It’s important to distinguish between the evidence of the senses and how we cogitively interpret that evidence. It is only when the latter enters the picture that so too does error.
Jon, I’m not attacking realism and certainly optical illusions can be explained ‘scientifically’.
In the case of the pencil in water as Geoffrey points out, it looks broken because the light coming off the pencil is actually being bent. The water is working as a lens and it’s creating the image you see - just like a magnifier creates a bigger image. These images are ‘real’ because they are formed by light whose path has been modified.
The case of the grey strip is more subtle though. Here the light coming from the grey bar into the eye is of a uniform shade of grey but we see a gradient. Here, for some reason, we’re getting information which is plain wrong.
So, the senses provide a lot of correct information, but they can also provide wrong information and there’s no way to know a priori if that’s happening.
That may be true, but the ‘interpretation’ is not always under control of the will. In the case of the grey bar, the ‘interpretation’ seems to be done automatically by the brain - and done wrongly.
The fact that you know it is done wrongly undermines that argument though.
-Jon
Wrong in the sense that if the bar was presented by itself without the background we would then see it as uniform in color. However, background colors apparently affect how our brains process the data. It may actually serve a useful function.
This happens when the brain processes the data of the senses. It doesn’t show that our senses don’t accurately pick up information about the outside world. It appears to show that at the higher level of sense-perception the brain might process the data in such a way as to present us with a misleading picture, but again this might actually serve a useful evolutionary function. In any case, at the higher level of sense-perception (above the senses taken individually and the data they provide) it is a rare exception that does nothing to undermine the general reliability of the senses and the higher level of sense-perception. (Both Rand and Aristotle distinguish between the individual senses and their raw data, sense-perception, and conceptual thought, btw.) To even recognize it as an exception, to even conceive of such things as non-existence, illusion and the like, presupposes existence, normality and general rules.
Wrong in the sense that there’s only one shade of grey but we see a different thing. What we see is not ‘real’.
If you consider the eye as an optical device, it is by no means accurate - it has a lot of ‘technical’ flaws. For instance, if there’s not enough light, it ceases to pick up color information.
If you consider the brain/eye system, you can see that it also fails sometimes, as the grey bar illusion shows.
Besides if raw data needs to be interpreted, then it ceases to ‘objective’. And if the interpretation is done automatically , it’s even questionable whether the mechanism can be properly described as interpretation. Also, we really have no access to the raw data the senses provide because the sense organs/brain combination work as a single system.
Agreed. I’m not arguing against existence and general rules - not sure what you mean by ‘normality’ though…
My concern is not that we’re not “seeing reality for what it is”, but that we’re not seeing the whole thing and that some of our conclusions derived from what we do see are whacky nonsense. Perception is not all-encompassing to the point where we can just arbitrarily proclaim to directly “know reality for what it is” in all cases. The limited scope of our sensory perception in and of itself would indicate that any kind of “reality for what it is” beyond this limited scope can only be inferred, not directly “known”. In fact, some of the greatest scientific discoveries of all time are entirely counter-intuitive to our direct perception of phenomenon. Not everything is a matter of mere direct empirical observation, but also that which is indirectly inferred from it.
But where did anyone say all knowledge must come from the senses?
-Jon
Sounds like you’re just rephrasing what I wrote.
The eye can be improved upon? So what. We can’t do without some device for seeing though and “see” objects directly “as they are” in some fantastical unrealistic sense of having sense-perception without sense-perception, sensation without senses, sight without eyes, hearing without ears, etc. We see what is out there according to the nature of the object, the laws of reality and the natures of our sense organs and brain processes.
So? None of this means that the realistic position needs to be proven against some idealist or solipsist default. Rather, the commonsense realist position is the default from which one has to operate in order to identify errors and exceptions. Radical doubt is pointless and self-defeating.
That sounds like the fantasist Kantian position that results in the absurdity that because we have eyes, we are blind, etc. What do you mean ‘objective’? Not that you necessarily are doing this, but it is absurd to posit omniscience or some mystical “direct seeing without seeing” as some standard according which even the best senses will necessarily fall short. Our senses and our faculty of sense-perception generally present things to us as they are, as mediated by our sense organs and processed by our brains of course, although such presentations are inevitably perspectival or partial. If they were not generally reliable our species would have died out long ago.
