me: "inductive reasoning can work..."
Lbird:
"No, it can't, mate. A pre-existing theory is always required to select and make sense of data."
You're just regurgitating a formula without paying attention to what I said. There are well known classes of inductive arguments where the argument does show the conclusion to be more probable if the premises are true. But, as I said, this is typically explained by a hypothesis. Natural kinds being an example. A hypothesis is what you call a "theory". so your last sentence here does not contradict what I said, nor does it show that inductive arguments under certain conditions do not lead from truth to probable truth. Hypotheses are not organized by linear chains of reasoning, but can support each other in various ways. When a deductive or mathematical probability argument is used to refute a hypothesis, it invariably also assumes in that context other hypotheses.
While I'm generally inclined to agree with you I think your view that Marx's analysis of capitalism rests on a priori assumptions is fallacious, but beating a dead horse will not bring it back to life. So I'd approve of the notion that 'marxian economics' or whatever could use a more empirical grounding but if you look at how Marx conducted his research you'll see the idea of his value theory didn't just pop into his head while he was in the restroom (but maybe I'm misunderstanding your point here). And looking at certain fields like econometrics I'm not even sure they have an idea what they're doing.