Tim Lewens has written a popular introduction to the philosophy of science, The Meaning of Science: An Introduction to the Philosophy of Science. In his first substantial chapter, he writes about what distinguishes science from non-science. Karl Popper and the demarcation problem arise here. He needs examples of near sciences:
Consider the trio of economics, intelligent-design theory, and homeopathy. The only thing that unites these three endeavors is that their scientific status is regularly questioned in ways that provoke stormy debate. Is economics a science? On the one hand, like many sciences, it oozes both mathematics and authority. On the other hand it is poor at making predictions, and many of its practitioners are surprisingly blaseé when it comes to finding out about how real people think and behave. They would rather build models that tell us what would happen, under simplified circumstances, if people were perfectly rational. So perhaps economics is less like science, and more akin to The Lord of the Rings with equations: it is a mathematically sophisticated exploration of an invented world not much like our own.
In a later chapter, Lewens recognize that economics is a diverse discipline. He writes about some interesting analyses in economics. And then we get:
In contrast to these empirically rich forms of economic inquiry [associated with Sen and Kahneman], much work in neoclassical economics is concerned with the largely theoretical analysis of how markets would work if they were populated with individuals endowed with perfect rationality - in other words, creatures of fantasy. We might be tempted to classify these areas of economics as science fiction. Alternatively, we might think that this brand of economics tells us not how the world is but how the world ought to be, if only people would think straight...
I think Lewens is more complimentary to homeopathy than he is to economics. (He does have a bit more to say about economics than I have quoted.) Controlled experiments in medicine, I gather, consider one intervention as applied to a population. Advocates of homeopathic medicine claim to be treating a whole, particular person in a way which cannot be easily analyzed such reductionist experiments. This, no matter how hostile you may be to it, is an interesting claim for a philosopher to consider. Maybe what they advocate are placebos. Suppose you have a patient that is skeptical of big medicine. Would he react better to a placebo if it is administered in an alternative setting? What, ethically, could such a practitioner say when prescribing extremely diluted "medicine"?
I still am of the opinion that labelling a claim in economics as "science" or "non-science" should neither add nor subtract to its plausibility, over and above whatever empirical evidence and disciplinary arguments already do.