The Consequence Argument
Posted: Mon, Mar 9, 2026
Today
- Introduce our new free will unit [25 min]
- Van Inwagen’s consequence argument against free will [40 min]
- More questions about first paper? [save 10 min]
Free will
Free will: A special kind of control at issue in moral responsibility (esp. praiseworthiness/blameworthiness—“is it on me?”).
- This is important to avoid “begging the question”: to assume the conclusion one is trying to prove.
- Here, we want to avoid prematurely assuming that one side of a live debate is correct by definitional fiat: if free will is, as Merriam-Webster says, “freedom of humans to make choices that are not determined by prior causes or by divine intervention,” then that already prejudically settles the question of whether casual determinism or divine foreknowledge precludes free will.
The free will problem
Trilemma: Three statements seem true individually but cannot be true together.
The problem of evil
- An omnibenevolent, omnipotent, and omniscient God exists.
- An omnibenevolent, omnipotent, and omniscient God is incompatible with evil.
- Evil exists.
One of the three has to go.
Theodicy: Attempt to justify God’s existence with evil.
- Maimonides’ divine providence
- The free will defense
The problem of free will
Determinism (≠ fate): At any time only one future is physically possible.
- Theological determinism: Every event is necessitated/fixed by God.
- Causal determinism: Every event is necessitated/fixed by a physical cause.
Trilemma:
- We have free will.
- Free will is incompatible with determinism.
- Determinism is true.
| Views | (1) Free will | (2) Compatibility | (3) Determinism | ||
|---|---|---|---|---|---|
| Incompatibilism | Libertarianism | True | False | False | |
| Hard incompatibilism | Hard determinism | False | False | True | |
| Hard non-determinist incompatibilism | False | False | False | ||
| Compatibilism | Soft compatibilism | Soft determinism | True | True | True |
| Soft non-determinist compatibilism | True | True | False | ||
| ??? | False | True | False | ||
Why believe (2)?
- If determinism is true, then we do not have the ability to do otherwise.
- If we do not have the ability to do otherwise, then we do not have free will.
Contemporary controversy: Whether what gives us free will is an “ability to do otherwise” (or “alternative possibilities”).
Peter van Inwagen’s consequence argument for incompatibilism
Informal statement of the argument:
If determinism is true, then our acts are the consequences of the laws of nature and events of the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us. (An Essay on Free Will, p. 16)
He formulates determinism in terms of logical entailment:
- P0 is a proposition that describes the entire state of the world at time t0.
- P is a proposition that describes the entire state of the world at a later time t.
- L is the conjunction of all laws of nature.
- Determinism: P follows logically from P0 & L.
His toy example: At t, J does not raise his hand.
- The stylized argument on p. 191.