One of the most contentious issues in the world today is that of free trade. For centuries, governments have undertaken efforts to protect domestic industries by erecting trade barriers. What is interesting is that a simple model shows that the gains of free trade far outweigh the gains of protection. So given that a government is acting rationally to raise the total wellbeing of the nation as a whole, it should easily decide to remove tariffs, quotas and other protections. In this article, I will prove that in a simplified example using a supply and demand model, there are high costs to protectionism and therefore net gains when a country pursues free trade.
In order to prove that the gains of free trade are greater than the cost, I will model a situation where the good in question is apples. To simplify the problem, I will aggregate the supply and demand functions. I will examine a single country, which I will call Protania, which under free trade will have an equilibrium where its’ domestic demand for apples is supplied by both domestic producers and foreign producers. Finally, I will assume that the domestic firms are inefficient with respect to foreign firms, either due climate reasons, technological lags, or some other reason. Because of this, it follows that it is safe to assume that these foreign firms supply apples to their home countries. As a result, Protania’s producers do not export any apples. So the domestic demand of foreign countries can be left out of the following thought experiment.
Under free trade conditions, with no quotas or restrictions, here are the demand and supply curves, and the equilibrium point:
A strong measure of welfare of the different groups are consumer and producer surplus.
Domestic Producers’ Surplus:
One of the simplest protectionist policy tools is the use of quota on imported goods. In the free trade equilibrium within my example, it is easy to see that foreign producers are earning a higher surplus, and that domestic producers could benefit from a quota system that protects them from more efficient foreign competition.
Let us suppose that the government initiates a quota. In order to assume a reasonable threshold for this quota, it is important to note that a government will likely allow some level of foreign imports. In other words, the quota will not be zero. However, the government would not initiate the quota unless it hoped to have some effect on production domestically, and as a result it will set the quota on imported apples at a level that is lower than the number of apples imported in equilibrium under free trade. In simpler terms, this means that the quota must be greater than zero but less than 31.5 apples. For the sake of simplicity, I will arbitrarily pick 15 as the maximum number of apples allowed to be imported.
This quota will change the supply function of the foreign firm into a piecewise function that is defined as and q=15 when quantity is greater than 15. In order to apply this effect to the greater picture, I integrated the foreign producer’s supply equation with the domestic producer’s, to achieve the following supply equation:
The demand equation remains the same, and the resulting equilibrium occurs on the second interval of the supply equation, at the point where quantity is 37.5 apples and the price is $8 an apple. As can be seen, the price has risen dramatically, and the quantity has fallen significantly. But this was expected, as any reduction in supply must result in higher prices thus less quantity. The interest part is whether consumer and producer surplus have changed.
Domestic Producers’ Surplus:
Total Surplus with quota=$369.63
|Free Trade||Quota System||Net Change|
|Total Producer Surplus||$81||$144.63||+$63.63|
|Total Foreign Producer Surplus||$56.7||$87.93||+$31.23|
|Domestic Producer Surplus||$24.3||$56.7||+$32.4|
|Total Consumer Surplus||$324||$225||-$99|
Given the two policy options, the above table shows that free trade maximizes total welfare. Further, if it is accepted that there are more consumers of a good than producers, than it is also true that free trade also spreads this welfare most evenly among the most people. Intuitively, the qualification of consumers being more numerous than producers is true for almost all markets. Regardless of whether a government values equality or efficiency, free trade seems to be the best route. It would appear that in almost every case, we would expect governments to pick free trade. The paradox is that governments choose protection more often than not. This is where cooperation problems are powerful explanatory models. In a future article, I will go more in depth into the strategic interactions behind free trade lobbying.
 As mentioned earlier, domestic supply and foreign supply equations are modified so as to be much less efficient at producing. This means that for a given price, foreign firms produce much more than domestic firms.
 13.5 is found by finding the quantity that the domestic firm will produce at the given price of $5.60 in the overall market.
 22.5 is the quantity produced by the domestic firms with the equilibrium price of $8.