Of course, the same argument is also made for the international hegemonic peace theory... Pax Romana, Pax Britannica, Pax Americana. So proponents of this would also argue for a unipolar world where America continues to reign supreme and is preferable to a more multipolar world where we see the 'rise of the rest' Sorry. Getting off tangent.
Well, in terms of military power, I think this is true. The era from say, 1789 to 1945 was a fairly violent one (not all the time, but plenty of significant wars) with wars 'scaling up' in terms of the degree of violence and misery they brought and involving many areas around the globe, mostly instigated by the competing leading 'nation-states' in Europe and some relative newcomers. (Not counting several fairly bloody civil wars) After WW 2, it became pretty much just 2 superpowers that were hegemonial powers limiting what others could do, and they avoided engaging each other in what they could do. And now, there is only one supreme military power left, which is not a bad thing for peace. Full-scale military conflict between two states has become fairly rare. Most of the remaining wars are civil wars & rebelions. (Some of which we barely hear about in the media).
But I didn't say that this is necessarily a good thing. One of the more popular theories that explains the progress (western) Europe made in science, manufacture, industry, trade, etc. relative to other parts of the world over the last 500 years or so (a progress that made it child's play to gain rule over most of the world in the 19th century) claims that this was due largely to the fact that Europe was NOT an empire, had this permanent competition, militarily and economically. I kinda believe in that theory. And as for the world now: there may be a lot less military competition now, but our economic system (capitalism) is one that strongly favors innovation and competition (but not so much competition in warfare).
Which is off topic, but I felt I had to add it.
So yes, when there is a state force monopoly, we often see more peace. But I wonder, if the amount of lives saved by state force monopoly is offset by the amount of people killed in Pol Pot's regime, PRC Cultural revolution, and the formation of the USSR and what the Ukrainians called a genocide of their people through forced collectivization and the subsequent famines counting in the millions of deaths alone.
I would find it hard to come up with numbers, but I do think that... yes, the number of lives saved was probably significant. Even when you talk about the former USSR: major famines were not at all rare under the Czars (or Tsars or however you spell that). Along with most of the world, conditions of what used to be the peasant-class (in pre-communist Russia, a class that was hardly elevated above the level of slaves and which compised the vast majority of the population) in most of what used to be the Russian empire did improve significantly during the 19th century, however bad some of the autrocities were. The same is probably true for China. I am very glad I wasn't born in a rural area in China, mind you, but overall, live did improve for the common people there as well. Probably a whole lot more than it did in hard-to-control places, divided by clans, different ideological or religious movements WITHOUT a near monopoly of violence (and arms) held by the state, like some central American countries, a lot of countries in Africa and Afghanistan. As Thomas Hobbes argued a long long time ago: cival war often gets so bad, so violent that for people, it is better to live under the absolute authority of a tyrant than to live without a ruler, without safety, being unsure who will come knocking on your door, raping your daughters and wive, taking your things, burning down your land next. Because a ruler, no matter how vile, has no interest in his people being in uproar, lacking safety, because he benefits from civil tranquility and peace.
Maybe Hobbes isn't right. Maybe there is something to be said for 'liberty or death'. I'd say that there are tyrants that really are so bad/insane that it would be much better to rise against them instead of falling in line (The german AH-example comes to mind). But in terms of actual NUMBERS of people being killed violently under most absolutist and tyrannical... I am going with the Hobbesians. Because the sort of war that causes most harm to people tend to be long-running civil wars and prolonged states of violent anarchy.
Again, you are right in that many successful partisans and rag tag fighters had help and aid in their struggles. But how did they get help and aid in the first place? They didn't secure all this help before they fought. They fought first... and aid came. An armed citizenry is the first line of defense against atrocities against people like Stalin, Mao, Pol Pot and Gadaffi. It slows them down. It buys time. It wears down the enemy's morale. Through guerilla fighting, it bogs down the main army until help can arrive from abroad. With firearms, you can raid supply depots and arm yourself with the enemies grenades and personal anti-armor or SAM missiles. You can cut off reinforcements.
