Brain In A Vat Revisited Analysis

1812 Words4 Pages

Zhiyuan Li
Philosophy 3000

In his paper Realism and Skepticism: Brains in a Vat Revisited, Graeme Forbes considers Putnam’s brains in a vat (BIV) argument. According to Forbes (1995), Putnam argues that in order for a normally embodied thinker to think about such concepts as brain, in and vat, she “must somehow be informationally linked to” instances of those concepts (206). However, Forbes does not consider (and he does not think he needs to consider) what particular sorts of informational links are sufficient to enable a thinker to think about the concepts, though he seems to suggest that an is-and-always-has-been BIV has no such informational links (206). In other words, a BIV cannot think about the concepts of brain, in and vat and it …show more content…

For Forbes (1995), a BIV is not a BIV-in-the-image because a BIV is a physical object, whereas a BIV-in-the-image is merely a mental image (206). But as indicated earlier, Brueckner (1986) interprets “the image” as “sense impressions had by the BIV” and therefore he thinks the reason why a BIV is not a BIV-in-the image is that a BIV does not have the sense impressions of being a BIV, but being a human being (150-1). I think Brueckner is misunderstanding Putnam here and Forbes’s account is more accurate. For the sake of argument, let us (temporarily) accept Brueckner’s interpretation (i.e. the image is the sense impressions had by the BIV) and apply it to the tree and tree-in-the-image case. Clearly, a tree is not a tree-in-the-image, but what makes it so? I think Brueckner should be committed to this answer: A tree is not a tree-in-the-image because a BIV does not have the same sense impressions of a tree when faced with a tree-in-the-image. But this is false. As Putnam sets up the scenario, a BIV is able to receive appropriate impulses from the computer so that it is able to have the perfectly normal sensory experiences of a tree when facing a tree-in-the-image (6). By contrast, Forbes does not bring in this potentially troublesome interpretation of “the image.” The idea of a mental image here is pretty self-explanatory and I don’t see why Putnam needs to adopt an additional …show more content…

This conclusion does not rule out the possibility that a BIV’s utterance that “I am a BIV” (in English) could still be true even though this cannot be uttered at all (a BIV can only utter that “I am a BIV-in-the-image” in English, which is clearly false). To put it in another way, Brueckner does not deny that one may be a BIV even if she is unable to have the thought that “I am a BIV” (in English). However, Forbes’s conclusion rejects this possibility.
I think Forbes’s reading of Putnam is more accurate here. Putnam (1981) writes, “In short, if we are brains in a vat, then ‘We are brains in a vat’ is false. So it is (necessarily) false.” (15) If Putnam is right that “We are brains in a vat” is necessarily false, it should be false in every possible world, including the one where a BIV is a BIV though it cannot have the thought that “I am a BIV” (in English), as Brueckner suggests. By contrast, Forbes’s conclusion that I am not a BIV is consistent with the way Putnam phrases his conclusion, and is therefore a more accurate account of his

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