Friday, November 6, 2015

Philosophers confused over causality

Physicists usually have a dim view of philosophers. One reason is that philosophers reject causality.

Here is a new philosophy paper with more nonsense on the issue:
Issues surrounding the role of causation/causal reasoning in physics have recently been the subject of considerable philosophical discussion (e.g., Norton, 2009, Smith, 2013, Frisch, 2014). There is a spectrum (or perhaps, more accurately, a multi-dimensional space) of different possible positions on this issue: Some, echoing Russell, 1912 take the view that features of fundamental physical laws or the contexts in which these laws are applied imply that causal notions play little or no legitimate role in physics – or at least that they play no “fundamental” role. Others take the even stronger position that causal notions are fundamentally unclear in general and that they are simply a source of confusion when we attempt to apply them to physics contexts (and presumably elsewhere as well. ) A more moderate position is that while causal notions are sometimes legitimate in physics, they are unnecessary in the sense that whatever scientifically respectable content they have can be expressed without reference to causality. Still others (e. g., Frisch, 2014) defend the legitimacy and even centrality of causal notions in the interpretation of physical theories. Those advocating this last position observe that even a casual look at the physics literature turns up plenty of references to “causality” and “causality conditions”. Examples include a micro-causality condition in quantum field theory which says that operators at spacelike separation commute and which is commonly motivated by the claim that events at such separation do not interact causally, and the clustering decomposition assumption referred to in section 5 which is also often motivated as a causality condition. Another example is the preference for “retarded” over “advanced” solutions to the equations of classical electromagnetism (as well as the use of retarded rather than advanced Green’s functions in modeling dispersion relations, as discussed below) where this is motivated by the claim that the advanced solutions represent “non-causal” behavior in which effects temporally precede their causes (violation of another causality condition). Similarly, there is a hierarchy of causality conditions often imposed in models of General Relativity, with, for example, solutions involving closed timelike curves being rejected by some on the grounds they violate “causality”. Causal skeptics (e.g., Norton, 2009 and to some extent, Smith, 2013) respond, however, that these conditions are either unmotivated (because, e.g., vague or unreasonably aprioristic) or superfluous in the sense that what is defensible in them can be restated without reference to any notion of causation.
This is hopelessly confused. If a philosopher cannot see that causality is essential to modern physics, then he has no understanding of physics.

Denying that physics is about causality is like denying that physics is about energy.

Even the guy (Frisch), who defends causal notions in physics, is also confused. See his paper (pdf), where he only allows for causality in the narrowest subfields of physics. His arguments have no merit either.

There are several arguments in play, all nutty. One is that a theory making precise predictions is not causal, because the outcomes are constrained by the math, not the cause. So Newton's F = ma is not causal. Another is that action at a distance is not causal, because it cannot be broken into a chain of events. So Newtonian gravity is not causal. Another is that time-symmetric theories cannot be causal, because the past has to cause the future without the future causing the past. Most physics differential equations are time symmetric, so this eliminates a lot of theories. Another is that indeterministic theories cannot be causal, because outcomes should be determined by the causes, and not by chance. So quantum mechanics cannot be causal.

Of course stochastic theories can be causal. Without getting into mathematical definitions, consider the statement "smoking causes lung cancer". Everyone understands this. But smoking does not cause lung cancer in every single smoker, and is not the sole cause of lung cancer. Smoking raises the probability of lung cancer. It has always been understood that causality can work with probability in this way.

Statements like "the moon causes the tides" are also widely accepted under either Newtonian gravity or general relativity. Under Newtonian gravity, you might object that there was no local causality, but there was non-local causality.

Philosophers do not just attack physics. Some have attacked evolution biology, in the Causalist-Statisticalist Debate. Here is a recent review of this issue. The argument is that principles like "survival of the fittest" have no predictive power, and do not give causal explanation. They just give a framework for generating statistics about nature.

1 comment:

  1. Roger,
    In this particular case he is actually correct. ‘Survival of the fittest’ is bogus as science and bad as theory.

    In all honesty, 'survival of the fittest' does not really mean much. Survival in this case is a statistically measurable strategy that works in a particular instance for a particular entity in a particular environment, but what may work in one situation for one organism does not mean it will work in another situation even with the same organism. The word 'fittest' is utterly useless as well, since it implies somehow that completely different survival strategies can be directly compared, they can't, as once again the comparisons would have to be made oranges to oranges, apples to apples, and you aren’t doing that with a such a squishy generality. One organism might be faster and escape its predator, another might fly to escape a non flying enemy, but another organism might have a defense mechanism of some kind (poison, armor, toxic smell, claws, etc), yet another might be capable of camouflaging itself to avoid detection, or somehow confuse its predators into considering it more dangerous than it actually is, or that it would taste bad, As I understand it, one particularly ridiculous life form actually started getting fat headed allowing it to outthink its natural predators but to the point it started to kill the females of the species because their birth canals couldn't accommodate the cranial size , imagine that! So unless what you are comparing is in a very narrow spectrum in a very narrow situation with a very narrow definition of success, like male marathon runners of a certain age in the the same well defined competition, you got squat for a comparison you could even use the term 'fittest' to describe. If I compare a male sprinter with a female marathon runner, how does that go? What if you have a male eighteen year old runner competing with a female twelve year old trivia savant on jeopardy? Where’s your concept of fittest anymore outside of a silly contest of similar contestants? It’s utterly meaningless as a concept outside of contrived situations. Horse betting is about making simple concrete predictions of outcomes of similar life forms in a similar competition of strategy and yet you would not call it a science, and outside of animal husbandry (which is about genetics and heredity not evolution theory) evolution theory has nothing to say or do with it.

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