Which to read first: ITOE or OPAR?

[HaloNoble6]

None of your examples indicate unreliability of the senses. In fact, they indicate the opposite. That man's mind is not omniscient in interpreting his sensory data has no bearing on the reliability of that data.

[Gabriel_S]

It is reasonable to PRESUME that sensations are accurate, but it must be a rebuttable presumption.

Are you going to use sensory data to rebut it?

[The Wrath]

None of your examples indicate unreliability of the senses.  In fact, they indicate the opposite.  That man's mind is not omniscient in interpreting his sensory data has no bearing on the reliability of that data.

So how do we tell the difference between our mind accurately interpreting sense data and our mind going haywire?

[The Wrath]

By the way, I'm not trying to argue that I don't trust my senses, because I do. And I admit that we really have no choice in the matter of whether or not to trust them. But it just seems that not having a choice in the matter doesn't necessarily mean they're correct.

[Gabriel_S]

I must say I'm somewhat disappointed that there's no discussion on why our senses are reliable sources of knowledge.  Seems that that would be pretty important when you're trying to construct a view of acquiring knowledge.

Did you read "The Senses as Necessarily Valid" in OPAR?

Are you looking for something else?

A philosophic (as opposed to a scientific) discussion of the senses should properly amount to not much more than:

(1) distinguishing the sensory from the interpretive

(2) establishing the axiomative nature of the senses

(3) discussing the distinction between sensory form from object

(4) demonstrating that the perceptual level of awareness is the base of knowledge

The above schema grounds all conceptual knowledge. It sets the stage for sweeping aside the plethora of skeptical arguments against the senses. OPAR discusses several such attacks (the most common and broadest sort). Of course, skeptical arguments are legion and one could fill an entire encyclopedia with their refutation. As soon as you diffuse one, two more will take their place. However, if you know in principle what is wrong with all such attacks then there's really no need to go around refuting the latest time lag argument.

Having said all that, if you desire a more thorough academic discussion of the validity of the senses and more detailed answers to a wider range of technical objections, there are works that deal specifically with the subject.

[The Wrath]

I haven't read OPAR yet. I plan to eventually, though.

[Gabriel_S]

By the way, I'm not trying to argue that I don't trust my senses, because I do.  And I admit that we really have no choice in the matter of whether or not to trust them.  But it just seems that not having a choice in the matter doesn't necessarily mean they're correct.

Actually, having no choice in the matter is, in a roundabout manner, what guarantees that they are correct. What assures the unassailability of sensory data? Physical causality.

The senses are physical instrumentalities that react inexorably according to casual law. This should integrate with your understanding from a previous chapter of OPAR (and from Ayn Rand's The Metaphysical vs. Man-made article) on the metaphysically given as absolute, and with the section on causality as a corollary of identity. If you integrate those two sections with the appropriate elaboration in the section of OPAR on the senses, then you should see that the validity of the senses is ultimately an expression of the law of identity.

The senses are as valid as the law of identity, and should stand in your mind with the same level of certitude.

[Gabriel_S]

I haven't read OPAR yet.  I plan to eventually, though.

Okay, well that would explain the questions. No problem. Understood.

Just be aware that these questions are addressed explicitly in the book. They are certainly the best source for their explication. In other words, get it from the horse's mouth!

[The Wrath]

I'll do that, but it may be a while. For now I'll just stick to asking questions. Besides, it always helps when I know a little bit about something before I start reading it.

[Cole]

What about:  hallucinations, illusions, myopia, ringing-in-the-ears, etc.?

Those prove the reliability of the senses- what you are sensing is what exists. In a hallucination, you are sensing the internal dysfunction of the dopamine neurotransmitter. The fact that we can know of the cause of a hallucination proves that this cause exists as a true, perceptual phenomena. The same reliability applies to illusions. Consider the stick-in-water example, in which a stick appears to bend in the water. This does not prove that the senses are unreliable. It proves that you are sensing a true, perceptual phenomena- that light waves move at a different speed through water than they do through air.

[The Wrath]

Okay, I'm gonna use the Matrix example again. If I'm in the Matrix my brain interprets this steak as being juicy and delicious (ignorance is bliss), but the steak doesn't exist. The information being fed to me is not accurate, because I don't know that I'm in the Matrix.

[Cole]

Hypotheticals that are outside the realm of existence are not helpful.

Saying "What if I could sense something that is non-existent yet could somehow produce sensory stimulation?" does not disprove the reliability of the senses. We are discussing the real world, as it exists. All that is real can be perceived. The fact is; it is not possible to formulate an argument against the reliability of the senses without the soundness of your argument depending on the reliability of the senses.

[Gabriel_S]

Okay, I'm gonna use the Matrix example again.  If I'm in the Matrix my brain interprets this steak as being juicy and delicious (ignorance is bliss), but the steak doesn't exist.  The information being fed to me is not accurate, because I don't know that I'm in the Matrix.

