Science Series By Erik Meira Originally published as a 5 part series released over the course of 5 days, this is all 5 posts as one continuous thread. You can read the entire thread at ptpodcast.com/pt-inquest/science-series/ A little background. I am a science geek, I have been since I was a kid, long before I became a physical therapist. I also love philosophy, discourse, and reason and devoted a large amount of my time to this as an undergrad. When I hear physical therapists discuss Evidence-Based Practice, I find that many can sound really scientific but often make mistakes in logic – mistakes that science inherently avoids. Much of this has to do with a lack of understanding of the history of the philosophy of knowledge and how science accounts for these known issues of knowledge. So if you are not familiar with René Descartes, David Hume, William of Ockham, or Karl Popper – you may be missing something… I Think Therefore I Am Philosophers have sought to find absolute knowledge for centuries. Absolute knowledge is something that can be known with 100% certainty. This has always been difficult to define. Almost anything that could be claimed to be known would always result in some kind of challenge taking that certainty below 100%. One of the best examples of this is Meditations on First Philosophy published in 1641 by René Descartes. Meditations was an attempt by Descartes to break down all knowledge to only those things that we can know with absolute certainty and then build from there. I’m not going to give you a play by play of the entire treatise, you can download the book for free onto any computer or e-reader (all classical texts are free now). I’ll just jump to the conclusion – the butler did it. It is in Meditations that Descartes developed the “Evil Demon” argument. What he points out is that there could be an “Evil Demon” that cannot be known or perceived who alters all of our reality so that we cannot trust any of our senses. Of course this is an unreasonable belief, but how do we KNOW with 100% certainty that this is not the case? If you are uncomfortable with this antiquated concept, you may also imagine the more contemporary allegory known as thebrain in a vat. You may be more familiar with this – The Matrix made a lot of money off of this concept. So in Descartes’ world of the Evil Demon, we cannot know anything about our external world with absolute certainty. We cannot even be sure of the existence of the world itself including other people and their thoughts. So what are we left with? Well, three things according to Descartes: • Mathematics • Logic (deduction) • Self existence Mathematics and logic exist because they are abstract tools not based in any kind of reality (they can be used to process knowledge, but are not knowledge themselves). That leaves you with only one thing that is absolutely certain – You exist. Not me, not your co-workers, not that guy who was talking to a lamppost this morning. Just you, YOU exist. That is all that you know for certain. Hence Descartes famous line, “I think therefore I am” (Cogito ergo sum for the Latin nerds out there). This is the primary problem of seeking knowledge – perceptions can be deceived and are not to be trusted. In its infancy, science went through a lot of growing pains with many dead ends to get around this problem. It is learning about these failures that we develop an understanding of modern science. Continuity of Nature So René Descartes really tied our hands here. He effectively took away all deduction (except mathematics and logic) and left us with imperfect induction. What does this mean? In critical thinking, we have deductive reasoning and inductive reasoning. Deductive reasoning is when you start with a premise that is 100% certain and build your argument from there. Inductive reasoning is when you start with an assumption to build your argument. The more likely that assumption is true, the stronger the induction, but you cannot say anything with 100% certainty. The problem is amplified when people use induction to conclude one premise, and then use that premise to build a new induction. The more that you do this, the weaker the induction becomes. Also, no matter how strong your inductive reasoning, you can never be 100% sure that you have anything amounting to real knowledge or validity. This is known as “The Problem of Induction”. How can we know anything with any kind of certainty? Monty Python has a great example of induction in their famous witch scene from The Holy Grail. I’ll supply the synopsis below, but if you have five minutes, watch the clip for yourself - it’s worth it. The villagers have a woman that they suspect is a witch and would like to burn her (as villagers like to do). They bring her to Sir Bedevere who is a “man of science” for an objective decision. Here is his “scientific” argument. Witches burn. Wood burns. Therefore, a witch must be made of wood. Wood floats. Ducks float. Therefore wood must weigh the same as a duck. If a woman weighs the same as a duck, then she must be made of wood. If she is made of wood, then she must be a witch. Therefore, if a woman weighs the same as a duck, she must be a witch. Now obviously there are many unsound conclusions and logical fallacies committed here, but you can see how simple inductions can lead to quite absurd conclusions, especially if it “sounds right”. Now, I’m not going to go into depth on validity of arguments and logical fallacies here, it is not the point of this series. If you would like to learn all about that, why don’t you take Critical Reasoning for Beginners at Oxford University? Did I mention that it is free, online, only 7 hours in total length, and can be downloaded to your iPod? So maybe we can try to give some guidance to induction to give us a little more substance. Here is where the Scottish philosopher David Hume comes in. In the 1700s, he made one of the first more effective attempts to tackle the Problem of Induction. What he points out is what is known as The Continuity of Nature. In a nutshell, we can observe natural occurrences and look for patterns. If we find that these patterns have always occurred, we can assume that they will continue to occur. He was quick to point out that this will fail to determine causation, but at least you can define continuity. From here you can make more accurate predictions about future outcomes. Definitely the underpinnings of science but there are still holes. The continuity is still based on assumptions with no real certainty. Great way to develop hypotheses, but we still have no concrete knowledge. Also we still have the problem of basing future premises on these assumptions, weakening our certainty even greater. Better than Sir Bedevere, but not by much. It is still susceptible to circular reasoning. Induction gives us only ideas, no reality. We need a better definition. We need a better way of verifying ideas. What is Ockham’s Razor? 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).