Occam's razor
- Scientific skepticism
- Pseudoskepticism
- Occam's razor
- Standards of evidence
- Skeptical quotes
- Extraordinary claims require extraordinary evidence
- Woo
Occam's razor is a logical device intended to help a person select which theoretical alternative to accept. It states that a simple explanation is preferable to a complex one if it explains the data equally well. Occam's razor can only be used to decide between two hypotheses which both explain the data equally well. It cannot be used to favor an hypothesis because it is conventional.
In frontier subject areas, there is often a simple paranormal explanation for an occurrence, and also conventional explanation which is more complex. To apply Occam's razor to these situations, one must set aside any ideas about which explanation is likely to be true merely because it is conventional. If you have a conventional explanation which is complex, and a paranormal explanation which is simple, and both explain the data equally well, then Occam's razor says you should choose the paranormal explanation. Occam's razor is an intellectual tool which has very narrow applicability, but has been much abused in debates.
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Abuse in skepticism
Occam's razor is often abused in skepticism, because it is combined with the principle "extraordinary claims require extraordinary evidence" in such a way as to allow a more complex explanation to carry more weight. Instead of sticking to the simplest explanation of the data, skeptics multiply entities (factors in their hypothesis). The razor is used as if it meant "the most conventional explanation is likely to be true." Take another example:
A pitcher of water has been spilled. The house where it is spilled is said to have a poltergeist. Many people have reported this. The house is guarded by an alarm system, which makes it impossible to enter from the outside without being seen. Everyone agrees the alarm is foolproof. However, because ghosts are unlikely, a skeptical explanation is that a prankster tunneled into the house from the road 50 feet away, then tipped over the pitcher and escaped, filling in the tunnel behind him. This explanation multiplies entities (creates complexities), but because the skeptic feels that it is more likely that a human exists than that a poltergeist exists, the skeptic feels he has the best explanation. Thus the unlikelihood of a poltergeist is weighed against the unlikelihood of the tunnel. So far, this is a legitimate argument about whether a poltergeist is so unlikely that we should prefer a wild explanation about a tunnel intruder.
However things go wrong when Occam's razor is used to bolster the skeptic's argument. The skeptic may say that his explanation is better because we do not have to postulate an unknown "entity" (a poltergeist), and thus per Occam's razor his explanation is to be preferred. The skeptic will claim his explanation is the "simpler" one. The problem with using Occam's razor this way is that only extraordinary phenomena are counted as "entities" which we "multiply," while conventional phenomena (pranksters, tunnels, filling in the tunnel etc.) are not counted as "multiplied entities." The skeptic may be right that his explanation is better, but Occam's razor has nothing to do with it because Occam's razor does not deal with how likely things are to actually exist in the world. In this example it is true in that the skeptical explanation requires fewer entities to exist in the real world (we don't have to add the entity "poltergeist"). But Occam's razor is not a way to determine what exists in the real world, only which full explanation of the data should be accepted. Per Occam's razor, a poltergeist should be accepted as the explanation, because while each of the two explanations postulate that an entity knocked over the pitcher, the skeptic's explanation requires tunnels and breaking and entering as well.
Using Occam's razor to decide reality
To Occam's razor, an explanation which is abnormal and simple has equal status with an explanation which is normal and simple. Occam's razor is merely a way of deciding which of two equally explanatory and equally probable hypotheses to choose. Another way of saying this is that Occam's razor does not distinguish between likely and unlikely explanations. Likelihood or unlikelihood have to be established based on data, and data re not always simple.Occam's razor is often incorrectly used to decide which data you would be more likely to find if you could find the data. When this happens the rule is being used not to decide which theory should be preferred, but to decide which theory we believe has proof. Those who use the Razor in this way do not care if factors are multiplied in an explanation, as long as all the factors are conventional. In our example, it does not matter to skeptics how many more factors the prankster explanation has or how unlikely they are, because this explanation has no extraordinary claims like "poltergeist."
Whether or not a claim is extraordinary has no relationship to whether or not it is simple. After all, the simplest explanation for a spilled pitcher is that it fell over by itself. This is the hypothesis favored by Occam's razor. It is improbable however because we have never before observed self-tipping pitchers. The fact that the simplest explanation of why the pitcher tipped over is wrong shows why Occam's razor cannot be used to decide which hypothesis is right but only to decide which of two equally likely explanatory hypotheses is better (pending a test of the hypothesis). Occam's razor cannot decide between a poltergeist and a prankster.
Occam's razor should not be used to help us decide what is real or likely to be real. Such things are to be decided by evidence. It is an abuse of Occam's razor to do anything with it besides choose the simpler of two otherwise equal hypothesis.[2]
In argument, Occam's razor is often used to defend baroque explanations with many unverified assumptions. In such cases "Occam's razor" stands in for the principle that "the most conventional explanation is likely to be true." Such conventional explanations are favored above simple but extraordinary explanations. This may or may not be a good way to do science, but it should be clearly stated for what it is, and Occam's razor should be kept sharp for when it is appropriate. There is no magical rule which relieves us of the need to collect and analyze data and to form our hypotheses based on what we deem the most probable reality. Science is a messy process which is always filled with uncertainty.
Don't use Occam's razor in place of the maxim that the most conventional explanation is most likely to be true.
A real-world example of the misuse of Occam's razor
According to the section titled Skeptical scientific investigation in the Wikipedia article on the "Paranormal,"
Scientific skeptics advocate critical investigation of claims of paranormal phenomena: applying the scientific method to reach a rational, scientific explanation of the phenomena to account for the paranormal claims, taking into account that alleged paranormal abilities and occurrences are sometimes hoaxes or misinterpretations of natural phenomena. A way of summarizing this method is by the application of Occam's razor, which suggests that the simplest solution is usually the correct one.[21] The standard scientific models gives an explanation for what appears to be paranormal phenomena is usually a misinterpretation, misunderstanding, or anomalous variation of natural phenomena, rather than an actual paranormal phenomenon.[3]
This is wrong in that Occam's razor tells us which hypothesis should be preferred, not which is correct. Occam's razor does not suggest that the simplest solution is likely to be correct. The passage also assumes that a conventional explanation will always be simpler, which is often incorrect. Even Wikipedia's own Occam's razor article states that:
Simpler theories are preferable other things being equal. The other things in question are the evidential support for the theory[4] Therefore, according to the principle, a simpler but less correct theory should not be preferred over a more complex but more correct one.
See also
References
- ↑ On Some Unfair Practices towards Claims of the Paranormal by Marcello Truzzi
- ↑ "91. 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, which 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." -An Enquiry Concerning Human Understanding by David Hume et al
- ↑ Wikipedia's Paranormal article, January 2012
- ↑ "when you have two competing theories which make exactly the same predictions, the one that is simpler is the better."Usenet Phyics FAQs
