If this election season has taught those watching US national elections one thing, it's that it would be nice to have another option. But in a country with a voting system where the candidate with a plurality takes all, the equilibrium number of parties is two.
Just because that number is the equilibrium doesn't mean that this is always the case. And 2016 certainly looks like a year where the political institutions are not in equilibrium. With the population becoming more politically polarized, appealing to both centrists* and fringe elements is getting harder than ever. But the incumbent two parties have economies of scale, ballot access laws and established network effects which provide them with a significant advantage against challengers.
Their biggest advantage of Democrat and Republican party officials is that the challenging parties don't understand the game they are playing. Most people interested in third parties believe the lie that their parties are all about their ideology.
Politics are as much about ideology as corporations are about making customers happy. It can be important, but there are other variables that matter much more. An ideologically consistent third party is not playing to win. They are playing to convince the major parties that they need to change their policies on the margin to convince people not to cast a protest vote for the third party.
Third parties are pretty serious about maintaining their ideological consistency. The Green Party has repeatedly fractured in an attempt to remain true to its values. The Libertarian Party is famous for its attempt to excommunicate its members for impurity or extremism even though its members generally agree on the direction that politics should be moving.
In order to play to win a third party would need to start thinking like a major party. They will have to make compromises to bring people that they only partially agree with into their tent. They will need to make compromises with some types of interest groups even as they take the fight to others. They will have to acknowledge the political reality that it takes more than a promised pure application of their favored ideology to sustainably win elections.
This year the Libertarian Party took baby steps towards this view when they nominated Bill Weld as the vice presidential candidate against the desires of some libertarian purists.
In order to stand a chance this election or going forward they are going to have to take stances that are more libertarian than the status quo, but more status quo than what libertarians generally prefer. Most parents will not vote for a group who wants the blanket legalization of an 18 year old's ability to purchase of crack, meth or heroin, but replacing prison with treatment isn't as scary. Baby steps in the right direction should be preferable to giant leaps never taken. And this type of stance will have to be sustained over multiple election cycles without splintering the Libertarian Party.
No third party stands a chance at long term relevance as long as they keep thinking and acting like a third party who just wants some attention for their ideology from the major parties. This is why any potential replacement to the GOP or the Democratic Party is more likely to come from splinter groups within the party than from third parties built around ideological purity. And considering the value of the party's institutions, network and brand, major changes are still more likely to come from a new group achieving internal control of the party than from one of the parties being replaced.
Take the above with a grain of salt. In this political season I should know better than to make an predictions at all about politics. I should probably just directly predict egg on my face. But the main takeaway here is that the people who put ideology first aren't playing the game to win and few people are incentivized to tell them this. Fortunately for Trump and Clinton, neither one of them seems to have this weakness.
*It would be nice to come up with a term that differentiates those with views that aren't clearly left or right from the business interests who support whoever can ensure the continuation of their favored specific rent seeking policies. Both of these groups are called centrist but I hold on to an irrational hope that they might one day be separate.