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# Do you believe in determinism? And which one?

In my personal philosophy, I’m leaning towards determinism: the view that our actions, decisions, and destinies are somehow decided – determined – in advance. However, I am able to differentiate at least between two types of determinism. Both have their issues, both need to be thought through more, and neither of them wins the argument for me. What about you?

I call my ideas of determinism Strong and Weak, respectively. This terminology comes from logic, where the stronger statement implies the weaker one, or has more consequences.

## Strong Determinism

Everything that happens in the universe is caused by immutable physical laws acting on particles of matter. Every present moment is a direct result of the past.

This is what is normally meant by the word “determinism.” In theory, we could predict a throw of a dice if we knew exactly how it was thrown, what are the characteristics of the table on which it falls, what’s the density of the air through which it falls et cetera.

Under this view, randomness doesn’t exist. Everything happens because it must happen. Terms like chance, probability, or random describe only our ignorance of the truth, not some intrinsic uncertainty.

Of course, this ignorance of ours can never be completely removed. Even if we knew perfectly all the laws of nature (we don’t), were aware of all factors affecting a thrown dice (we aren’t), and could precisely measure all relevant initial conditions (we can’t), our computers would still take thousands of years to make a precise simulation of reality and predict the result of the throw.

Simply put, the future is determined, but not practically determinable. There’s a theoretical concept called Laplace’s daemon describing an entity that is aware of all the natural laws and knows the precise initial state of the complete universe, and from this knowledge can infer the whole history of the universe to come.

The theory of strong determinism is very appealing to me. As a mathematician, I can imagine how a few deterministic physical laws applied under a huge number of different conditions can give rise to the unpredictably complex universe of ours. Even chaos can be deterministic (this is actually a real mathematical term). It’s difficult (but possible) to build some philosophical theories under strong determinism and there is a problem with the origin of those physical laws and the initial state of the universe. One is then reminded of Aristotle’s “unmoved mover”, or “God”…

## Weak Determinism

Everything that happens is meant to happen. No one can evade their firmly set destiny.

I would call this higher level determinism. Particles of matter or even physical laws now need not be determined. Specific physical processes need not be determined. What is determined is some kind of “destiny”, some kind of “end”. There may be several alternative histories leading to that same end. If I am destined to make a million dollars, I may get them by trading financial derivatives, excavating a treasure chest, working 9-to-5s for years, or by building a successful business and floating in on a stock exchange.

Another example. If I fell in love thanks to a string of six happy coincidences, I may believe I’d been extremely lucky. However, if the event of me and my lover meeting had been predetermined, it would have happened in any case. If we hadn’t sat next to each other on that bus ride, we would have bumped into each other when getting off the bus an hour later. Or we would have met two years later in a wholly different situation. The point is that what’s determined is the what, not the how.

The difficulty with this theory is deciding the proper level of abstraction. Where precisely is the “what” separated from the “how”? Why should the meeting of two people be an invariant of history, but whether it happens on a bus in 2008 or I don’t know where in 2010 should be left to coincidence? Who decides?

If we put this “level of determinism” too low, we may end up with strong determinism. If that electron was meant to descend to a lower orbital and emit 200 kJ/mol of energy, then… :-)

Putting the level too high also doesn’t help. Obviously I am destined to die, but if that’s the only thing the theory can say, it tells nothing new. How precisely will it happen is the undetermined “how”.

As a mathematician, I’d describe a weakly determined system by some “level of abstraction” parameter $\alpha \in \langle 0,1 \rangle,$ where the edge case $\alpha = 1$ corresponds to strong determinism and $\alpha = 0$ is the equivalent of a completely random, non-determined system.

Both theories raise difficult questions. It’s interesting to see that neither of them is in direct conflict with the idea of God. Strong determinism immediately writes off free will as an illusion and attributes it to the difficult predictability of the neurobiological processes of our brain. Strong determinism is also at odds with the theory of inherent randomness in quantum mechanics.

Weak determinism imposes some limits on free will but doesn’t disprove it completely. However, it also seems to imply the existence of some “higher purpose” in universe. One which says what is important enough to be determined, and what can be left to happening, erm,… non-deterministically. And what’s that anyway?

Lot of contemplation to be done yet… Any thoughts, my kind reader?

October 31, MMXI — Personal, Philosophy.