There is nothing in what Engels says here that is theoretical. Engels does not make theoretical claims for materialism itself but does claim that actual working theories or hypotheses don't make sense unless one assumes materialism.
Even though I consider myself a materialist I disagree with Engels on this. History simply proves him wrong.
Well developed scientific theories take on entity-like or what I would call "modular" aspects. They work both as models and as "theoretical objects" to use an Althusserian notion. So one can be an idealist or a dualist or a naturalist or even a "supernaturalist" and still develop workable and useful theories. Wallace, the co-creator of evolutionary theory was a conscious idealist and Newton was a conscious "supernaturalist." The theories they helped develop assume a certain amount of methodological naturalism in their testing but does not assume a materialist orientation.
Engels was often wrong in his scientific writings. But he his is a lot more subtle than you give him credit for. In Anti-Duhring and in some other writings published in that metaphysical postmortem collage novel "The Dialectics of Nature" he seems to come much closer to Kuhn's idea of "scientific revolutions" than to anything that you claim about "materialism". Engels more consistently called materialism a "world view" and I am not aware that he ever referred to it as a theory. Did Engels or any of the classical followers of Marx ever refer to "dialectical materialism" as a theory? Not that I am aware of. One assumes that Marx used his materialistic orientation and the dialectical method to develop his proposed theory of capitalism and to give hints at a possible theoretical approach to history. I remain a theory skeptic on the latter subject but Marx never claimed that materialism was itself a "theory."
Chris Doss wrote: "I actually don't think that "materialism" as usually defined makes a whole lot of sense." And elsewhere, I think, he states that there is no consistent definition of "matter."
Chris is correct there is no good workable definition of matter or body. We simply assume it. Engels himself pointed out in a comment on Spinoza's relation to Hegel, and then Lenin emphasized the point in his notes to Hegel's Logic, that a completely consistent idealism is almost indistinguishable from consistent materialism. On a consistent materialism that expressly addresses Chris's questions I would suggest Galen Strawson's essay in his response to Chomsky called "Real Materialism". It is a wonderful essay and whether Charles or Chris agree with it or not it rewards thoughtful reading. It can be found at the following url:
http://www.rdg.ac.uk/AcaDepts/ld/Philos/gjs/rmchomsky.htm
The fact is that none of the originators of materialism would recognize quantum field theory as a description of anything that they would have considered material. It is perhaps the strength of the materialism derived from the idealism of Spinoza and/or Hegel that QM can be considered a theory that describes matter, even if matter itself is undefinable and indescribable when we consider that fields of force are all that do matter.
Just a side-note: I am not sure if anyone follows debates in the philosophy of mathematics. Mathematicians tend toward philosophical idealism and for good reason. Various mathematical theories seem to come upon us as pre-existing objects. Personally, I am anti-Platonic idealism in everything except mathematics. In mathematics I think Platonic idealism is in fact another name for Real Materialism. Or put it another way... the numbers exist independent of human experience of the theoretical entities we used to describe the numbers.
This is just my choice of philosophy. But the reason I bring it up is that one can not accept the material reality of descriptions of provided by modern physics without taking some kind of position on whether the fields of force are "matter" or not. If they are not matter by fiat of definition then materialism is useless as a philosophical outlook. I think the same is true of what we call mathematics.
Jerry
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> The great basic question of all philosophy, especially of more recent philosophy, is that concerning the relation of thinking and being. From the very early times when men, still completely ignorant of the structure of their own bodies, under the stimulus of dream apparitions (1) came to believe that their thinking and sensation were not activities of their bodies, but of a distinct soul which inhabits the body and leaves it at death — from this time men have been driven to reflect about the relation between this soul and the outside world. If, upon death, it took leave of the body and lived on, there was no occasion to invent yet another distinct death for it. Thus arose the idea of immortality, which at that stage of development appeared not at all as a consolation but as a fate against which it was no use fighting, and often enough, as among the Greeks, as a positive misfortune. The quandry arising from the common universal ignorance of what to do with this soul, once its existence had been accepted, after the death of the body, and not religious desire for consolation, led in a general way to the tedious notion of personal immortality. In an exactly similar manner, the first gods arose through the personification of natural forces. And these gods in the further development of religions assumed more and more extramundane form, until finally by a process of abstraction, I might almost say of distillation, occurring naturally in the course of man's intellectual development, out of the many more or less limited and mutually limiting gods there arose in the minds of men the idea of the one exclusive God of the monotheistic religions.
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> Thus the question of the relation of thinking to being, the relation of the spirit to nature — the paramount question of the whole of philosophy — has, no less than all religion, its roots in the narrow-minded and ignorant notions of savagery.
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-- Jerry Monaco's Philosophy, Politics, Culture Weblog is Shandean Postscripts to Politics, Philosophy, and Culture http://monacojerry.livejournal.com/
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