Don "Cafe Hayek" Boudreaux wonders if economics, as a discipline, is
burdening the discourse with too many technical terms. I fear that he starts with a forced distinction.
Everyone agrees that if Sarah negligently drives her car physically into Silas’s car and thereby inflicts on it $1,000 worth of damage, Sarah violates Silas’s property right in his car and should compensate him for the damage. But suppose, instead, that Sarah, by agreeing to put her car up for sale, causes the price for which Silas can sell his car to fall by $1,000. Although the negative effect in the second example of Sarah’s action on Silas’s welfare is identical to the negative effect of Sarah’s action in the first example, only in the first example does Sarah incur an obligation to take account of the consequences on Silas of her action.
In the first case, the crash has affected the resale value of Silas's car, yes, although assigning liability for damaging a car is not the same as putting portfolio insurance on the car price. Gosh, there could be quite the common-room lunch question here, if anybody still meets for lunch in the common-room. In the second case, what does that price drop say about the supply and demand elasticities for used cars? But I'm getting pretty far from my story. Maybe it would be fun to crash a common-room lunch at George Mason to push what comes next a little.
Impressed by this difference separating example one from example two, economists call the consequence of the first of Sarah’s actions – her negligently causing physical damage to Silas’s property – a “technological externality,” while calling the consequence of the second of her actions a “pecuniary externality.”
I must confess to getting all the way through graduate training in public economics and a career with occasional incursions into environmental and public policy stuff without ever once encountering a "technological" externality, although I did encounter liability rules, and there's got to be a way to disrupt that lunch gathering with some comment about information technologies providing network externalities, but again, I'm getting away from my story.
Economists then proceed to wonder why the law requires compensation only for technological externalities but not for pecuniary externalities. After all, in both cases Sarah’s action harms Silas without his permission.
The answer economists give is this: The benefits to society from actions that cause technological externalities are generally lower than are the costs to persons who suffer technological externalities, while the benefits to society from actions that cause pecuniary externalities are generally higher than are the costs to persons who suffer pecuniary externalities. And so to ensure maximum possible economic growth – or, to increase the social welfare – the law punishes technological externalities but tolerates pecuniary ones.
That's one approach to take, I suppose. Might it be simpler to say something about liability being present in the case of the crash in a different way than it is in the car market, that is, when Sarah causes a car crash, she is in a different position with respect to Silas than she is when she puts a car on the market? Silas, after all, can cause the same $1000 capital loss to Sarah by putting his car up for sale. I think that's where the professor is going.
Yes, Sarah’s decision to sell her car decreased the market value of Silas’s car. But Silas has no property claim to his car’s previous market value. Silas, being a reasonable person (as we must assume him to be), knows that the market value of his car can change in response to the economic decisions made by strangers. Stated differently, Silas expects, with some probability greater than zero, that the market value of his car will fall. Therefore, Sarah’s decision to sell her car was already “internalized” on Silas. He took account of this possibility in his earlier decisions regarding what kind of car to buy and how long to maintain his ownership of that vehicle.
It might be simpler to recognize that pecuniary externalities are precisely what markets are about, because the prices that come out of market exchange are information available to active or inactive sellers alike. Whether you call that information "pecuniary externality" or "banana" might not be relevant.
But to show why “pecuniary externalities” is a mistaken concept, we need to do more than note that Silas’s expectations include the possibility that the market value of his car will fall because others might sell cars in competition with him. Another factor in play is that Silas would not want to be relieved of this expectation if such relief meant that everyone enjoyed relief of this expectation. To relieve everyone of the expectation of the possibility that the market value of their cars will fall would require that Silas himself no longer be free to offer his car for sale whenever doing so might cause a fall in the price of Sarah’s or Steve’s car.
Because Silas (it is reasonable to assume) wants the right to sell his car whenever he chooses and at whatever price he can fetch, he cannot legitimately assert ethical or legal standing to prevent Sarah from exercising the same right over her car. By giving this right to all persons, the law effectively recognizes that everyone under its jurisdiction agrees that all people have a right to sell their cars even if some car-selling actions harm some people at particular points in time by causing the market values of their cars to fall.
The law, therefore, doesn’t merely tolerate “pecuniary externalities” on the grounds that such toleration promotes economic growth. Rather, the law treats each person as ‘purchasing’ the right to sell his or her car by giving to all other persons the right to sell their cars. The law, in short – and unlike most economists – understands that “pecuniary externalities” are not externalities at all. They are mirages in economists’ minds.
Alternatively, perhaps the Welfare Economics Paradigm approach to teaching economics has some value. If, as the general equilibrium theorists tell us, an externality-free competitive equilibrium is Pareto efficient, and it is helpful to divide problems of costly information, with some information costs producing
price discovery and pecuniary externalities amenable to supply and demand analysis, whilst other information costs generating liabilities amenable to Coasian bargaining and assignment of property rights, and the set of information problems
warranting direct government intervention accordingly becomes
more narrowly defined.
Now that we've settled all that,
shall we take up the monopoly that produces a negative nonpecuniary externality?