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). 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. Falsifiability and The Flaming Laser Sword

So “Falsifiability and The Flaming Laser Sword” sounds like a new Harry Potter book. Maybe that is how Lord Voldemort lost his nose… Wait, what was I talking about?

Oh yeah, science! So we talked about how Descartes showed that we cannot know anything is true with 100% certainty. We also looked at the limitations of inductive reasoning, Continuity of Nature, and Ockham’s Razor. So when an idea holds up to these tests alone, there is still plenty of room for doubt. As a matter of fact, most things known to be pseudoscience will hold up quite nicely against these tests. So what can we really know?

Well, we can’t prove that something is true, but what about proving that something is false? This gets to the idea of “falsifiability” as defined by Karl Popper in the early 20th century. In order for something to be considered scientific, there must be an example that, if found, would falsify the idea. Confused? Let me clarify.

Let’s take the statement “All swans are white.” Now, with Continuity of Nature we would go around looking for white swans in order to support that statement. You are inferring a general rule from a number of individual cases (similar to a case series in medical research). You are looking to confirm the idea, which we have shown to be impossible. This is the heart of The Problem of Induction. It is also known as confirmation bias.

But what if we spent our time looking for a swan that was NOT white? Simply finding ONE example will very simply falsify the statement “All swans are white.” This is the goal of experimentation – To falsify, not to confirm. The very important point here is that although you can only INDUCE confirmation (uncertain), you can DEDUCE falsification (certain). Popper brought deduction back to the table after Descartes removed it over 300 years ago. You can use induction to come up with ideas, but they must be falsifiable in order for them to be scientific.

Einstein (pretty smart guy I hear) put it best. “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.”

So what about Descartes’ Evil Demon? You can never prove that the Evil Demon does not exist. That’s right, you cannot falsifiy that idea, therefore it is not science. This makes the Evil Demon irrelevant in scientific discussions. POOF! He’s gone. Pretty cool, huh? We defined a philosophical razor as a tool to define or categorize ideas. Popper’s Falsifiability is such a razor. But razors are small subtle instruments. The term “razor” does not convey the true power of the this tool. So the science philosopher Mike Alder didn’t refer to falsification through experimentation as “Popper’s Razor”. He called it “Newton’s Flaming Laser Sword”. If you have time, I strongly encourage you to read his entire article.

(Side note: Just like William of Ockham was never quoted to state what is now known as Ockham’s Razor, Newton himself never defined falsification though experimentation. He was, however, one of the first to famously engage in the practice. He was known for it and is now better known than Popper. Sorry Karl.) What the Flaming Laser Sword does is provide a razor sharp demarcation of science. The question that must be asked is, “Can we objectively challenge the idea?” If we cannot, then it is not science. Another thing that I would like to stress here: An unfalsifiable idea could be 100% right, it simply is not science. Technically, the scientific position is “No comment.”

History has shown that these unfalsifiable ideas rarely hold up over time so personally, I almost always take the skeptic’s position. In science this is known as “the null” – the stance that an idea is NOT true until properly tested for falseness (that is actually a word – go figure!).

This is why religion and politics create such heated debates. Just about every statement COULD be true depending on perspective and confirmation bias. If it was wrong, you couldn’t prove it. So people try to speak more loudly, passionately, confidently, and “expertly” about what they can induce. Sound familiar? Listen to people in the PT profession talk about the treatment of non-specific pain… Seppuku and The Tooth Fairy

Uh oh. Here comes the guru with 20+ years of experience.

“You are just some armchair philosopher! Who are you to say what is and isn’t science?” “Me? I’m nobody. But I do have this…” I then slam the flaming laser sword on the table knocking over glasses and dinnerware. “But I base all of my ideas on science,” says the guru. “Logically that makes my reasoning scientific.” “You sure about that? Have you actually tested your conclusions step by step?” I nod to the bright shiny sword on the table, blazing hot with the glow of a laser. I rather like this metaphor, but you may prefer, “SAY HELLO TO MY LITTLE FRIEND!!!” To each his own I guess. So now we are holding a razor sharp flaming laser sword, beautiful in its precision. I enjoy swords. I practice the Japanese martial art of iaido, which involves a connection with the sword. It’s great exercise, it’s mind clearing, it’s badass (or really nerdy?), and it helps me get out aggression in an appropriate way as opposed to writing angry blog posts with links to scenes from Scarface… Anyway, in iaido there is a kata (series of movements) known as junto where you perform the role of assistant in the ritual of seppuku. Seppuku involves turning your blade on yourself. This is what we as a profession need to do with the flaming laser sword. I’m not talking about that PT down the street practicing craniosacral therapy. Let’s face it, that guy stopped reading this a long time ago. I’m talking about you.

This is something that I have heard recently from many physical therapists that I consider scientifically minded: “Most IF NOT ALL of our success is due to non-specific effects.” Excuse me? What did you just say? If you believe that then go ahead and pack your bags and head over to the complementary and alternative medicine department – because that is their defense. Now I will be the first to admit that all treatments, from surgery to Reiki, have non-specific effects. I also agree that we should do everything in our power to ENHANCE those non-specific effects whenever we can – it’s like low hanging fruit. The science, however, is in the specific effects. They MUST be there for experimentation to occur and science demands experimental attempts to falsify. Subjective changes are great, but you had better show me something physiological. I can’t test objectively against perception.

