Also worth pointing out, to anyone who might wonder if the ideas behind homeopathy might actually make sense -- that this was pre-germ-theory. I.e., he didn't know microorganisms existed, or that they might have something to do with illness.
http://www.sciencebasedmedicine.org/index.php/lessons-from-h...
So let's go with "easily-invalidated hypothesis even at the time."
Sure, if, by "theory" you mean "outlandish idea someone made up without any basis in fact and might as well have pulled it out of their ass" ("just a theory") instead of "systematic framework of ideas intended to account for, explain and relate together a wide amount of existing observational and experimental data, and to predict the outcome of similar results in the same field in the future" ("scientific theory").
"Like cures like, and weaker is stronger" was not a "theory". It was a wild-ass guess which also turned out to be fantastically wrong. The thing that made homoeopathy practitioners think it worked was bad (non-blinded) patient experimentation, where things like the observer effect, confirmation bias, the placebo effect, regression to the mean, and a whole bunch of other psychological biases, all came (and still come) into play.
I meant it in the sense of classical greek philosophy, since that's what it seems most similar to. E.g. it sounds like an idea out of Phaedrus or something.
You do realize this process is the foundation of the scientific method, right? It's not like new drug ideas come from the science fairy.
And also you are wrong on your history. E.g. homeopathy was derived from a theory, not from patient experimentation.