Politicians do not like democracy

First past the post is favourable to the political class which is not good. Generally we can assume that the electorate is 'better' at making decisions than the government. Democracy enables the people to veto any decisions made by the government. It enables them to remove politicians who do not act in their best interests. If fptp is being used the people will not have a full choice and (for their vote to count) they will be reduced to choosing the least bad of the two main parties. This stifles democracy and in consequence stifles freedom. What is bad for democracy is bad for freedom. First past the post reduces the ease by which we can reject bad politicians and so it is a bad thing. The political class has a preference for fptp because it makes it easier for them to get into power. As opposed to being fully exposed to the electorate (as with pr) with fptp aspirant politicians only need to satisfy the demands of the mainstream parties. With pr the politicians must both gain the approval of their parties and then the approval of the people. Proportional representation makes it more difficult for politicians to get into power... and so is a good thing. That which is bad for the political class is a good thing and liberating because (whichever system is chosen) there will be a political class so for freedom we want to make the process rigorous. Pr is much more rigorous in removing bad politicians than fptp which is why it is preferable. Pr is preferable because it is more difficult for people to get elected. Pr makes it harder for the political class which is good for the people.