Whether or not we have a free will is an age old question in philosophy – whether we are truly in control of our decisions and whether our future is an uncertainty, slowly carved out into a reality by our thoughts and actions today. Whether we have this free will is a question that has a popular appeal for it directly affects they way we see the universe and our place in it. Though what is it that makes us believe we truly are in control of our decisions and whether when you’re faced with chocolate ice cream or vanilla there really is a moment of genuine uncertainty before you choose the vanilla.

Something inside us compels us to believe humans have free will. We probably therefore also believe animals such as dogs, cats and horses also have free will, sometimes your dog will want to go run after that ball you’ve thrown, sometimes he’ll be too lazy. We probably also believe tiny animals such as spiders and flies have free will too, spinning their webs and flying in different directions. But would we say we thought the amoeba (a single-celled animal) has free will…? Instinct tells me no. The amoeba is a single celled organised comprised of a handful of Atoms and atoms obey the laws of physics. Now if this line of reasoning leaves you a little uneasy then you really must agree with me that the point at which we believe free will comes into play is very very vague indeed. Is there a clear point when free will emerges, equally as consciousness does, or is it just an illusion we like to accept to provide meaning and purpose to our human lives.

Physics, the old and the new, biology and neuroscience all like to have a weigh in on this question. When one tries to pinpoint the centre of the human decision making process it is usually the brain that comes to mind. However if our biological shells and our brains are nothing more than a very large agglomeration of atoms and molecules (and who can provide evidence that they are not?!) then surely their complex processes can be reducible to the laws of physics.  In the classical view of physics the behaviour and movement of  atoms and molecules can be determined by whatever the set of initial conditions was in the system. Take the motion of billiard balls on a pool table, the initial conditions are like the configuration of the balls on the table, the position and direction of the queue and its momentum. From these initial conditions the subsequent movement of the balls can be perfectly mapped out. Without taking Quantum Mechanics into account, which we will do soon, if the atoms are thought to behave classically then their behaviour is predetermined from way back long ago when the atoms first came into existence i.e. the big bang. These initial conditions caused them to fly out in a predetermined trajectory at time zero and collide with other particles. Their combined momenta then acted as subsequent conditions which caused further collision. The process continues until life comes about as we know and the conditions for the next step of behaviour for these particles is always determined from what happened in the stage prior – there is never a genuine moment of instantaneous uncertainty of what will happen next.

If I precisely know the complete workings of a system i.e. the position of every particle and how the laws of the universe operate – I can tell you exactly what it will do in all future situations.

Now if you disagree with the statement that the behaviour of the atoms in the brain are subject to this determinism then you’re either going to weigh in with some quantum mechanics or you’re going to tell me you think I’ve taken this cold line of reasoning way too far and that not everything can be reducible down to the laws of physic – especially not the mind. For you to believe this you need to tell me that you believe that consciousness and our free will is an emergent property, which arises from these many interacting atoms making up the body and the brain. You have to tell me that at some point the sheer complexity of the system, these billions of particles whirring about in our brain suddenly come together to produce something special, an explosion of magic if you will. But at what effect does this come into play, when we reach 1 billion atoms, 10 billion? Who knows! Our understanding of consciousness and the complexity of the brain is so extremely lacking…but to believe that the behaviour of our brain is so fundamentally different from that of a collection of atoms and that our decisions are really products of our own consciousness as opposed to actions abiding by the laws of nature means there must be some extra process in place.

Classical physics is therefore a deterministic theory and when taken to its logical conclusion says that if we could know all the molecules and cells and how they were configured in the brain we could predict human thought perfectly. And although practically this is nearly impossible, according the classical physics it is theoretically consistent.

We need a saviour for our free will and our poor understanding of the conscious mind currently won’t do justice. Cue quantum mechanics. When the behaviour of particles is observed at the atomic level it is fundamentally indeterminate. We cannot say with certainty where an electron is and what speed it has – the best one can do is predict the probability of the measurement and it is only when the measurement is made can one be sure of the value.  Furthermore if the probability of two outcomes are 50:50, then the outcome that is assumed is entirely random. (Contrast this to classical mechanics where if we know all the initial conditions we can be sure of the outcome). As such the future is not set out in stone as the particles on the smallest scales do not obey the laws of classical mechanics, they obey quantum mechanics. Now many accounts of the debate stop here and exclaim hurrah, quantum mechanics restores randomness and chance to the universe, hence our actions are not unfolding in predetermined mechanical manner. But wait… is this really a saviour for free will or is it a falsehood in disguise? Let’s look a little closer.

Quantum Mechanics advocates in-determinism, in other words it is a probabilistic theory which states that the world is chaotic and random at the atomic scale. But then surely if an outcome is random then by definition it isn’t controllable. Just because the event is not fully predetermined as in classical mechanics that doesn’t mean the decision is one’s own. Just because the position of an electron can’t be predicted that doesn’t mean it’s there for a reason. A random future does not mean a chosen future.  To our dismay it’s as though both our theories end up at the same place:

Classical Mechanics -> Determinism -> No Free Will

Quantum Mechanics -> In-determinism -> Random Will -> No Free Will

Therefore it seems the only path we can follow to believe free will truly exists is to believe that somehow our minds behave in way that is superior to the direct product of the atoms that comprise them.. What basis we have for believing this I do not know.. but I believe I speak for all humans when I say something inside me compels it to be so – and that’s a scientist talking!