My reasoning: to the extent I have free will, I can consciously choose to delegate it to an unrelated source of entropy, such as a coin toss. That happens all the time, in fact, without any conscious input from me at all. We're immersed in randomness. ("Wow, if I'd left 3 seconds earlier or driven 1 MPH faster or slower, I wouldn't have been T-boned at that intersection." How can free will coexist with a statement like that?)
This sort of thing happens frequently enough to dispel both (soft) determinism and free will as viable concepts, IMHO. We all live in a Gaussian game, where everything that occurs is the sum of an unknowable and indeed unimaginable number of factors. The sum of a vast number of of random numbers may still be deterministic, in the sense that it could be rederived from a perfect copy of the system's original state, but I'd argue that this insight cannot possibly be useful since there's no way to store or represent such a copy in any environment where the original "me" is able to manipulate it.
This sort of thing happens frequently enough to dispel both (soft) determinism and free will as viable concepts, IMHO. We all live in a Gaussian game, where everything that occurs is the sum of an unknowable and indeed unimaginable number of factors. The sum of a vast number of of random numbers may still be deterministic, in the sense that it could be rederived from a perfect copy of the system's original state, but I'd argue that this insight cannot possibly be useful since there's no way to store or represent such a copy in any environment where the original "me" is able to manipulate it.