>were encouraged by world leaders and scientists alike

The Nazis (the real kind, not the Internet name calling kind) were working on an atomic bomb. The atomic bomb is a pretty good example of "if I don't do it someone else will".

That answer begs the question though -- "So what?"

It presupposes that we need weapons of every variety in an ever-increasing arms race, which is the very action under examination.

Most people accept "So the Nazis might have won the war instead if things were just a bit different" as at least a bit of justification. Most people consider "The Nazis are more likely to win the war" to be a substantial entry on the debit side of the ledger.

I would agree that doesn't necessarily end the argument instantly; the "instant win because I said 'Nazi' first" button is several decades past its best-by date. But on the other hand it's not something you're going to have much success with dismissing with "So what?" either.

> Most people accept "So the Nazis might have won the war instead if things were just a bit different" as at least a bit of justification.

I don't believe that our nuclear program ended up having any bearing on the European theater -- and the existence of our nuclear program might have (if we're conjecturing timelines) convinced the Germans to make an honest go at it rather than a sabotaged one.

We don't know how this timeline would play out again, either, and so we can't discuss how such a change would (likely) have played out.

Instead, we have to act from principles.

Appealing to "well, what about literal Nazis, huh?" is the worst sort of conversation shutting down -- it did absolutely nothing to stop literal Nazis and your hypothetical Nazis are just that, complete fiction you made up to try and justify your point. You literally invented a story to explain why other stories shouldn't be used as evidence.

> Most people consider "The Nazis are more likely to win the war" to be a substantial entry on the debit side of the ledger.

Completely unsupported supposition of the shallowest variety.

> But on the other hand it's not something you're going to have much success with dismissing with "So what?" either.

How about:

"Your fanfic about how nukes stop Nazis is no more useful for rational debate than mine where not building nukes ended the war early by revealing US moral superiority and breaking German morale, then went on to prevent the Cold War, the formation of a Soviet Bloc, the attrocities across Africa, Asia, the Middle East, and South America."

Your argument doesn't even deserve a "So what?"

It's an outright fallacy of emotional, Nazi based appeal. (Despite your disclaimer at the bottom.)

I can't help but think you didn't notice the name change on the comment chain here. Especially since you seem to have comprehensively missed all my points, since you were so busy replying to what you expected to have been written, rather than what was.

You presented a common argument in response to my post, even if you weren't personally advancing it; I addressed that argument with the rhetorical liberty that I was speaking in a dialog continuing the original exchange in which that argument was advanced. (This causes less indirection dereferences for people who do believe that argument trying to understand why I don't.)

The crux of why that argument is wrong is that it begs the question is precisely the same fashion, but dresses up that fallacy is faux predictive powers (eg, we can know what would happen if history changes) and emotional reaction to Nazis, which makes it wronger than the post I was originally replying to.

In all honesty, your post is so full of weasel words, it's unclear what point, if any, you're actually trying to make.