Two recurring themes of this blog are that you need a realistic understanding of how probability works in this world, and that evolution happens to you whether you believe in it or not.
Political third parties are my example today of people who suffer because they don’t understand the math of probability, nor understand how the unintended effects of cultural evolution in the U.S. electoral system makes their efforts counter-productive. In short, the mathematical probability of a third party succeeding at electing a presidential candidate at the national level in the U.S. is somewhere at state lottery-winner odds. Not only that, but the probability of forcing an exactly opposite result from their intended outcome is quite high, indeed more likely the more “successful” they are.
Evolved blind spots
Before we hit that math, however, a word on evolutionary blind spots. All vertebrates on Earth, including humans, have a blind spot in each eye where the optic disc of the retina has no photo-receptor cells, because this is the spot where the optic nerve “punches through” from the back of the eye. Cephalopods like the octopus have no blind spot, because their optic nerve fibers route behind the retina. We usually don’t notice our own blind spot because our brains “invent” content for that spot on the fly. Sometimes we get fooled by our spot, but usually we don’t.
The blind spot is there because of one fateful mutation in the common ancestor between cephalopods and vertebrates that occurred when the “eye” was a much more primitive collection of light-sensitive cells. Our branch of the family tree adapted to the “punch through” optic nerve, while our tentacled octopi cousins got the spot-free eye. There was no turning back.
My contention is that you can look at American political parties as evolved, and still-evolving, social structures that also began with a unique and unadaptable “blind spot” which fated the country to have only two viable political parties at any given time. That fateful and decision was the U.S. Constitution’s construct of the Electoral College, and the consequence was both undesired and unintended. And because of that “blind spot,” third parties in the U.S. will be fated to either (1) merge into their “closest ideological relative” party, or (2) serve as a “spoiler” in close elections, bringing to power the party that is further from their ideology than the alternative.
The octopus in this analogy is the British parliamentary system, which clearly does provide a place for, or even require the input from, third and fourth parties in building electoral coalitions. No “blind spot” exists for these parties.
Like it or not, the reality is that the Electoral College “blind spot” exists and there is little probability that it will self-correct without constitutional reconstruction. Our collective media “brain” also constructs a “made up” reality that allows most people, most of the time, to pretend that the blind spot does not exist. Third parties generate interest every election season, with lots of media stories touting their viability. They are all wrong.
The history of third parties
One way to look at this conundrum is to simply review historical results. We have had two dominant political parties ever since we got through the first few very messy Electoral College elections. The worst flaws showed up quickly, especially in the election of 1800 with a tie over the issue of who would be President and who would be Vice President. After that bug was patched, it became quite obvious that only a ruling and an opposition party could viably exist, and you either joined one or the other, or you were left out.
I think it is a fair reading of the intentions of the Founders, especially George Washington, that political parties, especially in their European style, should not exist. But they do. Anytime “two or three are gathered” to talk politics and work to advance a particular candidate or issue, you have a party, no matter what you call it. Small gatherings turn into larger gatherings as the path to power through aggregation becomes obvious. But quickly the math of voting turns the aggregations into “Ins” and “Outs,” with issues shaking out around that criterion perhaps more than some core, unchanging ideology. Thomas Jefferson’s “aggregation” of like-thinkers and Alexander Hamilton’s parallel “aggregation” quickly became the dominant political forces, there were basically only two viable parties from that point on, even as the parties themselves evolved, and even flipped roles. 
The dominance of Thomas Jefferson’s Democratic-Republican Party (which later evolved into the Democratic Party) took hold with his 1800 election. Only once in the 218 years since has one of the two major political parties “imploded” rather than “evolved.” The trauma of the pre-Civil War era forced the “roll-over” of the old Whig Party in the decade before, quickly reconfiguring into the Republican Party that ran John C. Frémont unsuccessfully in 1856, and Abraham Lincoln successfully four years later. So, if you are hoping for a rising third party, you need to hope for an implosion of one of the two dominant parties. I’m not, by the way, ruling that out for the near future.
By the way, you really need to ignore the labels. It is not that one party is called “Republican” and one is called “Democrat.” Major interest groups and their issues have migrated from one party to the others over the years, the most recent big one being the movement of the segregationist Southern Democrats to the Republican party after the passage of the 1964 Civil Rights Act, insuring the election of Richard Nixon in 1968.
Dinesh D’Souza and his ilk, in demonstration of this concept, are gaslighting whenever they accuse the current Democratic party of being the party of slavery. They know full well the historical evolution of the parties and are confident that many of their followers do not know that history. As a parallel example, one must be quite naive to think that nominal Republican Attorney General Jefferson Beauregard Sessions III is really in “the party of Lincoln.”
Instead of party names, I suggest that you just think “Party in Power” (PiP) and “Party out of Power.” (PooP – memorable acronyms). PiP is the gazelle in our evolutionary example, bobbing and weaving, trying to stay alive to vote another day, trying to keep its body and soul together. PooP, on the other hand, is the lion, trying to tear a limb (a key issue or interest group) off PiP in order to prevent it from getting re-elected. And if PooP DOES get elected, significant roles and issues will reverse sides and the chase begins anew. Think “Deficit Spending.” It is a sin only to the PooP, but necessary for governing if you are the PiP. We are living in the most recent example of this reality with the Republicans recently passing both massive tax cuts and an impossible-to-balance budget, throwing away decades of rhetoric about fiscal responsibility.
