The problem of induction (kind courtesy David Hume) states that causality isn't deductively justified.

Determinism, predicated on causality, isn't justified.

Ergo, free will is (at the very least) possible.

Is this argument sound?

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Geoffrey Thomas
    Jan 30 at 9:16
  • No. Hume himself was a free will compatibilist and endorsed determinism, see SEP, Hume on Free Will. Why was he unimpressed by his own arguments about the lack of any rational (both deductive and inductive) justification of causality? Because he was unimpressed by rationalism in general:"Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them." Why impress by the slave's failure when the master presses causality directly. So much the worse for rational justification
    – Conifold
    Jan 30 at 14:33
  • @Conifold, I see, but his problem of induction does put causation into doubt snd that weakens if not defeats determinism. Perhaps an unintended consequence. Jan 31 at 2:32
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    It puts it into doubt only for old school rationalists. Although few modern day philosophers are as dismissive of reason as Hume was, even fewer think that science needs a priori justifications or that a posteriori ones it does provide are lacking in persuasiveness. So, like him, they reject the rationalist standard of justification. As a result, the problem of induction remains a philosophers' toy puzzle of little impact.
    – Conifold
    Jan 31 at 8:28
  • Your argument needs a premise linking free will with causality - spelling out the relation(s) between the two.
    – Geoffrey Thomas
    Feb 1 at 12:25

1 Answer 1


As a compatibilist, I am drawn to query the inference from “Determinism isn’t justified” to “Free will is possible”.

“Free will” is about the capacity to choose, so I think your argument requires an additional premise that the restrictions on one’s capacity to choose are causal (in the Humean sense) in nature.

While this might appear obvious, the Compatibilist poses that even if the world in macrocosm is physically deterministic, that doesn’t remove the concept of freedom to choose from the equation.

My brain might be a physically determined causal entity but that doesn’t mean that the salient human concept of my chosen action is beyond my human control - the operative processes are my processes, and I still have responsibility (in the relevant human sense) for my actions and my behavioural patterns.

So, logically, the converse might also be true. The world might be wholly undetermined by physical causation, yet perhaps no faculty of choice might exist in that world. Maybe the absence of order is such that no truly meaningful “decisions” could ever be made, given the void of predictable consequences.

  • Good points. However, to my knowledge, compatibilism doesn't have an argument to back it up. It simply assumes that determinism is consistent with free will. As to your second point, I concur, although it seems rather odd to live by determinism and then believe in a randomness. Jan 30 at 9:31
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    "Compatibilist poses that even if the world in macrocosm is physically deterministic, that doesn’t remove the concept of freedom to choose from the equation." But it does remove it as originally understood. Changing the concept is changing the subject, as Quine would say, a sleight of tongue. Everything said after that is just talking past the issue. Compatibilism is, and has to be, an error theory, we err in what we take "freedom" to be. But error theory is always inferior to a direct theory. And compatibilism so far failed to produce convincing arguments that the latter is impossible.
    – Conifold
    Jan 30 at 14:48
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    Questions around the viability of compatibilism itself aside, the point of this answer is just to highlight that the inference from "determinism false" to "free will possible" is not trivial.
    – Paul Ross
    Jan 31 at 6:41

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