Sumários
Brain Replacement and Mind Uploading
6 Novembro 2024, 13:30 • David Yates
This week we will discuss some further thought experiments relating to the nature of consciosuness. Last week's thought experiments (Mary's Room and Nagel's Bat) are designed to show that conscious experience is not physical. They attempt this by first trying to show that facts of conscious experience (what it is like from a first-person point of view to be in certain conscious states) are not physical facts. We will begin by refreshing our memory of these thought experiments and examining the arguments they support.
We will then move on to consider three further thought experiments:
- Brain Repacement (Searle)
- Chalmers' "Absent Qualia, Dancing Qualia, Fading Qualia" response to Searle
- Block's Chinese Nation
These thought experiments are more specific than the others, as they explore the relationship between consciousness and information processing, computation and brain function. Here is the crucial question to consider:
- Is consciousness produced in the brain by information processing / brain function?
If consciousness is determined / caused / constituted by information processing, then it is a fairly abstract phenomenon: abstract enough that you could in principle upload your mind into a computer without losing your consciousness. But if consciousness is a primarily biological phenomenon (or perhaps, even deeper than that, a quantum physical phenomenon) then the uploading process will not preserve your conscious experience.
The strange thing about such thought experiments is that they seem to show that it is possible for there to be a zombie version of you: if the brain replacement or uploading process duplicates all of the information processing properties of the neurons in your brain, then it should produce a copy of you that has all the same abilities, dispositions, causal powers, etc. In other words, it will produce a copy of you that says all the same things you say, including talking about its own conscious states. If it does not have any conscious states, then it is a zombie copy of you!
David Chalmers' version of the brain replacement thought experiment is designed to show that in fact, a zombie functional copy of you is impossible at our world. Your consciousness, in his view, would be duplicated if you were uploaded. This is a very important philosophical question with lots of potential impact for future societies. Brain implants and uploading may become reality in the next 50-100 years.
All the thought experiments for this week can be found, in brief form, in the book. I am also going to upload some of the original articles for those who wish to read further. If you want to read about David Chalmers' views, in particular why he rejects Searle's "Fading Qualia" possibility (the idea that your consciousness would gradually disappear as your biological neurons were replaced with silicon neurons), you can read about it here: https://consc.net/papers/qualia.html
One thing we did not get time to cover in class was the possibility of group or hive minds. We will discuss that on Friday, but in the meantime you can read the entry on Block's Chinese Nation in the book on thought experiments.
Mary's Room
30 Outubro 2024, 13:30 • David Yates
In this session we will discuss the famous knowledge argument against physicalism, due to Frank Jackson. Here we have a thought experiment, connected to an argument, so it is a very useful case to consider if we want to investigate the nature and epistemic role of thought experiments. Here is a famous quotation from Jackson's paper, Epiphenomenal Qualia, which you can find in the readings folder. Also, you can read about the thought experiment in Peg Tittle's book, or in detail at the following entry in the Stanford Encyclopaedia of Philosophy: https://plato.stanford.edu/entries/qualia-knowledge/. (Be warned: the SEP is for professional philosophers as well as students, so it can be somewhat difficult for students to follow.)
"Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’. (It can hardly be denied that it is in principle possible to obtain all this physical information from black and white television, otherwise the Open University would of necessity need to use colour television.) What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then is it inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false." Frank Jackson, "Epiphenomenal Qualia"; p. 130.
The slides for Wednesday's class will feature this quotation and (at least in the beginning) nothing more. In class, we will try to formulate the argument contained in the passage, and consider what epistemic role, if any, the thought experiment plays. We will consider how a physicalist should respond to Jackson's argument, and focus on the role of intuition in the thought experiment.
Encontra-se aqui uma tradução portuguesa de um dos artigos de Jackson (publicado depois do seu artigo "Epiphenomenal Qualia", em que se encontra o texto acima citado). O artigo original é chamado "What Mary didn't know" e nele Jackson tentou esclarecer algumas dúvidas que surgiram em relação ao original. Tr: Ricardo Miguel.
https://criticanarede.com/mary.html
If you want to read more about panpsychism, which I discussed in the last class, you can Galen Strawson's article Realistic Monism.
- Important note about this to avoid confusion: in class I discussed panpsychism as a non-physicalist theory of consciousness, i.e. a theory on which there are facts about consciousness that are not physical. These are the facts that Mary learns when she first sees colour, and they come from the intrinsic natures of the fundamental particles in her brain. She learns, basically, about the intrinsic nature of her own brain states, when previously she only had complete physical knowledge of their structure and function. Strawson agrees with all that, expect he thinks that the new facts (the ones about the intrinsic nature of her brain) are also physical facts of a certain kind. Therefore, he thinks that Mary does not know all the physical facts before her release, and that there are physical facts that cannot be written down in books.
- Both are forms of panpschism, the only disagreement is about how we should define "physical". Are the facts about the intrinsic natures of fundamental particles a special kind of unexpressible physical fact, or are all the physical facts objective facts about the way things work and how they relate to each other?
The Ship of Theseus and other Fission Cases
25 Outubro 2024, 13:30 • David Yates
In the Friday session we discussed the Ship of Theseus puzzle and its implications for personal identity over time
- One standard response to the ship of Theseus is to say that the ship at sea is the original, but composed of different parts; while the ship in the museum is a new ship, composed of the original parts of Theseus' ship.
