Talking among ourselves

There’s a common theme in my last two posts, on the misunderstanding of QE and on the left’s attitude to morality in politics. In both cases, I’m objecting to the tendency for the left to simply talk amongst itself rather than try to persuade others.
To see what I mean, start from Norm’s valid objections - that efficiency is also a moral concept, and that “Marxism embodies a clear ethical standpoint”.
In both cases, though, the morality here is what Michael Walzer calls a “thin” morality - the sort of conceptions which have universal appeal. When Marxists claim that capitalism is unjust because it is based on exploitation, they are appealing to the “thin” idea that exploitation, being a form of theft, is wrong. Their opponents do not generally reply with the moral claim that exploitation is OK, but rather with the empirical(ish) claim that the capital-labour relationship is not exploitative.
Efficiency - in the sense I used it - is also thin. Most people agree that it is better that firms be run well than badly; yes, it’s healthy for firms to go bust - but because of competition and changes in tastes and technology, not because of bad management.
However, the moral talk I was most strongly objecting too is what Walzer calls “thick” - more detailed and particularistic conceptions which do not have such universal appeal.
And here’s the difference. Appeals to a “thin” morality stand a chance of persuading others because they too share such moral intuitions, but appeals to “thick“ morality are likely to win cheers from one‘s own side, but leave others cold.
For example, the claim that big bonuses are unfair invites the retort that they are in fact a fair reward for scarce talent. But my claim that they have adverse effects and are instead the result of theft has, I think, more chance of winning over neutrals.  Yes, at root it is a moral claim - but a thin one, not a thick one.
To take another example, Wilkinson and Pickett’s claim in The Spirit Level that inequality is wrong because it hurts us all is also an appeal to a thin morality. Their critics don’t argue the morality (which is thin)  but the empirics.
What’s at issue here are two conceptions of politics. One is that politics should be (of course it isn’t) a realm of ideal speech, in which we use standards of communicative rationality to try and reach intersubjective agreement, or at least understanding and tolerance. Given our lack of ability to make “thick” moral arguments, this requires an appeal to thin morality where possible.
The other conception of politics sees the public realm as an arena in which character is revealed; we make moral claims which are cheered by our own side and jeered by the opposition.
And this is where QE comes in. When what matters is getting a cheer from our own side rather than persuading others, standards of factual accuracy decline.  The left’s misunderstanding of QE is a form of Nadine Dorries’ “[choosing] the 'fact' I wish to believe.” (Of course, the right talks amongst itself as much as the left).
For me - and OK, this might be a “thick” moral claim - this debasement of politics, form what was never a high level to start with, is to be regretted.