Discussion

7 Novembro 2025, 11:00 • David Yates

If you want to think more about Hive / Group Minds, you can read the entry on Block's Chinese Nation in the book on thought experiments.

In the Friday discussion class we covered again the main points of the debate between Searle and Chalmers on whether "fading qualia" are possible. We then disucssed in more detail the possibility of mind uploading, and whether the subject would lose consciousness during the processs. We explained the relevance of the thought experiments to our personal and moral standpoint on mind uploading and brain replacement situations.

Mind uploading and brain replacement

4 Novembro 2025, 11:00 • 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

DIscussion

31 Outubro 2025, 11:00 • David Yates

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? 

Mary the colour scientist thought experiment

28 Outubro 2025, 11:00 • 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 Tuesday'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

Discussion

24 Outubro 2025, 11:00 • David Yates

In the Friday session we discussed the Ship of Theseus puzzle, and fission cases, and their implications for the identity of both objects and persons 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 and mental 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!
• The important point is that unless you think there is some essential metaphysical difference between ships and persons (and there may well be) then whatever you say about the ship, you should also say about persons and their identity. Can we survive replacement of our parts? Does it matter how many parts we have and how quickly they are replaced? Are you really numerically identical to a baby, or was Heraclitus right - can you ever speak to the same person twice?

We then 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. These cases are often taken to suppose a four-dimensionalist conception of space a time, in which all times are equally real, just as all places are equally real, and we as human being are located at multiple times (that is, we have temporal parts). Fission cases, that is cases in which a single person seems to divide into two persons, are actually cases in which one 4D person has a strange Y-shaped structure. Nothing divides! Instead, the 4D person is the thing that has two (or more) branches when seen as a being that extends in space as well as time. On this view, when fission happens (e.g. your brain is copied and placed in a new body, or a transporter accident occurs) a Y-shaped spacetime worm starts off having only one temporal part that exists at any given time, as we all are now. But after fission, that same Y-shaped person later has two temporal parts that exist at the same time, and which have different thoughts and experiences. On 4D-ism, this is no more mysterious than the fact that you have two legs that exist at different places.

We will return to this discussion next week.