There is no good argument against first past the post

We are lucky if the state complies with the democratic process since to have an election is not entirely consistent with government. If we are a government then we do not necessarily seek the consent of the people ('it is inconsistent for the state to be democratic'). So democracy is a luxury and something we should be grateful for if we are given it by the state.

We can understand that the government doesn't like elections and would prefer to remain in power unchecked. Because the state has no obligation to hold elections this makes it very difficult to form a coherent argument in favour of proportional representation (over first-past-the-post). If we are lucky to have elections to begin with and democracy is a gift from the state then it is inconsistent to complain that the gift is not good enough. It is in the power of the state to subsidise itself by reducing the extent of its accountability to the people. The state can choose to subsidise itself by using fptp and there is nothing we can do about it. We can expect that the state would prefer to use first-past-the-post (over pr) unless the state is acting in the interests of the people and liberty. But since elections are granted by the government there is no strong argument against non-democracy and in favour of liberal proportionality.