What evidence does your brother have for his claim? For a fuller treatment of monopoly, take a look at Dominic Armentano’s book, Antitrust and Monopoly.
Here is an article by Armentano discussing various arguments about monopoly:
http://mises.org/daily/1800
Here is Thomas DiLorenzo on the idea of “natural” monopoly, which in the jargon of economics is the claim your brother is making:
http://mises.org/daily/5266/
