Michael Strevens (NYU) gives a talk at the MCMP Colloquium (30 April, 2015) titled "The Mathematical Route to Causal Understanding". Abstract: Causal explanation is a matter of isolating the elements of the causal web that make a difference to the explanandum event or regularity (so I and others have argued). Causal understanding is a matter of grasping a causal explanation (so says what I have elsewhere called the "simple theory" of understanding). It follows that causal understanding is a matter of grasping the facts about difference-making, and in particular grasping the reasons why some properties of the web are difference-makers and some are not. Mathematical reasoning frequently plays a role in our coming to grasp these reasons, and in some causal explanations, deep mathematical theorems may do almost all the work. In these cases - such as the explanation why a person cannot complete a traverse of the bridges of Königsberg without crossing at least one bridge twice - our understanding seems to hinge more on our appreciation of mathematical than of physical facts. We have the sense that mathematics gives us physical understanding. But this is quite compatible with the explanation in question being causal in exactly the same sense as more unremarkable causal explanations.