How do we really know that we can trust our own logic, what we perceive, etc?

Talk about things that are not necessarily related to music or the guitar.
astro64
Posts: 691
Joined: Sat Aug 06, 2016 7:43 pm
Location: American Southwest

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by astro64 » Mon Mar 13, 2017 11:10 pm

Scientific theories are model descriptions of the world. They stand the test of time by being useful, i.e. provide proper predictions and explanations that let us do new things as gitgeezer mentions. By applying Occam's razor we demand that theories in different areas should connect to one another, so that we are not reinventing the wheel time and time again. But it is at some level totally irrelevant and most likely unanswerable if the theories are "the truth". We may be able to test whether the predictions are correct (i.e. "true"), but that doesn't make the theory "the truth". We don't ask for that standard. That is when we get in the endless discussions about "wait a minute, is what we perceive really happening or not". That is interesting to think about, but not strictly speaking relevant in assessing the quality of a theory. Many advanced and proven theories go completely against our instincts or our ability of perception, but that does not make them any less relevant.

User avatar
guitareleven
Posts: 698
Joined: Wed Sep 28, 2011 5:48 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by guitareleven » Tue Mar 14, 2017 3:02 am

glassynails wrote: ... but how do I know that what I see in front of me is "real" and not an illusion? ....
It's either real, or it's a real illusion. In either case-- it's real.

glassynails
Posts: 5594
Joined: Mon Jul 07, 2008 4:20 am
Location: Westbrook, Maine

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by glassynails » Tue Mar 14, 2017 4:29 am

guitareleven wrote:
glassynails wrote: ... but how do I know that what I see in front of me is "real" and not an illusion? ....
It's either real, or it's a real illusion. In either case-- it's real.
How do you know that it's either "real or a real illusion", there may be a third state. A dream may or may not be real or could be something entirely different. Everything and anything may be possible in this world, but we also have to assume even that. We don't know if there is really even a "world" or a "Universe", we can only assume these things. We cannot trust anything that are minds or senses tell us in theory. We don't know if the senses are real or if the mind is real. I cannot say that you exist and you cannot say that I exist.
"GLASSYNAILS" on Youtoob for my "no edit" - "no fakery" audio recordings. Just me, my Alhambra 7p spruce, and an Olympus ls-10 portable recorder.

Mr Kite

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by Mr Kite » Tue Mar 14, 2017 7:53 am

gitgeezer wrote:In an earlier post I suggested that "there is no absolute answer" and quoted Max Born's statement that "ideas such as absolute certitude, absolute exactness, final truth, etc. are figments of the imagination which should not be admissible in any field of science." But notice that Born is using the adjectives, "absolute" and "final." This leaves room for certitudes that are not "absolute" and truths that are not "final." Science needs certitude and truth that, though admittedly not absolute and final, is necessary to produce the foundation and confidence to move forward.
I don't think you can have a certitude that is not absolute, but that is only a linguistic point. I suppose you can dilute the notion of truth in this way if you like, but then you are not talking about the kind of truth that the OP was asking about ("how do we *really know* that we can trust..."). Diluting it, though, is a way of saying that science is not about truth, as astro64 has also said. This was my objection to your post of yesterday.

Mr Kite

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by Mr Kite » Tue Mar 14, 2017 8:03 am

glassynails wrote:
guitareleven wrote:
glassynails wrote: ... but how do I know that what I see in front of me is "real" and not an illusion? ....
It's either real, or it's a real illusion. In either case-- it's real.
How do you know that it's either "real or a real illusion", there may be a third state. A dream may or may not be real or could be something entirely different. Everything and anything may be possible in this world, but we also have to assume even that. We don't know if there is really even a "world" or a "Universe", we can only assume these things. We cannot trust anything that are minds or senses tell us in theory. We don't know if the senses are real or if the mind is real. I cannot say that you exist and you cannot say that I exist.
An illusion is something which appears to be something other than it really is, so being told that the world is a real illusion isn't much comfort for someone who is concerned that the familiar world may not be quite what it seems.

The only way I can make sense of the idea of a real illusion is as an illusion based on an underlying reality - i.e. there is a way that things truly are, but they don't appear that way. The third possibility is that you can have an illusion without there being any way that things truly are - which seemed impossible to me at first but grew on me over time. Mark Siderits has argued for this view.

glassynails
Posts: 5594
Joined: Mon Jul 07, 2008 4:20 am
Location: Westbrook, Maine

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by glassynails » Tue Mar 14, 2017 8:35 am

What could we possibly use to determine if something is either real or an illusion if we cannot trust our minds, our senses, or are own logic? All of my senses may tell me that there's a brick wall in front of me and I may even have that theory reinforced by seeing 10 people all standing there telling me that "Yes, this is a brick wall and it's here". They may also be an illusion to me.

