Word of the Week: Determinism

Determinists try to argue not only that the future is ‘determined’, but also that we have no free will over this matter. This has driven many supporters of free will to despair, as they can’t get to grips with the justification of determinism. So I’m going to see whether there’s any reason to believe that we have no free will.

In the deterministic view, every human action is not only influenced by what has come before, but is rather predetermined. Let P be a true description of the complete state of the universe at some point in the past; let L signify the laws of nature; and let F be any given event in future. According to determinism, P and L predetermine F. In other words: if we had total knowledge of the state of the universe 4 billion years ago (which is P), we could deduce, from the laws of physics (which is L), what I would eat for breakfast tomorrow (which is F). This is the thesis of determinism: due to the uniformity of the laws of nature, every single event, including every single human action, is predetermined. The following argument is my adaptation of Carl Ginet and Peter van Inwagen’s consequence argument, as articulated by Kevin Timpe. The argument begins by identifying two axiomatic modal operators, alpha and beta:

Axiom 1 (Alpha): ☐p > Np

Axiom 2 (Beta): {Np & N(p > q)} > Nq

The  ‘☐’ sign can be read as ‘It is logically necessary that…’ whilst ‘Np’ means ‘p is true and no one has, or ever had, any choice about whether p is true’.  Necessity, for our purposes, means ‘true in all possible worlds’, i.e. it cannot not be true. The symbol N, in turn, means that our free will has no say in the matter. The sign '>' means 'implies that'. Thus, the Alpha operator says 'it is logically necessary that p', which implies that we have no choice over necessary things. The Beta operator looks complicated, but it basically means that, from the premises that we have no free will over p and over p implying q, we can deduce that we have no choice over q. The argument then progresses to spell out the ‘definition’ (meaning) of determinism, its ‘corollary’ (synonym) and ‘axioms’ (assumptions or premises).

Definition 1: ☐{(P & L) > F }

Corollary 1: ☐{P > (L > F)}

Axiom 3: NP

Axiom 4: NL

So Definition 1 says that it is necessary that, given knowledge of a past situation P and the laws of nature L, it is possible to logically deduce any event F in the future. So this says that determinism is true – but it doesn’t say that free will is false! So the argument continues… Corollary 1 just rearranges Definition 1. Axioms 3 and 4 say that we have no free will over the past and the laws of nature. It follows, from Alpha and Corollary 1, that Proposition 1 is true:

Proposition 1: N{P > (L > F)}

Proposition 1, you may notice, looks just like Corollary 1. But it replaces the ‘☐’ sign for a ‘N’ sign. It’s just saying that, as well the past necessarily implying that the laws of nature cause the future, we also have no free will about this causation. It then also follows, from Proposition 1, Axiom 3 and Beta that Proposition 2, as follows, is true:

Proposition 2: N(L > F)

Now that we’re progressing onto the really important propositions, I’ll just say exactly what the symbols mean. Proposition 2 reads as ‘The proposition that the laws of nature entail any given future event and no one has, or ever had, any choice about whether the proposition is true’. It then also follows, from Axiom 4, Proposition 2 and Beta, that Proposition 3, as follows, is true:

            Proposition 3: NF

Proposition 3 reads as ‘F is true and no one has, or ever had, any choice about whether F is true’. In other words, any event F in the future has nothing to do with free will. We have absolutely no control over the truth of event F, and are ourselves determined by past circumstances P and laws of nature L. So this argument lends support to the claim that humans have no free will.

Nevertheless, the most devastating attack on Beta perhaps comes from Andrew M. Bailey, who says that Beta is not self-evident in any way. Bailey allowed p to be ‘Hurricane Katrina ravages the gulf coast’ and q be ‘Countless lives are lost’. According to Beta, based on Np and N(p > q), we are meant to infer that Nq. This means that, if we are not responsible for the hurricane, then we are not responsible for the loss of life. But this, as Bailey rightly points out, does not conform to our normal ethical standards of taking responsibility for saving lives in spite of natural disasters which are out of our control. We may not have free will over the hurricane, but Beta is wrong in inferring that we do not have free will over how we react to the hurricane. Therefore, Beta is not true in all cases, so should not guarantee the truth of the deterministic claim NF either. Nevertheless, this critique relies on there being some moral responsibility of saving lives, not necessarily free will. Free will and moral responsibility are not necessarily tied to one another, so even if we have responsibility to save lives due to a hurricane, it is entirely possible that we will be unable to save those lives for one reason or another. We may want to respond to situations, but that does not entail our having any control over such situations. Therefore, Beta is, albeit a controversial, a nevertheless strong operator, which is surprisingly resilient to attacks. Yet its controversy is enough to make us ask if free will might, in actual fact, exist, giving rise to the free will alternative to determinism.

Next week, I’ll consider those who advance the ‘free will’ thesis, to see whether they are as strong as determinism’s powerful logic. Advocates of this view are often called ‘compatibilists’, as they think that free will and determinism are compatible – a view that your average determinist will vehemently deny.