Fair enough, but that still doesn't support the previous poster's claim that the black transition from Republican votes to Democratic votes marks a shift from conservatism to liberalism.
In 1932, FDR ran as a conservative, or at least as a moderate (as did Woodrow Wilson). By 1936, he was running as a promoter of his New Deal and the fledgling welfare state, while Republicans were running as opponents.
Until 1936, there was no party of the welfare state, so by default blacks voted for the party of Lincoln and reconstruction (moreover, the Democratic party was arguably more fiscally conservative in the 19th century: witness Grover Cleveland).
So the real PC myth is that blacks were once "conservatives" (just because they voted Republican), only to be corrupted into liberalism. That line of thinking comes from naively projecting today's political debates and party lines back decades or centuries when they simply did not apply.
True, no can explain the black vote, or are unwilling to say what their theory is.
The black vote seems to be some kind of non-thinking, group think.