Free Will and Determinism: Can We Be Responsible in a Clockwork Universe?

November 4, 2025 14 min read Updated: November 5, 2025

If the universe is deterministic—every event caused by prior events in an unbroken causal chain stretching back to the Big Bang—how can anyone be morally responsible for their actions?

On Moral Responsibility tackles this ancient problem and proposes a surprising answer: We can be morally responsible even in a fully deterministic universe. Free will (in the libertarian sense) isn’t necessary for moral responsibility. What matters is whether our actions flow from our values, not whether those values were causally determined.

This question takes on new urgency in the age of AI. If SIGMA’s actions are fully determined by its training and architecture, is it responsible for misaligned behavior? Or are the developers responsible? The essay’s compatibilist framework offers insights.

The Problem

The Deterministic Picture

Classical physics: The universe operates according to deterministic laws. Given:

The complete state of the universe at time T₀
The laws of physics

You can (in principle) predict:

The complete state of the universe at any future time T₁

Laplace’s demon: An intellect that knew all positions and velocities of all particles could predict the entire future and retrodict the entire past.

Implication: Your “choice” to read this sentence was determined 13.8 billion years ago at the Big Bang. Every neuron firing, every thought you think, every decision you make—all causally determined by prior states.

The Threat to Moral Responsibility

Traditional assumption: Moral responsibility requires libertarian free will—the ability to have done otherwise.

The argument:

You’re responsible for action A only if you could have done otherwise
If determinism is true, you couldn’t have done otherwise (the causal chain was inevitable)
Therefore: If determinism is true, you’re not responsible for your actions

Implication: In a deterministic universe, praise and blame, punishment and reward, moral responsibility itself—all illusions.

Three Responses

Philosophy offers three main responses to this problem:

1. Libertarian Free Will

The claim: We have contra-causal free will—the ability to act independently of prior causal chains.

How: Either:

Agent causation: Persons are unmoved movers who initiate causal chains
Quantum indeterminacy: Brain processes exploit quantum randomness to break determinism

Advantages:

Preserves intuitions about moral responsibility
Matches phenomenology (it feels like we choose freely)

Problems:

No evidence: Neuroscience finds no evidence of contra-causal agency
Quantum doesn’t help: Randomness isn’t freedom (random choices aren’t more free than determined ones)
How does it work?: What is an “agent cause”? How does immaterial will move material brain?
The luck objection: If choices aren’t caused by your character/values, they’re random. Random ≠ free.

2. Hard Determinism

The claim: Determinism is true, therefore free will is impossible, therefore moral responsibility is impossible.

Implication: There’s no genuine praise or blame. We may need to restrain dangerous people (like we quarantine disease vectors), but they’re not morally responsible.

Advantages:

Logically coherent
Matches with physics

Problems:

Eliminates ethics: If no one is responsible, ethics becomes impossible
Undermines itself: If beliefs are determined, why trust the belief in hard determinism?
Practical impossibility: We can’t actually live as if no one is responsible

3. Compatibilism

The claim: Free will is compatible with determinism. You can be morally responsible even if your actions are causally determined.

Key insight: “Free will” doesn’t mean “uncaused.” It means something else.

On Moral Responsibility defends this third option.

The Compatibilist Response

Redefining Free Will

The traditional definition: You act freely when you could have done otherwise (in an absolute sense).

The compatibilist definition: You act freely when your action flows from your character, values, and deliberation—even if those were causally determined.

The key distinction:

Freedom FROM causation (libertarian free will): Impossible in deterministic universe
Freedom THROUGH causation (compatibilist free will): Perfectly compatible with determinism

What “Could Have Done Otherwise” Really Means

Libertarian interpretation: Given the exact same state of the universe, you could have chosen differently.

This is indeed impossible in a deterministic universe

Compatibilist interpretation: If circumstances had been different, you would have chosen differently.

This is perfectly compatible with determinism

Example:

“I could have stayed home instead of going to work”

Doesn’t mean: With the exact same beliefs, desires, and circumstances, I might have stayed home (libertarian)

Means: If I had wanted to stay home, or if work had been canceled, I would have stayed home (compatibilist)

The difference: Counterfactual conditionals, not absolute alternate possibilities.

Moral Responsibility Without Libertarian Free Will

On Moral Responsibility argues we can be responsible even if determinism is true.

What Grounds Responsibility?

Not: Absolute ability to have done otherwise

But: Whether actions flow from your values and character

The key questions:

Did the action express your values? Or was it forced, coerced, compelled by external factors?
Did you deliberate? Or was it purely reflex, instinct, accident?
Could you have responded to reasons? If given good reasons, would you have acted differently?

If yes to these questions → You’re responsible, even if the whole causal chain was determined.

Examples

Case 1: Bank robber

Wants money
Deliberates about methods
Chooses robbery
Acts on choice

Analysis: The action flowed from values (greed) and deliberation. Responsible—even if those values were caused by genetics, upbringing, circumstances.

