If everyone lies for their preferred cause, those who see through the lies trust no one, and those who don't see through them act on false information.
If everyone believes enemies of their preferred cause should be driven out of society, as many societies as causes arise, and none can so much as trade with another.
If everyone believes their opponents must be purged, everyone purges everyone else.
If everyone decides they must win by the sword, the Hobbesian state of nature results.
(Oh, hell, first I realize Kant was not an idiot, and now I realize Hobbes was not an idiot. Of course the state of nature is ahistorical -- that's part of the point!)
Breaking down the Schelling fence around the social norms built up over the state of nature is an effective way to gain power, but once you gain power, you have to make sure that the fence is restored -- and that's hard to do. It's easier to destroy than to build. You can't weigh winning by the sword against the status quo; you have to weigh one action with p probability of winning hard enough to restore the fence (and q probability of having your burning of the accumulated arrangements / store of knowledge be net-beneficial for whatever definition of 'net-beneficial' you're using, vs. 1-q probability of having them not be) and 1-p probability of just breaking the fence.
In reality, of course, fence-wreckers understand that the opposite side wants to preserve the fence, and use that to their advantage. (The rain it raineth on the just / And also on the unjust fella / But chiefly on the just, because / The unjust hath the just's umbrella.) Alinsky understood this: you appeal to moral principles when you're out of power, but if you get power, you crush the people who appeal to moral principles -- even the ones you espoused before you go power. If you have enough power to crush your opponents, you have enough power to crush your opponents -- but this represents... not quite a burning of capital, but a sick sort of investment which may or may not pay off. You may be able to crush your opponents, but it doesn't necessarily follow that your opponents aren't able to crush you. And if you crush your opponents, you can't use them, their skills, knowledge, etc.
This is the part where I attempt to avoid performing an amygdala hijack by using the phrase 'amygdala hijack', and reference Atlas Shrugged: the moochers crush the capitalists, so the capitalists leave, and the moochers don't have access to the benefits of their talents anymore so their society falls apart. It's not a perfect analogy -- it's been a while since I read it, but I don't think the moochers saw themselves as aligned against the capitalists. But it's close enough; if it helps, imagine they were Communists.
There ought to be a term for the difference between considering an action in and of itself and considering an action along with its game-theoretic effects, potential slippery slopes, and so on. Perhaps there already is. There also ought to be a term for the seemingly-irrational-and-actually-irrational-in-the-context-of-considering-an-action-in-and-of-itself cooperation-norms that you're so strongly arguing for defecting from.
There ought to be a term for the difference between considering an action in and of itself and considering an action along with its game-theoretic effects, potential slippery slopes, and so on. Perhaps there already is. There also ought to be a term for the seemingly-irrational-and-actually-irrational-in-the-context-of-considering-an-action-in-and-of-itself cooperation-norms that you're so strongly arguing for defecting from.
In the consequentialist ethics family, there's act consequentialism, rule consequentialism, and a concept I cannot recall the name...
The public debate is rife with fallacies, half-lies, evasions of counter-arguments, etc. Many of these are easy to spot for a careful and intelligent reader/viewer - particularly one who is acquainted with the most common logical fallacies and cognitive biases. However, most people arguably often fail to spot them (if they didn't, then these fallacies and half-lies wouldn't be as effective as they are). Blatant lies are often (but not always) recognized as such, but these more subtle forms of argumentative cheating (which I shall use as a catch-all phrase from now on) usually aren't (which is why they are more frequent).
The fact that these forms of argumentative cheating are a) very common and b) usually easy to point out suggests that impartial referees who painstakingly pointed out these errors could do a tremendous amount of good for the standards of the public debate. What I am envisioning is a website like factcheck.org but which would not focus primarily on fact-checking (since, like I said, most politicians are already wary of getting caught out with false statements of fact) but rather on subtler forms of argumentative cheating.
Ideally, the site would go through election debates, influential opinion pieces, etc, more or less line by line, pointing out fallacies, biases, evasions, etc. For the reader who wouldn't want to read all this detailed criticism, the site would also give an overall rating of the level of argumentative cheating (say from 0 to 10) in a particular article, televised debate, etc. Politicians and others could also be given an overall cheating rating, which would be a function of their cheating ratings in individual articles and debates. Like any rating system, this system would serve both to give citizens reliable information of which arguments, which articles, and which people, are to be trusted, and to force politicians and other public figures to argue in a more honest fashion. In other words, it would have both have an information-disseminating function and a socializing function.
How would such a website be set up? An obvious suggestion is to run it as a wiki, where anyone could contribute. Of course, this wiki would have to be very heavily moderated - probably more so than Wikipedia - since people are bound to disagree on whether controversial figures' arguments really are fallacious or not. Presumably you will be forced to banish trolls and political activists on a grand scale, but hopefully this wouldn't be an unsurmountable problem.
I'm thinking that the website should be strongly devoted to neutrality or objectivity, as is Wikipedia. To further this end, it is probably better to give the arguer under evaluation the benefit of the doubt in borderline cases. This would be a way of avoiding endless edit wars and ensure objectivity. Also, it's a way of making the contributors to the site concencrate their efforts on the more outrageous cases of cheating (which there are many of in most political debates and articles, in my view).
The hope is that a website like this would make the public debate transparent to an unprecedented degree. Argumentative cheaters thrive because their arguments aren't properly scrutinized. If light is shone on the public debate, it will become clear who cheats and who doesn't, which will give people strong incentives not to cheat. If people respected the site's neutrality, its objectivity and its integrity, and read what it said, it would in effect become impossible for politicians and others to bullshit the way they do today. This could mark the beginning of the realization of an old dream of philosophers: The End of Bullshit at the hands of systematic criticism. Important names in this venerable tradition include David Hume, Rudolf Carnap and the other logical positivists, and not the least, the guy standing statue outside my room, the "critical rationalist" (an apt name for this enterprise) Karl Popper.
Even though politics is an area where bullshit is perhaps especially common, and one where it does an exceptional degree of harm (e.g. vicious political movements such as Nazism are usually steeped in bullshit) it is also common and harmful in many other areas, such as science, religion, advertising. Ideally critical rationalists should go after bullshit in all areas (as far as possible). My hunch is, though, that it would be a good idea to start off with politics, since it's an area that gets lots of attention and where well-written criticism could have an immediate impact.