A question concerning perceptions.

[DavidOdden]

My question was more of an attempt to ascertain how we know certainly that things actually exist independent of our perceptions.

No criticism intended, but your initial questions point towards a different conclusion, namely that you're asking a question about the ontology of "seeing", i.e. is seeing in the brain (as opposed to in the toe, or on Mars or in the air). But this clarification tells me that you're really asking a more basic question, the classic BIV (brain-in-vat) question.

I think the best way to start answering the question "how do we know with certainty that what we see does exist?" is to answer the question "what does it mean to 'know' something?". What do you think it means to "know" something?

[Nicko0301]

No criticism intended, but your initial questions point towards a different conclusion, namely that you're asking a question about the ontology of "seeing", i.e. is seeing in the brain (as opposed to in the toe, or on Mars or in the air). But this clarification tells me that you're really asking a more basic question, the classic BIV (brain-in-vat) question.

I think the best way to start answering the question "how do we know with certainty that what we see does exist?" is to answer the question "what does it mean to 'know' something?". What do you think it means to "know" something?

Yes, I asked my original sight question in order to help me out with the BIV conundrum.

To "know" in this instance means to be certain of something (in this case, how do I know with absolute certainty that the things I am experiencing are actually "there").

Rationally I know that the whole BIV scenario is absurd. There is just this inexorable, pointless skepticism which haunts me, questioning the most obvious aspects of my knowledge.

[phibetakappa]

Brain in Vat BIV conundrum.

A clue to answer this so-called "conundrum" is that it asks us to take as unquestionable that objects of the conundrum exist; that there are complex objects and complex contexts of objects such as vats, brains, laboratories, scientists, electrodes, and all the scientific knowledge such as bio-psychology, optics, neurology etc. etc. as necessary to "plausibly" construct the BIV.

Why suppose those objects exist? How did the authors of the BIV scenario get the information about brains, scientists, laboratories, vats, electrodes, bio-psychology, etc?

We are supposed to take those assertions about the existence of those things as "knowledge"; knowledge which is supposedly "certain" enough to undermine our knowledge provided by our direct awareness of objects?

We are supposed to doubt the simple information provided by our 5 senses; but supposed to take undoubtable complex derivative knowledge such as laboratories, scientist, brains, vats, electrodes, and bio-psychology?

The answer is the authors of these BIV scenarios depend on and rely upon the existence of objects; their assertions, conclusions and proposed knowledge rests on and completely depends upon the existence of objects.

Not only do their assertions depend on the existence of objects, they depend on complex derivative knowledge which took thousands of years to develop using techniques which all depended on the existence of objects and the validity of our sense organs. At the same time they assert we must doubt the existence of simple objects, and the knowledge we have gathered about the existence of those objects using our direct awareness of objects given by our senses.

The BIV scenarios are self-contradictory.

Edited November 15, 2009 by phibetakappa

[DavidOdden]

To "know" in this instance means to be certain of something (in this case, how do I know with absolute certainty that the things I am experiencing are actually "there").

First, I'm asking about what "know" means, not what "know" means in a specific instance. In other words, I'm trying to determine what you would say the concept "know" refers to generally. Lemme give you a hopefully more obvious example. I might ask what "human" means, and then I'd want a definition that correctly identifies humans, and not just certain humans in a particular context.

Second, notice that you start by defining "know" in terns of "being certain" but then you paraphrase that as knowing with absolute certainty. But that's redundant, if "know" means "be certain" (and "absolute certainty" would be redundant -- being "certain" is sufficient).

It is a mistake, IMO, to frame the question in subjective terms, specifically in terms of the subject's emotional state (this is what I take away from the expression "I am certain"). Instead, you should frame the question in objective terms, that something is certain. Specifically, what is certain is a particular proposition or conclusion. You, then, must judge the conclusion. The conclusion describes a state of affairs, for example "This is a cat", and either that conclusion correctly describes a fact of reality (is true) or does not (is false). This is the basic correspondence theory of truth -- "To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true".

Now maybe we can return to your concern, which I will paraphrase: "What method do we use to judge propositions as correctly describing reality?". The very short answer, and the subject of Chapter 5 of OPAR, is "reason". I strongly urge you to read that chapter. Probably the most important idea that you will get from there is the impotence of arbitrary claims in epistemology, specifically, that a claim lacking evidence simply cannot be considered, and that even addressing the BIV claim is an affront to the concept "knowledge".

Huemer's book Skepticism and the Veil of Perception is aimed at dismantling skepticism, and he does address many of the common skeptic absurdities including BIV, in a generally comprehensible manner.

[Nicko0301]

First, I'm asking about what "know" means, not what "know" means in a specific instance. In other words, I'm trying to determine what you would say the concept "know" refers to generally. Lemme give you a hopefully more obvious example. I might ask what "human" means, and then I'd want a definition that correctly identifies humans, and not just certain humans in a particular context.

Second, notice that you start by defining "know" in terns of "being certain" but then you paraphrase that as knowing with absolute certainty. But that's redundant, if "know" means "be certain" (and "absolute certainty" would be redundant -- being "certain" is sufficient).

It is a mistake, IMO, to frame the question in subjective terms, specifically in terms of the subject's emotional state (this is what I take away from the expression "I am certain"). Instead, you should frame the question in objective terms, that something is certain. Specifically, what is certain is a particular proposition or conclusion. You, then, must judge the conclusion. The conclusion describes a state of affairs, for example "This is a cat", and either that conclusion correctly describes a fact of reality (is true) or does not (is false). This is the basic correspondence theory of truth -- "To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true".

Now maybe we can return to your concern, which I will paraphrase: "What method do we use to judge propositions as correctly describing reality?". The very short answer, and the subject of Chapter 5 of OPAR, is "reason". I strongly urge you to read that chapter. Probably the most important idea that you will get from there is the impotence of arbitrary claims in epistemology, specifically, that a claim lacking evidence simply cannot be considered, and that even addressing the BIV claim is an affront to the concept "knowledge".

Huemer's book Skepticism and the Veil of Perception is aimed at dismantling skepticism, and he does address many of the common skeptic absurdities including BIV, in a generally comprehensible manner.

Thank you so much for assisting me with my thinking. I should be ashamed that my thoughts are so muddled and my statements so ambiguous!

I will definitely read the books that you so kindly recommended.

[DavidOdden]

I should be ashamed that my thoughts are so muddled and my statements so ambiguous!

I don't think shame is appropriate. The point of this here place is to give you a place to work through your thoughts and practice saying what you mean directly. I mean, where else can you learn these skills??