Welcome to Part 2 of this series on Human and Robot Autonomy. Part 1 began by identifying the ‘will’ as the source of freedom and autonomy in the human and described its role in relation to other dimensions of the self. It then went on to underlining the point that ‘free will’ is never totally free. It is always constrained by (a) the way information flows to it from its social context, and (b) the capacity of the mind and the body. In Part 2 we are going to firmly grasp the nettle of free-will in the context of a universe governed by causal determinism. These and other related topics are discussed in more detail my recently published book ‘Rise of the Moral Machine: Exploring Virtue Through a Robot’s Eyes‘
Free Will and Determinism
So what we call ‘free will’ is rarely totally free. It is often constrained by both how we perceive the world, and what is physically possible in the moment of acting. But there has been much debate as to whether or not we possess even this limited notion of free will. The debate centres on the combination of two perspectives: (1) the mind-brain identity theory that asserts that the mind is identical to the brain, or rather to the states and processes that are within the brain (we shall return to this theory later in this section), and (2) the brain, like almost everything else in the universe, is subject to causal determinism. Let’s take a moment to briefly review the free-will and determinism debate, but note that this is a complex topic and it will be necessary to miss out significant amounts of detail on the different perspectives philosophers take on this issue.
Classical Newtonian physics asserts that all events that take place in the universe, including the ones inside our brains, are the result of a series of cause and effect chains: every event has a prior physical cause, without exception, even if those physical events turn out to be the thought processes in your mind. This is referred to as universal physical determinism, which was widely held to be true by philosophers and scientists up to the end of the nineteenth century.
What’s the Problem?
So why is universal physical determinism a problem for free will? The problem is that on the face of it they seem to be incompatible with each other. If our brains are subject to physical determinism, then the next thought we have is caused purely by the current physical state of our brains. Recall that brains are highly complex dynamical systems made up of many billions of microscopic components that emit and transfer electro-chemical impulses across densely interconnected networks. Living brains are always active and changing.
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When we talk about the state of a brain, we are referring to a snapshot of electro-chemical activity of the brain, together with the location and arrangement of all the molecules (ions, proteins etc.) that facilitate the brain’s operation. The deterministic nature of the physical processes in our brains is such that any given particular brain state will result in a particular next brain state, which doesn’t seem to leave any room for free choice.
Free will is never totally free. It is often constrained by both how we perceive the world, and what is physically possible in the moment of acting.
Let’s illustrate this issue by returning to our groceries shopper David who we introduced in Part 1. Imagine that we have two godly powers: the ability to examine David’s brain state, and the ability to rewind time. Suppose that just prior to the moment of choice about where he will go shopping, we take note of David’s brain state. Then in the next moment after David has decided to go to the superstore, we observe David’s brain state again. If we use our godly power to rewind time back to the moment just prior to David’s choice so that his brain is back in its original state, then causal determinism will require that his brain will go to exactly the same next state, which corresponds to choosing to shop at the superstore.
In a moment of godly playfulness, we decide to rewind time even further, back to when David was having his breakfast that morning. We take note of his brain state and observe that he wasn’t even thinking about going shopping at that point. As we allow time to role forward again, causal determinism dictates that we will see exactly the same sequence of brain states emerging, corresponding to David making exactly the same ‘choices’ over the course of the morning, right up to where he decides to go to the superstore.
In other words, the outcome of his deliberation over where to go shopping was already causally determined by his brain state at breakfast. This causal chain of brain states goes right back to David’s childhood; Every seemingly freely chosen thought and action throughout his life was caused by his very earliest brain states. If the outcomes of all our choices are already determined before we make them, then what room does that leave for ‘free will’? On the face of it, free will does seems to be incompatible with causal determinism.
