An informal dialogue between Michael Frank (M, italic) and Fred Dretske (F). Includes comments (indented, in brackets, italic) that Michael added later after an interview with Winograd that were intended to reflect Winograd's perspective.
M: Let's see. Seems to me like the element of Terry's philosophy or position that seems to bother a lot of people the most is the refutation of realism element. He has this view that instead of positing the objective existence of objects and properties, you just say that in the context of some discourse you assume, you take for granted the existence of objects and properties, but really they're not there, and in other discourses you could break that --
F: I think that he'd probably object to that way of putting it, he'd say, whether they're really there or not depends on what discourse you're in. You could quite well say that in some cases.
M: Right, but if you're trying to abstract away from all discourse, and look at it from a pure, I don't know, ontological perspective, you could - he might say that -
F: He'd probably say you can't do that; there is no such place to go to.
M: So what do you think about that? Do you think there is some absolute perspective you can go to, and from that perspective say what exists and what doesn't, what properties, what things are true and what aren't?
F: No, I don't think there are kind of perspectiveless positions, but I don't think my view, a realistic view requires such. It simply requires that however many perspectives there are, if there is a conflict between those perspectives, at most one of them's right. And I think that's the basis of realism, that there's a fact of the matter, something that's right.
[The eqivalent thing to this basis isn't missing from Winograd's view. It's just restated as follows: "there is a world." Or medium, or whatever. But breaking that world down into separate "facts", into objects and properties, is just a certain perspective on it, perhaps a useful perspective for our everyday provisional realisms, but by no means the objectively correct thing to do.]M: Is this right or wrong something we can discover by thinking about issues?
F: Well, in some cases thinking about, in some cases science. Their method for finding out who's right and what's right.
M: And, I suppose common sense is an element of that, too. But Terry would probably say that people's common sense doesn't always agree and that all arguments are ultimately founded in some kind of instinctive feel for what's true and what's not. And in trust, trust of authorities and trust of our own perspectives.
F: See, I don't think that's... it's wrong to ascribe what our senses tell us as something that's founded on faith or trust... I mean, someone says "I must have faith that you're in the room with me" - that's a total misdescription of what's happening, in a kind of cognitive or epistemological way. Now that gets into kind of deep problems in epistemology, and I think that's where the ultimate disagreement between Terry Winograd and me is, that we have different views about what can be known and how it's known, and what such knowledge comes down to.
[I'd like to hear more about what both Dretske and Winograd think about what can be known and how it's known.]M: I see. So you think that knowledge is grounded more in just obvious truth of...?
F: In our perceptual relationships to the world. I kind of take an informational view of this, that this is why we're endowed with the kind of information-delivery systems we have, so that we can kind of negotiate our way through and environment like this; that's what perception is, what knowledge is.
M: But sometimes perceptions are misleading.
F: Yeah. No instrument is perfect. M: And you can be convinced by some argument, if there's an authority who tells you something, and they have a good argument for it, they can convince you that what you're seeing isn't real, like, they can convince you that this is really a hologram or something. So maybe one could ask whether you might say that's always possible, that there could be another discourse in which someone could, where it would make sense to accept that what you previously said was an absolute truth, such as I'm in the room, or something, in the context of another discourse, would not be relevant, or would not be true.
F: Well, not that; I'm quite willing to admit that things could happen which would make me doubt, suspend judgement about a good many of the things that I now think are quite certain. I don't think that's particularly relevant to whether 1, I'm certain of them, or 2, whether they're true. I mean, if someone might convince me the golden gate bridge is too creaky to go across, untrustworthy, can't be trusted, and I might not go across it, I might not travel that way. If I did it might be quite safe or quite trustworthy. I don't think how gullible I am to the blandishments of skeptics has much relevance to what's trustworthy and what's not.
M: Well, one thing that truth of statements has to be founded on is the assumption of the objective reality of the objects that the statement talks about. However, it's not always so clear in nature what the precise boundaries of an object are, and it seems like one could conclude from that that maybe objectively there is no object per se, and that there are only different boundaries at which we delineate the object to deal with it in our statements.
F: Well, that I think's true, you might say, look, what we know is pretty much a function of how we carve up the world, if you will, and if we carved it differently, I mean we treat that chair over there as an object and not as 20 objects... yeah, we do, and one can imagine a scheme where things are carved differently, where that was grouped with the person in the next room and treated as one object... a distributed object. I'm quite happy to entertain those alternative conceptual schemes. I'm not saying that the only way to carve it is the way we carve it, I'm only saying that given the way we carve it, some things are true and some things are not. Now if we carved it differently, you would find an equal breakdown in what's true given that carving and what's false. These aren't incompatible. If someone treated that as a single object and said there's only one object in these two rooms, he'd be right, if I said there's two objects I'd be right; we're not disagreeing.
[A consistent view, but in practice we can never get to the "facts" of the matter, so why bother?]M: So you think we are open to carving things up in different ways.
F: I think that's what science does when we find physics so unkind, it's like...
