Fundamental Theorem of Poker

Poker has commonly been referred to as a 'battle of mistakes', the less mistakes you make and the more you induce from your opponents, the better off you will be. The qualities that best allow you to achieve this goal are a good hand reading ability and well thought out deceptive play; consistantly achieving both of these traits means you are likely winning the battle of mistakes and therefore abiding by the fundamental theorem of poker.

In his one of his poker books 'The Theory of Poker', author David Sklansky proposes a concept he calls "The Fundamental Thorem of Poker", which has gained a level of acceptance throughout the poker community. The theory is based on a mathematical expression, but is more commonly conveyed using plain English, Sklansky states:

"Every time you play a hand differently from the way you would have played it if you could see all your opponents' cards, they gain; and every time you play your hand the same way you would have played it if you could see all their cards, they lose. Conversely, every time opponents play their hands differently from the way they would have if they could see all your cards, you gain; and every time they play their hands the same way they would have played if they could see all your cards, you lose"

For example, you hold JJ in the hole and the pre flop action is folded to you in early table position, you raise three times the big blind and everybody folds around to the player in the small blind who calls holding 77 in the hole, the big blind folds. The flop comes AK5 and the small blind bets half the pot and you choose to fold your hand in the face of two overcards on the flop and an opponent betting into you. According to the fundamental theorem of poker, you have just made a mistake because you played the hand differently from the way you would have played it if you could see your opponents hole cards, your opponent induced you to make a mistake.

Using the same previous example, but this time you have a relaible read on the player in the small blind who now holds K5 in the hole, you suspect him to be very aggressive and capable of betting out of position on the flop with bottom pair, an inside straight draw or even absolutley nothing; you also think they are capable of making laydowns when facing a big reraise if they don't have at least top pair or better. Again, your opponent bets half the pot on the flop, but instead of folding, you choose to make a pot sized reraise and your opponent folds his pair of kings in the belief that you must have paired an ace in your hand. This time your opponent has played their hand differently from the way they would have played it if they could see your hole cards, you forced your opponent into making a mistake.