Einstein, Schrodinger, and the reluctance to give up hard determinism

Ethan Siegel on his Starts With a Bang blog has an interesting review of Paul Halpern’s new book on Einstein and Schrodinger, and their refusal to allow the implications of quantum physics to dissuade them from idea that the universe is strictly deterministic.  It’s an interesting post and one that I recommend reading in full.  I may well have to read Halpern’s book.

English: Hydrogen in (3,0,0)-state.
English: Hydrogen in (3,0,0)-state. (Diagram credit: Wikipedia)

The idea that the universe is fully deterministic is one that many people hold on to tightly, even though science has made that view questionable since the 1920s.  Things that happen with a particular quantum particle, such as an electron, can’t be predicted.  We can only assign probabilities to particular outcomes.  It’s only with populations of vast number of those particles that we begin to be able to make predictions.  Determinism appears to be an emergent phenomenon.

Many strict determinists find comfort in the notion that since the uncertainties average out over large enough scales, that we leave quantum uncertainty behind as we go up to the macroscopic scale.  And we do, to some extent.  It’s why we can use innumerable physical laws to make predictions.  But quantum uncertainty does intrude in the macroscopic world.  The very fact that we can do experiments that tell us about it is proof of that.  The question is to what extent it bleeds into macroscopic reality in natural processes.

Even if it only does so in one in a trillion interactions, within the uncertainty involved in any scientific measurement, in complex dynamic systems, chaos theory shows that that one in a trillion outcome can snowball in time to make those complex dynamic systems unpredictable, even in principle.  This means that complex dynamic systems such as the weather, economies, the human mind, and even sufficiently advanced computer systems, may have behavior that will never be predictable, at least not completely.

In my experience, those that do hold on to strict determinism, either don’t understand the implications of quantum mechanics (I won’t accuse them of not understanding quantum mechanics itself since even experts like Richard Feynman never claimed to have that understanding), choose to ignore those implications, or they tightly grasp on to interpretations of quantum mechanics that supposedly preserve determinism, such as the MWI (Many World Interpretation).

While I personally see the MWI as a candidate for reality, I’ve never been particularly impressed by the idea that it preserves determinism.  What does it mean to say that reality is deterministic when everything possible happens, but we still can’t predict what we’ll observe, even in principle, along our subjective timeline?   I’m not convinced that deserves the name “determinism.”  It certainly isn’t very useful for predicting future observations.

Anyway, Siegel’s post is a reminder that we’re all human and fallible, including the geniuses who, sometimes despite themselves, have broken new ground that call into question our most fundamental assumptions about reality.  And that reality itself has no obligation to conform to our most ingrained expectations.

Free will and determinism are separate issues

Deutsch: Transparente Präzisionswürfel aus Cel...
(Photo credit: Wikipedia)

Jerry Coyne as a new post up on free will.

One of the recurrent arguments made by free-will “compatibilists” (i.e., those who see free will as being compatible with physical determinism), is that those of us who are incompatibilists—in my case, I think people conceive of free will as reflecting a dualistic “ghost in the brain,” and find that incompatible with the determinism that governs our behavior—is this: “Nobody really believes in dualistic free will—the sense that one could have done otherwise. Thus, invoking your kind of incompatibilism is accepting a form of free will that nobody espouses.  So why bother to beat a dead horse?”

via Does the average person believe in determinism, free will, and moral responsibility? « Why Evolution Is True.

Actually, as a compatibilist myself, I’ve never made this argument, and I don’t really see it that much from the compatibilists I’ve read.  But anyway, I’m more interested in something else Jerry wrote.

He looks at a study that in a questionnaire that posited two universes.  In universe A, everything is deterministic.  In universe B, everything is deterministic except for human decision making.  The study then goes on to ask the respondents questions with interesting results.  I recommend reading Jerry’s post for the details.

But after covering those details, he makes this assertion:

To me, the data show that the most important task for scientists and philosophers is to teach people that we live in Universe A.

Except that we don’t.  Oh, our universe has a lot in common with universe A, but A is not the one we live in.  I covered this in detail in another post, but the TL;DR is that quantum uncertainty does affect the macroscopic world.  If it didn’t we wouldn’t even be aware that it existed.  And the fate of Schrodinger’s cat in the famous thought experiment is not determined prior to the cat being placed in the box, in other words the cat’s fate wasn’t set at the big bang.

Of course, given how deterministic the macroscopic laws of nature have been shown to be, in nature those effects generally would have to be incredibly small, within the margin of error of our measurements.  But that’s all it would have to be for the butterfly effect to kick in, snowballing in complex dynamic  systems to eventually make those systems inherently unpredictable, even in principle.

This is one of the reasons why I’ve said before that determinism and free will are really separate issues.  If you define free will as indeterminism, you’ve cracked the door open to libertarian free will.  Now, I don’t personally think quantum uncertainty rescues libertarian free will, since there’s nothing in that uncertainty that anyone could take credit for.  But if you’re basing your opposition to libertarian free will solely on determinism, you should be aware that determinism isn’t as certain as many assume.