There's a certain concept I don't understand. I don't believe in it, but I hear a lot of the seasoned posters around here use it though, so I figure they might be on to something...

The board is QQA

Hero has AK, but, due to preflop / flop action, has a solid read that the Villain has a Queen for trips. Because of this, he checks behind villain, evading his "trap" and hoping for an Ace on the turn. The turn is a third queen for QQAQ. The villain bets in the manner that screams quad queens.

However, the Hero, seeing three queens on the board, figures that the probability of (or the # of combinations that give) the villain quads are now greatly diminished. (Hero might call or something figuring villain for an ace).

Case 2:

Hyper Aggressive 4 bets Hero preflop. Hero calls with kings, figuring that while there are 6 combinations of cards that make AA, there are 12 that make AK, and so it is more likely that the villain holds AK here).

This concept (I suspect I may be presenting it wrong) makes me scratch my head. I am baffled at how this sort of after-the-fact reasoning can be used to estimate how much weight different hands should be given in a range. Isn't there some rule where the probability of an event is not effected by future events?

Analogy: A Bag holds four marbles: two are blue and two are red. Your friend draws a marble without showing it to you. You then draw a bag out of the marble: it is blue. You now figure that your friend probably has a red marble. Isn't this flawed since your friend had a 50/50 shot of having red/blue and has the same likelihood now? Does your discovery of new information after the fact affect the probability of your friends holdings? I say no, it doesn't.

I am sure that I'm mistaken in some manner, I'm just struggling with this concept and would really like to understand it.