Most people do not switch sides, but every four years, just enough people often do if there is enough opportunity for a PooP group to become a PiP. Over time, significant changes evolve in each party, but “over time” is usually the operative phrase. 
Teddy Roosevelt made a run at the Presidency with his Bull Moose Party in 1912, only succeeding in bringing the Democrat Woodrow Wilson to power at the expense of his former friend William Howard Taft. Ralph Nader’s success in Florida sealed the 2000 election for George W. Bush. And Jill Stein’s Green Party quite clearly gave us President Trump in 2016, and with it a concerted effort by Trump’s appointees to “trash” every pro-environment action from the last two decades. Was this in any way a better result than would have resulted from an electoral coalition with Hillary Clinton?
The election of 1968, with George Wallace winning five southern states, might be interpreted in a several different ways. The question was whether the loss of some southern racists and northern sympathizers to Wallace would hurt most the Democrats, their traditional party home since the “War of Northern Aggression,” or Nixon’s Republicans, who were courting them with his infamous “Southern Strategy.” Either scenario is pretty revolting, but in the end, this meant that the segregationists were gone from the Democratic Party forever, and eagerly embraced by the Republicans in a PooP to PiP move for that demographic, which ensured re-election for Nixon by a very wide margin in 1972, and it is still in place today.
The math of the Electoral College
These unsuccessful and counterproductive third-party runs were not just failures; rather they were likely inevitable. The mathematics of the Electoral College demands it. Most of the states are “winner take all,” which embeds a very high probability, “all or nothing” hurdle. A strong third party will suck the most votes from the party closest to it in ideology, greatly reducing the mathematical odds that the original party can reach the “winner take all” threshold. The result is handing all of the electoral votes for that state to that third party’s more ideologically-distant opponent. The most obvious example is Al Gore’s loss of the state of Florida due to the Ralph Nader bleed-off in 2000.
And then there is the Constitutional backstop. Assuming such a strong enough showing of a third party in the Electoral College that a presidential election was thrown into the House of Representatives, the reality of only two functional parties in the House comes into the play, and the party that is the most anathema to the third party is very likely to be put into power.
In short, when approached as a probability problem, the math for a third party electoral success is like putting your money down on the worst horse in the race, betting on a long-shot win. It just won’t work out the way you think it will.
Alternatives to the Electoral College obstacle
Despite high-profile candidates emerging every four years, the hard work of the political parties is done mostly by volunteers at the local and state levels, trying to run candidates and win elections in seats from the most basic city and county offices up through federal office. Ideological shifting of either of the two dominant political parties is likely easiest at the local level, as organized interest groups can often exert influence or even take over local organizations by just be being there for the “grunt work.”
The more recent rightward shift of the Republican Party is probably the best lesson on third party alternatives in recent years focusing at more local efforts. Three different forces radicalized the party from within, driving out almost all the old “Rockefeller Republican” moderates. 
- The “TEA Party” movement (standing for “taxed enough already”). This was a heavily “astroturfed” takeover of U.S. House of Representative seats one by one in conservative districts. Through financing by “dark money” groups like the Koch brothers, “TEA Partiers,” mostly older white men, became convinced that they were being overly-taxed by the federal government, even though the large majority of them were, in reality, paying well-below average rates of federal income taxes due to their age (as Social Security recipients) or lower-wage blue-collar employment. This resulted in an upending of House leadership under John Boehner and the rise of fiscal radicals.
- The ALEC (American Legislative Exchange Council) takeover of state legislatures. ALEC’s strategy was, and is, to actually write, down to the letter, state legislation favoring conservative causes, and to sponsor numerous individual state legislators who will bring these bills to the floor in each state where they have access to power. This has been one of the most successful ideological movements of recent decades in terms of legislative success. And I don’t mean that in a good way.
- The Federalist Society (officially the Federalist Society for Law and Public Policy Studies) is a group of conservatives and libertarians who have focused on changing the U.S. Judiciary at all levels, starting with entry-level judges, and going all the way up to the U.S. Supreme Court, with four of their members currently in place and a fifth due to be seated shortly. The negative effects will be felt for a generation.
In short, the math of the Electoral College ought to tell prospective third parties that their prospects for success are best begun at the local level, plus active coalition-building with the party closest in ideology, However, the every-four-years flash-in-the-pan fame (and in the Jill Stein case, apparent help from Russians) is often too much of a temptation to pass up.
- And do I need to note that both original “aggregations” were of land-owning, largely wealthy white men. The women, slaves, indigenous Americans and newer immigrants couldn’t even rate “Out” status.
- For an explanation of position-switching using a technique called “Markov chains” and the 180-position reversals of Trump Republicans, see this recent post.
- I also wrote about the decline of the moderate Republicans in an earlier post about George and Lenore Romney, Mitt’s parents.