How much did each of the authors of this paper causally contribute to its writing?

Some philosophers argue that in order to accommodate a range of our practices we must suppose that causation is not an all or nothing matter: it comes in degrees. We argue for two key claims. First, we can accommodate these practices without positing degree theoretic causation, and we can do so by appealing to various things that clearly do admit of degrees. So, positing causation by degree is unnecessary. Second, not only is positing degree theoretic causation unnecessary, but in fact there is no single thing, causation by degree, that could play the role required of it if it is to accommodate these practices. Thus, we conclude, there is no motivation to posit degree theoretic causation that arises from consideration of these practices.