Probability: it’s not what you think

I had a conversation the other day about probability. The guy I was speaking to convinced me rather easily that probability is not a study of the odds of events happening. It is the study of people’s ability to correctly predict the outcome of events whose outcome is out of their control and, arguably, already determined. They do this based on knowledge that they have.

If I roll a die, the outcome of the roll is not the subject of probability. Its outcome could be considered pre-defined, its outcome not the subject of chance at all. Assuming, let’s say, that the state of the universe has determined that the die will come up with a 4, then the chances of it being a 1, 2, 3, 5 or 6 are zero; and the chances of it being a 4 are 1, or certainty.

Probability only becomes useful on multiple trials of the same event, when the laws of the universe are such that the percentage of trials ending up with a certain outcome approximate to what we are taught is the probability that a single event will have that outcome. In poker, if I have a full house, aces and queens, then I don’t have, say, a 98% chance of winning. The cards are such that either there is a 100% chance of be winning, or a 100% chance of me losing. Nothing I can do will change that.


One Response to “Probability: it’s not what you think”

  1. The Caped Crusader on January 28th, 2009 13:18

    Try telling that Schrodinger’s cat!

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