Craniosacral therapy combined with acupuncture can demonstrate changes in subjective and perceived functional outcomes against controls. Does that make it science? Show me the objective physiological change and then show me EXACTLY how well you can predict that change via reliable and reproducible experimentation – THAT is science. In my opinion, pain can rarely be directly treated – at least not scientifically. As I keep hearing these days, pain is all perception (that sounds like the hopeless situation of Descartes’ “Evil Demon” to me). Now, given a specific pain pattern, mechanism of injury, and clinical exam (which has survived specific attempts to falsify in the literature), I can determine with a high and certain level of confidence that someone has likely torn their meniscus. With the help of a surgeon (after seeing first if time will heal it), the tear can be repaired and we can restore range of motion and the subsequent strength/coordination deficit after surgery, but we directly treated the torn meniscus and objective deficits, not the pain.

Similarly, I can evaluate someone with patellofemoral pain syndrome (or anterior knee pain or whatever you want to call it this week – I don’t have time for semantics) and could objectively determine that they are weaker in their quads and their hips on the involved side. I can also objectively treat that weakness resulting in a physiological change (increased strength through specific experimentally tested exercise prescription). Is it biologically plausible or even possible that this is causing their pain? Sure, but being biologically plausible and possible doesn’t mean shit. That is induction, not science. Until then, I’ll treat what I can objectively measure and change which in this case, is strength not pain. The reason that I provide treatment is because of pain, but that is not what I am actually treating – at least not scientifically.

What about chronic pain without any specific findings? There is evidence that treating the correlating depression is more effective than anything we could do. I don’t know if you are actually trained to treat depression, but I’m not. I don’t even know what CPT code I would use for that. Therapeutic exercise (97110) to get those endorphins going?

Now what about manual therapy? We all point and laugh at the lack of science behind things like acupuncture, craniosacral therapy, etc but then hold up manual therapy as being somehow more plausible (you already know what I think about mere plausibility). Maybe it is because we have all spent a TON of time and money on manual therapy continuing education and certifications. I smell a sacred cow… When I graduated from PT school, we all knew that manual therapy worked, but we just didn’t know HOW it worked. We simply could not find the specific physiological effect but we knew it worked because of the subjective and functional outcomes (sound familiar?). Remember, not just plausible ideas that have be inductively reasoned from scientific premises, but actual objective, experimental evidence.

It is now 15 years later and we still have no specific physiological effect. All we have now is, “Move it and move on.” Seriously? No physiological finding specific to the injured population that is then changed through manual therapy? Am I the only one uncomfortable with people calling that position “scientific”?

Actually I’m not. Read this editorial from the special issue of Physical Therapy Journal devoted to manual therapy. Now realize that it was written 20 years ago. Many of these concerns remain and many of the questions are still unanswered. Are we reasoning in circles? I really miss Dr. Rothstein… But what about the Clinical Prediction Rule (CPR) for spinal manipulations? Isn’t that science? Let’s go back to my example of Sir Bedevere:

That silly scene ends in an experiment where they try to see if the woman weighs more or less than a duck (I preferred building a bridge out of her). They answered their question but who cares? Their entire premise for doing the experiment was based on several steps of induction that were ultimately wrong. This is known as “tooth fairy science”.

Coined by Harriet Hall of Skeptic Magazine and Science-Based Medicine fame, tooth fairy science refers to a perfectly executed experiment based on a false premise. If you assume that the tooth fairy exists, you can produce all kinds of research on tooth value, room orientation, where the child sleeps, etc. No matter what your findings, if the tooth fairy doesn’t exist, your research is moot. Also, just because the research was conducted properly and may even be very reproducible and statistically significant, it does not retroactively verify the premise – it doesn’t make the tooth fairy real (sorry to disappoint).

Remember when I wrote that induction is useful to create testable hypotheses? It is but you must test EACH STEP. One, just ONE, untested premise that is assumed to be accurate can bring down all of the following data. Remember the tooth fairy is not always so obvious as Sir Bedevere’s witch.

Sure, you can cluster findings to see if you can predict who will respond the best to spinal manipulations but you still don’t have any specific effects. How do you know whether or not you are merely enhancing the non-specific effects? Limited hip rotation means they will respond well to a spinal manipulation. Ok. Maybe earlobe length is also a predictor. Is that actually useful information or are we simply looking for a way to confirm our hypothesis that manual therapy is effective beyond placebo? Like tooth fairy science, it skips a step. What if I created a similar CPR to find out who will respond the best to acupuncture or craniosacral therapy before I found a specific effect in which to test against? Would that make those scientific?

Don’t get me wrong, I like the intent and the authors have done a great job trying not to overstate things, I just question the sequence. Besides, when it was expanded to a larger and more diverse population, it didn’t do so well.

What about manual therapy and the neuroscience of pain? Ok, that might also be plausible. Now show me the experimental data that shows that manual therapy has a specific, consistent, measurable, and physiologic effect on that. All you have is pain and perceived function? Hmmm. Makes sense, could be right, but where is that experimental data? Can’t yet think of a way to falsify it? Well then – “No comment.”

Thank you for indulging me this series of posts. I hope that this has made you think about your application of Evidence Based Practice with a little more critical perspective.

Oh, and one other thing: Don’t just bitch about the APTA. Roll up your sleeves and volunteer or shut up. Your section, your chapter, and your national association all are in desperate need of your time and input and have plenty of opportunities for you to get involved. Make a difference in the game, not a complaint from the sidelines…

If you would like to leave a comment, go to the final post of the series.