Do the senses themselves (not what they deceptively reveal) exist in some form? [closed]

Question

Firstly, I accept that "I" probably don't exist, labelling a tree Barry and a baby child "Charlie" is the same useful construct for reference.

Secondly, the statements "thoughts exist" is true (at least from "my" perspective) because if it were a false thought, it's still a thought and the thought is always true.

I want to be certain and say "my sight exists, at least deceptively, but there is some kind of lens of observation", but I cannot prove it to myself like above.

I was thinking, I can draw "whats" in front of me on what appears to be a piece of paper, and what appears on the page is my minds image of what is in front of me, which has the potential to be deceived (hallucinate, believe 12x11=131 etc). But the paper itself (the lens of observation) does not have the potential to be deceived, it just exists, and is required for me to draw "what's in front of me".

I would like to be sure of my senses. Any help appreciated.

Answer 1

I have worked a lot with colour vision. The best answer I can some up with is may be condensed to...

We can measure the physical properties of light. We can measure the optical properties of the eye, and the sensitivities of the various senses within the eye. Things then get complicated very quickly. It is almost impossible to predict the nerve signals even before they leave the retina.

No-one has seen a sharp boundary between the pre-processing of a visual signal and the understanding of it. We can loosely point at bits of brain and say "this bit detects 3D motion", or "this bit recognises objects", but there is no clear bit that puts everything together and says "this is a red ball". The best conclusion is that our understanding and sense of what we see probably happens within the brain, but is not localised but spread out among all the bits that play a part.

Our visual systems are not the same. We learn to see, but we all learn differently. The 'that dress' image has shown that we interpret that image in one of two basic ways depending on our assumptions on what the illuminant in the image may have been.

There are also some parts of the visual system that live outside the main mass of the brain. The reflexes that point our eyes and open our pupils have a more direct control, possibly to reduce reaction times as our eyes are at the front and our visual cortex is at the back. But if you say our sense of what we see is "in the brain, and the connections to the optic nerve" then you are probably right-ish.

Are these senses real? It is hard to give a sensible answer. They are real for you. They will be mostly shared by another observer. But if you want to know what's actually going on in the brain, we cannot find or trace a 'red ball' signal, so we are unable to say anything more about it. Yet.

I have a book: "Colour: Sense and Measurement". You can download a PDF version. I don't claim to qualify as a philosopher: this was written to explain to artists how vision scientists try to stick numbers to colours. But it does deal with this sort of thing too.

Afterthought:

We may all see in slightly different ways. What if we all saw in the same way? Suppose we had cameras for eyes and the same pre-trained visual model for turning images into description. Suppose the signals for the red ball we are trying to catch were all in the same place, rather than spread out among different parts of the brain so it is hard to see how we know these separate properties belong to the same thing. I think none of this changes the 'reality' of our sensations.

Socrates said "I know nothing", and I know what he means. In that last sentence I have Socrates' (translated) know meaning know-with-absolute certainty, and my ordinary one. In a philosophy group we might be a bit more circumspect on how we use the word know, but the debate default is to use the common word values unless we explicitly add a sophistication. The question as posed has no such qualifications, and I answer it as such. We commonly talk about thoughts, opinions, dreams and other mind-furniture as things that exist, but may be in error. Our sensations are as real as these. Sensations may feel 'more real' as they were the prompt response to an external stimulus, but it is hard to argue this without knowing much more about the processes of intelligence, and how such things are assimilated.

So, there you go: sensations exist though the meaning of exist needs work in this case. Not great, but maybe it will do.

Answer 2

Cartesian doubt for sight works just like for thoughts: you can't be certain that what you see is real, just like you can't be sure that your thoughts are yours, but it is self evident that you have visual impressions.

Maybe they are the result of light bouncing on real objects and exciting your retina and your brain cells, maybe some alien technology is sending electric signals directly to your brain, maybe it's just a dream. That you can't know for certain, but the fact that you perceive an image is not up for doubts.

Your test of using a paper won't really help. After all, if we posit some magic or very advanced technology can artificially impress your optic nerve, why couldn't it do the same for your sense of touch and prioception, giving your the feeling that you are really touching, writting on and seeing a piece of paper that in fact does no exists. If all those experiences are simulated in a consistant way there would be no way to know for certain. There is simply no way that you can rule absolutely out the possibility that all your perceptions, memories and thoughts are fake.

The way out of this hyper skepticism is to consider not if it's possible to doubt but if it is reasonnable. In On Certainty, Wittgenstein argues that doubting for doubting is pointless: first we ought to have some reason to doubt. For exemple, if you grab a pen, feel it in your hand, write on a paper and see the words you intended to write and according to the movement of your hands, it is to say if everything looks and feel like the world is real a consistant, there is no practical reason to imagine all of it is anything but real. On the other hand if you intended to write "cat" and it reads "pumpkin", if you felt a pencil in your hand and the word are writtens as if it was a marker, it's time to inquire about those discrepencies.

