This article should be tagged "politics".

Okay--no Hitler is fine--but what is the exact scenario? With no Hitler--there is no rise of the Nazi party? Remember--Hitler didn't start the National Socialists--but he did help make them popular.

So what happens with the history of Europe in the 1920's and 30's... I think to answer any question here, you have to play out the scenarios and figure out what's going on...

I'll take a scenario--Hitler is killed in WW1 and never exists as a major figure..

Changes this would effect... 1920's.. German National Socialists in Bavaria are less popular than they are--they still exist--but not much happens with them and the remain one of the 50 parties trying to gain power. Germany still engages in military exchange with SU--Treaty of Rapallo (sp?) still exists Germany and rest of nations go through awfulness of early 1920's and then Locarno seems to fix things a bit. Streseman and the nationalist type parties might be a bit stronger without national socialists having a charismatic leader... but prolly not strong enough to dislodge the Social democrats. Depression hits like everything else--and German economy tanks..

Now--here's where the question comes--Germany survived the Depression better than a lot of other places--as the Nazis--when they got in power--totally boosted up the public works expenditures a lot.... but that happened post 1933, I believe...

What happens in 1930's Germany without the Nazis.. Hjalmar Schacht really was the smart econ dude under the Nazis--and he was one of the more "sane" people in it--in that his goal was to help the economy through exports and trade--something that was then quashed by Hitler in the late 30's with his Autarchy policies...

So--without the Nazis--does some sort of rightish-military-big-business party with Schacht in it become dominant? if so--who do they ally with? Do they stick with trying to get back at France--or do they worry more about Growing Soviet power? Without the Nazis--do the French Rightists (who were not powerless) find an alliance with German Nationalists to get back at those nasty commies who won't pay back all the money the French lent the Russians?

Or does Germany keep its anti-French bias--and make a more serious play to be allied with the UK? Without Hitler pushing the submarine stuff so hard--and trying to piss off the Brits with a bigger Navy--do they work out an arrangement with the Brits and offer themselves as a Continental bulwark against the growing socialism of France and the Soviet Union?

Also--who leads this Germany--people like Stresemann? or more military oriented folks? Eventually--if Germany pulls its economy out again with big public works--there is still the issue of Re-militarizing the rhineland--which Hitler just did without thought--could other Germans have done so? Maybe they try to align with Britain--and get their ok to do so--or do they sign a re-affirmed Locarno and pledge only defensive measures?

These are the kinds of questions to ask first before going further. Any long term ideas are going to be grounded in what happens at these periods. One could speculate that you'd still eventually get War--but it might even be a war between UK/Germany against SU in the 1940's as the SU tries to take over Poland... or maybe not?

Anyway.. thoughts from a Historian (of Technology) who spends a lot of time thinking about alternate european history..

If people are finding this a valuable exercise, you could always try out 'what if there was no American Revolution/it had been lost': http://www.gwern.net/Mistakes#the-american-revolution

The no Holocaust argument is quite solid: the extermination system was expensive, militarily counter-productive, and could only have happened given a leader lacking checks and balance and with an idée fixe that overrode everything else (general European antisemitism allowed the Holocaust, but didn't cause it)

Jews would probably still get interned at labour camps. When Germany would begins to lose the war, which seems probable and food shortages kick in, guess which camps are last in line for distribution? Also lots of people shot and dumped in mass graves probably also still happens. I would estimate a Jewish death toll from about 2 to 4 million.

Nuremberg Trials (by another name perhaps) also obviously still happen, since the interests of most of the major powers involved (if WW2 happens mostly as it did here) are also exactly the same. It would stand to reason that the trials mostly keep the same character.

No Hitler, yet undoubtedly we still have a (different) Shoah. And I bet Europe and America would probably develop pretty much the same symbolism around it as they did here..

And it was the height of stupidity to have gone to war, for a half of Poland, with simultaneously the world's greatest empire and what appeared to be the overwhelmingly strong French army. Yes Gamelin, the French commander in chief, did behave like a concussed duckling, and the German army outfought the French - but no-one could have predicted this, and no-one sensible would have counted on it, and hence they wouldn't have risked the war. Hitler wan't sensible, and lucked out.

