Wednesday, July 07, 2010

What Is Ockham's Razor

First Posted here in Feb. 2006

By Jose Wudka, 1998

When a new set of facts requires the creation of a new theory the process is far from the orderly picture often presented in books. Many hypothses are proposed, studied, rejected. Researchers discuss their validity (sometimes quite heatedly) proposing experiments which will determine the validity of one or the other, exposing flaws in their least favorite ones, etc. Yet, even when the unfit hypotheses are discarded, several options may remain, in some cases making the exact same predictions, but having very different underlying assumptions.
In order to choose among these possible theories a very useful tool is what is called Ockham's razor.
Ockham's Razor is the principle proposed by William of Ockham in the fourteenth century: ``Pluralitas non est ponenda sine neccesitate'', which translates as ``entities should not be multiplied unnecessarily''. In many cases this is interpreted as ``keep it simple'', but in reality the Razor has a more subtle and interesting meaning.

Suppose that you have two competing theories which describe the same system, if these theories have different predictions than it is a relatively simple matter to find which one is better: one does experiments with the required sensitivity and determines which one give the most accurate predictions. For example, in Copernicus' theory of the solar system the planets move in circles around the sun, in Kepler's theory they move in ellipses. By measuring carefully the path of the planets it was determined that they move on ellipses, and Copernicus' theory was then replaced by Kepler's.

But there are are theories which have the very same predictions and it is here that the Razor is useful. Consider for example the following two theories aimed at describing the motion of the planets around the sun.
1. 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.

2. 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.

Since the force between the planets and the sun determines the motion of the former and both theories posit the same type of force, the predicted motion of the planets will be identical for both theories. The second theory, however, has additional baggage (the will of the aliens) which is unnecessary for the description of the system.

If one accepts the second theory solely on the basis that it predicts correctly the motion of the planets one has also accepted the existence of aliens whose will affect the behavior of things, despite the fact that the presence or absence of such beings is irrelevant to planetary motion (the only relevant item is the type of force). In this instance Ockham's Razor would unequivocally reject the second theory. By rejecting this type of additional irrelevant hypotheses guards against the use of solid scientific results (such as the prediction of planetary motion) to justify unrelated statements (such as the existence of the aliens) which may have dramatic consequences. In this case the consequence is that the way planets move, the reason we fall to the ground when we trip, etc. is due to some powerful alien intellect, that this intellect permeates our whole solar system, it is with us even now...and from here an infinite number of paranoid derivations.

For all we know the solar system is permeated by an alien intellect, but the motion of the planets, which can be explained by the simple idea that there is a force between them and the sun, provides no evidence of the aliens' presence nor proves their absence.

A more straightforward application of the Razor is when we are face with two theories which have the same predictions and the available data cannot distinguish between them. In this case the Razor directs us to study in depth the simplest of the theories. It does not guarantee that the simplest theory will be correct, it merely establishes priorities. A related rule, which can be used to slice open conspiracy theories, is Hanlon's Razor:
``Never attribute to malice that which can be adequately explained by stupidity''.

Ockham's razor

Ockham's razor (also spelled Occam's razor, pronounced AHK-uhmz RAY-zuhr) is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation. William of Ockham (1285-1349), English theologian and philosopher, spent his life developing a philosophy that reconciled religious belief with demonstratable, generally experienced truth, mainly by separating the two. Where earlier philosophers attempted to justify God's existence with rational proof, Ockham declared religious belief to be incapable of such proof and a matter of faith. He rejected the notions preserved from Classical times of the independent existence of qualities such as truth, hardness, and durability and said these ideas had value only as descriptions of particular objects and were really characteristics of human cognition.
Ockham was noted for his insistence on paying close attention to language as a tool for thinking and on observation as a tool for testing reality. His thinking and writing is considered to have laid the groundwork for modern scientific inquiry.

Ockham's insistence on the use of parsimony (we might call it minimalism) in thought resulted in some later writer's invention of the term, Ockham's razor. Among his statements (translated from his Latin) are: "Plurality is not to be assumed without necessity" and "What can be done with fewer [assumptions] is done in vain with more." One consequence of this methodology is the idea that the simplest or most obvious explanation of several competing ones is the one that should be preferred until it is proven wrong.

Paranoid Patty's view: I fail to see much difference between stupidity and malice. The only difference being one of conscious intent. Whether there is intent to harm or not, the results of malice or stupidity, when directed at someone, are the SAME for that victim. The reason I need a real investigation, which I have been asking for for over a decade, in my own fascinating case, is to discover how much conscious direction existed in the "game."

With that discovery and concrete evidence, comes the knowledge of the difference between a brainwashed, idiot follower and a psychopath. I would like to know this for what should be obvious reasons.

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