Here's an interesting bad argument I think we've maybe touched on a few times before. Seems fallacious in the form described, but I'm not sure how to categorize it. Relevance? Ignoratio Elenchi?
1. Critics of W's policy X were right about the overall undesirability of X (because of hypothetical consequences Y).
2. But, those critics were mistaken in predicting the details of actual consequences Z as Y.
3. Thus, they were no more right about X than W.
You were right to tell me not to drink and drive, but not because I might wreck my car. It turns out I killed someone, so we're both right and we're both wrong about drunk driving. (You were right that I should not drink and drive, and I was right that the danger of wrecking my car was not the real reason to not drink and drive.) This would seem to be a nice ignoratio elenchi.
The difference between hypothetical consequences as reasons and unknown unintended consequences as reasons to do something seems to be an equivocation. Even if it turns out that I did not wreck my car, the danger of doing so is still a reason for not drinking and driving.
But the argument is interesting since forms of it seem to be good.
1. You said I had reason Y to do X.
2. I had reason Z to do X.
3. My not doing X is excusable because I didn't know that I had reason Z to do X though I knew that I did not have reason Y to do X.
Seems like sometimes the argument is really an attempt to conceal one failure in deliberation with another.
1. Your argument Y against policy X was a bad one.
2. And neither of us saw that there was a good argument Z against X.
3. Therefore, I wasn't wrong to do X.
In its political employment I suspect that it hangs on the falsity of the second premise, or on a different form of culpability if 2 is true. Either 2 is true and therefore you're incompetent (you ought to have known), or 2 is false, and therefore you're foolish. Though the first side of the disjunction is undermined by the claim "even my critics didn't see this" and so I should not be culpable for not seeing it either."
Anyone recall any good examples of this?