What do you know? What is Knowledge? And Do We Have Any?
Pritchard (Duncan)
Source: Ward (Dave), Pritchard (Duncan), Massimi (Michela), Lavelle (Suilin), Chrisman (Matthew), Hazlett (Allan) & Richmond (Alasdair) - Introduction to Philosophy
Paper - Abstract

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Author’s Abstract

  1. We know a lot of things – or, at least, we think we do. Epistemology is the branch of philosophy that studies knowledge; what it is, and the ways we can come to have it. This week, we’ll take a tour through some of the issues that arise in this branch of philosophy. In particular, we’ll think about what radical scepticism means for our claims to knowledge. How can we know something is the case if we’re unable to rule out possibilities that are clearly incompatible with it?
  2. Author: Professor Duncan Pritchard joined the Edinburgh department in 2007 as the new Chair in Epistemology. His research is mainly in epistemology, and his most recent book, ‘Epistemic Disjunctivism’1 has just been published by Oxford University Press.


Lecture 1: What is knowledge?
Lecture 2: Do we have any knowledge?

  1. The two brief lectures have a fairly full write-up (here: Link; summary above).
  2. Various items of extra reading are suggested on the website


Correspondent 1
  1. I liked the way he built up the argument for propositional knowledge. It was clear enough for me to follow! However, I do wonder why it took over 2000 years for someone (Gettier) to come up with a disproof of Plato’s argument. Strange – unless you think that all the exceptions have to be pretty far-fetched, and so maybe philosophers in previous centuries did not think this worth pursuing? Also, is there a use to which this can be put? Being of a practical mind, I wonder whether there is any important scenario where this sort of thinking might help, or is it just thinking for thinking’s sake? I suppose that is coming back to what was said in week one, where it said there had to be not only argument, but also vision in philosophy, or else what’s the point? So, what do you think Gettier’s vision is?
  2. The radical scepticism and brain-in-a-vat idea of course made me think of the Matrix, as he mentioned. (Did you ever see that?) Of course it may be a theoretical possibility that cannot be disproved, but is it likely or rational, one asks – or at least I do. Perhaps we exist in a dream within a dream within a dream (another film!) but again, I can’t really think of any practical use of thinking like this. Maybe you can, as of course you’ve studied all this a lot more than us.
  3. Mike’s comment on us not knowing as much as we think we do, was that it doesn’t matter, as long as it works! (maybe he’s thinking mathematically here?)

  1. I'm not sure there's any argument (as such) for propositional knowledge. There's an argument that if there is any, then it's "justified true belief" - but this is really an attempt to define "propositional knowledge" based on correct usage. Plato thought of occasions in which the word "episteme" was used and the circumstances in which we'd not say it applied; similarly the lecturer. "Justified true belief" is good enough for most purposes - even philosophical ones. I suppose that philosophers were confident they knew what knowledge was, but were more worried by the skeptical arguments that we don't have any. Anyway, the argument really comes in when Gettier and his followers argue that the definition isn't good enough to capture what we mean by "knowledge".
  2. It's interesting that Plato would have agreed that the word "knowledge" has a designative meaning - because he thought there was a Form of true Knowledge in heaven of which examples of human knowledge are pale reflections. Nowadays we don't think of abstract nouns as designating abstract objects that have some form of concrete existence somewhere. Or at least I don't. Plato did argue for the truth of definitions, because he thought there was something "out there" in heaven that the definition latched on to. Now we're just trying to be clear what it is we're talking about.
  3. As for the importance of all this - well, modern philosophy hails from Descartes, and his search for a sound basis for knowledge. So, nothing could be more important to philosophers than the thought - not just that we might not have any knowledge, but - that we don't even know what knowledge is. Personally, I'm not worried - I'm happy with justified true belief - or even with justified belief, and that the practical focus should be on beefing up the standards and procedures of justification so that our beliefs have the greatest likelihood of being true as is possible. The fact is that lots of statements that once counted as knowledge have turned out to be false, and no doubt many things that we claim to know today will turn out not to have been knowledge, on account of not having been true. But we might still have been justified in believing them and acting on them as knowledge.
  4. I don't know what Gettier's vision is - maybe it's just to point out a problem in the hope that someone will come along and fix it, or that it'll move philosophy on in some other way (eg. in recognising that the concept "knowledge" is less important than had been thought). At least it's a much more serious question that we might not know what knowledge is than that we might not correctly classify dodos as Columbidae.
  5. Well, yes - I've seen the Matrix and enjoyed it greatly. Philosophers have had fun with it too. I had dinner with a philosopher (Nick Bostrom) who considers it overwhelmingly probably that we are computer simulations (Click here for Note for some links). He has an argument for it. I disagree, you'll be glad to know, because I don't think computer programs are the sort of things that can have conscious experience. That's different from a piece of hardware that runs a computer program having conscious experience - I've nothing against sufficiently complex robots being conscious. But maybe I'm just prejudiced against simulation programs - the program has to be running on the simulation machine, so maybe the machine has multiple personality disorder3 run riot.

Correspondent 2
    One thing I didn't quite get was the patching up of the Classical Account (no false lemmas) to satisfy the Gettier-style cases. Prof Pritchard said (towards the end of the first video) that the "no lemmas" or no false assumptions would have satisfied the 'clock' case but NOT the 'sheep' case. Aren't these both the same? Both were based on false assumptions (that the clock was working and that the hairy dog was a sheep) whilst both being justified true belief and accidentally correct.

