Philosophy & My Old Husky I: Post Hoc & Anecdotal Evidence

dogpark065My Siberian husky, Isis, joined the pack in 2004 at the age of one. It took her a little while to realize that my house was now her house—she set out to chew all that could be chewed, presumably as part of some sort of imperative of destruction. Eventually, she came to realize that she was chewing her stuff—or so I like to say. More likely, joining me on 8-16 mile runs wore the chew out of her.

As the years went by, we both slowed down. Eventually, she could no longer run with me (despite my slower pace) and we went on slower adventures (one does not walk a husky; one goes adventuring with a husky). Despite her advanced age, she remained active—at least until recently. After an adventure, she seemed slow and sore. She cried once in pain, but then seemed to recover. Then she got worse, requiring a trip to the emergency veterinarian (pets seem to know the regular vet hours and seem to prefer their woes to take place on weekends).

The good news was that the x-rays showed no serious damage—just indication of wear and tear of age. She also had some unusual test results, perhaps indicating cancer. Because of her age, the main concern was with her mobility and pain—as long as she could get about and be happy, then that was what mattered. She was prescribed an assortment of medications and a follow up appointment was scheduled with the regular vet. By then, she had gotten worse in some ways—her right foot was “knuckling” over, making walking difficult. This is often a sign of nerve issues. She was prescribed steroids and had to go through a washout period before starting the new medicine. As might be imagined, neither of us got much sleep during this time.

While all stories eventually end, her story is still ongoing—the steroids seemed to have done the trick. She can go on slow adventures and enjoys basking in the sun—watching the birds and squirrels, willing the squirrels to fall from the tree and into her mouth.

While philosophy is often derided as useless, it was actually very helpful to me during this time and I decided to write about this usefulness as both a defense of philosophy and, perhaps, as something useful for others who face similar circumstances with an aging canine.

Isis’ emergency visit was focused on pain management and one drug she was prescribed was Carprofen (more infamously known by the name Rimadyl). Carprofen is an NSAID that is supposed to be safer for canines than those designed for humans (like aspirin) and is commonly used to manage arthritis in elderly dogs. Being a curious and cautious sort, I researched all the medications (having access to professional journals and a Ph.D.  is handy here). As is often the case with medications, I ran across numerous forums which included people’s sad and often angry stories about how Carprofen killed their pets. The typical story involved what one would expect: a dog was prescribed Carprofen and then died or was found to have cancer shortly thereafter. I found such stories worrisome and was concerned—I did not want my dog to be killed by her medicine. But, I also knew that without medication, she would be in terrible pain and unable to move. I wanted to make the right choice for her and knew this would require making a rational decision.

My regular vet decided to go with the steroid option, one that also has the potential for side effects—complete with the usual horror stories on the web. Once again, it was a matter of choosing between the risks of medication and the consequences of doing without. In addition to my research into the medication, I also investigated various other options for treating arthritis and pain in older dogs. She was already on glucosamine (which might be beneficial, but seems to have no serious side effects), but the web poured forth an abundance of options ranging from acupuncture to herbal remedies. I even ran across the claim that copper bracelets could help pain in dogs.

While some of the alternatives had been subject to actual scientific investigation, the majority of the discussions involved a mix of miracle and horror stories. One person might write glowingly about how an herbal product brought his dog back from death’s door while another might claim that after he gave his dog the product, the dog died because of it. Sorting through all these claims, anecdotes and studies turned out to be a fair amount of work. Fortunately, I had numerous philosophical tools that helped a great deal with such cases, specifically of the sort where it is claimed that “I gave my dog X, then he got better/died and X was the cause.” Knowing about two common fallacies is very useful in these cases.

The first is what is known as Post Hoc Ergo Propter Hoc (“after this, therefore because of this”).  This fallacy has the following form:

  1. A occurs before B.
  2. Therefore A is the cause of B.

This fallacy is committed when it is concluded that one event causes another simply because the proposed cause occurred before the proposed effect. More formally, the fallacy involves concluding that A causes or caused B because A occurs before B and there is not sufficient evidence to actually warrant such a claim.

While cause does precede effect (at least in the normal flow of time), proper causal reasoning, as will be discussed in an upcoming essay, involves sorting out whether A occurring before B is just a matter of coincidence or not. In the case of medication involving an old dog, it could entirely be a matter of coincidence that the dog died or was diagnosed with cancer after the medicine was administered. That is, the dog might have died anyway or might have already had cancer. Without a proper investigation, simply assuming that the medication was the cause would be an error. The same holds true for beneficial effects. For example, a dog might go lame after a walk and then recover after being given an herbal supplement for several days. While it would be tempting to attribute the recovery to the herbs, they might have had no effect at all. After all, lameness often goes away on its own or some other factor might have been the cause.

This is not to say that such stories should be rejected out of hand—it is to say that they should be approached with due consideration that the reasoning involved is post hoc. In concrete terms, if you are afraid to give your dog medicine she was prescribed because you heard of cases in which a dog had the medicine and then died, you should investigate more (such as talking to your vet) about whether there really is a risk of death. As another example, if someone praises an herbal supplement because her dog perked up after taking it, then you should see if there is evidence for this claim beyond the post hoc situation.

