There are a lot of potential moving parts in the fiscal cliff negotiations, and thus a lot of potential ways that matters could be negotiated and settled, postponed or left half-resolved. But sometimes simplification helps, and the best place to start when thinking about how things are likely to play out is with the following brute fact: No matter what Congressional Republicans offer the president and what they’re willing to concede, taxes on the wealthiest Americans are going to rise by at least $800 billion over the next decade. This is not a possibility, not a likely scenario, not a maybe or a might be; it’s just reality, conceded even by the notorious RINO Jim DeMint. Which means that it’s useful for analytic purposes to treat that $800 billion as a baseline, rather than as a live point of give and take in the negotiations, and recognize that any bigger deal John Boehner and Barack Obama are able to cut should be judged as much on how it balances spending cuts and tax increases beyond that baseline as on what it looks like overall.

In this framework, a deal like the one the president proposed recently, which outraged Republicans by combining a promise of just $400 billion in potential entitlement savings with $1.6 trillion in new taxes, would really be trading that $400 billion for only $800 billion in taxes — because the rest of the tax revenue is coming in no matter what. Or again, a deal like the one Senator Bob Corker of Tennessee has proposed, which combines just under $1 trillion in new tax revenue with roughly $850 billion in cuts to Medicare, Medicaid and Social Security (and some other cuts as well), would arguably really be trading only $200 billion in tax revenue for that $850 billion from entitlements — because, again, the other $800 billion in higher taxes is happening no matter what.

Once you think about the negotiations this way, the likelihood of a meaningful compromise seems to drop considerably. Because taxes are going up by $800 billion no matter what, it’s going to be awfully hard for John Boehner to persuade his members to vote for a deal that raises them even more, unless he’s extracted genuinely significant concessions from the Democrats on structural reforms to Medicare and Social Security. But by the same token, because taxes are going to go up by $800 billion no matter what, it’s going to be awfully hard for Democrats to accept a deal in which they have to swallow an unfavorable cuts-to-taxes ratio beyond that $800 billion baseline. So while there’s a sense in which, say, the Corker vision and the White House vision aren’t impossibly far apart — $400 billion on the entitlement side and $600 billion on the tax side, allowing for lots of sticking points and lots of fuzziness in the numbers — a deal that combined elements from the two proposals would prompt loud cries of “betrayal” from both sides. Republicans would look at the whole budget picture and see taxes rising by much more than entitlements are getting cut, Democrats would compare what they were guaranteed with what they actually got and see the outcome as an unnecessary sell-out — and both would have a point!

This doesn’t make a bigger deal impossible. But it would either require the Republican leadership to take their (already painful and internally divisive) surrender to reality on taxes to another level altogether, or it would require the president to triangulate against his own base on structural changes to entitlements in ways that neither his past record nor his current positioning suggests he’s about to do. (And no, raising the Medicare retirement age — a proposal whose wisdom depends on its design — is not the kind of change of which major deals are made.) Both scenarios seem much less plausible than one of the various “no deal” outcomes, which range from a Republican strategic retreat — pass a tax cut extension that doesn’t include the top rates, assume Obama will have to sign it, declare that the White House has what it wanted and try to turn the conversation to spending cuts thereafter — to the various “no surrender” options that conservative opinionmakers have been kicking around, most of which involve letting taxes rise across the board and leveraging either the subsequent public outcry or the debt ceiling vote to extract the kind of concessions that the White House is currently unwilling to give.

Since I’m the kind of trimmer who thought that Republicans should have cut a bigger deal during the last debt-ceiling debate — you know, back when Obama had every political incentive to look bipartisan, and $800 billion in tax increases wasn’t yet the baseline for negotiations — you can guess that I think strategic retreat would be the better part of valor. I recommend reading Bill Kristol and Philip Klein for longer treatments of the issue, but really this one bit from Klein says it all: “The time for Republicans to win the tax debate was during the 2012 election. They lost.” And pretending that defeat didn’t happen, and that a little more legislative brinksmanship will bring the country round, is a good way to postpone the day when Republicans begin to actually win tax debates again into a distant and fast-receding future.