1. He's 72 years old.
2. He's had multiple cancer scares.
3. He has never been clear about his plans - is he expecting to serve one term or does he think he'll survive until he's 80?
4. It seems to be a reasonable possibility that, if elected, he could die in office.
5. So, a vote for John McCain is a vote of confidence that his VP could serve the office as well.
6. He picks Sarah Palin.
7. She seems to be an up-and-coming star, but still a little green.
8. Picking her seems to be a gambit to overcome what seems to be a sure loss in November.
9. So John McCain's pick is focused on him winning rather than providing an adequate successor in the unfortunate, but possible, event that he doesn't survive his term.
10. John McCain cares more for his ambition than what is best for America.