In London exile in 1940, Charles de Gaulle decided “it was up to me to take responsibility for France” (“c'etait a moi d'assumer la France”). No U.S. president should assume he is, as de Gaulle almost mystically did, the nation, or is solely responsible for it. Remember this tonight when Barack Obama defends his choice to attack Syria.

U.S. power and security are somewhat dependent on a president’s stature, which should not be diminished unnecessarily. Neither, however, should America’s well-being be equated with a president’s policy preferences or political health. The real but limited importance of presidential prestige, and the real but limited diminution of it that would result from blocking Obama’s attack, both matter. But so do the manifest and manifold weaknesses of his argument.

George Orwell, who said insincerity is the enemy of clear language, would understand why our government talks of “quantitative easing” rather than printing money, and uses “enhanced interrogation” and “extraordinary rendition” rather than more concrete denotations. The debate about Syria has featured a peculiar phrase, “the vetted opposition.”

Used by those advocating intervention, it implies that most anti-Assad fighters have been investigated enough to dispel doubts about them as appropriate beneficiaries of U.S. actions. But John McCain’s breezy assurance (“I have met them”) is insufficient. Skepticism is warranted, given the prodigies of confusion in administration statements, including historical amnesia.

Bashar al-Assad’s use of chemical weapons is only his most recent, and he is not the first to have used such weapons in war since the 1925 Geneva Protocol proscribing them. But because attacking Syria is said to be necessary as reinforcement of the 1925 “norm,” it matters that the norm has been violated before.

In the 1960s, Egypt used chemical weapons against Yemen. Saddam Hussein used them not only against disobedient Iraqis but in the 1980-88 war with Iran. A March 23, 1984, CIA report said: “Iraq has begun using nerve agents … [which] could have a significant impact on Iran’s human wave tactics, forcing Iran to give up that strategy.” A new article by Shane Harris and Matthew M. Aid in Foreign Policy says that in 1988:

“The United States learned through satellite imagery that Iran was about to gain a major strategic advantage by exploiting a hole in Iraqi defenses. U.S. intelligence officials conveyed the location of the Iranian troops to Iraq, fully aware that Hussein’s military would attack with chemical weapons, including sarin, a lethal nerve agent.”

U.S. officials denied acquiescing in such attacks because Iraq never announced them. But Harris and Aid quote retired Air Force Col. Rick Francona, a military attache in Baghdad during the 1988 strikes, saying, “The Iraqis never told us that they intended to use nerve gas. They didn’t have to. We already knew.”

The argument for attacking Syria to strengthen a “norm” may be weaker than the argument for Congress halting the attack to strengthen constitutional balance. The outcome of the vote on attacking Syria may be less important than the fact of the vote. Through the physics of our Madisonian politics – one institution’s action producing another’s reaction – the nation has reached a constitutional moment.

Every policy choice occurs in a context conditioned by other choices. Barack Obama’s Syrian choice comes after multiple executive excesses that have provoked Congress to react against its marginalization, a product of its supine passivity regarding Obama’s unilateral lawmaking.

It is unfortunate that a foreign policy decision has catalyzed congressional resistance to presidential aggrandizement on many fronts. But no congressional vote about Syria can damage the presidency as much as Obama has done by overreaching, and by sophistical rhetoric that refutes his appeals for unconditional trust. The shriveling of his presidency probably became irreversible when laughter greeted his sophomoric claim that not he but “the world” drew a red line regarding chemical weapons.

After incessant calls for “bipartisanship” to supplant “obstructionism,” there has emerged a broad bipartisan coalition to obstruct his Syrian policy. His policy is doomed without many Democratic senators swallowing their pride, disregarding past convictions and becoming presidential poodles. Such canine obedience will express obedience to progressivism’s unchanging essence – exaltation of executive discretion and disparagement of the separation of powers. That is, implacable impatience with Madison’s constitutional architecture.

Obama hardly has de Gaulle’s kind of mystical identification of himself with his nation, or de Gaulle’s desperate reason for such a conflation. However, Obama’s recent references to “my military” have a French antecedent in Louis XIV’s l'etat c'est moi. This president has inadvertently made the case for strengthening the presidency by pruning the office’s pretensions.

© 2013, Washington Post Writers Group