Fortunately, there has been considerable research into medications and treatments that provide a basis for making a rational choice. When considering such data, it is important not to be lured into rejecting data by the seductive power of the Fallacy of Anecdotal Evidence.

This fallacy is committed when a person draws a conclusion about a population based on an anecdote (a story) about one or a very small number of cases. The fallacy is also committed when someone rejects reasonable statistical data supporting a claim in favor of a single example or small number of examples that go against the claim. The fallacy is considered by some to be a variation on hasty generalization.  It has the following forms:

Form One

  1. Anecdote A is told about a member (or small number of members) of Population P.
  2. Conclusion C is drawn about Population P based on Anecdote A.

For example, a person might hear anecdotes about dogs that died after taking a prescribed medication and infer that the medicine is likely to kill dogs.

Form Two

  1. Reasonable statistical evidence S exists for general claim C.
  2. Anecdote A is presented that is an exception to or goes against general claim C.
  3. Conclusion: General claim C is rejected.

For example, the statistical evidence shows that the claim that glucosamine-chondroitin can treat arthritis is, at best, very weakly supported. But, a person might tell a story about how their aging husky “was like a new dog” after she starting getting a daily dose of the supplement. To accept this as proof that the data is wrong would be to fall for this fallacy. That said, I do give my dog glucosamine-chondroitin because it is cheap, has no serious side effects and might have some benefit. I am fully aware of the data and do not reject it—I am gambling that it might do my husky some good.

The way to avoid becoming a victim of anecdotal evidence is to seek reliable, objective statistical data about the matter in question (a vet should be a good source). This can, I hasten to say, can be quite a challenge when it comes to treatments for pets. In many cases, there are no adequate studies or trials that provide statistical data and all the information available is in the form of anecdotes. One option is, of course, to investigate the anecdotes and try to do your own statistics. So, if the majority of anecdotes indicate something harmful (or something beneficial) then this would be weak evidence for the claim. In any case, it is wise to approach anecdotes with due care—a story is not proof.

  1. Doris Wrench Eisler

    There are propositions that are clearly wrong as in a recent fringe group’s belief that chlorine solutions are a cure for autism. Chlorine is highly toxic and should never be taken internally for any reason. No data needed. But the perception that statistics can be deceiving is correct and not new. Fluorine in drinking water has been defended for years because negative effects are not obvious, and differential effects have not been calculated. But it is reasonable to say that a small amount of something that has significant positive effects might also have significant negative effects under specific circumstances.
    The ill would be more susceptible to negative effects as would newborns, the very young (for whom the ingredient is intended) and those who drink large amounts of water. Many cities have eliminated fluoridated water in consideration of these possibilities, in favour of providing fluoridation to the group most apt to profit from it and in a form not taken internally.
    Some argue that small amounts of radiation in the environment is actually good for the general public because radiation is used in cancer treatment. This is patently false but you can’t convince the nuclear industry of it.
    It took over a hundred years to conclude that nicotine was carcinogenic and even longer regarding second-hand smoke. Politics and profit had a lot to do with that. Anecdotal evidence, or common sense, or taking into account that your heavy-smoking friends and relatives were dying might have saved lives.
    Concerning our furry friends I once listened to a vet praise to the skies a flea powder so powerful that a tiny fleck of treated dander on a sofa would kill any flea that came into contact with it. I wasn’t impressed. It seemed like overkill by a mile to me.The negatives are obvious, and I’m not a vet or statistician. But if a treatment for older, ailing dogs seems reasonable and causes no obvious pain or discomfort, it’s worth taking a chance. Reasonable chances are what reasonable people take.

  2. I wholly agree with you.
    Just few hours ago, an aunt, her son, his wife and I were talking about how someone doesn’t want to try a Korean-made chiropractic device. Because, according to that person, caused of the amputation of the arm of a elderly lady. Fortunately, we knew the lady that person was talking about and knew first hand what really happened. The truth was, the lady whose arm got amputated, slipped on the wet floor -it rained a few minutes before- outside the building and fell on her arm dislocating it. We don’t know what they did to her at the ER, but her arm went from bad to worst. Because she had been using the machine a couple of times before the accident happened, someone made a conclusion it is because of the device, that her arm got amputated. (Post Hoc Ergo Propter Hoc) That person is also inferring that, because of what happened, the device is dangerous to use. Even though there have been significant proofs of the effectiveness of the device particularly on stroke victims. (second form of Fallacy of Anecdotal Evidence)
    In the TV series “NCIS”, the protagonist “Leroy Jethro Gibbs” played by Mark Harmon, has rules which he and his team follows. “Gibbs’ Rule #3” goes “Don’t believe what you’re told. Double check”. Though the character is fictional, that rule could be applied to real life. In this age where there are a lot of information going around especially online, one should always do a great deal research before believing anything they hear or read.

  3. “The way to avoid becoming a victim of anecdotal evidence is to seek reliable, objective statistical data about the matter in question (a vet should be a good source). This can, I hasten to say, can be quite a challenge when it comes to treatments for pets.”

