Ockham's Razor

[aeest400]

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it is instructive to observe that it is almost always wrong.

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Ops! In an attempt to be contentious I was being a little wayward in my use of language. What I meant of course was that not that Ockham's razor itself was wrong, but any theory it promotes was, in the sense that in any non trivial scenario the will always be a more accurate theory.

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F=ma?

I think you're forgetting the need for empirical adequacy, which any Occam's Razor pretty much assumes.

[Piers]

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i.e. no cheating allowed).

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"Lets assume that no cheating is allowed.”

“Yes but what happens if someone cheats.”

“We are assuming that no on cheats.”

“Yes I know that, but what happens if nether the less someone cheats.”

… 10 years later…

… no one is allowed to cheat”

“I know that, but what happens if despite that assumption someone actually does….

….
… later…

… cheats”
“but…

….

[Piers]

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F=ma?

I think you're forgetting the need for empirical adequacy, which any Occam's Razor pretty much assumes.

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Am I?

F=ma, A useful approximation or absolute truth?

What’s force, what’s mass what’s acceleration? To define the mass of an object we put a boundary round it, is this how things really work?

Empirical adequacy not empirical accuracy good maybe you agree with me? F=ma is certainly adequate for most uses.

[Philo]

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I think the analogy with the computer generated string of output characters is a poor one.

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Of course you do. But that's only because it is, in fact, such a perfect example unpolluted with [censored] side issues. All you have are data, equally good (but differing in complexity) theories, and the ability to test them. I.E. a scenario where Ockham's razor is essentially the only relevant principle, and where it can be seen to be mathematically correct -- simple explanations will be more likely to be correct, all else being equal.

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A computer program is written by human beings who have knowledge of pi, and if the string of digits through the first 183,000 matched pi, that would be the reason one would believe that the next digit is likely to be the next digit of pi.

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Sigh. Actually, the assumptions going into these arguments are that the input program is randomly generated -- i.e. specifically not written by a human with knowledge of pi. Inductive inference and algorithmic probability are not results in psychology -- they are general logical and probabilistic conclusions resting on general principles.

Next you will argue that the programming language matters, or the specific type of computer -- no, it doesn't. An invariance theorem exists that shows that these arguments have the same content on essentially any computer in any language.

After that, you will object that computers have little or nothing to do with the universe or the rest of science. But from a physics point of view it turns out that the laws of the universe can be thought of more or less completely in the language of computing if you want to (quantum computing, specifically).

After that, the thread will probably just die because you'll shift the argument to some subtly different question that no one really cares about, but one where you're not quite so obviously and dramatically wrong.

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The programming example might be useful in saying something about induction (and I do believe that the assumption that nature is uniform or pattern-like is acceptable). If we see a pattern in nature that conforms to some law-like principle, then it's ok to postulate a 'law of nature' that relies on some principle like that nature is uniform. But being pattern-like is not the same thing as being more ontolologically parsimonious. Do you think justifying induction is the same thing as justifying OR?

If justifying OR is a straightforward empirical matter, why does it generate so much philosophical discussion, and why do philosophers offer various justifications that are non-empirical, like aesthetic, pragmatic, and deductive justifications? Are these philosophers all just thick-headed and ignorant, missing the easy-to-grasp point that OR is straightforwardly justified on empirical grounds?

[KipBond]

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Its amazing how the two most important, powerful concepts (this and evolution) both seem so ridiculous self-evident and simple, when you finally understand them.

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I would add Hume's maxim to this list:

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The plain consequence is (and it is a general maxim worthy of our attention) that no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish: and even in that case, there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior. When anyone tells me, that he saw a dead man restored to life, I immediately consider with myself, whether it be more probable, that this person should either deceive or be deceived, or that the fact he relates should really have happened. I weigh the one miracle against the other, and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous, than the event, which he relates; then, and not till then, can he pretend to command my belief or opinion.

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[Borodog]

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If justifying OR is a straightforward empirical matter . . .

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Why do you keep saying this, when that isn't what the people you are arguing with are saying?

[borisp]

According to the principles of this razor, it is more likely to be spelled "Occam" than "Ockham." So I agree with Borodog on whatever he says.

[KipBond]

The people arguing that OR implies that certain theories are more likely 'true' or 'correct' have different definitions of those words than is meant in an empirical/scientific sense.

http://en.wikipedia.org/wiki/Occam's_Razor

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Occam's razor (sometimes spelled Ockham's razor) is a principle attributed to the 14th-century English logician and Franciscan friar William of Ockham. The principle states that the explanation of any phenomenon should make as few assumptions as possible, eliminating, or "shaving off," those that make no difference in the observable predictions of the explanatory hypothesis or theory. The principle is often expressed in Latin as the lex parsimoniae ("law of parsimony" or "law of succinctness"):

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entia non sunt multiplicanda praeter necessitatem,

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which translates to:

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entities should not be multiplied beyond necessity.

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This is often paraphrased as "All things being equal, the simplest solution tends to be the best one." In other words, when multiple competing theories are equal in other respects, the principle recommends selecting the theory that introduces the fewest assumptions and postulates the fewest hypothetical entities. It is in this sense that Occam's razor is usually understood.

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[Borodog]

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The people arguing that OR implies that certain theories are more likely 'true' or 'correct' have different definitions of those words than is meant in an empirical/scientific sense.

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Not really. To wit:

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This is often paraphrased as "All things being equal, the simplest solution tends to be the best one." In other words, when multiple competing theories are equal in other respects, the principle recommends selecting the theory that introduces the fewest assumptions and postulates the fewest hypothetical entities. It is in this sense that Occam's razor is usually understood.

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What definition of "best"? My contention is that the only definition of "best" that can possibly have any meaning is "the most likely to be correct."

Again, if the simplest explanation is not more likely to be true than alternatives containing unnecessary complications, the what benefit is choosing the simpler one? What is the justification? These are the essential questions that keep getting dodged.

[KipBond]

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Again, if the simplest explanation is not more likely to be true than alternatives containing unnecessary complications, the what benefit is choosing the simpler one? What is the justification? These are the essential questions that keep getting dodged.

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The answer is this:

OR says nothing about which equally reliable & explanatory theory is "more likely to be true".

You can read a lot about this here:

http://en.wikipedia.org/wiki/Occam's_Razor

We use the simplest of equally reliable & explanatory theories for various reasons: practicality, easier to learn, apply, remember, teach, etc. Once the more complicated model provides a bit more explanatory & reliable predictions, then simplicity takes a back seat when we need to be more accurate.

You can argue that, indeed, it is the case, that the simplest theory is "most likely to be true", and then you could create your own maxim for that. But, that's not Occam's Razor.

But, I think you'll be hard pressed to show that this is the case. It seems to me that more complicated models are usually more reliable & explanatory than simpler models. We still use the simpler models sometimes because they are easier and are 'good enough', but we know they are not "more likely to be true". There may be exceptions, but I think they are rare. Of course, at some point you are going to have to define & present a way to measure "simplest".