I would like to make a simplified prisoners dilemma regarding presidential elections. Suppose there are 10 voters each election. 3 voters always vote republican (because they believe the party is always right), 3 other voters always vote democrat (because they believe the party is always right), and the other 4 voters are independent and always vote for the lesser of the "two evils" (because they believe that both parties are wrong but they prefer the least worse candidate for a given election cycle.) The 4 voters who vote for the "lesser of two evils" prop up the system. If they were to take their 4 votes and give them to a reform candidate then they wouldn't have to vote for the lesser of two evils. The vote total would be. 4 votes 40% towards reform candidate 3 votes 30% towards democrat 3 votes 30% towards republican But if one independent voter decides to vote for a "lesser of the two evil candidates" then the reform vote fails, because either the democrat or republican gets majority vote at that point. The 3 remaining voters realize that their votes will be waisted if just one independent votes for either of the two parties, thus all independents vote for the "less of two evils" even though all the independents would prefer a reform party. Both Republican and Democrat Parties realize that they will never lose duopoly power because independent voters would have to unify perfectly (if one independent votes for either of the two parties the reform is broken). Thus Republican's and Democrat's are never held accountable because they will never be replaced by a third party. Additionally, since both parties are unaccountable, they can honestly accuse each other of wrong doing. Thus perpetuating the "lesser of two evil" voting system.