Yep, that's what I said in the first paragraph of my original post. In purely empirical terms, scientific progress is usually quite conservative. However, if you look at the content of the theory, and not just the predictions that it makes, scientific progress looks much less conservative. In the case of the flat earth example, it is indeed true that the flat Earth theory was not totally wrong in the sense that it made some approximately correct predictions. However, it was totally wrong in its assertion that the Earth is flat -- it simply isn't.