Logic is the force that compels belief in the congruence bt a proposition and a state of affairs. Like class relations, it is purely immaterial, yet so constitutes knowledge as to inform human behavior. What knowledge is in itself no one can say, it is only known by its effects.

This isn't really concerned with your main point, but...

Are class relations immaterial? If so, what are the material relations Marx refers to?

I just mean that class relations aren't, em, material *stuff*. But, point taken, clearly they'd be part of what Marx refers to as the "material" world. Moreover, "ideas", ideology are also material for Marx. I'm not so convinced that mental entities are real entities of any kind at all. OTC, IMO ideas and mental entities are the dialectical opposite -- the negative -- of the real. What is real? The efficient, i.e., what effects phenomenal change (but that's another thread).

class relations are certainly material, and ideas are most certainly not material for Marx. where did you read this?

Insofar as ideas and ideology are the reflection of matter in men's (and women's) brains, they are indeed part of the ecology of material relations in, e.g. Capital. I glean this from David Harvey's lectures on Capital. Your mileage may vary. For Marx, philosophical materialism mean objective, not *stuff*.

Ideas and ideology are determined and produced by material relations, but are not in and of themselves material. I find this to be a crucial tenet of Marx's thought. But don't believe me... feel free to consult Marx. I recommend the Preface to A Contribution to the Critique of Political Economy - here marxists.org/archive/marx/works/1859/critique-pol-economy/preface.htm
or Part I of the German Ideology - here marxists.org/archive/marx/works/1845/german-ideology/ch01.htm
(*Sorry, my post count is not high enough to post links*)

Ideology in Capital is perhaps more tightly interwoven with material relations, but it is still not identical to those relations in themselves, as it is a distortion of materiality... at least in reference to commodity exchange.

I haven't watched those lectures though, so perhaps he picks up on something I don't. Do you have a link? I'd be interested in listening to them at some point...

Althusser does go on to assert that ideology is material, but that's a different story.

Trivas:

1) Logic is not a 'force'.

2) Epistemology studies "the congruence bt a proposition and a state of affairs", not logic. Logic is merely the study of inference.

3) Logic has nothing to do with 'class relations'; an argument is valid/invalid whether or not a worker or a capitalist constructs it.

4) Like the vast majority of dialecticians, you have not bothered to study the subject before you began pontificating about it.

You'll be advising us on brain surgery next!

And there is no excuse for this; there are scores of sites on the internet that woud have disabused you of your self-imposed ignorance -- but maybe not your dogmatism -- had you bothered to check before you began bashing away at your keyboard.

Obviously this is true. I think Marx somewhere comments that ideas can have a material force, though. Intellectual labour has a productive effect, for instance.

Insofar as class relations are a product of Marx's analysis of capitalism, they are part of his logic. Logic is what makes Marx's analysis compelling. I said nothing re who makes an argument.

Ideas can definitely have an effect on material relations; ideology, for instance, plays an essential role in reproducing existing social relations. But in the last analysis all ideas are subject to material determination. I find the distinction between ideas and materiality to be a crucial one for Marx.

Agreed, the distinction is important. But even more important is the nature of the relation between them. Ideas are never just a passive reflection of material relations; nor are they directly reducible to those relations.

Trivas:

1) I note you ignored my comment that you prefer to pontificate about logic from a position of what seems to be total ignorance.

2) Marx uses informal logic only in Das Kapital, as you have had pointed out to you many times. Informal logic is also blind to class relations. In fact, if it weren't, then Marx (a non-worker) would not have been able to develop a working class theory.

3) You also said:

I'd like to know how you know this.

Or is this yet another Trivas-dogma, which we must all unquestioningly accept, and with grateful thanks to, thee, the true prophet?

I don't know what informal logic is. Neither do I think it's what Marx meant when he referred to "his method". Nor do I understand what Marx's class status has to do with his analysis of capitalism.

Trivas7 & RL: I have one word for you, just one word:

semantics.

Terrific. Have you a thought to accompany that word?

I try not say with more what could be said with less, but here goes.

Rosa is using the term "logic" to mean the study of correct inference. From what I gather, you are using "logic" to mean, basically, a line of thought. There are not equivalent, but both of these are fair senses of the term "logic." This struck me as what was at the heart of your disagreement.

Trivas:

Now why does that not surprise me? But you have been told before. Here are some links; feel free to ignore them like you did last time:

http://plato.stanford.edu/entries/logic-informal/

http://en.wikipedia.org/wiki/Informal_logic

How do you know if you do not know what Informal Logic is?

Well, at least you are honest.

If by informal logic you mean Marx's ability to make interconnections amongst seemingly disparate things within a context, I totally agree that Marx uses informal logic. And this exactly characterizes his dialectical method.

Trivas:

No, as you would see if you actually bothered to read up on something before you began pontificating about it, informal logic underpins our everyday capacity to make sense of the world and to reason with one another (and this also involves making 'connections'). So, as I have noted before, this relates Marx's method the to dialectic as it appears in Aristotle and Kant, but more in tune with working class ways of reasoning.

And that is why Marx endorsed this summary of 'his method':

You will note that Marx calls this the 'dialectic method', and 'his method', but it is also clear that it bears no relation to the sort of dialectics you have had forced down your throat, for in it there is not one ounce of Hegel -- no quantity turning into quality, no contradictions, no negation of the negation, no unities of opposites, no totality...

Unless you mean the non-mystical version of the 'dialectic' outlined above, then no, this is not what 'characterises his dialectical method'.

I have no idea what you mean to say by this.

AFAIK It is only you who believes there is some mystical meaning to the dialectic.