Hezbollah instigated this round of fighting when it infiltrated the (UN-recognized) Israeli border and kidnapped two Israeli soldiers while killing others. Few doubt that Hezbollah was put up to this act of war by its masters, Tehran and Damascus.
By all accounts, Hezbollah possesses thousands of missiles, some of which can penetrate deep into Israel. And, oh yeah, its entire reason for being is to see that glorious day when Israel is wiped off the map. In other words, the strategic imperative is obvious, legitimate and pressing. Meanwhile, all a cease-fire will do is put off the inevitable, muddy the waters and give Hezbollah an escape hatch while it's on the ropes.
If Israel agrees to a cease-fire, the story so far will have frozen in place. And what does that story look like? It looks like a tale of Israel bombing civilian targets as an end in itself. It looks like the sort of "collective punishment" that Israel's critics routinely decry. It looks like an attack on a struggling democratic government in a beleaguered yet heroic Lebanon in order to punish terrorists only nominally under the Lebanese government's control. Stop now and Hezbollah not only will have been left substantially intact, but perhaps even politically strengthened, not necessarily among the Lebanese, but certainly in the region as a whole.
Israel's bombing campaign, unlike Hezbollah's, must have a larger goal than mere terror and bloodshed. I'm certain that it does. But if the situation freezes under the current circumstances, Israel's larger goal won't be apparent to much of the world. It will seem like a hugely disproportionate response in which Israel killed hundreds of civilians in order to get back two kidnapped soldiers. And Hezbollah will still be there, ready to dance for any coin Syria or Iran puts in its jukebox, threatening Israel and strangling Lebanon's democratic hopes.
Hezbollah can only be destroyed by a ground campaign. If Israel doesn't launch one, it will be worse off, laughter will echo in Damascus and Tehran, Lebanon will have been dealt an unjust and cruel blow for nothing, and we'll all be back here again in the near future.