Let's take this step by step. I may be wrong at any point, but here's how I read this:

1. In the quote above, Josh Marshall notes that BushCo, having found no WMDs in Iraq, falls back on the defense that Saddam Hussein had the intention and capability to build nuclear weapons.


2. The fact whether Saddam Hussein had either the intention or capability to build nuclear weapons is irrelevant to Marshall's next point, which is...


3. that the capability to build a nuclear weapon plus the intention to do so necessarily implies that Iraq must have had nuclear weapons.


4. From this Marshall says that claiming Iraq had the intention and capability to build nukes while in fact not having any is logically incorrect.

So it is Josh Marshall who's claiming that (intent + capability == nuke). Or to use a notation that I've just come up with and will only hopelessly confuse matters:

^intentNuke + ^capabilityNuke = Nuke

and thus in general

^intentX + ^capabilityX = X

Against this, the diarist notes that he wants to have a potato gratin, has the necessary ingredients for a potato gratin, but there is no potato gratin to be found in his house. So in his case, X = potato gratin, yet

^intentpotato gratin + ^capabilitypotato gratin ≠ potato gratin

Given this counterexample, we have to reject  Josh Marshall's implicit general claim that

^intentX + ^capabilityX = X

And then I started talking about necessary vs. sufficient conditions and—

The hell with this. I need something to eat. Maybe there's some turkee in the fridge...