No such thing. There are lots of proportional systems, each of which have different proporties.
> like Italy and Israel both have
what you say is explicitly not true in Italy, where the biggest party/coalition is automatically given enough top-up seats to give them a majority.
> is that a small party can be the deciding vote, and have a much larger weight than it merits. For instance: center-left party gets 48% of the vote, communists (they still exist here) get 4% of the vote.
If the seats were split 48-48-4, then the party wih four seats would have as much power as the other two, since any two parties form a majority. But under PR, legislatures typically aren't split between two big parties and a small one. In Israel, for example, the largest party got 28 of 120 seats.
> Another flaw is that, in Italy at least, since it is not the voters of a given district who decide on one of several candidates, it is the political party who decides who actually gets to be on the list of people sent to parliament.
This is the same as with FPTP: the party decides on the candidate, and if it's asafe seat, that candidate is virtually certain to be elected. There are several systems of PR where voters not parties decide which of a party's candidates are elected: STV and open lists, for example.
Italy has fiddled with its election laws a lot in recent years, and is probably going to do so again, so what may be true right now may not have been true in year WXYZ.
What I say certainly has happened in the past: witness the downfall of the previous Prodi governments, where support from minority coalition partners tanked the government.
Coalition governments built on many small parties are often weak.
> the party decides on the candidate
Often through relatively open primaries though. Witness the Republican race on right now. "The Party" likely wants Romney, because he's probably more electable than the others. A lot of people do not want him though, evidently.
Not to say any system is perfect, I agree with the poster who says that they all have problems. To think that one system is "the best" is a bit silly in my opinion.
> Coalition governments built on many small parties are often weak.
If by weak you mean "cannot rule without support of representatives who collectively were voted for by most voters" then IMO that's a feature not a bug.
> Often through relatively open primaries though. Witness the Republican race on right now.
That's true. There's no reason why a party couldn't choose list candidates through an open process, however.
No such thing. There are lots of proportional systems, each of which have different proporties.
> like Italy and Israel both have
what you say is explicitly not true in Italy, where the biggest party/coalition is automatically given enough top-up seats to give them a majority.
> is that a small party can be the deciding vote, and have a much larger weight than it merits. For instance: center-left party gets 48% of the vote, communists (they still exist here) get 4% of the vote.
If the seats were split 48-48-4, then the party wih four seats would have as much power as the other two, since any two parties form a majority. But under PR, legislatures typically aren't split between two big parties and a small one. In Israel, for example, the largest party got 28 of 120 seats.
> Another flaw is that, in Italy at least, since it is not the voters of a given district who decide on one of several candidates, it is the political party who decides who actually gets to be on the list of people sent to parliament.
This is the same as with FPTP: the party decides on the candidate, and if it's asafe seat, that candidate is virtually certain to be elected. There are several systems of PR where voters not parties decide which of a party's candidates are elected: STV and open lists, for example.