WHat is the difference? Well, there are two prongs to the response, which correspond to the phrases "known unknowns", and "unknown unknowns". In the case of e

WHat is the difference? Well, there are two prongs to the response, which correspond to the phrases "known unknowns", and "unknown unknowns". In the case of empirical studies of homeopathy, we see that it is actually ineffective. This gives us more confidence in discarding the "unknown unknowns" - there doesn't seem to be any strange effect going on that our current theories don't know how to describe. The second part though, is to point out that our current theoretical understanding of how the world works suggests that homeopathy is just bunk, that there is no known theoretical underpinning that could explain a response to a homeopathic medicine (well, apart from the placebo effect). Both responses re-inforce the other. If we just had a theoretical justification for refusing homeopathy, we might be wrong about the theory, or have overlooked a crucial factor. If we just had the experimental results, we might be tempted to conclude that the experiment wasn't well-enough designed. But when the experiment and the theory agree with each other, we can start to have a very high level of confidence that we know what we are talking about. If homeopathy does actually work, we would have to conclude that today's theories of physics and chemistry are wrong, and that all of the well-conducted experiments that have so far been done have had some fatal flaw in them. That's a highly improbable situation, which is the important information that politicians need to understand. It is important to explain that multiple lines of reasoning indicate that homeopathy just doesn't work.