User:Derek Ross/Prediction

Prediction is an interesting topic. Among the things that I find interesting about it are the limitations. These are partially dependent on how closely linked the present is to the future. But they're also dependent on how closely linked the predictions are to the future. Using these thoughts it's possible to classify predictions into four groups. Predictions which do not affect the likelihood of the predicted event; predictions which make the predicted event more likely to occur; predictions which make the predicted event less likely to occur and finally predictions which affect the likelihood of the predicted event in an unpredictable way.

Predictions which do not affect the likelihood of the predicted event

Examples of these are predictions of Lottery numbers, Weather forecasts, and general scientific predictions such as the predicted trajectory of an arrow leaving a bow. In some cases the prediction may be more likely to be correct than in others but in no case does the act of predicting affect the result.

Predictions which make the predicted event more likely to occur

If I predict that you will win the Lottery when you move to Glamis and tell you, this will increase the chances of your moving to Glamis (which I assume are non-existent at the moment). It may also increase the chance that you play the Lottery, assuming that you do not already do so. The combination of these two will increase the chances of your winning the Lottery over the chance if I had made the prediction and not told you.

Predictions which make the predicted event less likely to occur

If a fortune teller predicts that a client will die in a plane crash and informs the client, the client is less likely to travel by plane and thus less likely to die in a plane crash as a result. If a doctor tells a patient that he will die as a result of his lifestyle, the client is less likely to continue the lifestyle and therefore less likely to die as a result.

Predictions which affect likelihood of the predicted event in an unpredictable way

These are predictions which make the predicted event less predictable. For instance if I predict that a John Macdonald living in Portlethen will win the lottery, and tell people that this may increase the number of John Macdonalds in Portlethen from one to twenty as gullible lottery players move there in an attempt to increase their chances of winning. However this reduces the chances of me correctly predicting the lottery winner, perhaps turning a sure thing into a one in twenty chance.