

"If the price of new cars is falling, does this count as deflation? Yes, if people postpone buying a domestically-produced new car. But perhaps we should also look at the cross elasticity of demand for mechanics, to keep the old cars running longer.

You get the picture. Anyone with an Euler equation, some elasticity estimates, and some estimates of the extent to which the good is currently produced domestically, can keep this list going."

Don't ask me. Maybe it's a pun on the word "oil".

"The key point is this: the weights on various goods which make up an index which creates a useful definition of deflation in the current debate over monetary policy with a zero lower bound will be very different from the CPI weights, because the CPI definition is designed to be useful for a very different purpose. (The best CPI weights are those designed to maximise the truth value of the sentence "If nominal income rises at the same rate as inflation, then utility is the same".)"

This makes sense. An index is useful only for defined measurements. One index seems to be measuring the production of goods, the other seems to be measuring the relationship between income and inflation. But I'm no expert.

"So, with that definition of deflation in mind, do we currently have deflation? Should falling share prices be included? (And I do mean "falling", not "low", because falling share prices will have different effects on consumption and investment demand than low share prices.) What's the time period? I don't have the answers, but I think I have a way to find the answers."

Now, my position is that deflation, however you define it, is capable of being defeated by the Fed. So, I see the only real worry to be inflation, because, as the definition of deflation says:

Deflation=A decline in prices that are:
1) Sustained
2) Broadly Based

I do not believe that it will be allowed to be sustained.

2 comments:

Anonymous said...

Thanks Don! Before reading your post, I thought I might have been the only person in the intersection of the two sets: {those interested in deflation}^{those interested in the Principle of Charity}!

It's an old friend to me too, about 33 years since discovering Quine (Word and Object, IIRC?). I would disagree with you on one point though: I think that the Principle of Charity (or something like it) is the only way we can escape Philosophical Behaviourism.

I couldn't find an ungated link for a simple explanation of Euler equations in economics. If you have a consumer (or firm) trying to find the utility (profit)-maximising time path for present and future consumption (investment), the Euler equation that pops out defines a relationship between consumption (investment) today and consumption (investment) the next period and the own real rate of interest, plus an elasticity. (By "own" real rate I mean the nominal rate minus the expected inflation of the good in question).

But right at the end of your post you fall into the trap I was wanting us all to avoid: you resort to the conventional definition of "deflation" as a sustained and general fall in prices. Why is it useful to define it as sustained and general? And how general is "general"? I ducked the "sustained" question in my post (the answer is "sustained enough to affect expectations of future deflation"). But I did answer the "general" bit, and showed that some things should be excluded, but other things could be very important.

Nick Rowe

Donald Pretari said...

Thanks for your comment. I hope that it's fine to post it. If not, let me know.

Yes, I was simply comparing it to a standard definition in a previous post. I'm willing to follow you in this, I'm just using the terms as I understand them in the current debate.

I'm accepting the view that deflation can be defeated, so that inflation is always the worry, and, since I know you read Buiter and a lot of other blogs that I do as well, and you know more, I'm worried about inflation going forward after we borrow and spend our way out of this mess.

Tell me if you always post at that site, and, if you think of it, you might find a place to put up your comments on other blogs, because they're quite helpful. I really enjoy your comments and learn from them, so tell me if there's a way I can follow them.

Take care,
Don