The incompatibility of determinism and moral obligation
From an indeterminist's perspective, I support and defined the following argument for deontic incompatibilism: (1) If determinism is true, then no one ever can do otherwise than he does. (2) If no one ever can do otherwise than he does, then nothing anyone does is ever right, wrong, or obligatory. (3) Therefore, if determinism is true, then nothing anyone does is ever right, wrong, or obligatory.
They sense of 'can' I use in this argument is what I call "the power-'can' of ordinary language." The power-'can' has two (implicit or explicit) time indexes; one applies to the power itself, the other to the relevant doing. (In ordinary language these indexes usually are not explicit.) I argue that the power-'can' is a sense of 'can' with which the "ought implies can" principle holds true.
I review and respond to various accounts of 'can' proposed by compatibilists Bruce Aune, Keith Lehrer, David Lewis, G. E. Moore and others. Elsewhere I discuss writings by Peter van Inwagen and J. L. Austin.
To support (1), I utilize, argue for, and show the advantages of the Temporal Physical Possibility Requirements: If an agent, S, can at time T do A (not do A) at time T$\sp\prime$, then S's doing A (not doing A) at $T\sp\prime$ is jointly possible with the conjunction of the state of the world at T and the laws of nature. When arguing for these requirements, I focus on how most people use the power-'can' and how they would use it in various situations. I present and respond to objections to my arguments. Most of the objections are based on certain strong forms of contextualism.
I argue for (2) and defend my premises against various objections. One objection is based on a form of utilitarianism advocated by Fred Feldman. Other objections are based on an example by Harry Frankfurt concerning moral responsibility.
Two arguments against (3) are presented and I respond. They are developed from a suggestion by John Martin Fischer that people would continue making deontic claims if a consortium of scientists were to find strong evidence of determinism.