There is a passage by James Baldwin in his essay “Journey to Atlanta” that I believe explains some of the apprehension about Sanders’s grand plans in a way that I could never equal, and although it is long, I’m going to quote it here in full.

Of all Americans, Negroes distrust politicians most, or, more accurately, they have been best trained to expect nothing from them; more than other Americans, they are always aware of the enormous gap between election promises and their daily lives. It is true that the promises excite them, but this is not because they are taken as proof of good intentions. They are the proof of something more concrete than intentions: that the Negro situation is not static, that changes have occurred, and are occurring and will occur — this, in spite of the daily, dead-end monotony. It is this daily, dead-end monotony, though, as well as the wise desire not to be betrayed by too much hoping, which causes them to look on politicians with such an extraordinarily disenchanted eye. This fatalistic indifference is something that drives the optimistic American liberal quite mad; he is prone, in his more exasperated moments, to refer to Negroes as political children, an appellation not entirely just. Negro liberals, being consulted, assure us that this is something that will disappear with “education,” a vast, all-purpose term, conjuring up visions of sunlit housing projects, stacks of copybooks and a race of well-soaped, dark-skinned people who never slur their R’s. Actually, this is not so much political irresponsibility as the product of experience, experience which no amount of education can quite efface.

Baldwin continues:

“Our people” have functioned in this country for nearly a century as political weapons, the trump card up the enemies’ sleeve; anything promised Negroes at election time is also a threat leveled at the opposition; in the struggle for mastery the Negro is the pawn.

Even black folks who don’t explicitly articulate this intuitively understand it.

History and experience have burned into the black American psyche a sort of functional pragmatism that will be hard to erase. It is a coping mechanism, a survival mechanism, and its existence doesn’t depend on others’ understanding or approval.

However, that pragmatism could work against the idealism of a candidate like Sanders.

Black folks don’t want to be “betrayed by too much hoping,” and Sanders’s proposals, as good as they sound, can also sound too good to be true. There is a whiff of fancifulness.

For instance, Sanders says that his agenda will require a Congress-flipping political revolution of like-minded voters, but so far, that revolution has yet to materialize. Just as in Iowa, in New Hampshire there were more voters — or caucusgoers — making choices in the Republican contest than in the Democratic one. That, so far, sounds more like a Republican revolution. If that trend holds for the rest of the primary season and into the general election, not only would Democrats not be likely to pick up congressional seats, they could lose more of them.

That’s a stubborn fact emerging — a reality — and it is one that all voters, including black ones, shouldn’t be simply told to discount.

This is not to say that Clinton or Sanders is the better choice for Democrats this season, but simply that the way some of Sanders’s supporters have talked down to black voters does him a disservice, and makes clear their insensitivity to the cultural and experiential political knowledge that has accrued to the black electorate.