4. Terms of Exchange
Before analyzing the problem of the terms of exchange, it is well to recall the reason
for exchange, the fact that each individual values more highly the good he gets than the
good he gives up. This fact is enough to eliminate the fallacious notion that if Crusoe and Jackson
In exchange 5,000 berries for one cow, there is some sort of equality of value between
the cow and the 5,000 berries.
Value exists in the valuing minds of individuals, and these individuals make the exchange precisely
because for each of them there is an inequality of values between the cow and the berries.
For Crusoe, the cow is valued more than the 5,000 berries.
For Jackson, it is valued less.
Otherwise, the exchange could not be made.
Therefore, for each exchange, there is a double inequality of values, rather than an equality,
and hence there are no equal values to be measured in any way.
We have already seen what conditions are needed for exchange to occur and the extent to which
exchange will take place on given terms.
The question then arises, are there any principles that decide the terms on which exchanges are
made?
Why does Crusoe exchange with Jackson at a rate of 5,000 berries for one cow or 2,000
berries for one cow?
Let us take the hypothetical exchange of 5,000 berries for one cow.
These are the terms, or the rate of exchange, 5,000 berries for one cow.
If we express one commodity in terms of the other, we obtain the price of the commodity.
Thus, the price of one good in terms of another is the amount of the other good divided by
by the amount of the first good in exchange.
If two cows exchange for one thousand berries, then the price of cows in terms of berries,
the berry price of cows, is five hundred berries per cow.
Conversely, the price of berries in terms of cows, the cow price of berries, is one
five hundredth cow per berry.
The price is the rate of exchange between two commodities expressed in terms of one
of the commodities.
Other useful concepts in the analysis of exchange are those of selling and buying.
Thus, in the above exchange, we may say that Crusoe sold one thousand berries and bought
two cows in exchange.
On the other hand, Jackson sold two cows and bought one thousand berries.
The sale is the good given up in exchange, while the purchase is the good received.
Let us again focus attention on the object of exchange.
We remember from Chapter 1 that the object of all action is to maximize psychic revenue,
And to do this the actor tries to see to it that the psychic revenue from the action exceeds
the psychic cost, so that he obtains a psychic profit.
This is no less true of interpersonal exchange.
The object in such an exchange for each party is to maximize revenue, to exchange so long
as the expected psychic revenue exceeds the psychic cost.
The psychic revenue from any exchange is the value of the goods received in the exchange.
This is equal to the marginal utility to the purchaser of adding the goods to his stock.
More complicated is the problem of the psychic costs of an exchange.
Psychic costs include all that the actor gives up by making the exchange.
This is equal to the next best use that he could have made of the resources that he has
used.
Suppose for example that Jackson possesses five cows and is considering whether or not
to sell one cow in exchange.
He decides on his value scale that the following is the rank in value of the possible uses
of the cow.
1.
5,000 berries offered by Crusoe.
2.
100 Barrels of Fish Offered by Smith, 3. 4000 Berries Offered by Jones, 4. Marginal Utility
of the Cow in Direct Use. In this case, the top three alternatives involve the exchange
value of the cow, the fourth its value in direct use. Jackson will make the best use
Jackson said that for any specific exchange to occur, the marginal utility of the goods received must also be greater than the marginal utility foregone, that which could have been received, in another type of exchange.
It is evident that Jackson will always prefer an offer of more units of one type of good
to an offer of fewer units of the same good.
In other words, the seller will always prefer the highest possible selling price for his
good.
Jackson will prefer the price of 5,000 berries per cow offered by Crusoe to the price of
4,000 berries per cow offered by Jones.
It might be objected that this may not always be true and may be offset by other factors.
Thus, the prospect of 4,000 berries from Jones may be evaluated higher than the prospect
of 5,000 berries from Crusoe, if a. the psychic disutility of labor and time, etc., for delivery
over a longer distance to the latter, renders the prospect of sale to Crusoe less attractive
despite the higher price in berries, or b. special feelings of friendship for Crusoe
or hatred for Jones serve to change the utilities on Jackson's value scale.
On further analysis, however, these turn out not to be vitiating factors at all.
The rule that the actor will prefer the highest selling price for his good in terms of the
other good always holds.
It must be reiterated that a good is not defined by its physical characteristics, but by the
equal serviceability of its units to the actor.
Now clearly a berry from a longer distance, since it must call forth the disutility of
of Labor to Move It, is not the same good as the berry from a shorter distance, even
though it is physically the same berry.
The very fact that the first is further away means that it is not as serviceable as the
other berry, and hence not the same good.
For one price to be comparable with another, the good must be the same.
Thus, if Jackson prefers to sell his cow for four thousand berries from Jones as compared
to five thousand berries from Crusoe, it does not mean that he chooses a lower price
for his product in terms of the same good, berries, but that he chooses a price in terms
of one good, berries from Jones, over a price in terms of an entirely different good, berries
If these feelings cause him to sell to Jones for 4,000 berries rather than to Crusoe, he will not be able to sell them to him, and he will not be able to sell them to James for 4,000 berries.
So for 5,000 berries, this does not mean that he chooses a lower price for the same good.
He chooses between two different goods, berries from Crusoe and berries from Jones.
Thus, at all times, an actor will sell his product at the highest possible price in terms
of the good received.
Clearly, the converse is true for the buyer.
The buyer will always purchase his good at the lowest possible price.
This truth can be traced in the example just discussed.
Since at the point that Jackson was a seller of the cow, he was also a buyer of the berries.
Where the good in question, berries, was comparable, he bought at the lowest possible price.
Say, one five thousandth of a cow per berry in preference to one four thousandth of a
cow per berry.
In cases where Jackson chooses the latter price, the two berries are no longer the same,
but different goods.
If to buy berries, the purchaser has to range further afield or buy from someone he dislikes,
Then this good becomes a different one in kind from the good closer by or sold by a friend.