M: Everying becomes a wave... So you would say, it still doesn't mean that your original statement wasn't true, that, I don't know, this chair is brown, because that is assuming a specific way of carving it up which is included in that statement. Okay. So that's interesting. What else do you think about Terry's perspective on this thing. You think he would disagree with you on what you just said?
F: I think he would. Some of the things in his handout, John Perry was reacting often the way I would react to Terry, I mean we got a couple of philosophers together...
M: Like Perry was saying, you've gotta believe the chair you're sitting in is real! It's ridiculous...
F: So maybe that's kind of a typical philosophers way of reacting in this kind of... we would obviously analyze Terry's mistakes... confusing epistemology with ontology, how we know and whether we know with what's there to be known. Of course, Terry isn't going to agree with that way of describing his mistakes. But I nonetheless think that's the source of it.
[Terry knows what ontology is. He just doesn't think it's relevant or useful.]M: Epistemology vs. ontology? What do you think Terry thinks exactly? He thinks ontology is the same?
F: He looks at us, and he says look, we live in perspective, we live with conceptual schemes, we are kind of a community of truth-seekers, we have opinions and attitudes that are pretty much reflected in our... Now given this kind of way of thinking about it, truth, independently of the whole enterprise of finding this truth, sounds like an abstract commodity that doesn't bear on any practical issues, and thus is set aside as at best some philosophical convention. I think that's Terry's attitude, say, look, let's kind of get practical here, and see what actually determines our beliefs, and it will be things like a universe of discourse, and impingings on our sensory surfaces, and what's out there doing it, that's... He would regard that as the only available... in a way, I would say that's just doing epistemology. Don't mistake the limitations on our methods for an absence of what those methods are designed to tell us about. I may not have any way of telling what's in distant stars in outer space, I wouldn't conclude from that that there are no distant stars, or that they're hollow.
[Terry doesn't mistake the limitations on our methods for an absence of the world. He just doesn't think that it's useful, for his purposes, to accept a carving-up of the world into facts. (Not just a particular carving-up, but also the idea of the set of all possible carvings-up. Even just focusing on this set is making a distinction, and Winograd doesn't think it's a useful one.)]M: So there is some truth out there around us. Can you ask what truths are really there in the real world, independent of us?
F: I wouldn't call them truths, because truths are pretty much... a truth is what we believe or what we say, so you need kind of conscious agents to have truths, what's true is what conscious agents believe or say. But what's in the world that makes the truths true, sametimes called facts, states of affairs, those are there quite independently of whether there's conscious agents to describe them and have beliefs about them. Such is the, as it were, faith of a realist.
M: The world is there independently, but the world may not have a natural way of being carved up, in other words, so the world doesn't naturally have statements about it that are in terms of chairs and so forth. Let's say there's a world with no people in it, is it true, I mean absolutely, without reference to people at all, that "the earth is circling the sun", talking about objects that, these composite objects and so forth.
F: Well, see, I would say yeah, if you take people away it doesn't become a kind of homogeneous bowl of jelly with no carving, no joints, as it were, what it is out there is it has exactly the joints we, given our conceptual scheme, take it to have.
[I don't think the world is a homogeneous bowl of jelly. I never said that. The world is the world. You can characterize it any number of different ways, but each one is just a provisional reality, for the purposes of the discourse at hand. Characterizing it as having joints is a provisional thing, but saying that it's provisional isn't saying "the world is really homogeneous."]M: Well, because we're talking about it, but what if we weren't talking about it.
F: Then there would be the chair in the room independently, if we all got wiped out, there'd still be the chair.
M: But you're saying that now because you do exist, but if you you didn't exist now at all to talk about it, there would just be a bunch of atoms and molecules and so forth.
F: But there would still be the world the fact which, were I to talk about it, would make what I say true, and that fact is there's a chair in the room. Somebody else'd say ah, but we don't talk about chairs, we talk about several objects combining, I say fine, there's that fact in the world to which makes your statement true were you around to make it. What the world isn't like is such as to make my statement true and false at the same time.
[No, I'm not saying the world is like that. The world is a certain way. And most of our provisional systems of truth do depend on the way the world is. But you can't say that *really*, outside all provisionality, the way the world is should be described in terms of facts that it supports, because doing that is just a provision we adopt. A slogan for further thought: "There is a world" is a statement we adopt in our provisional reality, but you can't say (with total objectivity) that *really*, outside all provisionality, there is a world. This doesn't imply there isn't a world. But saying "there isn't a world" doesn't seem very useful conceptually. So could the realists have the same defense, that adopting the provision that "there are no facts" also doesn't seem useful?]M: But it's not like the world is making up the delineations, the objects. The world isn't doing that, we're totally doing that. And we always do that and we can't avoid doing that probably.
F: When we carve up nature, it isn't as though we're affecting nature, we're kind of partitioning, we don't affect nature in the way we conceptualize it, all we do is sort things out so that we can set about describing them, we may say I want these things to be in a class I call A and these things a class I call be so that I can say things about A's and B's. Now that doesn't affect the things I put in those classes.