@Shevek23 To be clear, I am aware of that but I was thinking more of very small microparties proliferating-in the UK, FPTP keeps parties somewhat consolidated so it's a smaller number of major parties and microparties and only two can be realistic majority or coalition leaders. Likewise, I wasn't talking about larger coalition governments so much as the equivalent of say 5-10 parties needed to hold a coalition down-less Lib-Lab, Lib-Con, or the current supply and confidence deal, than say trying to hold a government of "the cons, a UKIP-esque splinter part, some kind of Red Tory party, a few minor parties, and the Libs".
That was clear enough, but let's look at the actual British Parliament as it is first of all. What happened in the last election? The Conservative party held a majority, with 330 seats, until they themselves, hoping to improve their majority, held a snap election in 2016. The Westminister Parliament is of course first past the post, like the US Congress in that respect. It has 650 Members, but one of these, the Speaker, has a special status that is supposed to be neutral, and votes only according to certain customary rules to break ties, and their election is supposed to be uncontested, so really 325 Members are sufficient to hold a majority. The dynamic then is equivalent to 649 competitive seats.
The Conservatives having a decisive majority in Parliament in 2015 by the way was not reflective of the votes cast by the electorate; in truth they only held just under 37 percent of the votes cast--but with those, gained control of just under 51 percent of all seats in Parliament! This is one of the glaring evils of FPTP, from a point of view of effective accountability of the legislature to popular vote. Or so it seems to me anyway; the suggestion that a lot of little parties would prevent good governance and the suggestion that perhaps it is a good thing for direct democracy to be filtered through lenses that distort the bodies in this fashion are pretty closely related. The implication is that somebody or other knows better than the people or their chosen representatives, that processes that distort that raw public will are somehow desirable. A lot of people do believe that. But let's be clear what we want when we want something to override the will of the people!
In 2016 the Tories did not gain seats, they lost them. When the dust settled they had only 317 seats left in the OTL Parliament. In order to form a government they had no choice but to ask some other party to cooperate with them. With a gap of 8 seats they had two viable choices who to ask, given that other, larger parties, they could approach were more left wing than the alternatives they might prefer. The second party, Labour, had 262 and given the outcomes for other left wing parties had no shot OTL at forming a ruling coalition, nor would the Tories wish to partner with them. The third party was the Scottish National party with 35, but as I understand it they veer left too--in general Labour works better with the various "national" parties like Plaid Cymru. This left them a choice of asking either the Liberal Democrats, with 12 seats, or the Democratic Unionist party of Northern Ireland with 10. They chose the latter, smaller party.
Thus the very nightmare scenario you fear is close to reality despite the strong mechanism of FPTP allegedly "guaranteeing" voters will concentrate in large parties to have a chance to win! The Tory regime depends on keeping a pretty right wing Irish party happy with them.
Now suppose the election of 2016 had for the first time incorporated a Hamilton style maximum inclusion of small parties system such as I like, but people voted in exactly the same way for the same parties as OTL. In that case the Conservatives would still wind up the largest party with 275 MPs--which by the way is 42.31 percent of the total, a substantial gain over the mere 239 which would have been their proportional share in 2015! In fact, the Tories did gain actual support in the snap election, but lost their ill-gotten lead of 91 seats beyond what proportion would entitle them, seeing it whittled down by the semi-chaos of FPTP to merely 42! All of a sudden the need for third party support for the leading party to rule would be drastically multiplied, by a factor of 5!
But this reflects the will of the British electorate. Labour OTL gained 30 seats, up to 262, but proportionally should have had 2 less, 260. Note that in 2015 they had 232 but their proportional share would have been just 198, so ironically this snap election had the effect of calling a lot of voters who had gone "astray" with third parties home to the dominant two; between them their share of votes rose from 62.33 percent to 82.44! And yet it was the 2016 outcome that required the Tories to seek coalition. Remind me again how stepping away from the will of the people brings stability and order?
