I think I need you to clarify just exactly what you mean by somebody having an "N% chance" of beating someone else.
When you say, for example, that
Quote:McCain has probably a 40% chance of beating Clinton
What is that supposed to mean?
Does it mean that on a scale of 0 (no chance at all of beating Clinton) to 100 (certain to beat her), you put McCain's chances at around 40, and Huckabee at around 10? (Generous, that last)
If that is so, then, of course, it is obvious to any rational person that the sum of percentages could be 100N where N is the number of matchups.
However, I don't feel very happy with the idea of using mathematical type language, percentages, etc, to lend a spurious air of rigour and respectability to, in short to dress up, what is, essentially, just guessing.
Unless you use a word like "roughly" or "about", 40% implies 2 figures of accuracy, and you have to say why it's 40 and not 39 or 41. If you didn't intend to imply that degree of accuracy, (and I don't see how you could justify it) why not just say "On a scale of zero to ten, I'd give McCain's chances a value of four"?
After all, elections are not decided by the laws of probability.