(Attention conservation notice: mostly me trying to work out what I mean. If you know, feel free to get in touch)
Explanation is not a zero-sum game. You can add additional explanations without negating existing explanations. The loss of life after the flooding of New Orleans was due to Hurricane Katrina. And it was due to climate change. And under-investment in the levees. And a history of social exclusion based on race and class. All these explanations are true, there is no explanatory exclusivity.
I am reading Bruno Latour’s “Science in Action” where he gives the best (only?) account I have seen of how any explanation can be countered or superseded by subsequent explanations. Scientists seek to settle claims – to generate “black boxes” of fact, in Latour’s terms – but the process of scientific debate sees a flux of competing explanations. An experiment by A said X. But two experiments by Y said not-X. But Y isn’t using the correct equipment, of course his experiments give the wrong results. But X’s equipment is biased to give the answer X, Y has to use non-standard equipment. But Z has shown not-X with A’s equipment for sub-case Z. And so on. Explanations seek to settle, but can always be weakened by subsequent explanations which qualify, reframe or negate. It is not just that subsequent claims diminish our confidence that X is the case, on some linear scale where 0>confidence>1. Instead, there is a fundamental uncertainty in the very metrics we are judging.
We seek to define or find (domains) where exclusivity applies. Responsibility and blame feels like a domain where exclusivity applies – almost by definition, because we want it to apply. If it was my fault it is not your fault. We want blame to sum to 1, so that even in complex cases we sort through the responsibility of all involved an apportion a limited amount of blame to each party.
Obviously, when non-exclusive explanations originating from science are used in the moral domain, it is natural for people to interpret them exclusively. If your brain or your environment made you commit a crime, it is not your fault. In a similar way – perhaps essentially similar – freedom of the will is often talked about as an exclusive property. Is your choice at the moment free OR is it pre-determined? This is a fundamental misconception, in my opinion.
You need a tolerance for ambiguity to deal in non-exclusive explanations. Usually we seek to find a restricted domain where we can argue over explanations which are, temporarily, exclusive. Is it nature or nurture? Is dyslexia caused by cerebellar dysfunction or magnocellular pathway dysfunction? For the non-restricted domain the ground can always shift underneath you. Someone can come along a redefine any element of what you are arguing about, including the tools of argument themselves.