Michael Bloombergand Donald Trump are both businessmen, both are politicians, and both are billionaires. Obviously, then,they must know a lot about economics, right?

Not necessarily. As Don Boudreaux — a man who does know a lot about economics — correctlypoints out, success at business does not imply knowledge of economics:

Knowing how to run a business is not the same thing as knowing economics. To assume that the two domains of knowledge and expertise are the same is an error equivalent to assuming that a successful NASCAR driver is thereby an expert automotive engineer. Of course, it’s possible for a successful NASCAR driver to know something about automotive engineering, just as it’s possible for a successful business person to know something about economics. But success at each of the former tasks (driving a race car and managing a business) is not the same thing as, and requires very little familiarity with, the latter domains of knowledge (automotive engineering and economics).

Strong evidence – indeed, virtual proof – that knowing how to run a business successfully does not imply knowledge of economics is supplied by the great economics-policy differences that separate successful business people. Charles Koch, for example, is a far more successful business person than is Donald Trump, yet Mr. Koch’s understanding of economics differs markedly from Mr. Trump’s. If success at business were a sufficient indicator of deep and expert knowledge of economics, it would be nearly impossible to explain the deep differences that separate Mr. Koch’s professed understanding of economics from Mr. Trump’s professed understanding of economics.

I would go even further than Boudreaux and say that being a successful businessperson doesn’t even mean that a person knows much about business. Of course there are somebusiness people who, if they had to start over from scratch, could esuccessful again. But many more — perhaps even the majority — achieved their status because they relied on variables, ranging from ideal market conditions to just plain dumb luck, that cannot be replicated.

This is also whybusinesspeople rarelymake effective politicians: they tend to overestimate their knowledge of macroeconomicsand end up falling fordumb economic policies (e.g., trade protectionism).

Americans seem to recognize this “successful businessperson fallacy” almost intuitively. Yet every election a distressingly large percent of the populace endorsea wealthy businessperson for president, thinking the billionaire will be able to “fix the economy.” But the U.S. economy is not like a business and cannot be run like one. The major difference, asChristine Harbin writes, is that government is a monopoly and businesses operate in a market:

Because businesses face petitive pressure than government, they have an incentive to innovate their products, improve their services, drive down prices, e more efficient, etc. Government doesn’t experience this kind petitive pressure because it is the sole provider of its services, so it does not have an incentive to do those things. Government can afford to deliver sub-par service because it prohibits other firms from entering the market.

Another reason, Harbin notes, is that businesspeople make decisions differently thanelected officials:

Leaders made decisions differently in businesses and in government. Decisions are made by consensus in a representational democracy like the United States. In a business, the power to make decisions tends to be more centralized. Decisions are made by a select number of individuals, by polling all of the employees.

Participants also make decisions differently. In a market, individuals always get to decide what they pay for, whereas in a democracy, they have to go along with whatever the majority wants.

When evaluating a businessperson turned candidate, ask them, “Do you think running a business is anything like running the government?” Unless they answer, “No, they’re noteven close” then keep looking — because that’s a person who doesn’t know much about either business or governance.