> Agreed. At least if "science" in mid-19th c German means what it usually
> means to us today.
As used by Engels, it doesn't mean this.
It has the meaning Hegel gives to it in his account of what Marx calls "the dialectic of negativity."
Understood in terms of this idea:
"The business of science is simply to bring the specific work of the reason, which is in the thing, to consciousness."
It's "science" in this sense that constitutes Marx's idea of "critique."
“Reason has always existed, but not always in a reasonable form. The critic can therefore start out from any form of theoretical and practical consciousness and from the forms peculiar to existing reality develop the true reality as its obligation and its final goal.” http://www.marxists.org/archive/marx/works/1843/letters/43_09.htm
That this is the idea of "science" underpinning the "critique" that is Capital is reiterated in the 1877 draft letter to the editor of the Otecestvenniye Zapisky and in this 1878 elaboration by Engels of "scientific socialism" in Anti-Duhring (an elaboration republished in 1880 in Socialism: Utopian and Scientific).
It's also the basis of Marx's distinction, in the 1873 afterword to the second German edition of Capital, between "the mere critical analysis of actual facts" and "writing receipts ... for the cook-shops of the future." http://www.marxists.org/archive/marx/works/1867-c1/p3.htm
Ted