Who Is Dismal Now?
Economics was dubbed the "dismal science" in the 19th century for reasons that have been largely forgotten or suppressed. It may be that the name stuck because economics is, at its core, anti-utopian. The notion of scarcity is the foundation of economics, so economists see costs everywhere. They keep reminding people that there is no such thing as a free lunch, which is often an unwelcome message. Or maybe the name has stuck because some people are unsettled with the central role that the assumption of self-interest plays in economics. It is difficult to raise a crop of idealism from fields of self-interest, and to some, this is a dismal outcome.
However, there is an optimistic side to economics that suggests the term "dismal science" is inappropriate. Economists focus on market exchange and in exchange both buyer and seller emerge better off than they were before. Their focus on exchange makes economists ready and even eager to see interactions as positive-sum. In a positive-sum interaction there is a net gain because winnings exceed losses. Certainly a way of viewing the world that sees people constantly acting to improve their situation is not dismal.1
In contrast, many social scientists outside of economics make heavy use of power models to interpret the world, and one can make a strong case that this is a dismal way to view reality. Power models tend to see interactions as zero-sum, which means that any winning is balanced by a loss. If one person improves his situation, it must come at the expense of another whose situation has become worse. Power models tend to emphasize exploiters and victims, so look for them when you see discussions making heavy use of these categories. They are common in discussions of politics, gender, race, and poverty.
One reason those who use power models are not dubbed "dismal scientists" is that they are often utopian, (though utopianism is not a necessary part of any power model). Karl Marx, the most famous user of a power model, is an example. He saw the world as a struggle between the owners of capital and workers. The former had power and exploited the latter. The exploitation would stop when workers violently rose up to expropriate the expropriators. You might expect that, after the revolution, the workers that had seized power would use to exploit others; this outcome is logical in terms of power models. However, Marx said that power would not be transferred in this case, but would cease to exist, and a world of peace and harmony, a utopia, would come into being.
Marx labeled his utopian view of socialism as "scientific socialism" and labeled as "utopian socialism" the views of his contemporary socialists who were trying to establish socialism by experiment, that is, by science. This bizarre labeling has stuck and people use it without reflecting on its absurdity. Once a term comes into every day use, people just accept it. For example, have you ever noticed the absurdity of the term "underprivileged?" One can be unprivileged or non-privileged, but it is logically impossible to be underprivileged. This conservatism of language is probably the main reason economics, which is no more dismal than many other fields of study, is still known as the "dismal science."
1The idea of comparative advantage also has very optimistic insights. It says that diversity, rather than being the source of conflict, can lead to greater production and cooperation and that even those with low productivity can play a useful role in society.