If our history is to be believed the war aim was far more than half of Poland. Pretty much eastern Europe as well as the elimination of Bolshevism (an ideological plank of anything that could be called the Nazi party, Hitler or no). Also a plausible argument can be made that the German leadership at the time considered the war pre-emptive.

Besides the obvious point that Stalin may actually have planned to invade eventually, going of of the trends apparent at the time, the Soviet Union was rapidly industrializing and had just endured massive purges to both its military and civil personnel. It had just demonstrated its weakness by being defeated by freaking Finland. It was weaker in the early 1940s than it would be for the foreseeable future. Germany was a developed country for which it wasn't really reasonable to expect massive enough economic and population growth to preserve its position relative to the Soviet Union.

The longer Germany was not fighting the Soviet Union the better positioned, if a war did occur, the latter would be.

Given that overconfidence is one of the big causes of bad policy, maybe a world without Hitler would have worse policies if Stuart's guesses at the end were true. It would possibly be overconfident about niceness, negotiations, democracy and supra-national institutions. On the other hand, it might be more cautious about developing nuclear weapons. So maybe it would be more vulnerable to nasty totalitarian surprises, but have a slighly better safety against nuclear GCRs.

As a non-historian I don't know how to properly judge historical what-ifs well: not only am I uncertain about how to analyse the counterfactual methodology itself, but I am uncertain about what historical data we need to know in order to do a proper counterfactual. But looking at how different worldviews depend on particular historical events and doing at least some estimate of how robust those events were, might indeed tell us a bit about where we might have ended up with contingent world-views.

In my own field of human enhancement ethics it is pretty clear that some of the halo effect of Nazism and its defeat in WWII led to a very strong negative value association that is relatively arbitrary but affects current policies. Had they been doing bad sociology instead we might have been decrying sinister social engineering, while happily selecting the genes of our children. If there had been an anti-USSR WWII the same might have happened.

most of Europe allied against the USSR, a war that the USSR would most likely have lost.

Why would the USSR or Europe even start the war? They had no territorial issues to be worth a war (Balkans always simmered), France and Germany would not have become allies without a dire need, the UK and the US likely would have stayed out of it, and Poland was not suicidal enough to push for a war, however much they hated the Russians. Stalin had just consolidated his power in mid-1930s, and probably was more interested in economic development after nearly wiping out the peasantry, than in a war, given that Russia had no shortage of territory or natural resources. Maybe once he became paranoid in the 1950s, who knows.

Also, the odds of the USSR losing the war would not have been favorable without a concerted all-out effort by all of Europe and the US (it was tried once, in 1918-1922, with no success), something not likely supported by the public still somewhat receptive to the communist ideas.

If a general all-out war were delayed by 20-30 years, the nuclear weapons would have likely been developed in multiple countries at once (without a threat of war the secrecy would suffer), probably around the same time the industrial atomic energy production would.

Of course, all this is a rather pointless speculating, as there is no way to test any of it.

Like others, I'm not seeing the likelyhood of a big European war involving the USSR without Hitler. Hitler's absence wouldn't have made things go any better for the Soviets in the Winter War, and likely that would have discouraged Soviet planners from trying to take on anyone bigger when it seemed like they could barely handle Finland. A saner German government would likely have viewed Poland as a valuable buffer against the USSR, rather than trying to get past Poland to attack the USSR. I find it easier to imagine the USSR being much more aggressive in the East if they didn't have the Nazi threat in the West, though it's very hard to know what all could have happened with Soviet-Japanese relations and the various third parties that would have taken an interest.

But fun though thinking through the details is, your larger point is obviously more important. There's a tendency to view history as inevitable in general, and that seems to be wrong (so much luck involved!) and to offer the wrong lessons (seemingly similar situations can end up going wildly differently). Certainly it is very frustrating that Hitler has given appeasement such a bad name, when historically it has nearly always been an incredibly effective strategy (those who are bribed usually become motivated to play nice enough that the briber doesn't regret the decision, and further they're often motivated to eliminate potential rivals so that they get any potential future bribes themselves, so bribing one threat often protects against many).