I don’t think I called it interpretation. I think I called it processing.
Also, while we generally can’t isolate the bits of raw data, we do have a general direct awareness at a very fundamental level of the existence of reality outside our minds. Could we really be in the Matrix. Yes, that’s not beyond the realm of possibility. But until and unless strong reasons and evidence are provided for such a proposition, we have no reason to seriously entertain it except as interesting fiction.
Commonsense experience of reality. The real world vs. a virtual reality. Real things as they are vs. illusion, etc.
Of course sense-perception is partial and perspectival. We’re not omniscient or infallible. Concepts and knowledge are open-ended and subject to revision. And yes, just as with the half-submerged stick there is a deeper truth to most things than sense-perception alone can tell us.
Well, ultimately all knowledge does, although not all directly. In general much of our knowledge can only be indirectly traced back to our senses, if we care to go to the trouble. We build it up from other information that we do get directly from our senses. Or we learn it from others. Without experience our minds would be empty computers, so to speak. Our minds are hard-wired to work in certain ways according to their natures. But without external inputs there is nothing for them to work with. We may be capable of grasping the action axiom, but without ever experiencing action we would never form the concept of action. Without language, which requires whole human populations and the development of culture, we would not have concepts and so would be unable to think. So the very fact that I can think “I think” presupposes not only that “I am,” rather than being a premise for it, but also that “You are. And so are you. And you. And you. Etc.” (Although it may be reasonable to doubt whether a particular person exists or is human, depending on the context.)
Sure, but what I meant is one isn’t restricted to merely what one perceives. One can infer from known premises, conjecture &c. and nothing in the Objectivist epistemology says otherwise. But otherwise yes, agreed.
-Jon
The point is, the senses sometimes provide wrong information - that’s all.
Yes, which means there are a lot of variables involved, and the last one - ‘brain processes’ - is by no means well understood - and it’s debatable whether it can really be ever understood - unless you are a positivist, that is.
I’m not arguing for solipsism. And I’m not arguing against realism.
Ah yes. The randian misinterpretation and ‘refutation’ of Kant. Just as good as Rand’s views on government and anarchy…
Well, that’s some sort of kantian thing ?
The problem here is that I’m not making a claim. I’m arguing that Objectivists are making an erroneous, unbacked claim when they state that our senses are correct axiomatically. I am asking for evidence that proves that our senses are valid, nobody has yet provided that.
Erroneous? No, that remains to be established. I still want you to provide Peikoff’s argument, otherwise there’s no point in discussing this any further. I think Geoffrey’s pretty much cleared this up by bringing in the distinction between cognition and sense-perception.
-Jon
I’m referring to Peikoff’s argument.
My entire point is that nobody has ever provided me, nor have I ever found any evidence or “reason” that supports the “common sense” view of reality. You’re just committing an argumentum ad populum here, only because something is “common sense” doesn’t mean that it is necessarily true.
Nobody here in this thread has so far provided any evidence to support the validity of our senses. The question asked in this thread was whether or not anyone here could provide that evidence.
God and FSM are relevant when discussing the validity of our senses, because
So what about dreams? Or are those cognitive errors (below) as well?
Arguably there are a lot of people in insane asylums who have a completely different view of reality, and it would be safe to say that that is due to “cognitive errors.” The question is: how do you know we’re not experiencing a similar series of cognitive errors?
I’ll read those today.
Which is just an arbitrary distinction.
Ipse dixit.
-Jon
I explained why - but maybe you didn’t bother reading it. You can’t consider sense-perception by itself without taking into account what Geoffrey called ‘processing’. The system works as a whole.
There’s no shortage of evidence, and the burden is still on you to present a case for the contrary position.
? Dreams are internal. They say nothing for or against the validity of the senses.
Again, the burden of proof is on you. That abnormal people have biological and/or psychological disorders does not speak against the general validity of the senses.
YOu’re getting all the distinctions confused. I distinguished raw sensory data picked up by the senses, from sense-perception which includes the automatic processing (which again is distinct from conceptual interpretation). These are not arbitrary distinctions.