From The Economic Way of Thinking, eleventh edition, by Paul Heyne and others, p. 195:
Profit arises from uncertainty. In the absence of uncertainty, any differences between expected revenue and expected total cost would be competed away and profits would become zero.
That sounds to me like too strong a generalization. Some remarks.
1. It shows the influence of Frank Knight. But would Knight have bought such a strong statement?
2. Economists, including the authors, point out that profits as reported by business include opportunity cost, particularly the opportunity cost of capital. Economic profit is less.
3. Elsewhere, the authors want to insist, reasonably enough, that taxes are paid by individuals, even when those taxes are called corporate income taxes. I would think that consistency would require insisting that profits accrue to individuals, even when they are called corporate profits. But if all profits accrue to individuals, then I do not see how we can separate economic rent from opportunity cost. Maybe Bill Gates made a lot of money from Microsoft because he happens to have a very high opportunity cost. OK, that sounds absurd, but still, he has a higher opportunity cost than someone with less drive and ability starting a software business.
4. Talking about the profits earned by shareholders is tricky. In the portfolio theory of modern finance, there should be no excess return from taking diversifiable risk. Unless I know something that everyone else doesn’t, I will earn on average a lower return by buying shares in a particular stock than by buying shares in the market portfolio. (I think this point tends to cut against point 3 above.)
5. How do patents fit into the story? Firms obtain patents in order to protect profits. Are patents simply government-chartered monopolies, leading to artificial rents? Or are patents a return on investment in research and development? In the latter case, perhaps one would say that if the outcome of research and development were certain, then profits from those activities would become zero.
6. It seems to me that there are other sources of market power that are defensible. I am not talking about defensible in a moral sense, but defensible in the sense that they will not be competed away. For example, there is reputation. If my insurance company has a reputation for being sound, then potential competitors will find it difficult to persuade my customers to switch. Another example is network effects. Wal-Mart has a lot of customers because it has cheap prices. Because it has a lot of customers, it is in a strong bargaining position with suppliers, so it can keep its prices cheap. But if a lot of companies try to create network effects, and some succeed and some fail, is this another case of profit emerging out of uncertainty?
Going back to the quoted paragraph, I think that it is either false or uninteresting. If we do not stretch our definition of uncertainty, then it is false. Alternatively, suppose that we make it true by arguing that profit from investment in intellectual property, reputation, network effects, and so on is only due to the uncertainty involved in such investment. A forced tautology of that sort is not interesting.