It is better than I remember it, but in the end, a bit precocious.
It is not really a 'silence' in capital that he describes the worker as object rather than subject - that is the fact of capitalist domination, that it makes subjects into objects.
Nor is it the case that Marx' emphasis contributes to the objectification of subjects. On the contrary, the real damage would be done if alienated labour, were re-presented as its opposite, that is free subjectivity. To characterise un-freedom as if it were already freedom, that would be an apologetic for capitalism.
Those who praise EP Thompson's book are unaware of just what a negative influence it has been on the British working class. It is essentially a piece of Whig history, that presents a long procession towards power on the part of labour. I can remember reading it as a schoolboy and being emotionally stirred up by this grand tradition of labour's forward march. But then you look around you and wonder, where the fuck did all that go? What in Thompson's book is presented as an inexorable march had already been halted (in Hobsbawm's phrase).
A good alternative to Thompson on British Labour History is Richard Price, an American, I think. He makes the insightful point that the history of the working class movements are discontinuous, not uniform, constantly disrupted and destroyed, not learning lessons from previous generations. The other, Whig version, was an apologetic for the British labour bureaucracy, who thrived on this mythical history. Those who are impressed by Thompson's book should look at the vulgar model he based himself upon, AL Morton's History of the English People, and Morton's book with George Tate on British Labour.
To return to Lebowitz, the answer to the question where is the free subjectivity in Capital, the answer is in the artistic form of the whole itself. Marx' work is the literary equivalent of the 'political economy of the working class' that he describes in the preface to the third German edition. It is the reappropriation of a system of alienated labour in thought, as the precursor to the reappropriation of alienated labour in fact. Marx is right to say that it is as a work of natural science, because the system of alienation (capital) presents itself as external to man, like a natural force. The scientific concepts themselves are the work of free subjectivity that can be seen in capital. -- Jim heartfield