Science Series – Part 3: What is Ockham’s Razor?
This is Part 3 of a 5-part series that I am writing on science and PT practice. If you have not read Parts 1 and 2, do that first before reading any further…
A philosophical razor is a device used to define and/or evaluate an idea. Often it can be used to force an idea or method of reasoning into or out of a category. The razor that most people are familiar with is Ockham’s Razor.
When I was an undergrad, I had a philosophy professor who cautioned the use of Ockham’s Razor. It is one of the most misused and least understood positions in philosophy. Often summarized incorrectly as something along the lines of, “When comparing two ideas, the simpler explanation is better than the complex one.” Well, that is not exactly true. There are countless examples of the more complex being better such as Einstein’s Theory of Relativity vs. Classical Physics, Theory of Evolution vs. Intelligent Design, Germ Theory vs. “Succumbing to the Vapors”. Turns out, simpler in this respect is rarely better.
Another problem is that simplicity depends on perspective. To quote Dieter Gernert:
“Beyond trivial cases, the term ‘simplicity” remains a subjective term. What is compatible with somebody’s own pre-existing worldview, will be considered simple, clear, logical, and evident, whereas what is contradicting that worldview will quickly be rejected as an unnecessarily complex explanation and a senseless additional hypothesis. In this way, the principle of simplicity becomes a mirror of prejudice, and, still worse, a distorting mirror, since this origin is camouflaged.” (Read the whole article)
A “mirror of prejudice” is not a lofty goal. Just because something fits simply into your worldview doesn’t make it accurate or even necessarily the most simple. You can just use the principle of simplicity to dismiss ideas that are complicated TO YOU and continue to believe whatever you want to believe.
So how does one use Ockham’s Razor appropriately? Let’s start with a more accurate summary: “When faced with competing hypotheses, select the one that makes the fewest assumptions.”
It is a desire to strip the qualifiers from an idea. For example, Einstein’s original Theory of Relativity only worked if you assume that the universe is expanding. Since he assumed that it was static he added the “cosmological constant” to the equations to cancel out the expansion problem. Hubble (the man not the telescope) later demonstrated that the universe was in fact expanding making Einstein refer to the cosmological constant as, “The greatest mistake of my life.”
Did Einstein fail to employ Ockham’s Razor by adding the cosmological constant? Well, constants are not new to science and there are several examples (such as the Avogadro constant). What was simpler, adding a constant or assuming that the universe was expanding with no other known evidence at the time? Simplicity is relative.
Ockham’s Razor is a useful tool and something to keep in mind, but it is not by any means definitive. When we add this to Hume’s Continuity of Nature what are we left with? A whole bunch of plausible ideas that can never be proven to be correct with absolute certainty. Induction speculates about what might be possible, but it can never be proven. Any attempt to prove it “right” will fail. Descartes still wins.
But how many times do we mistake induction for science in physical therapy?
- Diagnosis “A” (Fact)
- It makes sense that treatment “B” would correct diagnosis “A” (Inductive Reasoning)
- Every time that I use treatment “B”, diagnosis “A” gets better (Continuity of Nature)
- Therefore the simplest conclusion is that “B” must be an effective treatment for “A” (Ockham’s Razor)
My point is not that such conclusions are necessarily wrong, but that they can’t be verified this way. So inductive reasoning, Continuity of Nature, and Ockham’s Razor can give us ideas about what MIGHT work, but they are not enough to establish knowledge. We need a better definition of science. We still need a better tool.
Continue to the next post, Part 4: Falsifiability and the Flaming Laser Sword.