My argument is not from cause to effect, but tracing the effect back to the cause. The effect of our perception of the physical world requires an adequate cause. That cause must be a real physical world. Could it be something else?Are you assuming that the world would be made of your perceptions or imaginations? Why else would you claim that the question whether the world is physical would depend on our ability to perceive physical things? — jkop
The effect of our perception of the physical world requires an adequate cause. That cause must be a real physical world. Could it be something else? — Samuel Lacrampe
I think your concern misses the mark. If only a spiritual world exists, even if it is uncaused, then we could never perceive a physical world, due the limitation of our imagination, as explained previously. But we do perceive a physical world. If a physical world exists, even if it is uncaused, then it explains the phenomenon of our perception. Now you demand a cause for the existence of the physical world. That is indeed left unanswered, but it stands outside of the original topic of discussion, which was to explain how it is that we perceive a physical world.Why do you not in return though, need to explain where the physical world comes from? — dukkha
tracing the effect back to the cause. — Samuel Lacrampe
It's a very common metaphor, so I would be very surprised if you were not already aware of its meaning. It's used in that way to mean "to imagine or visualise". To see with your mind's eye. It's not meant to be taken literally, hence the scare quotes. — Sapientia
Well, I perceive a table in front of me. This table is a physical object, even if that object is only imaginary.You can't jump straight into how it is that we perceive a physical world without first establishing that we perceive a physical world. — Sapientia
I am not sure I understand this. Can you present the argument?things like "blue" are perceptual, and thus lead to an ideal (or "spiritual") world. — Sapientia
Sure. Indeed, the existence of a physical world is not a necessary cause to the effect of my perception of physical things; but it is an adequate cause, thus a candidate. To refute this candidate, we would need to find other adequate causes to take its place. I can think of only one, which is God. Since God (should He exist) can create things from nothing, then He could create the idea of physical things in our minds without physical things existing in the real world.You've said that there must be a cause, yet there is no necessary connection between the one and the other. Or, if there is, can you demonstrate this? — Sapientia
I would describe the colour indirectly, by referring to its effects on people who can see it, by how they use the word 'red', describe things in which the colour occurs in nature, and its metaphorical uses etc. To imagine what it's like to see red is not to see anything, recall. Imagination is the evocation of an experience via knowledge of one's past or other experiences. Without any past visual experiences the blind can still use knowledge of other experiences, or knowledge of other people's visual experiences, in order to imagine what it's like to see red. — jkop
Well, I perceive a table in front of me. This table is a physical object, even if that object is only imaginary. — Samuel Lacrampe
I am not sure I understand this. Can you present the argument? — Samuel Lacrampe
Sure. Indeed, the existence of a physical world is not a necessary cause to the effect of my perception of physical things; but it is an adequate cause, thus a candidate. To refute this candidate, we would need to find other adequate causes to take its place. I can think of only one, which is God. Since God (should He exist) can create things from nothing, then He could create the idea of physical things in our minds without physical things existing in the real world. — Samuel Lacrampe
I don't see how that would work at all. Saying that green is the colour of grass and apples, that red is the colour of strawberries and apples, that cars come in many different colours, and that purple is the colour we associate with royalty and wealth, unless you're in Brazil or Thailand where it's the colour of mourning, won't help a blind person understand what it's like to see colours. How can you think it would? — Michael
If we regard the physical world as the 'cause' of our phenomenal experiences, then the existence of the physical world - thus defined - is an assumption, based abductively (and hence partly subjectively) on our experiences. Immanuel Kant believed in a such a physical world, but argued that its constituents were imperceptible and unknowable - and also, one would imagine, unimaginable. He called them 'noumena'. He went to great lengths in his second version of the Critique of Pure Reason to argue that this did not make him an Idealist (which seems to correspond to what you are calling a 'Spiritualist'), although he would agree to being a 'Transcendental Idealist', a term he made up to describe his position.I came up with an argument against extreme spiritualism, and would like your thought on the strength of it. Extreme spiritualism: the belief that the physical world does not exist, that all that exists is spiritual, and that the physical world is therefore all imagined. — Samuel Lacrampe
. . . ..won't help a blind person understand what it's like to see colours. How can you think it would? — Michael
A bind person lacks the ability to see; not to understand, nor imagine, what it's like to see. — jkop
That alone is enough for me to be able to imagine what it's like to detect them, or see them with my imagined super-naturally sensitive eyes.
Imagination is, unlike perception, an evoked experience which is closely related to perceptual experience but occurs under very different conditions. Instead of direct causal links and interaction with present objects there is knowledge, empathy, and the ability to evoke experiences we call imagination. Do you think that's controversial or false?
