I want to clarify the problems with determinism under atheism. (Please notice how I define atheism).
Thankfully, Sam Harris has already identified one of the problems for us:
What most people overlook is that free will does not even correspond to any subjective fact about us. Consequently, even rigorous introspection soon grows as hostile to the idea of free will as the equations of physics have, because apparent acts of volition merely arise, spontaneously (whether caused, uncaused, or probabilistically inclined, it makes no difference), and cannot be traced to a point of origin in the stream of consciousness. A moment or two of serious self-scrutiny and the reader might observe that he no more authors the next thought he thinks than the next thought I write.
This is an important concession from a very popular atheist writer who earned a degree in philosophy from Stanford and a Ph.D. in neuroscience from UCLA. He has expertise in the relevant scientific field, has lectured at TED, and has written New York Times best-selling books. Yet he tells us that the readers of his writing “no more authors the next thought he thinks than the next thought I write.” Or, as he puts it earlier in the same section of his book The End of Faith, “In physical terms, every action is clearly reducible to a totality of impersonal events merely propagating their influence: genes are transcribed, neurotransmitters bind to their receptors, muscle fibers contract, and John Doe pulls the trigger on his gun.”
A number of implications follow:
1. Determinism denies that we are rational agents. First, if we fail to be the authors of our own thought, then we can hardly take credit for what we think, reason, argue for, or write! Second, science demonstrates that we are only organisms who blindly express whatever “totality of impersonal events” describes our physical state and our physical environment.
2. Determinism denies that reasons affect our thinking. Instead, our own thought processes are scientifically described as what happens when “neurotransmitters bind to their receptors.” This is a physical process, described by reference to various neurological states. It is not a rational process, where various reasons are weighed for their truth value, and we then choose to accept the most logical or justifiable truth claim.
3. Determinism denies that we can choose to change our minds. Of course, determinism denies that we can choose to change anything about ourselves! We are entirely subject to physical causes, both those within and those outside of our bodies. Therefore, we have no ability to reason our way to a different position on a given subject. If we change our beliefs, it will be because our neurotransmitters just happened to bind to different sites than before.
To conclude:
1. Atheism leads to determinism.
2. Determinism denies that we are rational agents, that reasons affect our thinking, and that we can choose to change our minds.
Therefore:
3. Atheism leads to the denial of reason.