What is This Thing Called Knowledge?

In critical rationalism, duhem, experiments, induction on 13/07/2011 at 12:21 pm

Duncan Pritchard, who holds a chair in epistemology at the University of Edinburgh, published What is This Thing Called Knowledge? some years ago. He has three textbooks, two published books on epistemology, and approximately fifty journal articles to his name. Let me make this clear: Pritchard is no first-year undergrad at a community college. And yet, his What is This Thing Called Knowledge? has a short section on Popper’s response to the problem of induction that is … shameful. Just shameful.

Some highlights:

“If Popper is right on this score [on the problem of induction being unsolvable], then it follows that we needn’t be quite as troubled by the problem of induction as we might have thought we should be, since it is not as if as much of our knowledge of the world–gained through science–is dependent upon induction as we originally supposed. But does Popper’s rather radical solution to the problem work?

I wait with bated breath to hear Pritchard’s criticism.

There are a number of problems with Popper’s proposal; we shall here consider the two main ones. The first problem arises because if we understand our scientific knowledge in the way that Popper suggests, it’s not clear that we have all that much scientific knowledge. … It seems, then, that we can never know the unfalsified generalisations that scientists make; we can only know that falsity of those generalisations that have been shown to be false. It seems, then, that we lose a lot of our knowledge on the Popperian view after all. (bolding mine, p. 105-6)

This is a problem only if knowledge is taken to be justified true belief, but this problem exists only when said theory of knowledge encounters the problem of induction: inductive inferences do not in any way justify scientific theories. How is this then a problem for critical rationalism when critical rationalism does not take knowledge as justified true belief?

The second problem with Popper’s proposal arises because it is not obvious that scientists are able to deduce the falsity of one of their bold generalisations simply by observing what seems to be a decisive counter-example to the generalisation. … Suppose that for many centuries people have observed that emus were flightless, and so came to believe that all emus are flightless. Now suppose that one day a scientist comes into the room and claims that she’s just seen a flying emu. How would you respond? (bolding mine)

“… you certainly wouldn’t abandon your belief … just on the basis of this one instance of testimony. After all, given the long history of observations of flightless emus, other explanations of what this scientist seems to have observed seem far more preferable. At the uncharitable end of the spectrum, one might suspect that the scientist was simply wrong in her observation, or perhaps even deceitful. Even if one trusts the scientist … one could note that there are birds in the area which can look a lot like emus in certain conditions. More radically, one might simply assert that whatever this creature was that was flying, it couldn’t have been an emu, since it is characteristic of emus that they don’t fly, and so it must have been a different creature entirely … one that is just like an emu in every respect except that it flies.

Yes, Pritchard makes the elementary mistake of confusing the falsifiability of theories–the logical possibility of uncovering an existential statement that contradicts a strictly universal statement–with the falsification of theories. Does anyone think that scientists would uncritically adopt existential statements that corroborate scientific theories? Of course not! That is just stupid. Scientists would just adopt every single statement they were told! Why, then, should a criticism of Popper assume that scientists would uncritically adopt existential statements that refute scientific theories?

I cannot believe I am saying this, I hope that it is obvious that scientists do in fact spend a great deal of their time intersubjectively criticizing the purported results of tests, for the results of tests may in fact be erroneous. Good grief.

Since this pseduo-criticism keeps cropping up in popular expositions of critical rationalism, I’ve begun to worry about the current state of scholarship. Has Pritchard ever heard of a primary source? Has Pritchard ever read even a snippet of the relevant passages from The Logic of Scientific Discovery? And where was the reviewer during this whole process? Were they as inept as Pritchard?

“The point about all of this is that one isn’t obligated to take any observation at face value. Moreover, there seems nothing essentially irrational about objecting to the observation in the sorts of ways just outlined provided that the generalisation called into question by the observation is sufficiently well confirmed by other observations.” (106).


  1. It’s very difficult to find a good criticism of critical rationalism.

    Popper seems to have become a cautionary tale in the philosophy of science. Fairy tales are told about how a brilliant but arrogant young man presumed to slay the monstrous problem of induction; but his desire for glory blinkered him to his own weaknesses, and Popper was slain by the monster.

    This is what I imagine most students of philosophy are told about Popper. They are never encouraged to research this fiction or try to understand the nuances of Popper’s work. Occasionally, without blink or stutter, Popper is described as “brilliant,” and then accused of making elementary logical or factual errors.

    • The best criticism I’ve found is by people sympathetic to, or at least familiar with, CR: Miller and Tichy’s criticism of Popper’s theory of corroboration; Rowbottom’s recent reformulation of ‘rationality’ as a function of a community of critical and dogmatic individuals, rather than a function of individual behavior; Bartley’s work on CCR; &c.

