Conversation on yesterday’s post on free will has me thinking about determinism.
First, what is determinism? According to Merriam-Webster, my favorite dictionary because they seem to be extremely good at cutting to the chase, determinism is defined as:
a theory or doctrine that acts of the will, occurrences in nature, or social or psychological phenomena are causally determined by preceding events or natural laws
So, the basic idea of determinism is that everything has a cause, and that any appearance of uncaused actions, such as mental ones, are an illusion. As I argued in my free will post, I don’t think that libertarian free will is necessarily tied to determinism, but it’s pretty evident that a lot of people lean heavily on determinism as a reason for rejecting it.
Is that reliance justified? Can we say with certainty (to the extent we can say anything with certainty) that everything has a cause?
The standard answer to that question is, no, we can’t. Quantum events simply don’t behave according to our classic notions of how the world is supposed to work. Many quantum events appear to be random and uncaused. The foundations of determinism rest on indeterministic ground.
Why then are the laws of physics, above the quantum level, generally deterministic? As it turns out, single quantum events can’t be predicted, but large numbers of them follow statistical patterns. From these statistical patterns, deterministic regularities, natural laws, emerge.
Determinism is emergent. The layers below it are not deterministic. It is built on top of those indeterministic layers. Another way of looking at it is that determinism is a model of complex indeterminate events. A hard determinist should ponder that for a minute.
But, the fact remains that we have centuries of science which show that, above a certain layer, things are deterministic. And once things are deterministic, that should mean that all of the higher layers of abstraction (chemistry, biology, neuroscience, weather systems, etc) should themselves be deterministic, right?
Let’s back up and ask again what we mean by deterministic. What do we mean when we say something can be determined? Determined by whom? If no one could conceivably determine what a complex dynamic system will do, if it is only deterministic in principle, is it really still deterministic? What does it even mean to say that something is deterministic in principle?
Chaos theory is a field of study on the inherent limitations of making determinations on complex dynamic systems. The core idea of chaos theory is that no measurement is infinitely accurate. Anyone who has ever taken a high school or college science lab knows that every measurement comes with a margin of error.
Increasingly precise equipment reduces that error, but can never eliminate it entirely. As different measurements are taken into account, the errors multiply and snowball. Add lots of complexity and constant change, and some systems become inherently unpredictable, inherently indeterminate.
Most people have heard of the butterfly effect, the idea that a butterfly flapping it’s wings can eventually cause a hurricane somewhere else in the world. Small effects snowball into larger effects. And the small effect of errors in measurement snowball into unpredictability.
Of course, a determinist could insist that a perfectly omniscient being, such as Laplace’s demon, could still predict the effects of such a system. Quantum effects might be random, but that randomness doesn’t “bleed” out past the deterministic layer.
Except that they do.
Of course, the very fact that we are aware of quantum events shows that they do in fact bleed out into the macroscopic world, otherwise how would we be aware of them? But a clearer example is a famous thought experiment, Schrodinger’s cat.
Schrodinger imagined a cat in a box, with a device designed to release a deadly poison to the cat if a quantum event takes place. If we put the cat and the device in the box and close it, then wait until the quantum event might have taken place, the cat could be either alive or dead.
I’m going to skip any Copenhagen interpretation discussion here, but the important thing to realize is that the cat’s death or survival is not a deterministic event. The cat’s fate is not completely causally determined by events before it was placed in the box. Quantum events have affected a macroscopic event that should have been completely deterministic.
Although Schrodinger’s cat is a thought experiment, there have been real experiments (not endangering cats) to test the principle. It is a reality. Quantum events can bleed into the macroscopic world.
Of course, given the degree that we’re able to determine physical laws, such bleeding in nature must be incredibly rare and nuanced. But we can’t rule out that it happens within the margins of error in our measurements. And as mentioned above, the effects don’t have to be pervasive to eventually snowball in complex systems.
Determinism emerges at a certain layer. There is no guarantee that it persists above that layer. The effects of quantum uncertainty may be small at the deterministic layer, but it may be enough to cause indeterminate events to emerge at higher layers.
Determinism isn’t the slam dunk many assume it to be.
- Wormholes into the past (motls.blogspot.com)
- New Years Resolutions (kblakecash.wordpress.com)
- The Development of Quantum Mechanics (syesworldview.wordpress.com)
- Indeterminism in Neurobiology (livasperiklis.com)
- Determinism and Indeterminism (livasperiklis.com)
- Dumb Like Einstein, and Another Important Heresy (lodestarpartnersblog.com)
- Create the World You Really Want (aquarianagethings.wordpress.com)