Very good essay thank you. The following part was awesome “Deliriously happy people are shown engaged in delightful activities, all thanks to the wonder drug Gulliblex. As they cavort, the announcer smoothly intones possible side effects, "may lead to blindness, seizure, or death."
As usual, Keith Parsons provides an informative and fascinating look at his topic. But I want to put in a defense of philosophical skepticism by pointing out that it is not incompatible with believing in an observer-independent external (i.e. "physical") world. One can be skeptical of our ability to know the physical world "as it is" without having to doubt that "it is." Philosophical skepticism is a position about knowledge rather than a position about existence of the physical world.
Nor did classical skepticism necessarily embrace "universal doubt" about knowledge. Carneades, for example, evidently argued that although nothing can be known with certainty, some knowledge is more likely to be true than other knowledge, and that we should focus on what can be known with the highest degree of probability.
As it turns out, it's hard to be certain of the beliefs of the classical skeptics who led the Platonic Academy in Athens—Arcesilaus, Carneades, and Clitomachus—because no writings of theirs survive, and their arguments must be constructed primarily from rebuttals of critics. Clitomachus wrote over 400 books explaining Carneades' philosophy, and not one survives. The main thing we understand about them is that they denied that there could be any objective "criteria of truth" and they cast doubt on the idea that our senses portray the world "as it really is."
Thus the story of GE Moore holding up his hands as if that refuted skepticism demonstrates Moore's confusion about philosophical skepticism. Carneades would say that Moore's hands, which we see and perceive through our senses, are an appearance and thus not the same as Moore's real hands. He would not deny that Moore has real hands, but would deny that his real hands necessarily comport with what our senses perceive. (If Moore had read Bertrand Russell's book, The Problems of Philosophy, I think he would have comprehended the point.)
Modern neuroscience agrees with the ancient skeptics. As Jeff Hawkins, author of A Thousand Brains (2022), explains "There are no sensors in the brain itself, so the neurons that make up your brain are sitting in the dark, isolated from the world outside. The only way your brain knows anything about reality is through the sensory nerve fibers that enter the skull. The nerve fibers coming from the eyes, ears and skin look the same, and the spikes that travel along them are identical. There is no light or sound entering the skull, only electrical spikes." (p 173) He continues, "And since we do not perceive spikes, everything we do perceive must be fabricated in the brain. Even the most basic feelings of light, sound and touch are creations of the brain; they only exist in its model of the world." (p 174)
This means that we don't perceive the world; what we perceive is instead a sensual "stand-in" for the world, a "virtual reality" created by the brain. Hawkins again, "The truth is, we perceive our model of the world, not the world itself or the rapidly changing spikes entering the skull. As we go about our day, the sensory inputs to the brain invoke the appropriate parts of our world model, but what we perceive and what we believe is happening is the model. Our reality is similar to the brain-in-a-vat hypothesis; we live in a simulated world, but it is not in a computer—it is in our head." (p 175)
Thus, we do not "perceive" the world; what we "perceive" is a virtual reality or simulacrum created by the brain which evolved to stand-in for the world, and which provides the organism (hopefully) with a reliable basis for action. In this context, philosophical skepticism begins to make a lot of sense.
Biological organisms like us have no way of perceiving or knowing the organism-independent external ("physical") reality. What we "know" is the "virtual reality" and corresponding cortical "model" which the brain creates and presents to us from hints the body has obtained via its sense organs. This virtual reality is what we naively mistake for the external world around us.
Pragmatic empiricism—the method of the sciences—coordinates the relationship between the model of the world created thusly by our brains and the actual "physical" external world which which our bodies interact (the world our brains can never actually "know"—what we can "know" is the virtual stand-in).
Anyway, philosophical skepticism has legs in the 21st century.
Your essay reminded me of the book by Charles Seife, "Proofiness, How you're being fooled by the numbers," 2010 Penguin Books. I would be curious to know if you've read it?