The point being, you can't have metaphysical certainty (as in, complete, absolute certainty) about whether what you see is real, but you can have the next best thing that is practical certainty, a certainty always up for scrutiny and revision but efficient enough, considering you have managed to rely on it to live your life so far.

Answer 3

Senses in the classic understanding are both subjective experiences, and like most philosophy of mind aligned with a physical system which metaphysically is presupposed to be a requirement for the senses in question. Thus, there is the subjective experience of the visual field (subjective) and the visual system including the eyes, optic nerves, visual cortex and so on (objective). So this is a specific manifestation of the greater strategy of using neural correlates of consciousness. From WP:

The neural correlates of consciousness (NCC) refer to the relationships between mental states and neural states and constitute the minimal set of neuronal events and mechanisms sufficient for a specific conscious percept.2 Neuroscientists use empirical approaches to discover neural correlates of subjective phenomena; that is, neural changes which necessarily and regularly correlate with a specific experience.3 The set should be minimal because, under the materialist assumption that the brain is sufficient to give rise to any given conscious experience, the question is which of its components are necessary to produce it.

Now, to answer your ontological question, it all depends on what you mean by 'exist', and there are a number of positions. A mereological nihilist would admit that particles-as-sensory-systems exist, but not the sensory systems (which are an abstraction and not real, but ideal). Most would accept that this is extreme, and certainly the physical systems for our senses exist because their individual components are empirically observable. But the question of the relationship between the mind and subjective experiences of our senses and the brain is historically a contentious issue.

More than one hundred years ago, the popular idea was that of idealists who reduced matter to thought. A subjective idealist might fit that description. Today, the physicalist view of reducing thought to matter is dominant. An eliminative materlialist might fit that position. There are positions that attempt to balance that. An dualist maintains a greater existence and tolerates idealist and physicalist thoughts. So, the question of do the 'senses' exist, largely depends on the metaphysical presuppositions that undergird this notion of 'existence', and it may come as a surprise, but there are many definitions of existence. When you have theory that you can defend on existence, you now have a meta-ontological theory, and are fully in the business of philosophy.

My personal view is, like Quine, to be ontologically stingy; my strategy is not existential quantification, but to reserve existence as 'physical existence' which means directly or indirectly apprehensible to empirical observation. Thus, senses, are experienced, but do not exist; that is not to claim that they are imaginary, but that they are beyond detection by our senses, because senses are not constructed to sense senses; that role is played by consciousness. Of course, you'll find that many people on this forum might have a different take, and the issue is tied up with the ideas that illuminate Chalmer's purported hard problem of consciousness.

Good luck!

Answer 4

As the story goes, when René Descartes was exploring the idea of radical doubt, he found that there was only a single thing he couldn't doubt: his own existence. He reasoned that there was no way for him to experience thoughts if he did not exist. "I think, therefore I am." Everything else was possible to doubt.

We can apply this same concept of radical doubt to our own senses, such as sight. Am I currently seeing my desk and my computer in front of me? Or do I only think I'm seeing them, and in truth my brain is in a nutrient-filled jar where electrodes are sending signals to the right spots in my brain such that I believe I'm seeing when I'm actually not? Both are technically possible, and thus we can doubt either.

Of course, now we arrive at a semantics problem: what counts as "seeing"? To go back to our previous example, even if I lack eyeballs and it's actually electrical impulses that are making me think I'm seeing my workspace, an external stimulus is affecting me and my brain is parsing it. Does the falsehood of the entire perception I experience mean this doesn't count as "seeing"? I think the answer to that isn't static, and really depends on context and what you're after.

If that doesn't count as seeing to you, then we've arrived at your answer. But if it does, then we need to progress deeper. To do so, let's identify two ideas:

• I think I'm seeing.
• I'm seeing.

As you noted before, even if we can doubt the accuracy and the content of our thoughts and experiences, we cannot doubt that we are having thoughts and experiences. Because of this, "I think I'm seeing" cannot be doubted.

So what does "I'm seeing" mean? If it means the same thing as "I think I'm seeing", then it cannot be doubted. But if it means something different, if "I'm seeing" means something more than "experiencing something that I interpret as seeing", then it can be doubted.

If "I'm seeing" means I'm experiencing external stimulus, it could be internal stimulus.

If "I'm seeing" means I'm legitimately interpreting something, your ability to parse could be flawed and it could just be random noise.

It could even be that there's no stimulus to experience at all, and your subconscious is just making up experiences for you to have.

Etc.

While I'm open to alternatives, I have yet to find something beyond the facts that I have thoughts and experiences that is not possible to explain via alternatives, and thus can be doubted. I hope this helps to provide you with a framework that you can use to explore your ability to doubt by finding possible alternative explanations.

And as a final note, I hope that if you end up agreeing with my conclusion that your senses can be doubted that you don't find it distressing. Part of the beauty of life is that there's so much we can't be sure of, and doing our best to figure things out and find joy regardless.