With PR in 2016, a coalition would also be needed. But the outcomes would be quite different for the upper parties--interestingly less so for many of the minor ones! The minor ones in FPTP have apparently solid consitituencies in certain regions that somehow enable them to exist--indeed the OTL third party, Scottish National, would be downgraded in outcome to 20 versus 35. And further eclipsed by the fourfold surge of the position of the Liberal Democrats, who would rise from 12 seats to 48! The Greens would rise from 1 seat to 11, but Plaid Cymru drops but only by 1, to 3.
Here is the complete list with Hamiltonian outcomes:
Conservative 275--down 42 vs OTL
Labour 260--down 2
Lib Dem 48--up 36
Scottish N 20--down 15
UKIP 12--up from zero OTL
Green 11--up 10
Democratic Unionist 6--down 4
Sinn Fein 5--down 2--meanwhile I am told SF never takes their seats on principle.
Plaid Cymru 3--down 1
Eight of these 9 gained seats in OTL, except UKIP.
Social Dem & Labour (Northern Ireland, caucuses with Labour) and Ulster Unionist party would each hold 2 seats having gained none OTL
A single Northern Irish "Independent Unionist" gained her seat OTL FPTP and would hold that seat here as well
Three other parties--Alliance Party of NI, Yorkshire Party, National Health Action--would each hold a single seat.
I note that this ragtag scattering of small and regional parties is not unusual in the OTL FPTP system; it is quite common for a handful of single MP factions to show up there (unlike the US Congress). So to be clear, in Britain's case you are sounding an alarm about something that actually happens there all the time, or rather would if the true will of the British voter could be expressed in accurate sizing of the leading parties. The major thing that prevents a ragtag group of 5 or six small parties from holding the whip hand is not, let us be clear, that these are excluded from Parliament completely--rather, it is that generally speaking, the big parties get substantially more seats than are properly due them, which tends to guarantee one or the other holds a bogus majority, as was so grossly and egregiously the case in 2015 where the Conservatives, until they foolishly grasped for yet more, could legislate and govern unchecked despite not even managing as much as 40 percent of the vote!
Observe how grossly screwed the Lib Lab party, which by rights should be the third party in the current British system, was by the FPTP dynamics!
Consider how many British voters who cast votes in the FPTP system got no MPs at all for their pains: adding up all the votes cast for parties that failed completely to get any seats whatsoever, we have just over a million out of 32 million. Considering the lopsided manner in which some parties got far more than their share while others get far less, we can more systematically measure how distorted the outcome is with something called the Gallagher Index, which is a least squares measure of a type familiar to science students--square the deviation between the share of votes cast and seats received (as a quota of votes cast), sum them, divide by two and take the square root, and we have a number representative of how far off the seating is from proportional overall, accounting for all factors. For the Parliament of 2016, this GI is 6.49 percent. For the Hamilton apportionment (no system can be perfect, and under Hamilton's system about 185,000 voters still fail to get any PMs, and small deviations from perfect proportionality exist among the others that do get seats) the GI is on the other hand 0.4 percent!
Now look at the dynamic of forming a government facing the Tories--and also Labour! The Conservatives need 50 more members of a coalition, and their preferred choice of OTL is down 4, leaving only 6 toward that goal. Perforce the Tories must turn to parties that actually got a lot more support from voters than their OTL preference. (Remind me why this is a bad thing for democracy?) They cannot form a government without asking the Liberal Democrats to support them. Nor is this quite adequate, they need two more seats from somewhere! Aha, the dread specter of the small party holding the big one hostage emerges! But does it really? If the Lib Dems agree, then the Democratic Unionists are still there, to enable this coalition by a slightly larger margin than OTL to govern. Of course now the Tories must reconcile their policies with the Lib Dems to survive--but that I believe means that they must moderate their conservatism, which is what the British people voted for I think. To be sure there is the headache of simultaneously keeping DU on board as well, but how strictly necessary is that?
Not very! The Ulster Unionist Party has 2 seats (in the PR ATL) and can just fill the gap for an alternative 3 party coalition. There is that single independent Unionist who could cut it down to one seat that could be filled by the single Alliance Party Member. UKIP has 12 members to offer. The Conservative Party thus could seek to draw all of these into its coalition and thus hold a margin such that no single third party withdrawing (except the vital LibLabs) would cost it government.