Or what if an omnipotent evil demon is deceiving you? Or what if you are tied up facing the dancing shadows on the wall in Plato's cave? Or what if the noumenal categories of your mind create the phenomenal reality that you assume is real? Etc, etc.

These, and hundreds more, are all just variations on a few similar themes. Once you are able to unlock one or two of these skeptical arguments, you should grasp the error(s) of all the others (and of any possible other). For instance, with Kant, we have (thanks to Ayn Rand's trenchant identification) the presupposition that identity is the disqualifying element of consciousness. Once understood, the rest is simply a matter of details and application.

Just understand that's there's nothing original, distinct or particularly interesting about the Matrix example. It's really just a more elaborate version of Putnam's brain in a vat (which is really just a sci-fi version of Descartes' Evil Demon). See my post here for a little more: Flatland, Plato and Brains in Vats

Edited April 13, 2005 by Gabriel_S

[jrs]

Gabriel_S said "What assures the unassailability of sensory data? ... The senses are physical instrumentalities that react inexorably according to causal law.".

Very good. I grant your point.

But as Moose asked "So how do we tell the difference between our mind accurately interpreting sense data and our mind going haywire?".

That is, when can we rely on the naive (straight-forward) interpretation of our sensations?

Revising what I said before:

It is reasonable to presume that the NAIVE INTERPRETATION of one's sensations is correct, but it must be a rebuttable presumption.

Gabriel_S asked "Are you going to use sensory data to rebut it?".

Yes. The interpretation of ONE piece of sensory data must be evaluated in the context of the TOTALITY of sensory data. That totality is assumed to be substantially correct for this purpose.

[Gabriel_S]

But as Moose asked "So how do we tell the difference between our mind accurately interpreting sense data and our mind going haywire?".

That is, when can we rely on the naive (straight-forward) interpretation of our sensations?

I don't. In other words, if I get what you're saying I'd have to say that I don't rely on a naive interpretation of sensations; otherwise, you'll have to clarify what you mean by this. Actually, thinking about this a little more, I don't really understand what you're after here. Please elaborate.

Revising what I said before:

It is reasonable to presume that the NAIVE INTERPRETATION of one's sensations is correct, but it must be a rebuttable presumption.

Again, I'm not sure what NAIVE INTERPRETATION means in this context. Please explain.

Gabriel_S asked "Are you going to use sensory data to rebut it?".

Yes.  The interpretation of ONE piece of sensory data must be evaluated in the context of the TOTALITY of sensory data.  That totality is assumed to be substantially correct for this purpose.

The problem is that once you allow the possibility that the senses may deceive in a particular instance, there is no means by which to establish whether they are reliable or deceptive in any particular instance, including the majority or totality of instances. How do you know in the majority of instances that you aren't being deceived but in the minority you are receiving valid sensory evidence? Maybe the senses are deceptive ninety-nine times out of a hundred, and correct only once out of a hundred.

You see, you cannot appeal to sensory evidence to establish the validity of other sensory evidence, once you've already entertained the possibility that sensory evidence may be invalid. It's a self-contradiction. Further, you can't appeal to a conceptual analysis of sensory evidence to establish it's invalidity, since the sense-doubting concepts themselves are built upon the same faulty sensory data that is itself being called into doubt. Thus, the notion that we can and should rely upon the majority, totality, etc., of sensory data as the standard by which to determine if other sensory data is reliable is itself a conceptual commitment. And, what is that argument based upon? The senses?

Are you starting to see the problem with claiming that some sensory information may be invalid? Ultimately, such a position calls into doubt all sensory information (and, consequently, all conceptual knowledge). There is no higher court of appeals than the senses.

I hope that helps.

Edited April 14, 2005 by Gabriel_S

[jrs]

Gabriel_S:

You asked "... NAIVE INTERPRETATION ... Please explain.".

Let me use the standard example of the stick in the water. A straight stick will appear to bend when it enters the water because the light from the part of the stick below the surface is refracted (bent) as it leaves the water.

A naive interpretation of what one is seeing would be that the stick has a bend just at the point where it crosses the surface of the water, because a naif would assume that light always moves in straight lines from the object to his eyes.

Actually the naif would not even think in terms of light but would assume that he directly senses the object where it seems to be in his visual field.

You said "... you cannot appeal to sensory evidence to establish the validity of other sensory evidence, once you've already entertained the possibility that sensory evidence may be invalid. It's a self-contradiction."

I am no longer contending the the senses are invalid. I accepted your argument that one's sensations have a causal dependency on reality and therefore provide information about reality.

I have now moved back to the level of interpretation. And I am not contending that one CANNOT interpret one's sensations correctly.

What I am saying is that one must use higher reasoning to determine how to interpret them correctly; one cannot simply take correct interpretation for granted.

Remember, I said of sense data: "That totality is assumed to be substantially correct for this purpose.".