You underestimate how quickly people can get access to weapons. Look at how quickly the zionists managed to get in loads of weapons into Israel. They didn't have guns hidden under the floorboards of their home. For the most part, they didn't live in Palestine yet. And for the most part, they weren't even soldiers. Many had never fired a gun in their lives. They learned to be soldiers very quickly, and they got arms very quickly, and managed to beat the professional armed forces of several countries very soon after. Look at how quickly the Bolsheviks managed to arm their supporters in Russia. Of course... having a people with a partisan tradition and arms will help, buy time (or having people from the state military go over, as happened in Lybia, and has also happened in Syria).
Another good example: During WW II, the germans met with resistance fighters in many countries. And yes... those who had a 'tradition' of preparing against the 'state' (often communists) were often some of the ones offering fiercest resistance. One of the places German occupiers had most trouble was former Yugoslavia. Especially the area that is now Serbia. There was a kind of guerrilla resistance war going on there, and the Germans never managed to fully control the region. Even as part of the Sovjet block, Serbian controlled Yugoslavia managed to maintain a fairly independent position. But it is often said that that same 'militant' tradition was responsible for the rise of those out of control Serbian militia's after the fall of the iron curtain, militias that were responsible for ethnic cleansing, genocide, systemic rape and lots of violence. It seems to be a double-edged sword. Same with Afghanistan, of course.
And well... realistically... think about a MODERN western country. The UK is a good example of a country in which most people do not have a shotgun or riffle in a cupboard, do not walk around with a fire-arm. Even most of the police-force goes around without those. So... you'd say that the UK would be fairly... pacified, in that sense, not able to offer much resistance.
But really... say if the highly unlikely happened, and say that ... uhm... there was a coup, led by prince Harry, supported by the UK military, taking control of the houses of Parliament. All airports ceized, all media shut down except for the BBC, with a colonel in charge. Prettty unthinkable, of course, but... let's pretend. What would happen? Would the citizens of the United Kingdom be forced to accept it, unresistingly, because they would barely have arms?
My prediction would be: there would be immediate strikes all over the country, making it impossible for it to function, for the 'ghunta's' forces to move around, excert any control. They might shoot some people, but few would follow their orders, except at gun-point. If (miraculously) the military were to follow prince Harry, a lot of the police-force would defect Wales would rebel, Scotland and Nothern Ireland would too. And very quickly, even with Britain being an island, there would be lots of weapons coming in, military aid given. Or if not given, bought, and if there was no money, that could be borrowed (just as the US did during it's civil war). Soon, there would be a counter military and Harry's Ghunta would never get control of the country. At least, that is what I think. A people may appear passive, but when they really believe in something, when they are really outraged, they can get pretty fierce pretty quickly. I think the birth of Israel is evidence of that.
And I don't think it would be all that different in the USA. So... I really don't think that lots of people having guns at home or on their person is a prudent or necessary safe-guard against the US government turning despotic. If the USA were to turn into a democracy, it would not be through a 'hostile take-over' that would be resisted by most people. It would be (and allow me to vent my nerd-side and quote George Lucas) 'under thunderous applause'.
Hitler mostly came to power via democracy. The SA weren't that armed. They were mostly thugs. If the German jews were armed they could have fought back and formed partisan groups, like Polish jews did.
True, though those thugs were 'aiding' the 'democratic' push of the nazis, by spreading fear, intimidating opponents and by generating a violent situation that caused some to think that voting for a strong 'law and order' candidate was the way to go. But you are correct about that. I don't think it would have mattered all that much if the jews living in Germany would have been armed or not. The thing was that they never imagined things would go as far as they did. It was beyond what they could imagine, mostly. If they had known or been able to imagine what the nazis really had in mind, more of them would have fled the country (many did, of course). And if more of them had tried using violence, it would also have been an excuse for the nazis to label them terrorists and go all out against them. There WERE still militant people in Germany eager to resist AH (some of them with access to weapons): mostly communists, anarchists etc. but their 'resistance' didn't stand much of a chance, and it provided Hitler with the same sort of excuse. Many voted for him out of fear of these commies/terrorists.
Anyway... sorry about being so long winded. The above is my view.