The distinction I'm making is being hypotheses that involve new objects and hypotheses that involve new properties for old objects.

For instance, consider planetary motion before Newton. You could have hypothesized a "dark" force that moved the planets. Or you could hypothesize that a force you already know exists (gravity near the Earth's surface) also exists for each body of the solar system, has unlimited range, and follows an inverse square law.

Ok, I get your distinction, but (and I'm a complete neophyte non-professional here, so bear with me), the layman's explanation for dark matter has been, "We don't know what's causing it, but it acts like gravity, and the only thing we know of now that has gravity is matter, and it appears (hah) to be invisible to all of our known electro-magnetic radiation, so we call it "dark"".

So I apologize if I've misunderstood, but based on that I don't think hypothosizing this unknown phenomenon as some sort of "dark matter" is entirely out of line.

Thanks for your explanation.

Could whatever idiot down voted this explain your reasoning so I can completely and utterly refute it? Thanks.