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
It takes for granted that the options it considers are mutually exclusive.