> In elementary macroeconomics you learn it is impossible to make a profit because in a competitive market because it is rational for me to lower my price by on

> In elementary macroeconomics you learn it is impossible to make a profit because in a competitive market because it is rational for me to lower my price by one cent to get the deal and then it is rational for the competitors to do that until the point that profit is zero. I did not take macro economics, but this does not sound correct to me. If the profit is zero, then why do it? Surely the statement should read ...rational for the competitors to do that until the point that the profit is zero _plus one exchange unit_. If there is no profit at all, then it is not rational to do the thing. Profit can be extremely thin, but it should still be there.