You could also say that "Well either the brick wall is there or it isn't, but who's to say it both is and isn't there. Who's to say that I am here? I cannot even really tell if I exist or I don't.
"GLASSYNAILS" on Youtoob for my "no edit" - "no fakery" audio recordings. Just me, my Alhambra 7p spruce, and an Olympus ls-10 portable recorder.

Mr Kite

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by Mr Kite » Tue Mar 14, 2017 8:58 am

glassynails wrote:What could we possibly use to determine if something is either real or an illusion if we cannot trust our minds, our senses, or are own logic?
Nothing - if you are sceptical even about logic then you have no foothold. If you accept logic then you can argue that the concept of reality is incoherent. You can also argue that the regularity/reliability in what we observe can be explained by dependent origination, which may therefore be a useful viewpoint to adopt, but which (since the notion of reality is incoherent) is not ultimately real or true. At that point you may find that you are a little less attached to truth.

PeteJ
Posts: 708
Joined: Fri Jul 08, 2016 12:52 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by PeteJ » Tue Mar 14, 2017 9:05 am

gitgeezer wrote:
PeteJ wrote:Philosophers do study truth, and sometimes they find it
Yes, if you're talking about "natural philosophy," also called "science." But tell me one "truth" that any other form of philosophy has found.
Really I should not have to answer this in the internet age and I can't do so briefly, but I'll give a couple of examples. First, metaphysics proves the absurdity of all positive metaphysical positions. Second, Yoga allows us to understand what this result means. Between them they establish the unity of the universe and of consciousness, and to explain all metaphysical problems. For the Perennial philosophy the only purpose of getting up in the morning is to establish the truth.

PeteJ
Posts: 708
Joined: Fri Jul 08, 2016 12:52 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by PeteJ » Tue Mar 14, 2017 9:06 am

glassynails wrote:What could we possibly use to determine if something is either real or an illusion if we cannot trust our minds, our senses, or are own logic? All of my senses may tell me that there's a brick wall in front of me and I may even have that theory reinforced by seeing 10 people all standing there telling me that "Yes, this is a brick wall and it's here". They may also be an illusion to me.

You could also say that "Well either the brick wall is there or it isn't, but who's to say it both is and isn't there. Who's to say that I am here? I cannot even really tell if I exist or I don't.
I would want to ask again, why do you not trust logic?

glassynails
Posts: 5594
Joined: Mon Jul 07, 2008 4:20 am
Location: Westbrook, Maine

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by glassynails » Tue Mar 14, 2017 10:42 am

PeteJ wrote:
glassynails wrote:What could we possibly use to determine if something is either real or an illusion if we cannot trust our minds, our senses, or are own logic? All of my senses may tell me that there's a brick wall in front of me and I may even have that theory reinforced by seeing 10 people all standing there telling me that "Yes, this is a brick wall and it's here". They may also be an illusion to me.

You could also say that "Well either the brick wall is there or it isn't, but who's to say it both is and isn't there. Who's to say that I am here? I cannot even really tell if I exist or I don't.
I would want to ask again, why do you not trust logic?
I do because I believe that as far as I can tell it works, but I cannot ever ultimately know whether or not the outcomes of trusting it are real or an illusion or that there's really a mind using logic to make a decision.

For example - I have to turn the car key to start my vehicle in order to drive somewhere or at least that's how I believe it appears. You and I would most likely say that it's logical that you have to turn the key in order to start the car to drive somewhere. How do I know that by turning the key I'm really "starting the car" and then "driving somewhere". How can I really tell that by turning the key a real car is starting and I am really going somewhere and that it's not an illusion? How do I really know that there's an "I" sitting in the car turning the key?
"GLASSYNAILS" on Youtoob for my "no edit" - "no fakery" audio recordings. Just me, my Alhambra 7p spruce, and an Olympus ls-10 portable recorder.

Salvador
Posts: 202
Joined: Tue Nov 24, 2015 10:59 am
Location: Asia

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by Salvador » Tue Mar 14, 2017 11:08 am

For me we are only human, so it's difficult to answer things we can't explain. Even the old wise men in the past did not find the answers. Even humans from the future also don't know the answer. Like John Titor, who claims he's from the future. He was asked about aliens but he did not give a straight answer. So even humans in the future also don't know hehe.

Mr Kite

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by Mr Kite » Tue Mar 14, 2017 11:45 am

PeteJ wrote:I would want to ask again, why do you not trust logic?
Glassynails wrote:I do because I believe that as far as I can tell it works, but I cannot ever ultimately know whether or not the outcomes of trusting it are real or an illusion or that there's really a mind using logic to make a decision.

For example - I have to turn the car key to start my vehicle in order to drive somewhere or at least that's how I believe it appears. You and I would most likely say that it's logical that you have to turn the key in order to start the car to drive somewhere. How do I know that by turning the key I'm really "starting the car" and then "driving somewhere". How can I really tell that by turning the key a real car is starting and I am really going somewhere and that it's not an illusion? How do I really know that there's an "I" sitting in the car turning the key?
I'm confused Glassy. If you trust things provided that, as far as you can tell, they work, then why the scepticism about whether there is a car or a person or a mind? Surely it does work out when you treat those things as existing.