Enter the Compatibilists
Some philosophers like Hume and Hobbes, however, have argued to the contrary, insisting that free will is indeed compatible with causal determinism. The core of this compatibilist argument centres on understanding freedom as the absence of constraints. According to this view, to be free you need to (a) have the ability to do what you want, and (b) not be blocked by doing what you want by any constraints. Since neither of these conditions contradicts causal determinism, you can still be endowed with the ability to do what you want as long as there are no constraints blocking that freedom.
This view that freedom is the absence of constraints is an interesting one that has a natural intuition. But the kind of freedom we are talking about is freedom of the will, which runs at a much deeper level than merely the absence of constraints to doing what we want. As we saw previously, the will is the source of freedom and the freedom is in the wanting rather than the acting. Compatibilists argue, though, that this freedom of the will can be treated in a similar way to freedom of action. Their two conditions can be re-framed to describe freedom of choice as follows: we have freedom of choice if (a) we have the ability to choose something, (b) there are no constraints on us making that choice.
The core of this compatibilist argument centres on understanding freedom as the absence of constraints.
The next step in the compatibilist’s argument makes the link between causal determinism and free will as the absence of constraints. To illustrate this, let’s enact our godly powers on David and his shopping dilemma once again. Imagine that David really gives this some thought, and weighs up all the pros and cons of each option: “the corner shop is closer, it’s good to support local businesses, . . . on the other hand the superstore has more choice and often lower prices”. Then David arrives at a decision, he will go to the superstore.
If we then rewind time to the point when David first began to think about going shopping, causal determinism would dictate that, starting at the same brain state, he would go through exactly the same rational thought processes and end up making the same decision as the first time. If, they argue, the outcome of the rerun of his thought processes was that David decided to go to the local shop instead, then that would constitute a non-deterministic outcome, which according to them would be irrational. Determinism means if you repeat the same past, you get the same future. Non-determinism means if you repeat the same past, you do not necessarily get the same future.
This argument is quite compelling. The sense of free will that many of us hold to is that we have ultimate control over the direction of our will, which is not determined completely by our past. But compatibilists argue that if we do operate in this way with non-deterministic outcomes to our decision making, then this is incoherent and infeasible. It amounts to going through life making random choices – which is, in effect, making no choices at all.
Does Quantum Indeterminism Help?
It should be noted, though, that all of this is founded on the assumption that the will, and more generally the mind, is subject to physical or causal determinism. An interesting twist in the story of causal determinism and free will came with the advent of quantum physics, which radically challenged the classic scientific view that the entire universe was subject to causal determinism. The discovery which led to this remarkable u-turn was made in particle physics.
The sense of free will that many of us hold to is that we have ultimate control over the direction of our will, which is not determined completely by our past.
In brief, the issue is centred on the fact that sub-atomic elements exhibit properties of both particles and waves, and the state and position of these elements could not be known with certainty. The prevailing theory in quantum physics is centred on Heisenberg’s uncertainty principle which is that particles do not have an exact position and momenta at the same time. Consequently, it is not physically possible to predict their future behaviour. It is argued, therefore, that physical determinism does not exist at the sub-atomic particle level and the majority of physical scientists no longer believe in universal physical determinism.
The fact that universal physical determinism is no longer a viable scientific proposition does not remove the issue of its compatibility with free will. Although events at the sub-atomic level are not causally determined, it is clear that on larger scales causal determinism is still at play. When a force is applied to a physical object, the direction and speed with which it moves can still be predicted accurately using formulas based on causal determinism. It is reasonable to ask, though, whether quantum indeterminism has an influence on the processes that occur in the brain. Does it occur on a large enough scale for the sub- atomic uncertainty to have an effect on neuronal firing patterns, for example? The current scientific consensus is that quantum effects are too small to have an impact on the higher order processes in the brain, and that the brain is still subject to causal determinism.
The next blog in this series will return to question the assumption that the mind is identical to the brain (the mind-brain identity theory), and begin to explore an alternative perspective on human autonomy.
One response to “Human and Robot Autonomy – Part 2”
Fascinating -provoking new frontiers – thank you !