Because preferences are tied to specific individuals, we say that preferences are subjective. Loosely speaking, the difference between a subjective versus an objective statement, is akin to the difference between an opinion versus a fact. It makes sense to say, “Mary prefers vanilla ice cream to chocolate, but John prefers chocolate ice cream to vanilla.” These two statements are perfectly compatible, because preferences (in this case, preferences for ice cream flavors) are subjective and can differ from person to person.
In contrast, it does not make sense to say, “The ice cream has 300 calories for Mary, but 280 calories for John.” The number of calories in a serving of ice cream is an objective fact; it can’t differ from person to person. Mary and John might disagree with each other about how many calories the ice cream has, but in that case at least one of them is simply mistaken. Yet both of them could be simultaneously “correct” when Mary says, “Vanilla tastes better than chocolate,” while John says the opposite. To repeat, Mary and John can disagree with each other about which flavor of ice cream tastes better—with neither one nor the other being wrong—because preferences are subjective. There is no “fact of the matter” concerning which ice cream tastes better, the way there definitely is an objective way to demonstrate how many calories are in a serving.
Warning! Many critics of economics—both from the progressive “left wing” as well as the religious “right wing”—totally misunderstand what economists mean by saying that preferences are subjective. These critics think that economists are somehow endorsing moral relativism, or that they are saying no one can judge the actions of anyone else. But these complaints are without merit, because economists aren’t saying those things at all!
Remember, we are simply tracing out the logical implications of our decision to classify observed behavior as purposeful action. If we see Mary go up to the counter and choose vanilla ice cream, while we see John go up to the counter and order chocolate, we won’t get anywhere in our understanding unless we realize that Mary and John have different tastes when it comes to ice cream flavors. As we will see more clearly in Lesson 6, the only satisfactory way to explain market prices is to first recognize that preferences are subjective. This recognition in no way condones the preferences of particular individuals.
For example, an economist can’t possibly explain the price of tobacco without acknowledging that some people prefer to spend their money on cigarettes, rather than on other products. After the economist states this fact, he can—with perfect consistency—then ground his teenage son when he catches him smoking in the garage with his hooligan friends. If you’re still not seeing the distinction between professional analysis versus personal beliefs, forget about economics and consider an FBI profiler. To track down a serial killer, the profiler needs to “think like the killer,” and try to understand what desires are causing the killer to act the way he is. Obviously this analysis doesn’t mean that the profiler is neutral with regard to the actions the killer takes, or that murder “is a personal choice.”
To sum up: When people engage in purposeful actions, they are motivated by desires that are not necessarily identical from person to person. In order to explain exchanges, economists must recognize that preferences are subjective.