What exactly would all the gloating anti-war types here consider sufficient intelligence to believe something?

Terrorists tell you that they're working with Iraq. Don't believe them, they might be setting you up. Anti-Saddam Iraqis tell you something. Don't believe them, they have an axe to grind. Saddam's flunkies tell you something. Don't believe them--Saddam is feeding them misleading information. Satellite pictures--you might be wrong. Intercepted phone calls--same thing.

And yes, sometimes you're wrong. That's how intelligence works.

Does anyone see any end result for this kind of thinking other than complete paralysis?

Or maybe we should just go the Kerry route. Absorb attacks, bury the dead Americans, then retaliate. Assuming you trust whatever intelligence points to the aggressor, of course.