By Barb Shelly, Kansas City Star editorial page columnist

Happy Independence Day.

There seem to be three prevailing theories about Sarah Palin's shocker announcement that she's resigning as governor of Alaska:

1) She's resigning ahead of a massive scandal.

2) It's a brilliant decision to rev up her presidential prospects.

3) It's another misguided, impulsive decision, and yet more evidence that Sarah Palin should never be president of the United States.

I lean toward No. 3. Sarah Palin is a very intriguing character, but she has no depth. She can work a crowd, but she can't debate policy. She can get herself elected governor of Alaska, but she can't finish out a single term. I think we'll see her giving speeches and becoming a fixture on the radio and TV talk shows. But she's going to have to show a lot more depth before people will trust her to hold a high national office.

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