There are pros and cons with both systems. A two party Presidential system is very stable. The balance of power often shifts from one party to another and governments rarely dissolve. A winning party doesn't have to compromise and can get things done whether people like it or not. It's efficient. But not everyone is represented. About 1/3 of Americans consider themselves "independent," yet 1/3 candidates are not independent. They are almost always from one of the two major parties.
A system of equal representation is rather weak, yet everyone is heard. The balance of power rests in many political parties. Thus it's rare for one party to have total power. They must compromise and work with the other parties. This creates moderate solutions and keeps the leader in check. The main problem is that many governments under proportional representation last mere months before new elections are called. If one party leaves the coalition, the government often has to resign and call new elections. Sometimes parties won't even form a coalition. Belgium had an election in June 2010, and they have not been able to form a coalition since then. They've been without a sitting government for 8+ months now!
Look at the image below. Not one party gained 20% of the vote since 1987. This makes the coalition very weak.
Best post so far. This post reminds me of how I'm supposed to write essays.
Anyway, yes, a two party system is efficient. At the same time, you are sacrificing equal representation.
A multiple party system offers equal representation, but at the same time, you are sacrificing efficiency.
There is a trade off between the two. Now, how do we make a system that is both efficient AND offers equal representation?
I believe Belgium has a Parliament where the Executive Branch is connected to the Legislative Branch. Whenever the coalition of parties holds the majority, the prime minister or president changes.
Now, in our system, it isn't. If the Republicans hold the majority, there could still be a Democratic president.
Now, to handle efficiency, there still is a problem. Now, I am not so sure why in Belgium it is so difficult to hold a majority of more than 50%, but there system will be a bit different. The coalitions need at least 50% of the parties to vote, now that will be difficult. If we have parties' interests included in the bill, and then we have each INDIVIDUAL delegator to vote on it, we might have a majority.
If there cannot be more than 60% in favour, and there is no compromise between each side, then what can be done is the Judicial Branch decides it. This is my "radical" solution to the problem. Of course there will have to be balancing act in this process. If the President determines that it will be impossible to get Congress to agree and pass the law, the Supreme Court may do that. The Supreme Court can turn the request down if it chooses to.
Now, this is just an egg of an idea. Please scrutinize this as much as possible. I know that the Supreme Court's only responsibility is to determine if a law is Constitutional, but if they have the ability to impeach, then they COULD have the job to settle Congress' disputes.
This could also be bad since it may not be what the people want, but if they vote for the president, and the president elects the Justices, then they are kind of choosing the Justices themselves but through a middle man, easing the pressures of the Justices for reelection.
Another "radical" idea is to have a change of Justices every sixteen years. That way somebody who has been on the seat since Nixon who still thinks he was innocent, wouldn't be a part of ideals of the current nation.
So to sum it up:
Congress will be divided into parties so that no single party can hold a majority, making equal representation more visible. If Congress cannot form a majority in favour of a bill, then the president may ask the Supreme Court (only once) to decide what the final decision on the bill will be. Justices only serve for sixteen years (four presidential terms). If the Supreme Court says no, then the decision is final UNTIL those four presidential terms are over (Justices cannot be elected more than once for the Supreme Court).
So that is how it would work. All three branches are relayed to make a law final. This would solve the problem of efficiency and equal representation in the lawmaking process, as well as having some positive side affects. It would help the Supreme Court reflect the more recent views on old cases.