    This is also a challenge for doctors treating humans. And actual doctors who publish, can be quacks and kranks too. Robert Lustig, is a highly qualified doctor. But, his position on high-fructose foods is utter quackery. The chemistry of sugar is well understood, wherever Lustig got his initial idea about fructose, it did not originate from science, but something planted the seed.

    A friend who’s a doctor. One of his problems is the way some of his patients react when he tells them they need to lose weight. They go on the internet and say libelous, professionally damaging, and generally horrible things about him. It might be in their minds that he fat shamed them, so it’s fair game to strike back.

    People have an old pet that dies naturally. They’re angry; in the anger phase of the Kubler Ross model. They strike out at their vet, the manufacturer of the medication. The dog was old and it died, and nothing could help it, is too hard to accept. Dog plus time, equals no dog.

    So, the internet will be flooded with all kinds of claims and theories from marketers to bereaved pet owners in relation to glucosamine-chondroitin complex. A product commonly prescribed by vets. What is this stuff anyway. Glucosamine, is an amine of the sugar; glucose. The body of a dog or man, can produce it by eating sugar and fat, or eating meat. Chondroitin is a derivative of Chondrin. And Chondrin is the jelly like stuff you get, when you boil down cartilage. The dietary theory being, if you want strong cartilage, you should eat cartilage. Now, if you look at the typical dog food, you’ll see jelly, bone meal, meat and other meal, if you check the labeling, it may even likely say there’s added glucosamine (you’ll sometimes see this labelled as a component of human food). American dogs, eat better than many billions of people on this planet.

    The stuff isn’t poison. But, if there’s so much of the stuff in the dog’s food to begin with, why would the vet prescribe a little chalk pill of it for the dog……Unless, of course….it’s not actually for the dog.

    The dog might prefer chicken soup.

    You could ask the vet, but maybe they don’t want the secret of their owner anxiety medication out of the bag. But they may believe it works; old dog has minor injury, they’re given the supplement, they recover from their injury. The belief of the efficacy of praying to Catholic saints follows the same Post Hoc Ergo Propter Hoc principle. And the fear of what happens when you don’t pray appropriately to the same saints. (in the Voodoo tinged end of Catholicism, the saints will not set out to harm you…but if you neglect them, don’t be surprised if they in turn neglect you. The Catholic patron saint of dogs, is St Roch. You could try a little prayer. I’ve known many people who swear by this kind of thing, they even say it works if you don’t believe in it.)

  4. Kevin Henderson

    Sorting out evidence for whether a product’s online reviews are accurate is also fascinating. Experience helps. Making purchases and assessing the value of the purchase personally is very useful to cross check the previous reviews. Critical reviews can more easily be identified as reasonable or outliers.

  5. My husky definitely prefers chicken to her medication. But, peanut butter makes the medicine go down in the most sticky way.

  6. I have been reading your blogs on scientific method with great interest as my main interest in philosophy has always been in this direction. I came across Mill’s methods of induction many years ago and was entranced by them. Eventually when I got university to study philosophy, being almost word perfect on the above-mentioned methods, I looked forward to what was called the philosophy of science where I assumed, the above-mentioned methods would be given some attention. Such was not the case however. It became obvious to me that probably all of my co-students and possibly some of the lecturers had no familiarity with this aspect of Mill’s work. As part of the undergraduate course we had to give lectures and I decided Mill’s methods would be one of them. The lecture at which two professional philosophers were present was received quietly. I looked forward to questions being asked at the end of the lecture as is the procedure, but received nothing in the nature of a penetrating question even from the professional philosophers. As I recollect my grade for the lecture was very good, so I assume the fault was not mine. It does seem that in this respect Mill is almost certainly a completely forgotten man. Additionally it also appears that few if any practicing scientists are aware of Mill’s work although much of their research reveals that thought has taken place along the lines laid down by Mill. It does appear from the monumental progress that has been made in science that ignorance of Mill’s methods has not been detrimental to progress in this direction, and I suppose the methods can be regarded these days as a common sense approach to problems. Philosophically speaking I feel that there is still a place for Mill in so far as the philosophy of science and its history is concerned but my own experience does seem to suggest that this is not the case.

  7. Don Bird,

    I think Mill is suffering from the general fate of useful philosophy: when philosophy is very useful, people seem to think that it is not philosophy. Thus, they can say “philosophy is useless.”

  8. I am of the opinion that people who say philosophy is useless are in fact unknowingly, making a philosophical statement. It is very difficult to meet a person who has no opinions whatsoever. Everybody has opinions on how to conduct one’s life, bring up one’s children, how to relate to others, and what is, or is not, the case. To a very large extent they are prepared to argue in favour of what they believe to be true. This is precisely what the person purporting to be a philosopher does, the only difference being the philosopher has taken steps to extend his knowledge of the world and also to find some way of broadcasting his views in what he believes to be a correct and comprehensible manner, although some have failed rather badly so far as comprehensibility is concerned. Our inborn instinct of curiosity is I think the basis of what we know, what we think we know, and how we are to express it to others. This is surely the basis of philosophical thought, which is to be found in varying degrees of ability, in the vast majority of human beings.

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