On the one hand, I’m sure faithful BHL readers are sick of this. On the other hand, people are writing in widely-read political news sites that Clinton should go to extraordinary lengths to blow up the Johnson-Weld ticket. (Note: Actually offering a cabinet post in exchange for an endorsement would be a federal crime.) And the Washington Post editorial Board is repeating the claim that “Mr. Johnson takes more support from Hillary Clinton in three- and four-way polls than he does from Mr. Trump” as part of an ominous warning to Weld that he could be the Ralph Nader of 2016, swinging the election to the Republican.

So: unto the breach.

In the new Fox News poll Clinton leads by 5 in the 2-way race, by 3 in the 4-way race. Net of -2 from adding the third parties.

Stein polls at 4%. On any reasonable view of where her votes come from, she accounts for the whole loss to Clinton– probably and then some. Johnson’s 8% could be neutral, but most probably draws 1-2% net from Trump, making up some of the Stein effect.

And this is the pattern in almost every poll I’ve looked at that compares the 2-way and 4-way races. It’s the pattern in a large majority of states including most swing states. It’s the pattern you would expect from two former Republican governors running a ticket against a deeply unpopular (und un-conservative and unhinged) Republican nominee. It’s the pattern you would expect from the fact that (at this writing) six traditionally-Republican newspaper editorial boards, including the very conservative swing state New Hampshire Union Leader and the rock-ribbed Chicago Tribune and Detroit Free Press, have endorsed Johnson. I’m happy that Johnson and Weld have run a more leftward campaign than Libertarians usually do, and have emphasized Libertarians’ liberalism on drugs, crime, policing, imprisonment, and war. I’m happy that they’re bringing some young liberals into the movement, and I think that’s good for the future of libertarianism. But it’s still the case that the low-tax, free-market, free-trade candidates running against a protectionist Republican consistently bleed off a few more disaffected Republicans than they do Democrats. And the punditry, commentary, and strategy that pits Clinton’s interests directly against Johnson-Weld’s is mistaken.

The Post editorial mentioned above doesn’t itself offer any support for the claim that Johnson hurts Clinton. It just links to this John Fund piece as its footnote. But Fund provides no valid evidence for that claim, just a combination of ecological fallacies and fallacies of division. Johnson is strong among young people and out west, therefore… (without doing anything to see who those young people or westerners would otherwise support, or weighing their effect against those of other Johnson supporters). Clinton’s lead shrinks in a four-way race, therefore… (without distinguishing Stein’s effect from Johnson’s).

But what’s true of [Johnson + Stein] is not automatically true of Johnson, and in fact it is not true of Johnson. It’s the same mistake over and over again, in all these articles and commentaries, and now they’re feeding on each other, citing each other, and building a conventional wisdom out of something that isn’t true.

Update: We can quickly see the same thing in the Monday morning Morning Consult poll.
2-party: 46-39, Clinton +7
4-party: 42-36-9-2, Clinton +6

Yes, Clinton is hurt (net of -1) by including the third-party candidates. But on a reasonable assumption about where Stein’s 2% of voters go in the 2-party matchup, they fully account for that change of 1 point. That leaves Johnson somewhere between neutral and helping Clinton by 1 net point.