Mayor: There has been a long debate in city council about how to accommodate projected increases in automobile traffic. Today, our choice is clear: either we adopt my plan to build a new expressway, or we do nothing. Doing nothing is not a viable option because our existing system of roads would be in gridlock within ten years given even a conservative estimate of future traffic levels. City council should ttherefore adopt my plan.
The reasoning in the mayor's argument is most vulnerable to the criticism that it takes for granted that the options it considers are mutually exclusive.