Very good essay thank you. The following part was awesome “Deliriously happy people are shown engaged in delightful activities, all thanks to the wonder drug Gulliblex. As they cavort, the announcer smoothly intones possible side effects, "may lead to blindness, seizure, or death."
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As usual, Keith Parsons provides an informative and fascinating look at his topic. But I want to put in a defense of philosophical skepticism by pointing out that it is not incompatible with believing in an observer-independent external (i.e. "physical") world. One can be skeptical of our ability to know the physical world "as it is" without having to doubt that "it is." Philosophical skepticism is a position about knowledge rather than a position about existence of the physical world.
Nor did classical skepticism necessarily embrace "universal doubt" about knowledge. Carneades, for example, evidently argued that although nothing can be known with certainty, some knowledge is more likely to be true than other knowledge, and that we should focus on what can be known with the highest degree of probability.
As it turns out, it's hard to be certain of the beliefs of the classical skeptics who led the Platonic Academy in Athens—Arcesilaus, Carneades, and Clitomachus—because no writings of theirs survive, and their arguments must be constructed primarily from rebuttals of critics. Clitomachus wrote over 400 books explaining Carneades' philosophy, and not one survives. The main thing we understand about them is that they denied that there could be any objective "criteria of truth" and they cast doubt on the idea that our senses portray the world "as it really is."
Thus the story of GE Moore holding up his hands as if that refuted skepticism demonstrates Moore's confusion about philosophical skepticism. Carneades would say that Moore's hands, which we see and perceive through our senses, are an appearance and thus not the same as Moore's real hands. He would not deny that Moore has real hands, but would deny that his real hands necessarily comport with what our senses perceive. (If Moore had read Bertrand Russell's book, The Problems of Philosophy, I think he would have comprehended the point.)
Modern neuroscience agrees with the ancient skeptics. As Jeff Hawkins, author of A Thousand Brains (2022), explains "There are no sensors in the brain itself, so the neurons that make up your brain are sitting in the dark, isolated from the world outside. The only way your brain knows anything about reality is through the sensory nerve fibers that enter the skull. The nerve fibers coming from the eyes, ears and skin look the same, and the spikes that travel along them are identical. There is no light or sound entering the skull, only electrical spikes." (p 173) He continues, "And since we do not perceive spikes, everything we do perceive must be fabricated in the brain. Even the most basic feelings of light, sound and touch are creations of the brain; they only exist in its model of the world." (p 174)
This means that we don't perceive the world; what we perceive is instead a sensual "stand-in" for the world, a "virtual reality" created by the brain. Hawkins again, "The truth is, we perceive our model of the world, not the world itself or the rapidly changing spikes entering the skull. As we go about our day, the sensory inputs to the brain invoke the appropriate parts of our world model, but what we perceive and what we believe is happening is the model. Our reality is similar to the brain-in-a-vat hypothesis; we live in a simulated world, but it is not in a computer—it is in our head." (p 175)
Thus, we do not "perceive" the world; what we "perceive" is a virtual reality or simulacrum created by the brain which evolved to stand-in for the world, and which provides the organism (hopefully) with a reliable basis for action. In this context, philosophical skepticism begins to make a lot of sense.
Biological organisms like us have no way of perceiving or knowing the organism-independent external ("physical") reality. What we "know" is the "virtual reality" and corresponding cortical "model" which the brain creates and presents to us from hints the body has obtained via its sense organs. This virtual reality is what we naively mistake for the external world around us.
Pragmatic empiricism—the method of the sciences—coordinates the relationship between the model of the world created thusly by our brains and the actual "physical" external world which which our bodies interact (the world our brains can never actually "know"—what we can "know" is the virtual stand-in).
Anyway, philosophical skepticism has legs in the 21st century.
Hello Professor Parsons!
Your essay reminded me of the book by Charles Seife, "Proofiness, How you're being fooled by the numbers," 2010 Penguin Books. I would be curious to know if you've read it?