What Distance Must An Object Be For Its Appearance To Equal Its Real Size?

Zetherin

Tue 2 Mar, 2010 12:04 pm
@Pythagorean,
Pyrrho wrote:

There does not seem to me to be anything more to it being "really" four feet long

I don't know what you mean, but if the board is 4 feet long, it's really 4 feet long. This is not a matter of a appearance, it is a matter of reality.

Pyrrho

Tue 2 Mar, 2010 12:33 pm
@Zetherin,
Zetherin;134636 wrote:
I don't know what you mean, but if the board is 4 feet long, it's really 4 feet long. This is not a matter of a appearance, it is a matter of reality.

And when you say it is really four feet long, what, exactly, do you mean? If there was some dispute about its length, would you not simply take out a measuring tape (or other measuring device) and lay it next to the board, and compare the length of the board with the markings on the tape (or other measuring device)? Is there anything more to be done? Is it anything more than that?

Zetherin

Tue 2 Mar, 2010 12:35 pm
@Pyrrho,
Pyrrho;134646 wrote:
And when you say it is really four feet long, what, exactly, do you mean? If there was some dispute about its length, would you not simply take out a measuring tape (or other measuring device) and lay it next to the board, and compare the length of the board with the markings on the tape (or other measuring device)? Is there anything more to be done? Is it anything more than that?

The point is that reality and appearance are two different things. That is all I was getting at. And she (Gracee) seemed to be confusing the two.

ughaibu

Tue 2 Mar, 2010 01:12 pm
@Zetherin,
Zetherin;134648 wrote:
The point is that reality and appearance are two different things.
What's the difference?

Gracee

Tue 2 Mar, 2010 01:25 pm
@ughaibu,
Zetherin;134632 wrote:
Let's not confuse things. We are not talking about size, we are talking about the appearance of size. Things are a certain size whether we perceive them to be so or not.

But it is impossible for us to know anything other than appearence, even in terms of size. Who is to say that anything is a certain size? All we can know is what we see; we assume that size is constant, and it is our perception of it that changes, but this is, as Russell says a 'working hypothesis', i.e. the most convenient and commonsensical conclusion to come to about the world, given the evidence.

The real question here is what defines size? In terms of measurement, yes it seems that no matter where an object is in your visual field it will always measure the same length on a ruler. But in terms of how we view size, both the size of the ruler and the object - in fact even each cm on the ruler - are going to change as we view them, so even saying something is 10cm means nothing, except as in relation to other objects in the world.

Zetherin

Tue 2 Mar, 2010 01:29 pm
@ughaibu,
ughaibu;134669 wrote:
What's the difference?

What is, and what we perceive to be, are two different things. Optical illusions demonstrate this. Perhaps you should have a look at those. You will see there can be a big difference between what we perceive, and what is.

ughaibu

Tue 2 Mar, 2010 01:33 pm
@Zetherin,
Zetherin;134685 wrote:
What is, and what we perceive to be, are two different things. Optical illusions demonstrate this. Perhaps you should have a look at those.
I dont think that optical illusions do demonstrate that. I perceive my computer and I'm pretty sure that I'm perceiving reality, if I'm not, how do you explain the appearance, to you, of this post?

Zetherin

Tue 2 Mar, 2010 01:38 pm
@ughaibu,
ughaibu;134689 wrote:
I dont think that optical illusions do demonstrate that. I perceive my computer and I'm pretty sure that I'm perceiving reality, if I'm not, how do you explain the appearance, to you, of this post?

Perhaps you should click on the link. Optical illusions demonstrate that our perception of reality, and reality, can be different. We can, for instance, mistake that a line is a certain shape, or a block is a certain color, depending on the illusion.

When did I say that you couldn't perceive what was real? I am merely saying that what we perceive is not always real; it is sometimes an illusion (an illusion is what is not real, it is a 'false perception'). And so, we should then conclude that what we perceive, and what is real, are not always the same. That is what I mean when I say they are two different matters.

ughaibu

Tue 2 Mar, 2010 01:43 pm
@Zetherin,
Zetherin;134694 wrote:
we should then conclude that what we perceive, and what is real, are not always the same. That is what I mean when I say they are two different matters.
Well, perception and that which is perceived are different kinds of things, and we can be mistaken about that which we're perceiving, but generally speaking, I dont see any reason to think that we are mistaken, in most cases.

kennethamy

Tue 2 Mar, 2010 01:44 pm
@Pythagorean,
If I see an flying airplane at a distance, it does not look like an airplane close up, but it looks exactly like an airplane at that distance. What size does an airplane have to look for it to look it real size?

Zetherin

Tue 2 Mar, 2010 01:49 pm
@ughaibu,
ughaibu;134697 wrote:
Well, perception and that which is perceived are different kinds of things, and we can be mistaken about that which we're perceiving, but generally speaking, I dont see any reason to think that we are mistaken, in most cases.