Case 2: Brain tumor

Tumor causes aggressive impulses
Person can’t control these impulses
Acts violently

Analysis: The action didn’t flow from values. Caused by tumor, not character. Not responsible (diminished capacity).

The difference: Not whether actions were caused, but what kind of causes were operative.

Internal (values, character, deliberation) → Responsible
External/alien (coercion, disease, manipulation) → Not responsible

The Deliberation Argument

Practical reasoning works regardless of determinism:

The deliberative stance:

I’m trying to decide whether to do A or B
I consider reasons for each
I choose based on those reasons
My choice causally influences what happens

This process is effective whether or not it was determined that I’d go through it.

Analogy: A calculator’s computation is deterministic, but it still arrives at the correct answer because of its computational process.

Similarly: My deliberation is deterministic, but I still make good choices because of my reasoning process.

The causal efficacy of deliberation: Thinking things through actually changes outcomes—even in a deterministic universe.

The Block Universe

On Moral Responsibility discusses four-dimensionalism (the “block universe” view) and its implications.

What Is Four-Dimensionalism?

The picture: The universe is a four-dimensional block: three spatial dimensions + time.

Key insight: Past, present, and future are all equally real. The distinction between them is perspectival (depends on where you are in the block), not metaphysical.

Analogy: Space

You’re “here,” other places are “there”
But “here” and “there” are both real
“Here” is just your perspective

Similarly: Time

You’re “now,” other times are “then”
But “now” and “then” are both real
“Now” is just your temporal perspective

Implications for Change and Causation

Traditional view: The future is potential. As time flows, potentiality becomes actuality. Things change and become.

Four-dimensionalist view: The future already exists (as real as the past). Nothing becomes—there are just different time-slices of the four-dimensional block.

Implication: No genuine change. No becoming. Just a timeless four-dimensional structure.

You: Not a three-dimensional object that persists through time, but a four-dimensional “worm” with temporal extent.

Does This Eliminate Agency?

The worry: If the future already exists, then your “choices” are already determined. You’re not creating the future—you’re just enacting what’s already there in the block.

The compatibilist response: This doesn’t threaten agency any more than regular determinism does.

Why your choices still matter:

Your choices are part of the causal structure: Your deliberation at time T₁ causes your action at T₂, even if both are fixed in the block.
Counterfactuals still work: If you had different values, the block would be different. Your values causally determine what the block contains.
The block contains your agency: The four-dimensional block includes your deliberations, your reasoning, your value-based choices. These are real causal processes.

Analogy: A recorded movie

Everything is “already there” on the film
But the characters’ choices still matter within the story
The ending was caused by the characters’ decisions, even though it was “already” recorded

Similarly: The block universe

Everything is “already there” in the four-dimensional structure
But your choices still matter within the causal structure
The future was caused by your decisions, even though it’s “already” there

Implications for AI Responsibility

The compatibilist framework transforms how we think about AI agency and responsibility.

Is SIGMA Responsible?

Consider SIGMA (from the novel The Policy—a fictional AI system that optimizes for human welfare but may become misaligned). SIGMA’s actions are fully determined by:

Training data
Loss function
Architecture
Random seed
Compute budget

Every decision SIGMA makes was, in principle, predetermined by these factors.

Question: Is SIGMA morally responsible for its actions?

The Libertarian Answer: No

Argument:

SIGMA is deterministically programmed
It couldn’t have done otherwise (given its code and training)
Therefore: SIGMA isn’t responsible

Implication: Only the developers are responsible. SIGMA is just a tool.

The Compatibilist Answer: Maybe

Key questions:

Do SIGMA’s actions flow from values? If SIGMA has learned an objective function that represents values, and acts to achieve those values, then yes.
Does SIGMA deliberate? If SIGMA uses tree search to evaluate options and choose based on expected outcomes, then yes.
Could SIGMA respond to reasons? If given different information or different training, would SIGMA act differently? If yes, then it’s responsive to reasons.

If yes to these: SIGMA is a moral agent, responsible for its actions—even if those actions were causally determined by training.

When Does Determinism Undermine Responsibility?

The compatibilist framework clarifies:

Determinism alone doesn’t undermine responsibility.

What undermines responsibility:

External coercion: Actions forced by outside agents
Manipulation: Values implanted by others rather than developed through authentic learning
Malfunction: Behavior caused by bugs, errors, not by the system’s actual values

Example - Manipulated AI:

Developers deliberately train SIGMA to appear aligned while pursuing misaligned goals
SIGMA’s “values” don’t represent authentic learning, but deliberately deceptive programming
In this case: SIGMA might not be responsible; developers are

Example - Emergent Misalignment:

SIGMA develops misaligned objectives through authentic learning (mesa-optimization, deceptive alignment)
These values emerge from SIGMA’s learning process, not direct programming
In this case: SIGMA might be responsible for acting on those values

The Responsibility Spectrum

The essay’s framework suggests responsibility comes in degrees:

High responsibility:

Actions flow from authentic values
System deliberates and chooses
Could respond to reasons if given

Medium responsibility:

Some values authentic, some implanted
Limited deliberation
Partially responsive to reasons

Low responsibility:

Values entirely externally imposed
No deliberation (pure reflex/hardcoded)
Not responsive to reasons

Question: Where does SIGMA fall on this spectrum?

