In a recent comment, a writer seemed to hold that Occam’s Razor is an ironclad logical principle that should end all debate. This post will explore the logic behind this view. Therefore I believe a basic description of formal and informal fallacies are in order.
Formal fallacies apply to formal logic, and if a formal logical statement is fallacious, it is always fallacious and therefore nonsensical. In logic, a valid formal syllogism would be:
1. All men are mortal.
2. Socrates is a man.
3. Therefore Socrates is mortal.
Another logical statement would be:
1. If S, then P.
2. S is true.
3. Therefore P.
Such statements are valid logical arguments, and are objectively, necessarily true, not based on opinion. You can learn as much as you would like about formal logical principles in any logic text, such as Introduction to Logic by Irving Copi. An example of a formal fallacy would be:
B1. All dogs are mammals.
B2. All cats are mammals.
B3. Therefore all cats are dogs.
In logical terms, this syllogism does not have a single, distributed middle term. The middle term mammals is not handled correctly. To be valid, there would need to be a premise such as “Fido is a dog.”
Another formal fallacy would be:
C1. If S, then P.
C2: Z is true.
C3. Therefore, . . . . ?
In this one, C1 and C2 are not connected at all, and no logical statement is made. Such are logical fallacies.
Informal fallacies are fallacies that invalidate arguments. They do not apply in every instance, but only apply when they apply.
“Bip is wrong about this math formula because he’s from Cleveland.”
Bip may indeed be from Cleveland, but this has nothing to do with his skills in math. There would appear to be no connection between Cleveland and mathmatics. However, if there were only one school in Cleveland, and the teachers there historically taught everyone in town incorrect math skills, then it very well may be correct that since Bip is from Cleveland, we can conclude that his math skills are poor. Another example:
“This article must be true because Dr. X says it is true.”
Well, why? Are things true merely because a person says so? Not usually, but this statement would depend on whether Dr. X was actually an authority that, because of his situation, was always correct about what was in the article.
So what is Occam’s Razor? William of Occam (b.1285) was a philosopher who held that given two possible explanations for an event, the simpler explanation is to be preferred. It would not be logical to prefer a cause that required a huge number of preexisting events as opposed to a cause that only required one or two. Say that a mother hears a noise and goes to the kitchen and sees the child standing next to a broken cookie jar. It could be that a breeze blew the window open, a bird came through the window, pecked the jar, and flew out the window. It could also be possible that the child knocked it over. Which is more likely? Occam’s Razor would say that your time and energy should be put into the simpler explanation first, for that is probably the true one.
However, Occam’s Razor is not a formal fallacy, and therefore only applies when it applies. It really could be the case that the bratty neighbor kid put a bird on a stick, pushed it through the window, and knocked over the jar. Until we investigate, we do not know for sure.
Most people today do not study formal logic. Those in the technical sciences are often more familiar with the nuances of their technical specialties rather than the strict ways to form arguments. Imposing Occam’s Razor might be useful in deciding where to dedicate limited research budgets, but tells us nothing about true causes. If Occam were always true, why do the research at all, since we would always know the answer prior to the study?
The popular definition of evolution involves a massive number of mutations in just the right circumstances, resulting in human DNA molecules having about 3 billion pieces of information. Such a process is clearly a very large number of causes that would all have to be in place in the correct sequences. By contrast, “God did it” takes only one step. If Occam’s Razor were always true, we would bypass scientific research entirely. Occam is useful, but is not always true. In the case of gradualistic evolution compared to “God did it,” Occam’s Razor tells us nothing about which is true.
Another example of how informal fallacies are sometimes applied, see the article on the vertical cosmological argument and the fallacy of composition, see here.