The Theory of Political Coalitions
Encyclopedia
The Theory of Political Coalitions is a book on positive political theory
written by William H. Riker
published in 1962. It uses game theory
to formalize political theory. In it, Riker deduces the size principle. On its postulates, politicians are proved to form winning, minimal-size coalitions. The work runs contrary to a previous theory that politicians try to maximize their respective votes. Riker supposes that attracting more votes requires resources and that politicians run to win. So, a rational politician tries to form a coalition that is as large as necessary to win but not larger.
We now have three possible winning coalitions:
If we now presume that the power will be divided according to strength within the coalition, the parties will prefer the largest relative size within the coalition. The result is that the coalition "Party C and D" will be the winning coalition. The largest party is thus kept from power.
Positive political theory
Positive political theory or explanatory political theory is the study of politics using formal methods such as social choice theory, game theory, and statistical analysis. In particular, social choice theoretic methods are often used to describe and analyze the performance of rules or institutions...
written by William H. Riker
William H. Riker
William Harrison Riker was an American political scientist who applied game theory and mathematics to political science....
published in 1962. It uses game theory
Game theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
to formalize political theory. In it, Riker deduces the size principle. On its postulates, politicians are proved to form winning, minimal-size coalitions. The work runs contrary to a previous theory that politicians try to maximize their respective votes. Riker supposes that attracting more votes requires resources and that politicians run to win. So, a rational politician tries to form a coalition that is as large as necessary to win but not larger.
Minimal size coalitions
An example. Lets imagine a five-party system after a general election. The representation is given:| Party A | Party B | Party C | Party D | Party E | ||
|---|---|---|---|---|---|---|
| Number of representatives | 5 | 40 | 26 | 25 | 4 | Sum: 100 |
We now have three possible winning coalitions:
| Party B and C | Party B and D | Party C and D |
|---|---|---|
| 40+26=66 representatives | 40+25=65 representatives | 26+25=51 representatives |
If we now presume that the power will be divided according to strength within the coalition, the parties will prefer the largest relative size within the coalition. The result is that the coalition "Party C and D" will be the winning coalition. The largest party is thus kept from power.