  1. You may have a point about the similarity of the cases, but no doubt they'd say that the error in the "dog" case is rather closer to home than in the clock case. That is, the time of day is what it is irrespective of whether the clock is working - so it's an independent check we have to make to ensure that the clock is working, and an assumption that it is (as it always has been in the past). However, whether the field contains a sheep is immediately connected to whether we've seen one. If we've seen a sheep, then there's one in the field, while if we've seen a normally reliable clock telling the time, that doesn't tell us (without the further lemma that the clock is working) that the time is that told by the clock. It would be a parallel with the "dog" case if somehow what we were looking at wasn't the clock we expected (there are such cases in Midsommer Murders - someone puts a mirror in the way so that the clock we see isn't the clock we expect to see).
  2. Now, if we in fact can't tell the difference between a dog and a sheep, that does call into question the reliability of our perceptive faculties - but it's a step closer to home (as I alleged above). Even if our faculties are perfect, in the "time of day" case (so we are actually seeing the clock we expect, not another one that we've no reason to think is accurate) we still have a further lemma - that the clock we perfectly see and expect to be accurate actually is working on this occasion, and not telling the right time by chance.
  3. Maybe it depends on what you mean by "assumed". We've made no attempt at all to check our assumption that the clock is working. But the whole point of knowing that there's a sheep in the field is that we had good evidence that the animal we saw was a sheep - but say we'd not looked carefully enough - we'd just assumed that the far-away blob was a sheep - then this wouldn't be a Gettier case at all - it would be a case of unjustified true belief, which isn't knowledge even on the classical account.
  4. There was a technical inaccuracy in the quiz, I thought. In both the mid-lecture quiz and the final quiz, you were supposed to accept the statement "The proposition must be justified", in that if you didn't you got the answer marked wrong (I tried it in the mid-lecture quiz). But propositions aren't the sort of things that are justified - they are true, false, interesting and so on - it's a belief in the truth of a proposition that can be justified. Knowledge is a relation between a true proposition and the purported knower, and the statement "The proposition must be justified" doesn't involve the epistemic agent. What they had intended to put was just that "The belief in the truth of the proposition must be justified". And as this is a course on thinking and expressing oneself clearly, we ought to take exception to inaccuracies. But not going so far as to fail to score full marks!

Correspondent 3
    The lecturer talked about radical scepticism (in particular the brain-in-a-vat argument). He posed the question "How do we know that we are not a brain-in-a-vat?" Well we know we are not a BIAV because we can communicate with people and read things that impart knowledge to us that we could not know ourselves (like the workings of the cell, for instance). Doesn't this prove that we are not a BIAV?

  1. I don't think your attempt to debunk the BIAV thought-experiment4 (TE) quite works. Of course, there are lots of vague elements to the TE, which is an objection to TEs in philosophy on general. The claim of the TE is that it's possible to imagine all the sensory input being fed into the BIAV, and this would include communications with what appear to be other people and the exposure to knowledge. Isn't that what's supposed to be happening in "The Matrix"? Before Neo gets disconnected, he thinks he's living a normal life - learning stuff, talking to his friends, working on the computer - but he's radically mistaken. All this information comes from The Matrix itself, fed into his brain through the connection that goes in through the back of his head. So, he's not really typing on his computer and learning stuff from the internet - he gets all his information - much of it incorrect - from The Matrix, or rather from the creator of The Matrix. He learns true things about cells, but while he has cells, they aren't the cells he thinks he has, because the cells he might see are simulations of real cells - and his computer is a simulation of an archaic computer, and so on. Or so we are to imagine, and it's not obviously impossible.
  2. I had dinner once with a philosopher (Nick Bostrom) who considers it overwhelmingly probable that we are computer simulations (Click here for Note for some links). This isn't quite the same as being a BIAV. He has an argument for it. I disagree, you'll be glad to know, because I don't think computer programs are the sort of things that can have conscious experience. That's different from a piece of hardware that runs a computer program having conscious experience - I've nothing against sufficiently complex robots being conscious. But maybe I'm just prejudiced against simulation programs - the program has to be running on the simulation machine, so maybe the machine has multiple personality disorder5 run riot.
  3. Another philosopher thinks that even if we are BIVs, we do have the knowledge we think we have - because (if I remember correctly) when we say "I have two hands" the meaning of these words arises from their common use, so the word "hand" stands for "simulated hand". He – David Chalmers – is a very prominent guy, so can't be dismissed out of hand, but I don't agree with him. It's an onward link from the previous link - "Chalmers (David) - The Matrix as Metaphysics"; there's an onward link to the actual paper, which is still on-line.


In-Page Footnotes

Footnote 2: The principle that to know something, you need to know that you know it – but there are lots of things that we know that we don’t know that we know until asked. So, while we might not know whether we’re dreaming, this doesn’t stop us knowing things about the external world. Provided we are in fact not dreaming, but are perceiving the world, we don’t need to know that we are perceiving the world in order to know what these perceptions tell us.

Text Colour Conventions (see disclaimer)

  1. Blue: Text by me; © Theo Todman, 2020
  2. Mauve: Text by correspondent(s) or other author(s); © the author(s)

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