My understanding of Miles' position is that people's subjective states of mind do matter. However, what changes those subjective states is best understood not as minds changing other minds but as social conditions changing minds. He's not denying the role of, say, learning to have different attitudes and beliefs. He is saying, however, that the learning takes place *because of* social conditions. He wrote this last year, I've quoted it below.
At the time, Julio wanted to know why blacks ever bothered to protest their conditions. To which I responded (see link) that the answer was obvious: there was never a time when there wasn't some form of protest among slaves and, later, freed blacks under Jim Crow. So, slaves and freed blacks engaged in social struggle, building a movement -- which means they were building what Sarah Evans and Harry Boyte called "free spaces" where they nurtured practices and and norms that nurtured practices of freedom and commitment toward liberatory struggle. In other words, they created alternative institutions. And engagement with those alternative institutions is what brought those opposed to ending slavery and those opposed to the civil rights struggle "change their minds".
I would add that my hunch is that while people might become "enlightened" through reading, hearing speeches, and encountering other forms of rhetorical persuasion, I suspect that these "changes" are very superficial. They can be undermined simply by encountering an opposing rhetoric. The changing of minds (of subjective states), I think, is probably deeper, richer -- permanent, if you will -- when people are engaged in what Marxists sometimes call "political practice" (which some people interpret more broadly than merely being engaged in some sort of "conventional" politics.
At any rate, here's what Miles wrote, which does not deny the role of subjective states, at all: http://mailman.lbo-talk.org/2008/2008-July/011982.html
My response: http://mailman.lbo-talk.org/2008/2008-July/011995.html
Miles wrote: We know what came first here; there's no "chicken and egg" problem. The vast majority of Southern whites were opposed to desegregation in the 50s; the end of public segregation occurred prior to that vast majority "changing their minds" about desegregation. (Segregation forever!) There is no ambiguity in the data here: The social change--public desegregation--came first; the white population's support for desegregation came later.
Now, political mobilization is important; but that's not necessarily about "changing minds". The civil rights movement brought together people with shared goals and beliefs; it did not create those goals and beliefs from nothing. As andie and I noted, a great deal of the variation in political beliefs is due to family background and long standing religious affiliation, not "road to Damascus" conversions. (Simple example: the liberal Northern college students who participated in the freedom marches did not have to have their minds changed to participate; given their family and religious backgrounds, they were already on board!) So sure, political mobilization was crucial, but that had little to do with changing opponents' minds.
<...> All this is predicated on the false assumption that changes in attitudes can somehow shape social conditions. Even if people have attitude X or have been persuaded to have attitude X, social change can only occur through social processes and institutions that are independent of any one individual's thoughts and behavior. Simple example: imagine a very greedy person in a hunting and gathering society who wants to be wealthy. Regardless of that person's individual desire, he will never be wealthy, because that type of society does not sustain an infrastucture that allows immense accumulations of wealth. --And just so with any psychological characteristic: attitude X cannot create social facts; only social processes can do that.
From this perspective, spending a lot of time and energy "changing minds" is an ineffective political strategy. The history of social transformations and revolutions is quite clear: a committed and well-organized minority can foment significant social changes, even if they haven't persuaded the majority. (The American Revolution is another example that comes to mind. Only about 1/3 of the colonists supported the revolutionaries. According to the "first step is to change minds" argument, the revolutionaries had it all wrong to take action before they had majority support!)