Two flavors of determinism

Imagine a universe that is simply set of particles in a box with hard reflecting walls. Let there be n particles, and imagine that they interact with each other according to some fixed set of mechanical laws (these laws need not be the Newtonian laws we are familiar with). The particles can bounce off each other as well as off the walls, they can be sticky so that they sometime form clusters, and they exert forces on each other and can alter trajectories through some kind of force fields. But it is a closed system, and in a sense it is a static situation: the future follows without any novelty from the state of the system at any given time. The future is an illusion in this mechanical universe, and time is simply a parameter.

For example, suppose n = 1. The simple particle just bounces around like some simple kind of “pong” game, where its collision with the walls is the only thing that can happen. Make it two particles, n = 2, and it isn’t really any more interesting, although now there are some times where the particles might bounce off each other. No matter how big we make n, the situation, in principle, stays the same. It is a strictly deterministic system, closed, and no novelty can emerge.

In such a system, if conglomerates of many particles form, maybe they will appear to make complex motions and would, were anyone watching it from without, maybe appear to be alive and initiating such motion voluntarily. But we can see this is would be an illusion….it is still the forces within the closed system that are completely determining the evolution of the system.

Such a picture of our universe was, I think, what Laplace had in mind. Indeed, here is his famous quote about it (taken from the Wikipedia site on Laplace):

“We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.”


The term “Laplacian Determinism” is often used to describe this vision of the universe, and within this picture all animal activity in particular is imagined to be caused by forces on the particles comprising the animals. The seeming ability of life forms to initiate motion and perform actions is an illusion in such a model. Otherwise the actions of an animal would be over-determined---that is, one could not introduce voluntary action in this model, as it would result in inconsistencies.

Here I am going to call this “Type 1 Determinism”. It is my suspicion that no one really believes in this type of determinism today. Rather the determinists of our age generally seem to subscribe to a “higher level” of determinism.

I will refer to this as “Type 2 Determinism”. In this picture, the emergence of novel forms and animals that can in a sense initiate motion and actions is not contested, but it is argued (maybe even subconsciously in a great many cases) that an animal can only act based on its physical nature in concert with its memory of lessons learned from the past. This is analogous to what we think about the PC’s on our desks or our laptops. They have a certain physical architecture and hardware (which is analogous to the bodies and genes we are born with), but a wide variety of applications (programs) have been installed that make each computer virtually unique. But the computer cannot initiate anything….its behavior is entirely set by its resident programs and its basic hardware (the hardware that the computer was first configured with plus any hardware devices that have been added).

Perhaps we can add the possibility that “randomness” could also be involved. The animal, as well as the computer, could be hit by a cosmic ray that flips a bit or diverts a neuron. Chance meetings and exchanges with other animals could be included here, or they could be counted as environmental interactions.

So hardware plus installed programs plus random interactions with the environment seem to exhaust the possibilities here. How could an animal, in particular a human with conceptual awareness, perform an action for any reason other than these three? Action has to be caused does it not? It does no good to say it is caused by ones free will, for there seems to be no way to even frame that in a way that does not involve these deterministic factors.

In contemporary terminology hardware corresponds to "nature" (i.e., genes), while the acquired experience (analogous to installed software) corresponds to "nurture". There has been an ongoing battle between these two camps in recent decades, although it seems that today most everyone accepts that both nature and nurture play important roles in how people behave. But both of these mechanisms are deterministic, and if they are considered to exhaust the causes of action, leave no room for free will.

Let me add that in no way do quantum mechanics or chaos theory present ways out of either Type 1 or Type 2 Determinism. The former still involves deterministic evolution of a state, while chaos simply limits an observer’s ability to precisely predict the future. And if quantum computers become available, it is not clear how they could escape the limits of hardware plus installed programs.

Yet the odd thing is that I believe that we all assume that we have free will (we may well assume that other people do not, however). I emphasize that this is not a conscious assumption in many cases (though among philosophers and physical scientists it may often be so). As far as I can tell, there is no mass movement to stop punishing crime, although it is not clear how anyone could attach blame to an entity limited by “Type 2” (or Type 1) determinism.

My intent in this particular note is not to solve the problem of how humans might nevertheless have free will---indeed, I do not think it can be solved----rather, I just want to illuminate the fact that the kind of determinism that so many 19th century scientist and philosophers believed in was different than the form generally accepted in our age (especially by those trained in the social sciences).

But the puzzle has some confusing aspects to it: for one thing, I think both types of determinism are plausible and persuasive, and yet they logically collide. That is, they cannot both be true. It would have to be one or the other that specify behavior, because taken together they would over determine it. Type 1, though apparently largely ignored today, really seems to be hard to argue against. Isn’t it just physics carried to its logical, reductionist conclusion? And do we really think there is anything in the universe other than entities that are subject to the laws of physics? On the other hand, Type 2 Determinism also seems very cogent, for what else could determine our behavior, other than our accumulated past experiences acting in concert with our genetic makeup?

So to summarize: we have an enigma. There are two distinct, mutually incompatible forms of determinism. Both cannot be right, because either physics mechanism or nature/nurture must cause behavior. Yet both seem like they have to be correct. And on top of that we all seem to believe we have free will, which is clearly incompatible with both Type 1 and Type 2 determinism. Philosophy----“ya gotta love it!” If nothing else, it should keep us humble, and just reveling in the mystery is enough for me. And, OK, it is fun too!