I still haven't had a lot of time but I dashed this out as quick as I could -
While I respect what you have said in many ways, and we have found certain common ground (politically if not conceptually), I continue to believe that you have missed the central point of this entire discourse. And I think one of the red flags that gives this away is in your posting where you claim that you are a socialist because it is the “best” system, but if someone could prove to you that libertarianism was the “ideal” then you would go with that. It seems that, as many scientists or rationalists do, you are basing your statement on an assumption of an ‘objective optimal,’ when in fact no such optimal obtains. All notions of “best” or ‘ideal’ (at least at the social level) are not in any manner objective but rather based entirely upon ethical lifeworld assumptions. Socialism could only be seen as the “best” system if we share certain ethical assumptions about how the world ‘ought’ to be. In other words the word (like all words ultimately) are just labels of convenience predicated upon what we hope can be social agreements. But again, such social agreements often do not obtain.
This brings us to the real crux of the problem and the real point of Habermas’ Theory of Communicative Action. Anyone, at any time, can simply reject your assumptions no matter how ‘right’ or ‘factual’ or ‘rational’ (or anything else) you believe them to be. If a religious person says to me ‘you must act in this way because God says you must,’ I can of course simply say I don’t believe in God so I am free to act in a different manner. He can reply, for example, that I risk going to hell, and he may be right or he may be wrong. Similarly, an ecologist might say to me ‘if you don’t act this way then the ‘laws of nature dictate that you will end up with an environmental catastrophe. The ecologist may be correct or he may be incorrect, but either way I can reject his claim based upon the claim that the reasoning is faulty, but much more importantly based upon my own ethical judgments. I can simply say, ‘I don’t care if there is an ecological disaster so I can act whatever way I choose.' Ironically, in both cases the religious person and the scientists will probably reply the same way, viz., “It is irrelevant what you think because this is what will happen regardless of how you feel.” Both parties may claim to be correct but I can still choose to reject both because neither claim is binding to my behavior unless I agree with the background assumptions and choose to act in a manner consistent with those assumptions. As long as I am alive, I can reject either. This is what was so important about Montaigne’s skepticism. Montaigne essentially said that trust in ‘reason’ is a pre-rational assumption because anyone is free at anytime to reject reason itself. You might say that they won’t get very far or that their rejection is ‘irrelevant’ to the facts but this is not the point, they can still stand by their rejection and there is no conceptual way around this. Thus proscriptions for actions are only meaningful if people share ethical assumptions. Someone might say that fascism is the ‘best’ system of social organization because it will result in the greatest number of people working at any one time, or they may say that free-for-all anarchy is the best system because it will result in the strongest being victorious. But someone else might say that the best system of social organization would be the one that resulted in the greatest number of beach towels being produced because beach towels are sacred objects and that is what all of society should be designed to produce. But you could have very little meaningful discourse with that person about social organization if you didn’t share their assumptions about beach towels. And herein lies the rub.
Now, this discussion is, for the moment centered on social or political (i.e. normative) questions. But I make these points because this is where it all started. I think the wider questions are really too big for this forum. (The wider questions being the epistemological ones – but the same basic formula applies, people can reject any claims you make about reality based upon their rejection of your assumptions. You may say they are wrong but this won’t necessarily change what they say or do) In Being and Nothingness, Jean-Paul Sartre struggled with the whole problem of proscriptive action and he comes to the same conclusion I do, that nothing is proscriptive unless it falls within certain parameters that conform to what Sartre calls one’s “project.” And for years I have tried to see a way out of this problem but I have never found one. Our actions are only contingent if we make them contingent, that is to say if we are making certain assumptions about the desired outcomes or the best ethical behavior. Again one might claim that people are using, say, science or even ‘facts,’ to ‘inform’ their choices and you might be correct. But the problems still follow you conceptually. Someone might look at the so-called facts differently from you (as happens all the time), they might decide to use a different set of facts, they may decide for whatever reason to reject said facts, or (and this is the biggest problem of all) we have no real way of knowing whether they are adopting certain facts to support a pre-rational or a priori set of goals or desires, or whether the facts have actually informed those desires. For my part I think people generally see what they want to see to support their basic beliefs.
Anyway, the gist of what I am getting at is not that you are wrong about the facts or even about the existence of facts, or that scientific claims play no part in social or normative processes. Instead, I am saying that they are not binding to action and I think that is clear in many people’s behavior because everyday people do all sorts of things that you may say are contra indicated. And at the bigger level, social systems are always about basic lifeworld assumptions because no capitalist, for example, could ever ‘prove’ to me that his is the best system because what a capitalist wants out of life and society are different from what I want, it is as simple as that.
And a last point, I still must take issue with your claim concerning the reduction of war since WWII. It was only after the War that Western capitalist nations began to mass produce arms for the international market and sell them en masse to Thrid World Countries. Furthermore, it was during the post-war period that the so-called super-powers ran hundreds of proxy wars throughout the globe. The post-war period has been the greatest period of mass warfare the world has ever seen and only a deeply Western-Centric viewpoint could fail to see this. A quick list of the countries involved in large scale armed conflict since the war should make this clear to say nothing of the fact that a number of these wars have involved, over the years, more tonnage of armory than the entire Second World War.