January 5, 2007

To Gettier or Not to Gettier

I recently constructed a Gettier case (described below), designed to show that Justification-reliabilism is insufficient as a reply to Gettier. (For a full discussion of the application of this Gettier case, check out my blog post 'Un-discriminating Reliabilism'.) However, some have questioned whether the Gettier case I constructed is really a Gettier case at all (see comments in aforementioned link). Specifically, one reader felt that the subject described actually does have knowledge. I would like to get other folks intuitions on this question. Do you think the following represents a genuine Gettier case:

Suppose S has strong perceptual evidence for, and comes to believe, the proposition:
(a) There is a red cube in the box on the table.
Now, it so happens that there is in fact a red cube in the box on the table, though the cube is being obscured from S’s visual field by some sort of barrier. Furthermore, the box is rigged up to a computer which projects a visual hologram of a red cube in the box. However, the computer is programmed to only project the hologram of the red cube in the box when there is a real red cube in the box. Moreover, S lacks any of this background information, and forms her belief that (a) purely on the basis of the hologram of the red cube. All of the following seem true in the above case:
(i) (a) is true

(ii) S believes (a) is true

(iii) S’s belief that (a) is justified (i.e., formed via a reliable process)
Ex hypothesi, (iii) is true since the computer is programmed to only project the hologram of a red cube when there is an actual red cube present (one may build in whatever stipulations one likes, such as that the computer is eternal and infallible in its operation etc.). Thus, S’s belief that there is a red cube in the box is reliable (and, according to justification-reliabilism, therefore justified) since the process by which the belief was formed would, given the computer’s programming, tend to produce true beliefs. However, I believe this represents a bona fide Gettier case since, though S has a justified (i.e., reliably formed) true belief, we wouldn’t say that she has knowledge.

It may also be interesting to get a non-philosopher's intuition on this question, so you may consider trying it out on a roommate or friend and letting me know what you come up with. Cheers.

Labels: , , ,


Blogger Ang said...


I think S knows the cube is in the box.

Your hologram case sounds very similar to a cases of prosthetic vision. Consider the following. Suppose S has lost his eyes, but a video camera is mounted on his head and hooked up to his optic nerve. This camera, however, picks up radiation that is unaffected by the box (the barrier between S and the cube). Does S see the cube? It sees he does. And it seems he knows the cube is in the box too.

I think the key here concerns how the hologram is being generated. If the hologram that matches the cube is generated *because* of the cube that is in the box, it seems you have described a case of a sort of "prosthetic" vision.

I analyze a number of cases using holograms in my paper on perception, available at my website.

Take a look, in particuar, at section 2, pages 12-16.

1/13/2007 07:52:00 PM  
Blogger AVERY ARCHER said...


I agree that in the case of "prosthetic vision" you describe, the subject does see the cube and also has the relevant knowledge. However, I believe there is a difference between such cases and the Gettier case outlined in this post, and it is a difference that gets to very heart of the point I'm driving at. In short, your subject has global reliability, whereas my subject only has local reliability. That is, given your description of prosthetic vision, we have no reason to believe that the subject goes around mistaking holograms for real cubes. In fact, far from suffering from any such deficiency, your subject has the added ability to see through black boxes!

In the case of my subject, however, it seems clear that she lacks the ability to discriminate between actual red cubes and holograms of red cubes. Admittedly, in the present (i.e., local) case, the subject's belief that (a) happens to be true, and it could not (again, only in this local case) have easily been false. Thus, the subject possesses local reliability. However, her local reliability does not translate into the type of global reliability that would prevent her from being deceived by holograms of red cubes in general. (We may say that it is merely a matter of luck that her belief that (a) is reliably formed, read locally reliable.) I believe it is this fact that lies behind the "common sense" intuition (or at least what I claim to be such) that my Gettier subject lacks knowledge.

In sum, if your example is to effectively mirror my own, then the subject in question must possess visual abilities that are only locally reliable. The case of prosthetic vision does not seem to fit the bill. Of course, modifications can be made to the above Gettier case so that the subject is globally reliable (just like your subject in the prosthetic case), but that would defeat one of the central purposes for which it was constructed in the first place.

1/15/2007 07:28:00 AM  
Blogger Ang said...