Interesting. I wonder how widespread this phenomenon is among the non-congenitally blind. In cases in which this "imagination blindness" occurs, perhaps it's because the visual cortex is being co-opted by something else (assuming that the visual cortex is even involved in imagining sight to begin with).There's an interesting article on blindness by Oliver Sacks called The Mind's Eye. In it he even describes how someone who was once sighted but lost his sight (due to an issue with his eyes, not with his brain) can't even imagine visual things any more — Michael
Interesting. I wonder how widespread this phenomenon is among the non-congenitally blind. In cases in which this "imagination blindness" occurs, perhaps it's because the visual cortex is being co-opted by something else (assuming that the visual cortex is even involved in imagining sight to begin with). — Arkady
It was found that the imagined patterns and seen patterns produced similar waveforms, supporting evidence for the claim that the visual cortex is activated in a similar manner during both imagination and perception.
If we regard the physical world as the 'cause' of our phenomenal experiences, then the existence of the physical world - thus defined - is an assumption, based abductively (and hence partly subjectively) on our experiences. — andrewk
I agree with Kant that he was not an Idealist (in the sense typically applied to George Berkeley, although Berkeley called himself an Immaterialist). — andrewk
He believed in the existence of a physical world. He just also believed that it was unknowable. — andrewk
As previously stated, I defined "physical" as: matter and energy. I would now add "anything that is perceived by the senses" for further clarity. Now a table is made of matter (atoms). Thus the table I perceive is physical.I perceive a table in front of me. This table has not been demonstrated by you to be a physical object, whether that object is only imaginary or otherwise. — Sapientia
But the definition of perceptual is "involving perception especially in relation to sensory experience", and "sensory" is related to physical things. Thus according to that definition, this would make the perception of "blue" lead to acknowledging a physical world, not idealism, would it not?things like "blue" are perceptual, and thus lead to an ideal (or "spiritual") world. — Sapientia
To say that "the existence of X is an adequate cause for my perception of X" is really the common sense hypothesis and is therefore the default position. If you were to object to this, you would have the onus of proof to refute the claim, not me.By what method are you assessing whether or not a candidate is adequate? — Sapientia
I guess not always. But how about perceiving things directly through the senses (seeing, hearing, smelling, touching, ...)? Aren't things that are perceived through the senses necessarily physical?From the fact that you perceive something it does not follow that the world is physical — jkop
I defined "physical" as matter and energy. I perceive a table. The table is made of matter, thus is physical. Therefore I perceive a physical world.Begs the question. — dukkha
The table is made of matter — Samuel Lacrampe
. . .We once had a blind poster on the old forum who asked us to explain sight to her and she couldn't make heads or tails of it, which is expected. — Michael
And when you imagine seeing neutrinos with your super-naturally sensitive eyes, what do you imagine? A tiny little ball, perhaps? I'm no scientist, but I'm pretty sure that would be completely wrong. — Michael
. . .the blind person must have had some experience that is something like colours for them to understand colours, which they don't. — Michael
How can the blind evoke an experience of a kind they've never had? — Michael
I think it reasonable to suggest that those who've never experienced sight at all would be like the one who can't remember, given that the information was never in the brain to begin with). — Michael
But science claims that tables are made of matter. Surely I can appeal to the authority of science on this. At the very least, the scientific claims become the default position, and so the idealist disputing the claim agreed upon by science would have the onus of proof, not me.An idealist would dispute that the table is made of matter. — dukkha
Now a table is made of matter (atoms). — Samuel Lacrampe
Investigate what it means for something to be physical, does it leave anything out?Aren't things that are perceived through the senses necessarily physical? — Samuel Lacrampe
As previously stated, I defined "physical" as: matter and energy. I would now add "anything that is perceived by the senses" for further clarity. — Samuel Lacrampe
Now a table is made of matter (atoms). — Samuel Lacrampe
But the definition of perceptual is "involving perception especially in relation to sensory experience", and "sensory" is related to physical things. — Samuel Lacrampe
Thus, according to that definition, this would make the perception of "blue" lead to acknowledging a physical world, not idealism, would it not? — Samuel Lacrampe
To say that "the existence of X is an adequate cause for my perception of X" is really the common sense hypothesis and is therefore the default position. If you were to object to this, you would have the onus of proof to refute the claim, not me. — Samuel Lacrampe
I agree with this, but I think there is still a misunderstanding on the term "physical". Let me try to define it another way: A thing is physical if it has spatial attributes such as length, height, volume, etc. It is also physical if it has attributes related to energy, such as speed, force, noise emission etc. Finally, it is physical if it can be detected (by instruments) and measured. Under that new (less than perfect) definition, a table is definitely physical, even if only an illusion. My whole argument is not prove that the table that I perceive is real, but that if the perception of physical things exist, then there must exist a physical world somewhere.Science can't really tell you if the world is real or not. — Wayfarer
Yes. Concepts such as logic, morality, and justice are not perceived through the senses, and yet are undeniably real (at least logic for most people). They are therefore non-physical things. I would also add spiritual things like souls, angels and God, but these concepts can be controversial and so we can leave them out. If you disagree, what would you consider physical things versus non-physical?Investigate what it means for something to be physical, does it leave anything out? — jkop
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