At this juncture, with Obama leading in pledged and total delegates, but Hillary still stubbornly holding on to a super-delegate lead, I think it's worth examining the arguments for and against seating the Michigan and Florida delegations. I'm going to do this separately, because although the two states get lumped together, the situations are actually quite different.

Michigan:

The big argument in favor of counting the Michigan delegates (and I'm talking about Democratic delegates here), is that "if the delegates aren't seated, the Michigan voters will be disenfranchised." I have not heard any other arguments from this side of the debate (got one? Please post!)

On the other hand, the arguments against seem to be as follows (let me know if I miss any here, too):

1. "Michigan's Democratic Party knew what the consequences were of violating the DNC rules about primary dates. They should have to abide by the rules and not get special treatment." Indeed, it would seem to be (albeit slightly) unfair to the delegations from states who played by the rules and didn't move their primaries up to seat the Michigan delegation. Not to mention, it could unleash a mad dash of states moving their primaries up next time around: "Well, Michigan did it and didn't get punished; we probably won't either!"
2. "Obama's name wasn't even on the ballot." True dat. And history teaches us that candidates whose names aren't on the ballot almost invariably fare worse than those that are. For example, in the 2006 midterm election, Texas' majority-Republican (52% R vs. 32% D) 22nd Congressional District, which had had a Republican representative since 1979, voted for Democrat Nick Lampson (whose name was on the ballot) over write-in Republican Shelley Sekula-Gibbs, 52% - 42%. Now, Tom DeLay's Abramoff Scandal problems may have also played a part, but there are other examples of this phenomenon, and it certainly could have been in play here.
   
3. "How do we figure out who gets the 'Uncommitted' delegates?" Yes, while Obama's name wasn't on the ballot, neither were Edwards', Richardson's, or Biden's. Dodd's was, but he had dropped out of the race at that point. Also, the candidates who kept their names off the ballot did not file the necessary paperwork to make themselves eligible for write-in votes. This leads to the question of how, if the delegation is seated, to divvy up the pledged delegates. Would Obama get all the "Uncommitted" delegates? Or would they remain "uncommitted" and could vote for whomever they pleased? What about "uncommitted" voters who might not prefer Obama? There would indubitably be some wheeling and dealing going on here to determine the delegates' instructions.
4. "It was an open primary on both sides. A lot of Democrats and independents who preferred Obama might have voted in the Republican primary, where their votes would be counted (since the Republicans only stripped HALF the delegates from the state), rather than the Democratic one, where they knew their vote wouldn't actually count." Also a valid point: this might have affected the final results of the primary.
5. "Democrats who knew their votes wouldn't count might have just stayed home." Also a possibility. This, too, might have affected the outcome.
6. "They didn't campaign in the state, and Obama always does better in states he campaigns in." This is true: Obama has fared far better than his polling average in most states he campaigned in (New Hampshire and Nevada are the exceptions). There's certainly room for doubt whether that would have been the case here (Michigan was an early state, like NH and NV), but it also could certainly have swayed the outcome.
   

Note that many of these arguments don't deal in absolutes. They deal with things that could have swayed the outcome. There is no proof from either side that the vote was or was not affected significantly by these factors.

Florida:

There are several other arguments I have heard in favor of seating Florida's delegation besides the "disenfranchisement" argument used for Michigan, above:

• "It was the Republican-controlled legislature and Republican Governor Charlie Crist who picked the date for the primary. The Democrats had nothing to do with it, so it's unfair to punish them!" On the face of it, this seems like a very sound argument. It was, indeed, House Bill 537 (2007 session) that moved the Florida primary date to January 29th, in violation of the DNC's rules. However, the final bill passed the Florida House 118-0. The original bill passed the House 115-1, and another version passed the Senate 37-2. Thus, it's clear that there was no real Democratic opposition to the bill. Looking at the Whip's brief of the bill, we see the following text:"Under Republican Party rules, if any state holds its primary before February 5, 2008, that state may lose up to 90% of its delegates to the national convention...Under Democratic Party rules, only Iowa, Nevada, New Hampshire, and South Carolina may hold a primary or caucus before February 5, 2008. Any state violating this rule would be subject to a reduction in delegates similar to the Republican Party’s...HB 537 gives priority to selecting a candidate rather than sending more delegates to a convention. [emphasis mine]" So, it seems obvious that the Florida Democrats knew they were likely to lose their delegates (up to 90% of them), and yet were willing to support (remember, it passed with NO OPPOSITION) the bill anyway. If they felt that priority should be given to an early primary over sending delegates, it seems they got exactly what they asked for.
  
• "Gov. Crist said that he would veto any bill with a date other than Jan. 29, so Democrats had no choice but to support a bill with that date." If this is true (I haven't seen any evidence either way), it still needs to be noted that HB 537 moved the primary. If the bill had been defeated (by a strong opposition from the Democrats, for example, or a filibuster--can you filibuster in Florida?) or just never made it out of committee, the primary would have still happened: it would have happened (by law, no less) on March 11th.
  
• "It's not fair to punish the voters for what the DNC did." No, it's not fair that the voters should "suffer" because of the DNC. However, it seems fairly obvious that this situation cannot be squarely laid at the DNC's doorstep. However, whether you blame the DNC or the Florida Democrats, or Gov. Crist, or the candidates, it doesn't change the fact that the Democratic voters of Florida are the ones who are being punished.
  

Arguments against seating the delegates are pretty much the same as Arguments #1, 5, and 6 against seating the Michigan delegates.

Conclusion:

It seems clear to me, based on the above arguments and evidence, that the Michigan delegation should definitely NOT be seated as it is currently configured [full disclosure: I am an Obama supporter]. So much about that race might have been altered by the circumstances under which it occurred that it is reasonable to assume the votes (as they stand right now) are not an accurate reflection of the voters' preferences, and thus, would disenfranchise many of them regardless. And although there are no absolute guarantees here, I think a "preponderance of the evidence" (the same standard used in civil law cases) indicates the race's outcome was skewed.

For Florida, there are fewer arguments against, but I think that this delegation, too, should NOT be seated as it is currently configured. It's clear from the evidence in the Whip's report that the Florida Democrats were aware that their delegation would be adversely affected by supporting the bill, and that all chose to support it anyway. While I agree that the voters of Florida have been poorly served by their legislature, it seems foolish to blame the DNC or Mr. Obama for the Florida Democrats' poor judgment.

I do, however, think that re-voting (or holding a caucus) would be a viable option. It is one that the DNC has proposed in both cases, but is generally poorly received, due to the immense costs (both temporal and financial) of holding new votes. Hopefully, however, some compromise might be agreed upon before the convention.

Got other arguments for or against? Look at the same arguments/evidence and come up with a completely different conclusion? Just think I'm an idiot? Please respond!