If you need to go back as far as the Indian Wars to find an adaquate number of examples of the U.S. acting vengefully I'm not sure which one of our arguments that strengthens. Also, that was done out of avarice for their land, not vengeance, which doesn't make it better but is actually a rather important distinction in this discussion.
Oh, but there was both. "Remember the River Raisin", the long history of scalping, there were plenty of atrocities committed for revenge, not simply to get people out of the way. And as the River Raisin refrain shows, we saw Native American crimes against us and wanted retribution for them.
Yeah, and how far have Trump and objectivism actually gotten? Obamacare is still the law of the land and it's looking probable it will stay that way, every racist thing Trump has tried to do has gotten blocked by the courts and is opposed by majorities of public opinion, and on it goes.
If all you care about is legislation and court rulings and high-minded concerns like that, then I don't think you're taking this inquiry seriously. What's your case here? Trumpism isn't an expression of American vengefulness because judges think some of his plans are unconstitutional? Or because Obamacare repeal, something his Party demonstrably cares about way more than he does, wound up a contradictory mess? That's proof that America is fundamentally magnanimous? You're not looking at this carefully, because if you did, then you might actually focus on the rallies, the bloody-mindedness of Trump's remarks, and how, although his polls have repeatedly suffered from this, that, or the other offense, they always return to an equilibrium, as we get used to his rhetoric and decide it's not so bad. More to the point, we'll go to bat to defend innocent Muslims and Hispanics, but terrorists? They're beneath our contempt, and the difference between liberals and conservatives here isn't even so much one of empathy, but more that liberals are more willing to distinguish innocents from "bad guys". But for bad guys, Obama's presidency proved that the left is perfectly happy to drone you and your family along with you.
The War on Drugs and the penal system can get pretty screwed up, but it's important to understand that one of the things that drove those policies is that American society is really violent (even if you take away all of our gun crime, the American murder rate is still twice as high or higher as the ENTIRE murder rate of most other first world countries) and that drugs made it a lot worse. I don't defend the racism that also drove it and the effects it's had, but that's at least something of a fig leaf.
Yes, American society is violent. The question is why we tolerate this kind of violence when other societies push for more responsive law enforcement and actual gun control. Plenty of reasons, but one that can't be ignored is that for many of us, we see the violence primarily concentrated in minority communities, and we rationalize it away as a consequence of those communities' lawlessness. We think that for them, it's deserved. That's what I really mean by vengefulness. It's not even about the violence, so much as the ways we justify it to ourselves. The poor, minorities, criminals, foreign enemies, they don't deserve our pity, and so we give them none.
To compare this stuff to American foreign policy and claim it supports the notion that the U.S. could go literally insane if Flight 93 wasn't delayed is a pretty weak case IMHO.
Again, this is indicative of you not reading my posts carefully, since that wasn't the case I was making. My point was that the American public would have tolerated greater abuses than were committed IOTL, and the real bottleneck is the willingness of the Bush Administration to commit more war crimes. But as for the high-minded foreign policy you bring up, and your accusation that I didn't have enough examples, well, did I forget to mention that not only did we come up with the Morgenthau Plan, but we implemented a watered-down version of it, over British objections? Morgenthau himself certainly had his reasons for wanting to punish the Nazis, but you have to wonder, why were FDR and Truman so willing to go along with it, more so than the British or the Soviets, who had much more personal reasons to want revenge against the Germans? Again, I'd say it's indicative of the judgmental American mentality. We only abandoned it when it became clear that West Germany would welcome in the Soviets if we continued, but 1945 to 1947 were dark times for Germany. We still owe a lot to the cultural influence of the Puritans, and I'd consider this attitude another of their cultural artifacts.