I don't think it is incoherent at all. The problem comes when people try to shoehorn free will causality from the back end. If we just look at free will as a cause, instead of a result, everything works.
So, are you contending that free will operates independent of causality? If so, what does that mean? How are thoughts and decisions valuable if they aren't the product of previous brain states? How would that be different than 'random'? The concept seems incoherent to me for exactly that reason. The way most people describe free will produces decisions and choices without rhyme or reason. That hardly seems like a 'free will' worth defending.
No, I am saying that free will is a cause.
Yet is, itself, without cause? Again, what does that even mean? If our thoughts and decisions aren't based on our memories and experiences, what are they based on? Anything at all? Pure random whim?
The fact that science cannot currently explain how people make decisions does not change the self evident fact that we make decisions.
Who says science cannot explain how we make decisions? It's evident that the brain is, in fact, a thinking machine. It's activities can be observed, both at the micro and macro levels, as people think and react. On the other hand, there's exactly no evidence that something other than the physical mechanics of the brain is the 'cause' of our thoughts. It's nothing more than an intuition, and misguided intuition, in my estimation.
To be clear, I'm not saying there's no such thing as free will - but I am saying it's a mistake to believe that free will exists independent of causation. We are the end result of the causes that create us, but that doesn't contradict our role as deciding creatures.