As a general rule, economists relying on supply and demand curves without properly discussing the assumptions that sit underneath their graphs can be ignored.
Alan Evans' book Economics, Real Estate and the Supply of Land is an effort to refute Ricardian notions of land supply and rent, and offer an alternative neoclassical theory of land supply. The arguments in this book are taken by many who believe that reducing government involvement in town planning will decrease the price of housing. Evans’ reasoning is questionable to say the least, and supported by elaborate graphs with often biased assumptions and interpretations.
One of Evans’ aims is to refute the Ricardian proposition ‘that the price of land is high because the price of corn [read: houses] is high, and not vice versa’.
To do this he constructs a model economy with a fixed land supply where two agricultural uses compete for land – potatoes and corn. In the figure below we see his construction of this economy on the left, with demand for corn inverted so that the intersection of corn and potato demand determines the equilibrium share of land devoted to each crop, and the equilibrium rent of land at point A.
He then proceeds to add a demand shock to potatoes ‘for some reason’. The new blue line represents the new increased demand for potatoes which enables potato growers to bid up prices for land previously grown for corn and reduce the amount of land used to grow corn. He concludes with the following -
Now it is quite clear that the increase in the rent of land is not caused by the increase in the price of corn. Exactly the reverse is true. The price of corn has risen because the price of land has risen.
The rent for land is not solely determined by the demand for the product.
First, it is still quite clear that at the new equilibrium the price of land for corn is still determined by the new higher price for corn. You could just as easily argue that every time a potato grower buys land from a corn grower he decreases the output of corn and the price of corn rises, thereby leading to an increase in the rents of land available for growing corn.
Second, he fails to notice that all he has done with the model is to demonstrate the inflation mechanism following an increase in money supply for one purpose. He increases total demand (potatoes plus corn) but shifts preferences towards potatoes so that corn demand is constant. The end result of his demand increase is to increase all prices in the model economy – potatoes, corn and rent.
Followers of Say would jump straight to this conclusion. You can’t simply increase total demand in the economy – demand is comprised of supply.
An actual demand shock, which models a change in preferences from corn to potatoes, is shown in the right hand side figure. You will notice that total demand remains constant and therefore the rents for this fixed quantity of land also remain constant.
So no, land rents do not determine prices. Prices determine rents.
Another example of poor reasoning is when Evans argues against a 100% land value tax. He argues that a tax of that nature would ‘freeze’ land development because there would be no incentive for a owner of agricultural land to sell his land to a developer for housing development, since he would not capture any of the value uplift. The rent achieved by the owner of the land will remain the same as when it is rented to the farmer – zero.
Yet in chapter 8 he argues that the value of land grows in anticipation of future higher value uses. In these cases, when the site is genuinely worth more as housing, the tax would be at a rate that reflects that higher value, and not the agricultural value. Therefore, the owner of the land will be facing a tax on the land value for housing while only receiving rents at agricultural values. As the city expands and the value of his land for housing surpasses the value for agriculture, he has a great incentive to sell or develop immediately to avoid losses.
Although I don’t support a 100% land value tax, I do support shifting the tax burden towards land and fixed rights to natural resources.
What we do learn from this book is that even the experts are prone to bias that affects their ability to apply objective logic and reason.