Any game in which a number of players must play for portions of a fixed amount of material, i.e. chips, money, xp, energy, etc. The meaning of this is that whenever one player increases their score, the score of the rest of the group must decrease by the same amount. Poker is the best example of a zero sum game. Blackjack and other house games are also zero-sum games, but for all practical purposes they are not, as you will be thrown out of the casino long before the house lets you make any significant dent in their cage.

A common logical fallacy is to compare a complex issue in economics to a zero-sum game. This is most frequent when you hear about how, say, the United States has one quarter the population of India, yet consumes three times the world's resources. This may be indicative of an inequality, but the statement erroneously implies that if we Americans were to limit our consumption, this would somehow encourage the GDP of India to rise. In all likelihood, the opposite would be true, as the decrease in consumption would include a decrease in consumption of Indian goods, which would depress the nation even more. Another reason this argument is bad is because some of the goods consumed are not static resources, such as grain, which (these days) is grown according to demand.

You may also find that some noders complain about how other people's writeups get voted on and cooled more than theirs, as though voting was a zero-sum game. Although there is indeed a limited number of votes available per day, this is fallacious because it implies that all votes are used every day, and that if other nodes didn't get voted on, their nodes would get voted up.

A zero sum game is one in which the total amount of 'points' remains constant. One player's loss is the other player's gain. Payments are made only to the other players.

The simplest of zero sum games is the classic matching coins game.

• Two players agree to one being "even" and the other being "odd".
• Each player shows a penny.
• If both show the same side, then "even" wins the penny from "odd".
• If each shows a different side, then "odd" wins the penny from "even".
Or, the payoff for the game.
```
._______odd______.
Even Head|  1,-1  |  -1,1 |
Tail|  -1,1  |  1,-1 |
```

Adding up the payoffs in each cell, the sum of them is 0, hence, a zero sum game.

Formally this is defined as: If all the wins and losses in a game are totaled, treating losses as negatives, the sum for each set of strategies chosen is 0.

Or, less formally, a zero sum game is one in which one player's winnings equal the other player's losses.

You might imagine adding up all the universe's resources: labor, land, raw materials, equipment, technology, knowledge, etc... into a pie. At different times, different people may have control of different percentages of this pie, but the size of the pie isn't constant. Improvements in technology can get you access to other planets, more solar radiation, deeper into the ocean or earth's crust, more efficient use of existing resources - thus increasing the size of the pie. If the size of the pie can be increased, then of course other actions can also decrease it.

This isn't to say nothing should ever be done about the relative amounts of the pie that different people control. Obviously the more parts of the pie allocated to serving a smaller percentage of the population, the less that will be available for everybody else. However, it is both a fallacy to say that society can only be improved by improving the pie's distribution, and a fallacy to say that society should only be improved by increasing the size of the pie.

Resource allocation is very important to the survival of society. If I spend all my time, food, and energy building a bridge that many people will use, while someone else spends all his time and energy building a bomber and explosives to take out the bridge, then in the end, the resources allocated toward both our activities were pretty much wasted.

On a less extreme scale, if I use up a lot of resources to build a bridge that nobody wants to use, then my personal efforts were wasted.

The spectrum continues: if I spend a lot of resources in trying to convince others to buy a product they didn't originally want (advertising), and keep doing it until I finally convince them to want it, and then spend more resources to produce the things they've been convinced to want, that too isn't exactly an efficient use of resources.