- On this theory, things are constituted by (but not identical to) specific collections of parts, which can change over time without the things in question losing their identity. So far so good...
- But what then should we say about persons? If we are constituted of our fundamental physical parts, but not identical to them, it seems there must be two things located where we are at any given time: a person that can survive part replacement, and a specific aggregate (collection, structure) of fundamental physical particles that cannot survive part replacement.
- Problem: at any given time, that specific collection of parts has all the same physical properties you have at that time, so there seem to be two things where you are, thinking your thoughts. It's the same in the ship case: there is a specific collection of planks and a ship, but they can't be identical, because the ship can survive replacement of its planks, but the specific collection of planks cannot!
- Maybe this is not much of a problem: the specific collection of fundamental particles located where you are at a given time t does not even survive one second later than t, since the particles are constantly in flux. Perhaps it does not even have time to think anything before it is replaced by a new collection!
We then discussed the idea that people are essentially psychological beings, while human animals are not. A human animal can continue to exist after brain death, for example, but arguable a person cannot. But this raises an even worse problem than the one above:
- The human animal located where you are can survive replacement of its fundamental particles, in fact it is older than you are: it once existed as a foetues, whereas you existed as a separate person (arguably) only from the moment of birth. Perhaps this isn't quite right, but you get the point. Anyway, the human animal where you are could definitely survive after the person you are no longer exists.
- Thus, there are two living things where you are: a person that could not survive loss of all its mental states (consciousness, belief, memory etc.) and a human animal that existed before you had any of those features, and could survive without them again in the future.
- How many living beings are thinking your thoughts right now? It seems like we must say they are two!
We then briefly discussed fission cases, which are cases where we imagine a single person dividing into two persons, either because of hypothetically possible brain surgery or a sci-fi transporter accident. We will return to that discussion next week.
Introduction to Thought Experiments
23 Outubro 2024, 13:30 • David Yates
This week we will begin discussing thought experiments.
Reading suggestions
Chapter 3 of Chris Daly's book An Introduction to Philosophical Methods will be very useful for this topic. Also very useful will be Peg Tittle's book What if? Collected thought experiments in philosophy. I will refer you to specific thought experiments from Tittle's book in the topic descriptions below.
We will first introduce some metaphilosophical ideas, concerning the following questions:
- What are thought experiments and how do they differ from scientific experiments?
- What is the epistemic role of thought experiments? (Are they sources of knowledge / justification?)
- If thought experiments are sources of knowledge, what is their proper domain? (What is it we can learn about from them?)
- Are thought experiments just disguised arguments, or something more?
- Do thought experiments depend on our intuitions, and if so, is that a problem?
Once we have briefly discussed some of these issues, we will begin our survey of some classic philosophical thought experiments with the famous Ship of Theseus puzzle. We will consider what, if anything, this imagined puzzle tells us about the nature of material objects and the way in which they persist over time. Briefly, the Ship of Theseus puzzle goes like this. Sailors at sea would repair their ships while at sea, and this often included the replacement of one or two planks of wood. A ship can clearly survice replacement of a single plank, that is, it is the same ship after the replacement as it was before. This is just the same as the way in which we humans survive replacement of our constituent molecules. But eventually, that means it is possible for a ship to contain none of the original planks that constituted it. This is an interesting fact, but not yet the puzzle we will be concerned with. Here is the puzzle:
Suppose the original planks and all the other parts of the original ship are kept after they have all been replaced. They are taken away to a museum, one by one, where they are eventually reassmbled to form a ship. Where now is the original Ship of Theseus? Is it the one that is still sailing at sea, that was gradually repaired, or is it the reassembled ship in the museum? Both ships, it seems, have a very strong claim to being the original. But originally, it seems there was only one ship, and now there are two! One ship cannot be identical to two ships, so where is the original Ship of Theseus? Things we will think about in class:
- What does this puzzle and similar cases tell us about survival and identity?
- Do the same lessons apply to us as people?
- Is this similar to "fission cases" - another kind of thought experiment in which one person seems to become two - or is it different?
- Were there two ships all along, which were eventually separated from one another?
Once we have considered these questions, we will return to our initial questions about the nature of thought experiments. Does the puzzle teach us anything we did not already know? If so, is it a disguised argument, or did we really conduct some kind of experiment into the nature of reality?
You will find brief descriptions of many, many thought experiments (including the Ship of Theseus and the others we will look at in this part of the course) in Peg Tittle's excellent book, "What if - Collected Thought Experiments in Philosophy"
Em português, este problema chama-se o Problema do Návio de Teseu. Este artigo no Compêndio em Linha em capaz de ser util - a primeira parte é relativamente fácil ler e contém uma versão simples do problema. https://compendioemlinha.letras.ulisboa.pt/wp-content/uploads/2015/01/composicao-material.pdf
In Friday's class we will consider Fission cases and Personal Identity over Time. Fission cases are thought experiments that depend, typically, on some empirical knowledge about how the brain works. However, they go further that that and ask us to imagine scenarios in which one person can seemingly divide into two.
Readings for this week (all very short, 1-2 page articles from Peg Tittle's book, describing some very interesting philosophical thought experiments):
Identity of material objects: "Hobbes' Ship of Theseus" (pp. 68-9)
Personal Identity: "Perry's Divided Self", pp. 82-3; and Parfit's Fission (pp. 84-5)