The Determinist's Paradox

The Story According to Newton

When Isaac Newton, the knight of Woolsthorpe, wrote down his three laws of motion, some people were greatly relieved. "Finally", they said, "we have a grand unified theory. Now to understand a system, we just have to find the right forces and plug them into Newton's second law with the correct initial conditions, and solve it to predict the evolution of the system in time."

Indeed, when taken literally, the implications of Newton's equations were astounding. It implied that the future of the universe can be exactly predicted to the last detail if the initial conditions of the universe and all the forces operating in it are known. Whether we have the machinery to actually do it in practice is beside the point. The real marvel of Newton's scheme lay in the prediction of a deterministic universe, where every single event, no matter how small or insignificant, has been decided in advance, during the birth of the universe itself. Indeed, the fact that you are now sitting in front of a computer reading this blog, was in principle predictable at the beginning of time itself. This picture of the universe came to be known as the "Newtonian clockwork". Needless to say, it was the deadliest form of fatalism the human mind had ever invented. It had the power to render human will unnecessary, morality obselete, and consciousness merely a helpless onlooker of the inevitable.

Enter Quantum Mechanics

However, quantum mechanics has partly salvaged this situation by declaring the falsity of Newtonian mechanics at the atomic level, and proclaiming at least the atomic world to be inherently non-deterministic. The most famous, and the most misunderstood, expression of this God-knows-what'll-happen anxiety is to be found in Heisenberg's uncertainty principle. However, what the ramifications of this are for the predictability of the macroscopic world are yet to be fully decided.

The Paradox

When I first came across this confounding clockwork framed by Newton, I desperately tried to find my own way out of this cage, and after some thought I arrived at what I called the "Determinist's paradox". It is a simple thought experiment which I believed "disproved" the possibility of a deterministic universe. This is how it goes.

Suppose the universe is deterministic. So you design an instrument that takes in the current state of the universe as input and outputs the state at any future time. Now, there is a glass of water standing on the table in front of you. Your machine tells you that at 7:00 pm the glass is going to be full (empty). Then at 6:59 pm you deliberately empty(fill up) the glass, thus altering the foretold future. This outcome contradicts the starting assumption that the universe is deterministic.

This is a very simple thought experiment; but remember that the essential idea used is that conscious beings are capable of making small and deliberate changes in their environment. So any pre-determined state of the universe is potentially capable of being disrupted, by however small an amount, by a conscious agent who can make a choice.

This, in short, is the Determinist's Paradox.

Incidentally, a friend of mine told me that this is akin to what is known, in a different context, as the Cafe de Santa Fe Paradox. Interested people may look it up.

Also, I was recently reading "Notes From Underground" by Dostoevsky, and was surprised to realize that some of the narrator's thoughts correlated well with these ideas of mine.