I never disagreed. Perhaps it was my choice of words.

Gracee wrote:

The real question here is what defines size? In terms of measurement, yes it seems that no matter where an object is in your visual field it will always measure the same length on a ruler. But in terms of how we view size, both the size of the ruler and the object - in fact even each cm on the ruler - are going to change as we view them, so even saying something is 10cm means nothing, except as in relation to other objects in the world.

In order for us to perceive the object as 10cm, we need relation (if I'm not mistaken - I was just reading an article on perception). But the object would still be 10cm, if it was in fact 10cm, no matter if we perceive it to be or not. There is an objective world which exists no matter how it is perceived.

Gracee

Tue 2 Mar, 2010 01:50 pm
@ughaibu,
ughaibu;134697 wrote:
Well, perception and that which is perceived are different kinds of things, and we can be mistaken about that which we're perceiving, but generally speaking, I dont see any reason to think that we are mistaken, in most cases.

You should read the Meditations, i think your view will be slightly different after that...
But to summarise Descartes, illusions show us that often what we perceive is not true to reality, which leads to scepticism about the validity of our perceptions. He also cites the example of hallucinations and dreams, often when we are having a vivid hallucination or dream, we are unaware that what we are seeing is not reality, so how can we be sure that we are not dreaming or hallucinating right now. Finally, he cites the example of an evil deceiver. This is a matrix like scenario, where an all powerful deceiver is controlling all our perceptions, and projecting them into our minds like a film. What we are seeing is qualitatively indistinguishable from reality, so how are we to know that it is not reality?
This is the problem we are faced with about the reliability of our perceptions, do they really show us what is there, in an independent world, or is everything we are seeing just inside our minds?

---------- Post added 03-02-2010 at 07:54 PM ----------

Zetherin;134705 wrote:

In order for us to perceive the object as 10cm, we need relation (if I'm not mistaken - I was just reading an article on perception). But the object would still be 10cm, if it was in fact 10cm, no matter if we perceive it to be or not. There is an objective world which exists no matter how it is perceived.

Agreed, if we take for granted that a mind independent world exists, then an object will continue to be 10cm no matter how it is perceived, but what does this really mean?
I think this is what the post is about... i mean, does saying something is 10cm give us any useful information about its true size?
I don't think so, because even a 10cm object varies to us according to where that 10cm object exists.

ughaibu

Tue 2 Mar, 2010 01:55 pm
@Gracee,
Gracee;134707 wrote:
illusions show us that often what we perceive is not true to reality, which leads to scepticism about the validity of our perceptions.
It doesn't lead me to such skepticism, because some As being Bs doesn't imply that all As are Bs. And I would reject your "often".

Zetherin

Tue 2 Mar, 2010 01:57 pm
@Pythagorean,
Gracee wrote:
i mean, does saying something is 10cm give us any useful information about its true size?

Yes, it does. We usually perceive reality accurately. If measurements didn't give us any useful information on true size, how do you suppose things like skyscrapers are built? Do you have any idea how precise some of those measurements must be?

kennethamy

Tue 2 Mar, 2010 02:02 pm
@Gracee,
Gracee;134707 wrote:
You should read the Meditations, i think your view will be slightly different after that...
But to summarise Descartes, illusions show us that often what we perceive is not true to reality, which leads to scepticism about the validity of our perceptions. He also cites the example of hallucinations and dreams, often when we are having a vivid hallucination or dream, we are unaware that what we are seeing is not reality, so how can we be sure that we are not dreaming or hallucinating right now. Finally, he cites the example of an evil deceiver. This is a matrix like scenario, where an all powerful deceiver is controlling all our perceptions, and projecting them into our minds like a film. What we are seeing is qualitatively indistinguishable from reality, so how are we to know that it is not reality?
This is the problem we are faced with about the reliability of our perceptions, do they really show us what is there, in an independent world, or is everything we are seeing just inside our minds?

---------- Post added 03-02-2010 at 07:54 PM ----------

.

The argument:

1. We are sometimes mistaken

Therefore (2) we may always be mistaken.

Is invalid.

And even Descartes recognizes that, because after he makes that argument, he points out that the conclusion does not follow, and he goes on to the dreaming argument.

Gracee

Tue 2 Mar, 2010 02:18 pm
@kennethamy,
ughaibu;134715 wrote:
It doesn't lead me to such skepticism, because some As being Bs doesn't imply that all As are Bs. And I would reject your "often".

kennethamy;134723 wrote:
The argument:

1. We are sometimes mistaken

Therefore (2) we may always be mistaken.

Is invalid.

And even Descartes recognizes that, because after he makes that argument, he points out that the conclusion does not follow, and he goes on to the dreaming argument.

Yes, the illusion argument is fairly weak due to the irregularity of illusions, and i'm not 100% advocating it, just pointing it out. However the final total deception argument is stronger. There really is no way of telling weather or not what we are percieving right now correlates with any mind independent reality.

