Ockham's Razor

[lucaspa]

Ockham's Razor is often stated: "the simplest explanation is the correct one"

Poor William of Ockham. This is actually the position he argued against. Others argued that nature always takes the simplest path. Thus, since the angle of reflection = angle of incidence, it was thought that the angle of refraction must = 1/2 the angle of incidence, because this was the next "simplest" equation. Ockham thought this unnecessarily limited God.

What William of Ockham actually said was that, in describing a phenomenon, do not use unnecessary entities. His example was a typical statement of his time: “A body moves because of an acquired impetus” vs “a body moves”. The "acquired impetus" was a force that was thought to be imparted to a body and kept it moving. But Ockham noted that "move" was simply a change in position over time. Therefore, the correct way to describe the phenomenon was "a body moves". Leave out "impetus" or any other cause entirely.

“Consider for example the following two theories aimed at describing the motion of the planets around the sun:

The planets move around the sun in ellipses because there is a force between any of them and the sun which decreases as the square of the distance.

The planets move around the sun in ellipses because there is a force between any of them and the sun which decreases as the square of the distance. This force is generated by the will of some powerful aliens.” http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node10.html

The author stated that the last is not the simplest and was therefore wrong. HOWEVER, the first one also violates Ockham's Razor because it is not the simplest way to describe the phenomenon of planetary orbits. The correct Ockham statement is "The planets move around the sun in ellipses." No need to add ANY "force".

So the Razor has become, incorrectly, a way to evaluate hypotheses and to eliminate hypotheses you don't want. It is particularly used to eliminate "supernatural" hypotheses, as it was used here.

But the statement "the simplest explanation is the correct one" is not correct. There are far too many examples out there where the simplest explanation turned out not to be correct. This is particularly true in biology.

 

[lawtonfogle]

Ockham's Razor is often stated: "the simplest explanation is the correct one"

Poor William of Ockham. This is actually the position he argued against. Others argued that nature always takes the simplest path. Thus, since the angle of reflection = angle of incidence, it was thought that the angle of refraction must = 1/2 the angle of incidence, because this was the next "simplest" equation. Ockham thought this unnecessarily limited God.

What William of Ockham actually said was that, in describing a phenomenon, do not use unnecessary entities. His example was a typical statement of his time: “A body moves because of an acquired impetus” vs “a body moves”. The "acquired impetus" was a force that was thought to be imparted to a body and kept it moving. But Ockham noted that "move" was simply a change in position over time. Therefore, the correct way to describe the phenomenon was "a body moves". Leave out "impetus" or any other cause entirely.

“Consider for example the following two theories aimed at describing the motion of the planets around the sun:

The planets move around the sun in ellipses because there is a force between any of them and the sun which decreases as the square of the distance.

The planets move around the sun in ellipses because there is a force between any of them and the sun which decreases as the square of the distance. This force is generated by the will of some powerful aliens.” http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node10.html

The author stated that the last is not the simplest and was therefore wrong. HOWEVER, the first one also violates Ockham's Razor because it is not the simplest way to describe the phenomenon of planetary orbits. The correct Ockham statement is "The planets move around the sun in ellipses." No need to add ANY "force".

So the Razor has become, incorrectly, a way to evaluate hypotheses and to eliminate hypotheses you don't want. It is particularly used to eliminate "supernatural" hypotheses, as it was used here.

But the statement "the simplest explanation is the correct one" is not correct. There are far too many examples out there where the simplest explanation turned out not to be correct. This is particularly true in biology.

Oh, say...


The planets move around the sun in ellipses because there is a force between any of them and the sun which decreases as the square of the distance. This is caused by <massive dump of physics from quantum mechanics and the Higgs boson all the way up to relativity>.

 

[Assyrian]

Wouldn't 'unnecessary entities' only apply to postulating a new force to move the planets, while Newton proposed a known entity, gravity, the same force that pulled Newton and his legendary apple to the ground?

 

[lucaspa]

Wouldn't 'unnecessary entities' only apply to postulating a new force to move the planets, while Newton proposed a known entity, gravity, the same force that pulled Newton and his legendary apple to the ground?

See below for one answer to this argument: it is too restrictive for scinece by unnecessarily eliminating possible new causes.

However, in terms of William of Ockham's original Razor, "unnecessary entities" applies to any entity that is unnecessary to describe the phenomenon. When describing the motion of planets, you don't need any force to describe that. All you need say is "The planets move around the sun in ellipses". You don't need any "because". As soon as you say "because" you are going beyond the Ockham statement and adding an "unnecessary entity".

What we call the Razor today actually is closer to something Newton proposed. In the second edition of Principia, Newton listed 4 "rules of reasoning in philosophy" Look at #1:

"We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearance". Doesn't this sound more like what we call "Ockham's Razor" than what William of Ockham stated?

Several scientists and philosophers of science have noted some severe problems with Rule #1. I will now quote from John Losee's A Historical Introduction to the Philosophy of Science, 4th edition, pg 83-84.

"In support of Rule 1, Newton appealed to a principle of parsimony, declaring that nature "affects not the pomp of superfluous causes". But exactly what Newton meant, or should have meant, by a "true cause" has been a subject of some debate. For instance, both William Whewell and John Stuart Mill criticized Newton for failing to specify criteria for the indentification of true causes. Whewell remarked that if Newton meant to restrict the "true cause" of a type of phenomnea to causes already known to be effective in producing other types of phenomena, then Rule 1 would be overly restrictive. It would preclude the introduction of new causes.

(Notice, Assyrian, that you made the argument Whewell is arguing against.) However, Whewell was not certain that this was Newton's intended meaning. He noted that Newton may have meant only to restrict the introduction of causes to those of "similar in kind" to causes that previously have been established. Whewell observed that, thus interpreted, Rule 1 would be too vague to guide scientific inquiry. Any hypothetical cause could be claimed to display some similarity to previously established causes. Having dismissed these inadequate alternatives, Whewell suggested that what Newton should have meant by "true cause" is a cause represented in a theory, which theory is supported by inductive evidence acquired from analysis of diverse types of phenomenon.
Mill likewise interpreted "true cause" so as to reflect his own philosophical position. Consistent with his view of induction as a theory of proof of causal connection, Mill maintained that what disntinguishes a "true cause" is that its connection with the effect ascribed to it be susceptible to proof by independent evidence."

I would note that the term "sufficient" is being ignored by Losee. What generally accepted criteria do we have that a cause is "sufficient"? Within the limited area of being a material cause, we may have such criteria. But extended to a general idea of "sufficiency", there is a failure of consensus on criteria.

All in all, Rule 1 does not work as a means of theory evaluation. I would note that science has discarded Rule 3:

"In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accuarately or very nearly true, notwithstanding any contrary hypothesis that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions."

IOW, by Newton's rules, we can't falsify theories! Instead, data that contradicts them simply is viewed as exceptions to the theory.