Since most Americans know next to nothing about the woman Sen. John McCain has selected as his vice presidential nominee, we must rely upon the media, her Alaskan colleagues and personal acquaintances who do know her to help us assess Ms. Palin’s suitability for the job she aspires soon to hold. Numerous such sources have portrayed her as an unbridled opportunist who will, without warning, turn on anyone at all — even one of her own campaign managers — in order to curry public favor, win votes or to benefit otherwise. The same seems to be true for any position on any issue she may hold. If she perceives that sentiment is running strongly against her position, she’ll switch it in a Fairbanks minute — and then pretend as if she had been on the right side all along. A certain much-ballyhooed claim on a once-earmarked bridge comes to mind.