The senate filibuster, like most technologies, is morally neutral; it is neither good nor evil in itself, but can be used for either. The Democrats, who have lost most other options, are hanging onto it desperately (but rather weakly, like a hypothermia victim whose fingers are becoming too numb to grasp). The Republicans are taking the high-minded, stern and rather hypocritical line that the Democrats are using a tool the Framers never intended, impeding the smooth functioning of government, and imposing the will of an elite, hopelessly liberal, out-of-touch minority.
The best place to go to settle this is, of course, the Federalist Papers, the user's manual for American government. (RTFM.) While the Framers did not specifically mention the filibuster, they were painfully aware, based on recent and ancient history, of the necessity of checking the impulses of a democratic majority. In fact, despite the mindless repetition of the word "democracy" in social studies classes and school assemblies through-out our education, the Framers were as scared of direct democracy (which they would have characterized as mob rule) as they were of hereditary kingship or other forms of autocracy. In Federalist 63 there is a long and interesting passage, worth quoting at length:
[T]here are particular moments in public affairs, when the people stimulated by some irregular passion, or some illicit advantage, or misled by the artful misrepresentations of interested men, may call for measures which they themselves will afterwards be the most ready to lament and condemn. In these critical moments, how salutary will be the interference of some temperate and respectable body of citizens, in order to check the misguided career, and to suspend the blow meditated by the people against themselves, until reason, justice and truth, can regain their authority over the public mind? What bitter anguish would not the people of Athens have often escaped, if their government had contained so provident a safeguard against the tyranny of their own passions? Popular liberty might then have escaped the indelible reproach of decreeing to the same citizens, the hemlock on one day, and statues on the next.
In the Framers' conception, the Senate itself was considered to be a check on the passions of the House of Representatives. The latter was directly elected (at the outset, Senators were appointed by the state legislatures) and served for amuch shorter period of time. The Framers believed the representatives would be less likely to take a disinterested, long term view, and be more likely to respond to the passions of the mob. The design principle implemented by the federalist system was to make things hard to do. The Framers wanted minorities (at least elite ones) protected, and did not want democratic impulses leading to massive overnight changes which might destroy their carefully calibrated system.
There are alarming indications that the Republicans are contemplating such permanent changes in the system. The Republicans' complete disregard of federalism, illustrated by their intervention in the Terri Schiavo case, culminated in House Majority Leader Tom Delay's intemperate statement that "The time will come for the men responsible for this to answer for their behavior." Delay was referring to federal judges who had refused to over-rule state decisions in the Schiavo case. Delay cannot tolerate two of the basic building blocks of federalism: the idea of an independent judiciary, and that of a federal government not permitted to intervene in state matters. Delay's behavior, as the head of an extremely powerful majority in the House, is the danger the Framers were trying to protect us against by building in various mechanisms to slow the action of the system and preserve its decentralization.
To the argument that the Framers did not contemplate "supermajorities" being necessary for the Senate to act on matters of significance (because the ultimate effect of a filibuster is to require a supermajority to effect closure), Federalist 63 reminds us that the Framers thought such an approach was crucial at least in one kind of deliberation: the making of treaties, which were required to be approved by a majority of two-thirds of the Senators present. Note the following admonition, in its discussion of the fairness of the two-thirds rule:
[T]he government must be a weak one indeed, if it should forget that the good of the whole can only be promoted by advancing the good of each of the parts or members which compose the whole.
The Republicans would do well to remember that, if they end the filibuster, it will not be available when they need it one day. Today, it is one of their leaders, Tom Delay, who makes the filibuster necessary; his vision of a complacent, obedient and weak judiciary, if implemented, will cause much more serious harm to the system than the preservation of judicial independence by the blocking of a few conservative appointments.