But now consider the position of Labour. It does not trail the Tories by a large amount. Gaining the support of the Lib Labs, there are a lot of choices available for closing the 27 seat gap that would remain. The Scottish Nationalists would fill most of it, and leave just 7 more seats to be picked up. The Greens alone could more than do it, meanwhile Labour too has many options in that most of the small factional parties remaining veer left. Perhaps they could persuade Sinn Fein to take their seats and help govern? But they don't have to do that--Plaid Cymru, perhaps the Yorkshire Party, I would assume the single National Health member, all seem likely to work well with Labour, and I am told the Irish SD&L Party is really just Labour with an Irish accent.
It boils down then to the LibLabs being the "tail that wags the dog," for that party determines which of the two large ones will govern and can name its own terms. But is this a bad thing? LibLab is presumably a very moderate party, with possible interests in working with either Conservatives or Labour. At this point, it becomes the job of the political leadership of all three parties to craft arrangements appealing to common values that taken together, represent the will of a solid majority of British voters. With prior and broad agreement, the dominant party will modify its platform to appeal to LibLab as well, and together they govern as one.
None of the ragtag small parties are in a position to veto or upset this balance. Each coalition must include a third party, but that third party is expendable! It can be replaced by others, and what I would do, as Tory or Labour leader, is drum up as many as my party and I judge the LibLabs can tolerate, for maximum votes and maximum flexibility, so if one or two throw a fit they can leave without changing the dynamic. Only the LibLabs are in a position to throw it one way or the other singlehanded, and they must appreciate that despite their power in this they remain a minority. If they choose to break a working coalition over an issue that the majority of voters do not support, they are likely to lose some votes while the wronged coalition big partner may gain them. Or both may go down in favor of the opposition big party and other small parties that gain in the face of this spectacle.
The notion that government is held hostage to irresponsible little parties is clearly false in this case.
But what happens if we listen to the siren song of hurdles, and put up additional barriers to achieving membership in Parliament? Note that this would be a deviation from British custom first of all, in that quite small parties are already able to get seats in the current system.
How big a hurdle do we want? Let's start with 1 percent, which is quite low. At a stroke, all parties getting less than the Green Party in 2016 would be out--and by the way, it would be necessary to exempt the Speaker's seat because they generally have very low turnout in their customarily noncompetitive elections. 1,777,000 votes, 130,000 more than under FPTP voters would have their choices tossed away as though they had not voted at all. The effect of this on the Gallagher index, a compound of overrating the performance of the top several parties and dropping the majority of parties from consideration completely, is to raise it from 0.4 percent to 1.9 percent, nearly a factor of five. It is still far below the 6.5 resulting from the irrationalities of the FPTP system to be sure, but even more voters have effectively lost their influence in Parliament. What have we gained for this sacrifice?
The Tories have lost their third party, DU, as supporters, but they gain more of their own members--now up 11 to 286, while their vital coalition partner, the LibLabs has gained two as well, so a conservative-moderate coalition is simpler and stronger. Meanwhile Labour gains 10 seats, so that with LibLab their alternative coalition also has a margin of 5 without needing other members. The Scottish Nationals and Greens remain to pad a Labourite government in large coalition with 31 more seats, whereas the Tories have available to them just UKIP for 12 more seats. The left leaning total coalition would be larger by 4 seats.
The German hurdle of 5 percent is being bandied about as reasonable. What would it do to the 2016 election?
Well, only three parties--Tory, Labour, and LibLab, cleared that bar in 2016. Clearly the coalition dynamic is simplified down to the ultimate. The fundamental dynamic is still the same though--someone must court LibLab. Meanwhile, the number of voters cast aside as insufficiently compromising of their values to qualify for effective control rises by nearly 2.1 million, tripling the number excluded in FPTP OTL, to 3.27 million or ten percent of the whole electorate. Accordingly the Gallagher Index rises to 5.5 percent. We have a somewhat less awful deviation from voter desires than with FPTP, but at the cost of excluding far more of them.
