This is in fact a far more interesting question than this endless yatter about speculation.
I've been trying, not too successfully, for nearly 50 years to figure out precisely what various writers mean by "historicism." It's used in all sorts of contexts and almost never defined by the writer using it.
I've decided myself to use it as "The meaning of an event is to be found in its origins," and as such it is the _opposite_ of what Marx meant by _historical_, as in the phrase I quote frequently here, "The anatomy of man is a key to the anatomy of the ape." Another anti-historicist phrase is "The Present as history." And of course we can only see the present as history by looking _back_ on the present from a hypothetical future point. This is what Marx did in _Capital_: There he mentions socialism NOT as a goal but as a hypothetical future from theperspective of which one can see capitalism as historical.
Bertell Ollman ahs written on this topic, calling it "doing history backwards." The presnt explains the past, but the past deos NOT explain the present.
What brad means by it though is a mystery to me.
Carrol