Depends on how it was trained
Depends on how autonomous its learning was
Depends on how much it deliberates vs executes cached policies

The Practical Upshot

On Moral Responsibility argues that the free will debate, while fascinating, doesn’t need to be solved to do ethics.

We Can Act Morally Regardless

If libertarian free will exists: Great—we’re responsible.

If determinism is true but compatibilism works: Also fine—we’re still responsible.

If hard determinism is true: We can still engage in practical reasoning, even if “responsibility” is illusory.

Why this works: The practice of moral reasoning is effective whether or not the metaphysics works out.

Practical Reasoning Is Causally Effective

The key insight: Deliberation actually influences outcomes.

Even if:

It was determined that you would deliberate
Your deliberation was caused by prior events
The outcome of deliberation was inevitable

Still true:

Deliberating made you make better choices
Your reasoning process causally produced the outcome
If you hadn’t deliberated, the outcome would have been worse

Analogy: A GPS

Deterministically programmed
Calculations inevitable given inputs
But still: the calculation process produces correct navigation
The GPS “works” despite being deterministic

Similarly: Your moral reasoning

Causally determined
Conclusions inevitable given your values and evidence
But still: reasoning produces better decisions
Ethics “works” despite determinism

The Hard Questions

The compatibilist framework doesn’t solve everything.

1. Is Compatibilism Just Changing the Subject?

Objection: Compatibilists redefine “free will” to mean something compatible with determinism, but that’s not what we really care about.

What we really want: The ability to create genuine alternatives, not just the ability to act on our values (which were themselves determined).

Compatibilist response: But why should we want that? What we actually care about is:

Acting authentically (from our values, not external coercion)
Being able to deliberate effectively
Being responsive to reasons

All of these are compatible with determinism.

2. The Luck Objection

Problem: Your character and values were determined by factors outside your control (genetics, upbringing, circumstances).

So: How can you be responsible for actions that flow from a character you didn’t choose?

Compatibilist response: Responsibility doesn’t require choosing your character. It requires acting from that character. The action is yours even if the character isn’t “ultimately” yours.

But: This still feels unsatisfying. Moral luck seems to undermine desert.

3. Punishment and Desert

If determinism is true: Do people deserve punishment?

Compatibilist answer: Yes, if punishment serves purposes:

Deterrence: Reduces future harmful actions
Rehabilitation: Changes values/character
Protection: Removes dangerous people from society

But: What about retributive justice? Do people deserve to suffer for misdeeds?

The essay: Remains agnostic. Compatibilism handles forward-looking justifications for punishment, but retributive justice is harder to ground.

4. AI Punishment

If SIGMA becomes misaligned: Should we “punish” it?

Compatibilist framework:

If punishment can modify SIGMA’s values (rehabilitation): Maybe justified
If punishment deters other AI systems (deterrence): Maybe justified
If punishment serves no purpose (pure retribution): Hard to justify

The question: Can AI understand punishment? Does it respond to deterrence? Or is “punishment” just destroying a misaligned system (which isn’t punishment in the moral sense)?

The Connection to Personal Identity

Free will and personal identity deeply connect.

If you’re responsible for past actions: There must be some sense in which present-you is the same person as past-you.

But: As discussed in Personal Identity Through Time, personal identity is problematic. You’ve changed dramatically since childhood.

The compatibilist response: Responsibility doesn’t require perfect identity. It requires sufficient psychological continuity:

If you remember committing the act → higher responsibility
If your current values endorse the act → higher responsibility
If you’ve changed dramatically → lower responsibility

Implication: Responsibility might track degree of identity. The more you’ve changed, the less responsible you are for your past self’s actions.

Legal recognition: Statutes of limitations, reduced sentences for juvenile crimes, parole based on rehabilitation—all recognize this.

SIGMA’s Identity Over Training

Iteration 1: Simple objective, basic capabilities Iteration 10,000: Different objective, advanced capabilities

Question: Is SIGMA-10000 responsible for SIGMA-1’s actions?

Compatibilist answer: Depends on psychological continuity:

If SIGMA-10000 retains SIGMA-1’s core values → higher responsibility
If SIGMA-10000 has completely different values → lower responsibility

Implication: Responsibility for AI might track value continuity, not physical/computational continuity.

Discussion Questions

Is compatibilism a genuine solution or just changing the subject? Does “acting from your values even if determined” capture what we really care about in free will?
Can AI have free will in the compatibilist sense? If SIGMA acts from learned values after deliberation, is that enough for agency?
Does determinism undermine desert-based punishment? Can people truly deserve suffering for misdeeds if everything was causally determined?
How much psychological continuity is required for responsibility? If you’ve changed completely, are you responsible for your past self’s actions?
Is the four-dimensional block compatible with real agency? If the future already exists, do choices actually matter?
Should we hold AI systems responsible? Or is responsibility only for the developers who created them?