Anyway, I would not say that your expectation that you need to turn the key in order to start the car has much to do with logic. Take the old syllogism

All men are mortal
Socrates is a man
Therefore Socrates is mortal

Your position seems to me "well how can I be sure that all men really are mortal, or even that there is such a thing as man, let alone that Socrates is one". In other words you are doubting the premises of the argument. You wouldn't be doubting its logic unless you were saying "well even if all men are mortal, and even if Socrates is a man, there is still no way to know whether Socrates is mortal".

If you are not doubting logic in that sense, there is actually quite a lot you can do in terms of investigating the reality / unreality of the things around you.

PeteJ
Posts: 708
Joined: Fri Jul 08, 2016 12:52 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by PeteJ » Tue Mar 14, 2017 12:09 pm

Mr Kite wrote:An illusion is something which appears to be something other than it really is, so being told that the world is a real illusion isn't much comfort for someone who is concerned that the familiar world may not be quite what it seems.

The only way I can make sense of the idea of a real illusion is as an illusion based on an underlying reality - i.e. there is a way that things truly are, but they don't appear that way. The third possibility is that you can have an illusion without there being any way that things truly are - which seemed impossible to me at first but grew on me over time. Mark Siderits has argued for this view.
I'd agree with what you say earlier about certain knowledge having to be absolute, Good point.

The orthodox view among those who speak of space-time phenomena as illusory is that there is a way things are but they do not appear to be this way to our physical senses, which are unable to detect anything other than appearances. Mark Siderits (and Graham Priest likewise) have adopted a heterodox view for reasons unknown to me and not explained by them.

PeteJ
Posts: 708
Joined: Fri Jul 08, 2016 12:52 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by PeteJ » Tue Mar 14, 2017 12:25 pm

glassynails wrote:
PeteJ wrote:I would want to ask again, why do you not trust logic?
I do because I believe that as far as I can tell it works, but I cannot ever ultimately know whether or not the outcomes of trusting it are real or an illusion or that there's really a mind using logic to make a decision.

For example - I have to turn the car key to start my vehicle in order to drive somewhere or at least that's how I believe it appears. You and I would most likely say that it's logical that you have to turn the key in order to start the car to drive somewhere. How do I know that by turning the key I'm really "starting the car" and then "driving somewhere". How can I really tell that by turning the key a real car is starting and I am really going somewhere and that it's not an illusion? How do I really know that there's an "I" sitting in the car turning the key?
I see what you mean but feel you need not be pessimistic. Nagarjuna, Kant, Bradley, Spencer Brown and others have shown that logic can prove the unreality of space-time phenomena. Here 'unreality' would mean 'reducible', thus not metaphysically real.

You're right to say that this is just a calculation thus not knowledge. But this the whole idea of Yoga, that with practice we can know the truth. Those who go looking for it come back to report that the universe and even our own body and mind is not what naive realism would have us believe. They say that you and all of us can know that time and space and all it contains are conceptual phenomena. It just takes a bit of work. Vast numbers of people have claimed to know this, not just to have worked it out.

But logic does its job well enough. It can prove the unreality of these phenomena even it cannot bring complete certainty or understanding.

I feel you'd enjoy a foray into mysticism. You could try Mohrhoff's book on QM if you're into the maths, or Bernardo Kastrup's books on idealism for a gentle introduction. Or, the Tao Teh Ching and the Upanishads if you want to blow your mind.

Or how about The Sun of Wisdom by Gyamptso, in which he explains how Nagarjuna uses logic to prove that nothing really exists or ever really happens.

User avatar
guitareleven
Posts: 698
Joined: Wed Sep 28, 2011 5:48 pm

Re: How do we really know that we can trust our own logic, what we perceive, etc?

Post by guitareleven » Tue Mar 14, 2017 12:37 pm

glassynails wrote: ...Who's to say that I am here? I cannot even really tell if I exist or I don't.
The answer has already been given to you, in having been referred to Descarte's Cogito ergo sum.

You are to say you are here. You can tell that you exist. You have direct experience of yourself, by which your own existence is indubitable. The experience is more direct than any of the sensory phenomena the existence of which you question; that very questioning confirms to you your own existence. If you doubt that, and decide to assign the workings of your own mind, including the doubt you entertain, to the same class as what you perceive to be the external phenomena of perception, the nature of which you question, then the proposition that your own existence may simply be yet another illusion is defeated by infinite regress; i.e., the doubt suggests my mind exists, but I doubt the true existence of that doubt; but that doubt suggests my mind exists, but I doubt the true existence of that doubt about the doubt; but that doubt suggests my mind exists; but I doubt the true existence of that doubt about the doubt about the doubt, but that doubt suggests my mind exists, etc. See? that a mind must exist to entertain the doubt always arises, no matter how far you continue in this vein.

Return to “The Café”