I'm having trouble understanding how the global/local distinction is relevant to whether our subject sees (and knows that there is) the red cube in the box.

Maybe it would help if you explained how you would describe another similar case. (Sorry for throwing all these variants at you!) Suppose someone glues five paper-thin devices to the sides and the top of your box. The devices fit the box exactly. On the inside surface of each device is an array of cameras which pick up radiation from the red cube on the inside of the box. The outside surface *displays* what the cameras pick up.

Hopefully, all I have done here is to give a technical explanation of *how* the hologram of the red cube is being generated. So this is also a case of local (not global) reliability.

With the thought experiment so described, it seems to me that our subject sees the red cube. In fact, the devices seem straightforwardly to allow the subject to "see through" the otherwise opaque box surface.

1/16/2007 10:11:00 PM  
Blogger AVERY ARCHER said...

My distinction between local and global reliability was intended only to address the epistemic question, not the perceptual one. (You were more explicit regarding the perceptual claim in the version of your comments posted on my blog, so I responded to the perceptual claim there.) But just to recap the main point I made on my blog, I believe the prosthetic subject does “see” the cube because she can, inter alia, successfully refer to the cube demonstratively. My Gettier subject, by contrast, cannot. Why? Because if she attempted to do so, she would point to the hologram and not to the cube (which, ex hypothesi, is hidden from view). In short, she will inevitably get things wrong.

To make this explicit, let me exaggerate the original scenario a bit: Imagine that the black box is the size of a room. In the middle of the room, the computer projects a hologram of a cube. The hologram is causally linked, via the computer, to a real cube which is hidden from view in the far right-hand corner of the room. Now, according to my Gettier case, the subject forms the belief, “there is a cube in the room”, based solely on the hologram located in the centre of room. Thus, if asked to point to the red cube, she would point to hologram. In short, she mistakes the hologram for the genuine article. Now, this does not undermine the truth of her existential claim, “there is a red cube in the room”, but it does seem to undermine the claim that she sees the red cube. If she does in fact “see” the red cube, then why doesn’t she point to the red cube? Why does she point instead to the hologram?

I think the mistake you’re making is that you’re trying to force the particular set-up of my Gettier case to fit your prosthetic vision model, when it does not. I’m not denying that you could modify my Gettier case sufficiently so that it becomes one of your prosthetic cases. But at that point, it would cease to be my Gettier case.

Your new case seems to suffer the same basic problem as the others. Notice that the end result of your set up is that the subject is allowed to straightforwardly “see through”, as you say, the otherwise opaque box surface. Presumably, this means that the subject in your example can, in at least some meaningful sense, successfully refer to the cube demonstratively. However, as I've already pointed out, my Gettier subject cannot. Given this crucial dis-analogy between the two cases, the fact that the subject in the one case sees and knows that (a) does not not warrant the assumption that the other subject does as well.

1/18/2007 07:10:00 AM  
Blogger Larry Hamelin said...

I think after two thousand years of mucking about with these weird edge cases, it might be time to throw in the philosophical towel and declare that our intuitions about what constitutes "knowledge" (and "truth") are unworkable, and start working on fixing our intuitions, and leave the description of our actual messy, fuzzy, evolved systems of belief-formation to the cognitive scientists and neurobiologists.

5/21/2007 06:03:00 PM  
Blogger Cian said...

I find here as when I first encountered the Gettier problem that the notion of justification is the central issue.

Your statement (iii) that the belief that (a) is justified is one I find uncomfortable. Or rather, the question as to how a belief is justified I find uncomfortable. In that I at first doubted whether Gettier's examples had justification and got distracted from that by worries over what constituted justification.

One thing that tends to get mentioned is the KKp principle, that one knows that they know proposition p. I see justication somewhat like this; a positive (rather than vicious) circle; where to Kp, one KKp, which means they KKKp, etc.

In that for justification it seems that the 'knower' ought know they are justified: a reliability of which they are not aware seems just as distant as a truth that may be coincidental, and the operation of justification seems to be to bridge the gap between knower and truth known.

Maybe that's an inconsistent conception of justification and its role - any thoughts?

3/18/2009 03:28:00 PM  

Post a Comment

Subscribe to Post Comments [Atom]

<< Home