Basically a hurdle as large as 5 percent comes close to replicating the overall irrationality of FPTP. A smaller hurdle does less harm, but harm is done for no good reason. It is simply not true that the small parties we get with maximum inclusion derail coalition politics. A very small party is critical only if the nation is finely on a balance, and in that case it is probably for the best if a breakdown in coalition forces a new election or a period of weak government, since this focuses the electorate on the issues at hand. Papering over the issues by steamrollering out 20 times more effective votes than is strictly necessary strikes me as a cure worse than the disease, where the disease is precisely the failure of publics to come to workable agreement.
I would also note that the optics of the outcome is skewed toward the OTL apparent conservative dominance, while with more inclusive outcomes, the fact that British voters on the whole skewed a lot less rightward is more apparent. A Tory-LibLab coalition commands more members than a Labour-LibLab coalition, while sorting the parties left and right and combining all of them with the lower hurdle or the no-hurdle Hamilton method gives the leftist coalition the edge.
What would the options have been in 2015 by the way, when OTL the Tories held a thin but comfortable victory margin in their own right? Under PR they and Labour both would suffer considerably! As it happened in that election, the separatist from EU UKIP party enjoyed a tremendous level of success in polling, but got just one seat in Parliament by FPTP. Proportionally though they would have gotten 82 seats by Hamilton's Method. Without including UKIP in their coalition the Conservative Party would have been barred from forming any majority coalition. With it they would need only a handful more they could hope to get from many sources. However, Labour, assuming that party would never agree to combine with UKIP, has no viable path to majority whatsoever. The LibLabs, getting 51 seats, and Scottish National with 31, and Greens with 25 would not be enough to close the gap with the Tories and no amount of scrambling for the smallest parties on any conditions could get them victory. The upshot is that as government without the LibLabs would have been impossible after the 2016 election, so UKIP would control whether the UK could have a viable government or not in 2015, only more strongly, and they would have no option but to do so with the Tories.
Would raising the hurdles fix this? No, it would not. A drastic 5 percent hurdle would include only the top 4 parties, skewing the choices rightward as in 2016, limiting them in order to Tory, Labour, UKIP and LibLab. Labour would still have no prospect of governing without dealing with UKIP. The Tories would indeed pick up a new option, which would be to govern with a slim majority in coalition with LibLab, leaving both the middle parties out.
So in this case, having high hurdles would indeed give the Conservatives an option other than aligning with a party that some people (me included) considers an unsavory far right wing as well as lunatic bunch. But the reason UKIP would stand so high in 2015 is a that a whole lot of Britons voted for it. Without that brand of right wing lunacy no single majority bloc would exist, and the only one possible would be right wing. Meanwhile it is not clear to me that the Tories would actually prefer to favor the respectable LibLabs if their basic agenda is more strongly supported by the radical UKIP. Thus the value of the high hurdle is dubious at best. Voters in 2015 voted a range of options that veered hard right, much as they did in America the next year. Again the only reason the Tories have better options with the hurdle is that they themselves would gain 33 seats at the cost of voters for smaller parties who presumably favored less extreme options--it is this disproportionate padding of a mainstream party that gives it the freedom to choose which ideological direction it might veer in and all the recent history of that party suggests to me they would choose the harder right option--for they could have built a stronger coalition with LibLab in 2016 OTL that with DU, but they chose the latter.
It is my belief that if Britons approached each election knowing they could vote for the candidate and party they most strongly believed in, without fear of it being cast aside by the rough and unpredictable FPTP nor by an arbitrary hurdle, they would pick a faction and, assuming that the leadership and MPs continued to pay close attention to their deep concerns, stick with it. As issues change over time, some parties would lose support while others gain, parties will die out while new ones form. But by and large the voters will pick stable factions, and the factions will form stable alliances. We would not have seen the rise of a party like UKIP in the first place; rather certain parties already in place would hae gained some strength and the showdown on the issue of separation from the EU and whatever else motivated UKIP voters of OTL would have been aired out earlier. Other conservatives along with people to the left who had their own issues with EU would have to show their hands, showing where they stand, earlier, and be judged well or badly by their various constituencies.