  2. It makes me think that a lot of philosophy is about towing the party line. It’s like all these intellectuals read the same pamphlet attacking Popper, because their arguments are near word for word the same. That these arguments are (1) wrong, (2) wrong, and (3) have been refuted by critical rationalists what seems like uncountably many times, seems never to change the story.

    The Popper fairy tale meme is remarkably robust. What is it about the contemporary philosophers mind that makes it such a fertile environment for a meme which is so utterly wrong on so many levels?

    • I think three anecdotes are necessary:

      First, when as an undergraduate, I took an intro to philosophy class. When we covered the problem of induction, the professor gave an example of looking under plants and each time seeing a lady bug, and how after a large enough number of corroborations, the probability of seeing a lady bug under the next plant increased.

      Of course, I was a snot-nosed brat back then, so I thought I could talk to the teacher.

      After class, I told the professor that after Carnap, the example was a case of equivocation–it confused statistical analysis with scientific theories, and therefore inadequate if it were to properly reflect scientific theories: we have an infinite number of plants to look under, so the probability cannot increase for the next plant. He pulled rank, and said that I would understand when I was older.

      Later on in the year, we were given two readings on Popper–I remember this fairly vividly: a bit from Conjectures and Refutations and Putnam’s critique of Popper’s theory of corroboration. I offered to scan Popper’s reply to Putnam so that the class would get a chance to see both sides, but the professor said that it would be too much reading.

      At that point, I gave up.

      Third, again as an undergrad, during lunch one day with another professor, we started talking about the problem of induction. I brought up Popper’s solution as a viable option. He responded that a refutation corroborated the negation of the scientific theory, as if this was a criticism of Popper’s solution. I said (paraphrasing), “The statement ‘This here is a non-black raven’ is identical to ‘Not all ravens are black’. What of it?” He kept insisting that this was a serious criticism. Now I see Constantius on the CR thread making the same argument.

      What’s going on here? Am I taking crazy pills?

      • Most critical rationalists are amateurs.

        I never finished college; I don’t personally know anybody who is interested in philosophy. (I know a retired philosophy professor, but he long ago stopped being interested in philosophy!) Because of ongoing immigration procedures, I am currently unable to work legally; I do some unofficial work for a local general contractor and gas station owner. Even if I could work legally, I don’t have any particularly useful qualifications or experience; I certainly have no formal education in philosophy.

        If it wasn’t for the fact that I, of course, think I am right, I would otherwise consider it a bad sign that you agree with me.

        On that note, do you have access to the criticisms you mentioned in the other comment (particularly Miller and Tichy’s criticism of corroboration)? I can’t access any of the papers, and I want to do some research for a post I am writing for the Critical Rationalist Blog.

        • Lee,

          Most critical rationalists are amateurs because (in part) there are more amateurs than philosophers.

          I have both papers, and can send them to you. Rowbottom’s work is readily available on his website.

          I’m quite lucky to have access to JSTOR and other electronic journals. As of this moment, I have … approximately 550 electronic articles on CR that would love to be shared.

          • Well, there are more amateurs than philosophers. I really meant that a higher proportion of amateurs are critical rationalists than philosophers.

            In any case, you have my email. I would appreciate it if you would share those papers and any others that you believe are particularly interesting. I would also be interested in reading papers that you have written.


        • Lee,

          I plan on sending you a link sometime this week–after looking through a few other folders, I have approx. 680 papers!– I would have to ask David Miller for permission to send a few papers, and it’s just better to send you the rest before contacting Miller again.

          Sorry, I plan on staying anonymous.

  3. I have no intention of publicly revealing your identity.

    And I look forward to receiving the papers!

  4. It is good to see you on the CR blog!

    What if you send me the stuff you send to Lee?


    As you may have noticed on the CR blog I have been listing some of the abominable misrepresentations of Popper. A trained monkey could work through the shelves and find millions of examples, but I don’t have a trained monkey so I have to do it myself. Not sure where to go with it.

    It needs to be put on record but the more or at least equally important task is to demonstrate the power and utility of the ideas. My favorite applications are Austrian economics and classical liberalism.


    • Thank you for the compliment.

      I’ll send you the articles once I’ve removed a few I promised David Miller I would not share. They’re mostly on logic and probability, so you aren’t missing much.

      I’m favorable to Austrian economics and classical liberalism, although I think CR after Bartley helps out non-justificatory ethics. I know little about aesthetics or metaphysics, so that leaves my two areas of interest: epistemology and the philosophy of science.

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