Are our choices fully determined by prior causes/environment/biology, and if so, how should we define morility/moral responsibility?
Consciousness has causal influence due to its content, not solely because of the physical aspects of its material correlates. A conscious state includes a desire or intention, it includes the ability to envision a future state and establish a strategy for attaining that state, it includes the ability to foresee the consequences of one's decisions, evaluate and choose among alternatives, and then act upon those choices. That makes it more than a purely physical state, it is a conscious state with reference to a future possibility, and no such reference is part of any purely physical state. Such conscious states can have causal effect to bring about further states for the sake of values and purposes, and intents. Values, purposes, and intents are not reducible to the purely physical state of the determinism argument.
If determinism is true, then every choice you make comes from causes you did not choose. Your biology, your environment, and your past experiences shape every decision.
Almost every argument against Free Will presupposes determinism without establishing determinism as a fact. Determinism is not a conclusion of science, on the contrary, it is directly contradicted by our two most successful scientific theories, Quantum Physics and Relativity Theory resoundingly refute the idea of "determinism".
The philosophical doctrine of determinism is nothing more than an archaic and failed concept that is unscientific and completely faith based. Initially it was nothing but a “thought experiment”, and in the two hundred years since, it has never made any credible advance beyond being an abstract theoretical “thought experiment”. By “any credible advance” I mean evidence, evidence that it is something more than a thought experiment, and there has been none whatsoever.
Two centuries ago, what Laplace proposed was, IF reality is completely circumscribed by Newtonian mechanics (and it isn’t), AND the motion of every particle in the universe can in principle be predicted from exact knowledge of its position, momentum, and the forces acting on it (and it can’t), AND everything occurred within a single, universal reference frame where an absolute Euclidean space and an absolute time that passes uniformly (it doesn’t), AND that as such, time and space are autonomous and independent aspects of reality (and they aren’t), THEN “theoretically”, all events, including human action, are ultimately determined by purely physical causes such that, there is one and only one possible effect for a particular cause or set of causes, (there isn’t).
The attempt to deny the self-evident experiential reality of human consciousness and the associated fact that we are morally responsible causal agents is a very extraordinary claim and extraordinary claims require extraordinary evidence, and the unfounded and completely faith-based belief in determinism doesn’t constitute extraordinary evidence by any stretch of the imagination. It follows that there is no logical or scientific reason to think determinism is true.
If all of those factors were exactly the same, you would make the same choice every time. That means you could not have done otherwise in any real sense.
The strongest argument for the existence of free will is that we all observe it during every conscious moment, it is always a fundamental and significant part of our experiential reality, hence it is self-evident. Consequently, the denial of free will is necessarily a rejection of the very concept of empirical evidence, and the argument against Free Will becomes a rejection without “proof”, which eliminates induction as valid. These two aspects of the approach clearly reject the very basis of science and scientific knowledge, leaving nothing but detached abstractions that have nothing whatsoever to do with the real world.
Philosophy is concerned with saying something which is true or significant, science with doing something which is effective. Science is about the real world, grounded in perceiving and doing, the argument against Free Will is completely abstract and invalidates both perception and doing, it is a complete rejection of science as valid, and philosophically it amounts to a rejection of the very basis of truth and significance.
In the end, there is no valid basis upon which the rejection of Free Will can be said to be true of reality.
If that is the case, then moral responsibility has to be redefined. Instead of saying people deserve blame or praise, we should focus on outcomes. Punishment should be about preventing harm and shaping behavior, not retribution. The goal becomes managing causes, not judging people as if they created themselves.
On the contrary, “If that is the case”, then there would be no reason to redefine moral responsibility, in fact, there would be no reasoning at all. The very idea of scientific or judicial objectivity, as well as of ever reaching philosophical truth, requires human beings to be free and responsible causal agents. Thus, if we're engaged in this enterprise of learning about truth and distinguishing it from falsehood, we are committed to the idea that human beings have the associated mental freedom to choose among options. Determinism renders a devotion to intellectual integrity meaningless, it renders morality, science, philosophy, truth as meaningless concepts. Reasoning and logic require freedom to choose among alternatives; determinism is just not compatible with objective truth seeking. If all beliefs are predetermined, then there is absolutely no justification for claiming that anything is true.