Zetherin;134717 wrote:
Yes, it does. We usually perceive reality accurately. If measurements didn't give us any useful information on true size, how do you suppose things like skyscrapers are built? Do you have any idea how precise some of those measurements must be?

In practice, 10cm does mean something, and i'm not refuting this claim, but again, it is only meaningful in relation to other objects in an independent external world.
But the fact remains that we cannot reach that external world because of the veil of perception, and anything 10cm does vary in size depending on its location in our visual field. So if you take away objects, take away the world even, you are left with a concept, an idea, of 10cm which is inherently meaningless.

Zetherin

Tue 2 Mar, 2010 02:21 pm
@Pythagorean,
Gracee wrote:

But the fact remains that we cannot reach that external world because of the veil of perception

But what makes you refer to it as a "veil"? Why not refer to it as a "window", as we are often perceive reality accurately?

kennethamy

Tue 2 Mar, 2010 02:29 pm
@Gracee,
Gracee;134738 wrote:
Yes, the illusion argument is fairly weak due to the irregularity of illusions, and i'm not 100% advocating it, just pointing it out. However the final total deception argument is stronger. There really is no way of telling weather or not what we are percieving right now correlates with any mind independent reality.

Oh, I don't think it is that dire. We cannot do it with complete certainty, but that does not mean we cannot do it with something less than certainty. We can have varying amounts and kinds of evidence. I am fairly sure that there are pigeons in Trafalger Square, and that I am justified in being sure there are.

---------- Post added 03-02-2010 at 03:31 PM ----------

Zetherin;134739 wrote:
But what makes you refer to it as a "veil"? Why not refer to it as a "window", as we are often perceive reality accurately?

The veil bit is that we are supposed to observe things only darkly through their representations. Objects are not pinned right on our retinas.

Gracee

Tue 2 Mar, 2010 02:55 pm
@kennethamy,
Zetherin;134739 wrote:
But what makes you refer to it as a "veil"? Why not refer to it as a "window", as we are often perceive reality accurately?

But the fact is we don't know we're perceiving anything accurately, again, check out Decartes' total deception argument, or just watch the Matrix! In either scenario what we are seeing is not reality, but it looks just like reality, so we simply cannot tell the difference.

Kant also says we can't even talk about reality, because we have our own conceptual scheme which means we project certain qualities onto the world that aren't really there. For example, the fact that things do get smaller as we move away from them, this doesn't happen in reality, but if our minds didn't do this, the world would be unperceivable. He uses the example of rose tinted sunglasses that we can't take off, our minds are like the sunglasses, they make the world seem different to how it really is.
I'm not explaining very well... try this In As philosophy; how does Kant's conceptual scheme work? - Yahoo! UK & Ireland Answers

kennethamy;134750 wrote:
Oh, I don't think it is that dire. We cannot do it with complete certainty, but that does not mean we cannot do it with something less than certainty. We can have varying amounts and kinds of evidence. I am fairly sure that there are pigeons in Trafalger Square, and that I am justified in being sure there are.

This is true, and some philosophers do say that we don't need certainty in order to know something. However, the definition of knowledge is a true proposition, and if we can't really say whether the proposition 'there are birds in trafalger square' is true with 100% certainty, can we really say we know it?
I would say no, but for all practical purposes, we will say we do.

Its really one of those philosophical dilemmas which is impossible to answer, but it really doesn't affect the way you live your life. Personally that's why i prefer ethical philosophy, but i'm studying this stuff right now and i have an exam in May, so i thought i'd get some practice in!

Zetherin

Tue 2 Mar, 2010 03:00 pm
@Pythagorean,
Gracee wrote:

But the fact is we don't know we're perceiving anything accurately, again, check out Decartes' total deception argument, or just watch the Matrix! In either scenario what we are seeing is not reality, but it looks just like reality, so we simply cannot tell the difference.

Unless we have a reason to doubt, why would we? Extreme skepticism leads to infinite regression, and can actually manifest itself as a form of paranoia.

Just because it's logically possible we could be living in the Matrix, doesn't mean we should doubt that we are living in reality.

Quote:

Kant also says we can't even talk about reality, because we have our own conceptual scheme which means we project certain qualities onto the world that aren't really there. For example, the fact that things do get smaller as we move away from them, this doesn't happen in reality, but if our minds didn't do this, the world would be unperceivable. He uses the example of rose tinted sunglasses that we can't take off, our minds are like the sunglasses, they make the world seem different to how it really is.
I'm not explaining very well... try this In As philosophy; how does Kant's conceptual scheme work? - Yahoo! UK & Ireland Answers

I would really try offering a source better than yahoo, but I will take a look

But if Kant says we cannot even talk about reality, I certainly disagree. What rational person wouldn't?