The unificationist theory of causal explanation offers a theory of causation and explanation with no causal primitives. Kitcher proposed that it offered an account of explanatory asymmetry, but his proposal has been criticized for being too dependent on contingent facts and surreptitiously supposing causal realism. In addition, critics have argued that unificationism cannot account for asymmetry in a world with symmetric laws of physics and is lead to accept backwards explanation in certain epistemic situations. Unificationism has been defended from some (...) of these objections. We critique those defenses, rejecting some and developing others, as well as adding new ones. In doing so, we argue that objectors are wrong to treat explanatory asymmetry as an a priori matter and that unificationism is appropriately sensitive to the right sort of empirical facts. (shrink)