What are the strengths and weaknesses of logical determinism?
Answer by Gideon Smith-Jones
A typical philosophy instructor’s question. You take any theory or view X, and then tack on, ‘What are the strengths and weaknesses of…’ without any thought to whether or not it makes sense to ask that question in the case of this particular X.
Logical determinism is not a thesis, theory or claim — true or false — although it appears to be one. Today, as I write this answer, it is Thursday. Let’s say that tomorrow, Friday, either Britain will declare war on Germany or it is not the case that Britain will declare war on Germany. It is not important how probable or improbable the two alternatives are. We can state, as a matter of logical necessity, that there is no other possibility. One of these two alternatives must be the case.
‘So what?’ you may very well ask. Have I given you any important information? No. One cannot deny the law of excluded middle ‘P or not-P’ without self-contradiction. It is irrelevant what proposition one substitutes for ‘P’ — whether, for example it is a past or future tense statement — the result is the same. If you exhaust all the possibilities then you exhaust all the possibilities. Nothing else is possible.
The reason for taking an interest in logical determinism is the false belief that it entails fatalism. If it is true that tomorrow Britain will declare war on Germany, then even if Germany agrees to all Britain’s demands and pays an extra 100 billion Euros to sweeten the deal, Britain will declare war on Germany. If it is true that tomorrow Britain will declare war on Germany, then even if a giant meteorite destroys the Earth before midnight, Britain will declare war on Germany.
Obviously, this is just silly.
Somehow, implicitly — and illicitly — a further move has been made that makes the claim ‘P or not-P’ seem to say more than it actually does say. The thought goes something like this. When I consider the statement, ‘Britain will declare war on Germany’ I am picturing a possible fact, that either exists or it doesn’t exist. The fact is ‘out there’, in the future, waiting to happen, one way or the other, like a statue waiting for the unveiling ceremony. It is as if the future history of the universe is written indelibly in marble or granite, just waiting to be revealed.
That is just a picture in the fatalist’s head. It has no meaning beyond that.
Let’s say that a row over the EU is boiling over, to the point where it is looking increasingly likely that Britain will declare war on Germany. War seems inevitable. Yet there is still the possibility that it can be averted. Britain’s declaration of war won’t be a fact until it happens. If you say, ‘Either war will be declared or not,’ you are not saying anything. If you say, ‘The decision is a fact now, which nothing can alter or prevent,’ then you are making a false metaphysical statement.