The following essay will focus on what’s called agent causation. It’s clear that the inspiration for this notion is the widely-accepted view that quantum mechanics is fundamentally indeterministic (e.g., such as in radioactive decay). In other words, it doesn’t abide by the strict causal determinism of classical physics. Many readers will now be able to see the appeal of agent causation when it comes to the debate about free will. That’s for the simple reason that it includes the idea that human actions are neither determined nor random. Instead, the (human) agent has complete control of all his/her actions.
It may seem odd to some readers that quantum mechanics has been used to advance a position for free will. Of course, other people have embraced this reliance on quantum mechanics.
At first, it almost seems as if the argument is that because quantum mechanics is “weird”, then this must (or at least may) explain free will. This parallels the often-quoted position about consciousness. As in:
“Consciousness is a mystery, and quantum physics is a mystery; maybe they’re the same mystery.”
Of course, it will be very easy to tie consciousness and free will together. So no wonder the quote above is relevant here. For a start, you can’t have (human) free will without consciousness. More accurately, you can’t have free will without self-consciousness.
Agent Causation
Quantum mechanics breaks the strict causal determinism of classical physics. And libertarians jump on that. They detect a “gap” between physical determinism and non-physical agent causation.
Another huge factor in that appeal is the fact that those who believe in agent causation are mainly inspired by the requirements of morality. For example, the American philosopher Ned Markosian believes that a person’s actions are caused only by their own agency. Such (free) actions form or shape the moral character of human persons.
Roderick Chisholm’s incompatibilist view is even more clear. He believed that free action originates from the agent alone. (See origination.) In other words, free action is never determined by prior physical events. That said, the agent can be aware — and reason about — prior physical events.
Quantum Randomness!
The first — and most obvious — thing to state is that quantum-mechanical randomness cannot possibly be the basis for free will. How on earth would an action caused by a random quantum fluctuation in the brain be the basis of an agent’s rational choice? However, the libertarian has an answer to that question. As the American philosopher Theodore Sider puts it:
“A libertarian might concede that quantum randomness is not *sufficient* for freedom, but nevertheless claim that quantum randomness *makes room* for freedom, because it makes room for agent causation.”
On the surface, that just seems like a statement of a position, not an argument for it. The idea is, however, that the libertarian acknowledges the nature of quantum randomness. Thus, it only makes room for agent causation.
We must now be given an explanation of what agent causation is, and how it makes room for freedom.
Sider then provides an explanation of this too. He writes:
“After assigning these probabilities, the work of quantum mechanics is complete. According to some libertarians, agent causation now steps in. After quantum mechanics sets the probabilities, Hitler himself chooses, by agent causation, which decision he will in fact make. Physics sets the probabilities, but *people*, by agent causation, ultimately decide what occurs.”
Many readers will realise that this is the same as the first explanation, only with the addition of the name ‘Hitler’ and some extra detail. In other words, the quoted passage above still doesn’t explain what agent causation is. It’s no use saying that agent causation now steps in after quantum probabilities are set if we aren’t given an explanation of what agent causation is.
In the quote above, we have a scenario which is completely scientific in nature. And then, all of a sudden, something that hasn’t been given a scientific explanation — the agent — jumps into that scenario. Indeed, if the agent and its actions haven’t been given a scientific explanation in the first place, then what justifies the second word “causation”?
Nonetheless, certain libertarians believe that their account is not anti-scientific. Their scenario is meant to make science and agent causation exist together. More importantly, it’s meant to make science and human freedom gel together. But, so far, that’s only via stipulation or fiat.
In any case, Sider states that “the coexistence picture makes agent causation a slave to quantum-mechanical probabilities”. In other words, the libertarian thinks that there are two very different things here: quantum probabilities and agent causation. Yet Sider is arguing that the former must in someway determine the latter.
Another way of putting this is to state that there’s no point in accepting the existence of quantum-mechanical probabilities and their relation to agent causation if that precise relation isn’t mapped out. What role do the probabilities play if we can question how the agent can neatly override them?
Sider puts the case in another way. He states that
“[a]gent causation, if it is to be worth anything, must be capable of disrupting the probabilities given by quantum mechanics”.
Thus, something non-physical would need to disrupt something physical (if also probabilistic).
Again, it can be asked why libertarians accept probabilities — or even so much as mention them. In other words, if they painted a picture of free will without any mention at all of probabilities, then what difference would that make?
What is an Agent?
What of this agent, and how does it interact with the physical brain? Is the word “causation” at all justified in this context?
There is at least a partial explanation of what an agent is. Negatively, it is said not to be an event which can cause events. In other words, an agent is an entity of some kind. When we see an agent as an entity, not an event, then agent causation can be distinguished from event causation. The latter is when an event causes another event. (Such as punching someone in the face causes that person to pass out.) In the former case, however, an entity can cause various events.
This position goes back to Scottish philosopher Thomas Reid. He believed that agents are the only entities which/who have a will. Wills, embedded in human persons, can cause events.
Alternatively, perhaps we can get to the agent via the brain.
Many people believe that the complex system that is the brain can exhibit emergent properties. These properties may include intentions, consciousness, and agent causation itself. Thus, just as some see consciousness and intentions as being emergent, so too can the agent be seen that way…
But, again, saying that the agent is emergent doesn’t say what it is or how it brings about any form of causation. Indeed, the non-physical agent would need to be responsible for what’s called “downward causation” on the physical brain…
This is the Cartesian problem of mind-brain interaction all over again.
From the Quantum Scale to the Classical Scale
One phrase readers will often find in this debate is “leveraging quantum effects”. It’s the agent (or brain?) who/which is supposed to do this leveraging. This suggests that agent causation could be a higher-level phenomenon which is compatible with fundamental physics. However, it still wouldn’t be reducible to physics.
Relatedly, in order for quantum effects to influence a macroscopic action (like moving left rather than right), they’d need to be amplified to a classical scale. The American philosopher Daniel Dennett made these points when he picked up on this issue:
“Most biologists think that quantum effects all just cancel out in the brain, that there’s no reason to think they’re harnessed in any way. Of course they’re there; quantum effects are there in your car, your watch, and your computer. But most things — most macroscopic objects — are, as it were, oblivious to quantum effects. They don’t amplify them; they don’t hinge on them.”
It was then that Dennett referred specifically to Roger Penrose, who “thinks that the brain somehow exploits quantum effects”.
This is Dennett’s position again:
Sure, there are quantum happenings in the brain as a whole or in neurons individually. Then again, there are quantum happenings in your car, watch and television.
Against Dennett, it can be said that it may be true that in order for Dennett’s car to be a car, it doesn’t depend on the quantum effects which are occurring inside it. However, why should that also be true of the brain and its relation to free will (or consciousness)? The nature and functioning of a car (or watch) is very different to the reality and functioning of the brain and its relation to free will. A car is (to use Dennett’s word) “oblivious” to the quantum effects inside — though only if it is treated qua car! However, it’s indeed the case that a car can be analysed as a medium of quantum effects.
We’ll now need to know exactly why quantum effects don’t transfer to the brain as a whole. Alternatively, why aren’t quantum effects (to use Dennett’s words) “amplified” and “exploited” by the brain? More specifically, we’ll need to know why such things don’t cause (or bring about) free will (or consciousness). In other words:
Why is there such a sharp dividing line between Dennett’s quantum effects in the brain (or in neurons) and free will (or consciousness) itself?
Surely there can’t be such a neat and tidy cut-off point (a Heisenberg cut) between these two worlds. Then again, it’s not logically absurd to argue that there is such a divide, just not a neat and tidy one.
