Zero-sum fallacy
A zero-sum fallacy is a logical error committed by assuming that some quantity is constant when it is not. The name comes from a concept in game theory.
In game theory a zero-sum game is one in which the total payout to all participants is constant, regardless of the results. Thus chess is a zero-sum game (when one player wins the other must lose) and so is poker (the total number of chips in the game remaining constant).
The most often cited example of a supposed zero-sum fallacy is in economics, where simplistic arguments might assume that the giving of a certain amount of wealth to one person (e.g. through taxation and subsidy) necessarily results in others losing the same amount of wealth. In fact economic activities can increase or reduce the amount of wealth in the world, making the economic 'game' non zero-sum.
Another supposed zero-sum fallacy is in green politics, where it is sometimes assumed that because there is a finite amount of energy available to mankind, activities such as industry must produce irreversible pollution. In fact industrialisation increases the amount of energy available, so without industry the amount of energy available is even more limited, and again the industrialisation 'game' is not zero-sum.
The contradiction to this fallacy is sometimes summed up in the phrase 'rather than arguing over who gets how much of the pie, increase the size of the pie'.
