Welcome to this week's Open Discussion Thread. This thread is a place for posts/comments which are related to philosophy but wouldn't necessarily meet our posting rules (especially posting rule 2). For example, these threads are great places for:

• Arguments that aren't substantive enough to meet PR2.

• Open discussion about philosophy, e.g. who your favourite philosopher is, what you are currently reading

• Philosophical questions. Please note that /r/askphilosophy is a great resource for questions and if you are looking for moderated answers we suggest you ask there.

This thread is not a completely open discussion! Any posts not relating to philosophy will be removed. Please keep comments related to philosophy, and expect low-effort comments to be removed. All of our normal commenting rules are still in place for these threads, although we will be more lenient with regards to commenting rule 2.

Previous Open Discussion Threads can be found here.

My argument in a nutshell is that Mary's Room is an intuition pump for the "common sense" notion that experiential knowledge (qualia) are not "physical information." However "physical information" is so ill-defined in the paper as to be almost meaningless, and insofar as it is defined, does not appear to constitute an argument against physicalism. Mary's Room might be an interesting thought experiment about something, but its not grounds for something like panpsychism or idealism, because it reveals nothing about the limits of what can be described through purely physical means.

Here's Jackson's definition of "physical information:"

It is undeniable that the physical, chemical and biological sciences have provided a great deal of information about the world we live in and about ourselves. I will use the label 'physical information' for this kind of information, and also for information that automatically comes along with it. For example, if a medical scientist tells me enough about the processes that go on in my nervous system, and about how they relate to happenings in the world around me, to what has happened in the past and is likely to happen in the future, to what happens to other similar and dissimilar organisms, and the like, he or she tells me -if I am clever enough to fit it together appropriately -about what is often called the functional role of those states in me (and in organisms in general in similar cases). This information, and its kin, I also label 'physical'.

First off, this is a laughably vague definition. Does "all the physical information" only include the Core Theory? What about higher level concepts like entropy and temperature? Jackson seems to admit them, but it's not clear. He also says that it includes "happenings in the world around me, to what has happened in the past and is likely to happen in the future" but as we will see then contradicts that in his future responses to criticism. Nor is there any reckoning with why this should be the definition of physical information. I feel quite certain there are others.

Mary "acquires all the physical information there is to obtain" about the color red and what happens when people see it.

Surely no one is suggesting that the only difference between reading a book about hiking, and taking a hike are ephemeral qualia and that tells us something about the fundamental nature of reality, right? So when Jackson talks about "knowing all the facts" this is more like a Laplace's Demon-type of "knowing all the facts" that includes all possible physical information that could be known — that should be the foundation of the inquiry and that is in fact Paul Churchland's formulation:

1. Mary knows everything there is to know about brain states and their properties.
2. It is not the case that Mary knows everything there is to know about sensations and their properties.
3. Therefore, sensations and their properties are not the same (≠) as the brain states and their properties.

If you frame it in terms of brain states, then by definition that physical information would include the physical experience and sensations of seeing red — all the brain states and associated qualia. So nothing is new when Mary sees red — she has in effect already seen it by virtue of possessing every relevant brain state already.

But Jackson objects to this characterization and says, "The whole thrust of the knowledge argument is that Mary (before her release) does not know everything there is to know about brain states and their properties because she does not know about certain qualia associated with them. What is complete, according to the argument, is her knowledge of matters physical."

If the question is, "are there non-physical facts?' then by saying, "Mary knows all the physical facts, but not these others," isn't Jackson just begging the question?

Jackson basically admits this outright in response to Churchland: "My reply is that [Churchland's reformulation] may be convenient, but it is not accurate. It is not the knowledge argument. Take, for instance, premise 1. The whole thrust of the knowledge argument is that Mary (before her release) does not know everything there is to know about brain states and their properties, because she does not know about certain qualia associated with them."

Again, this is not a problem if this is not a debate about physicalism. But if it is, then Jackson is begging the question.

The analogy I came up with in another very unsatisfying Reddit thread is this:

A piece of written sheet music is not the same thing as the music itself. In order to know everything about the music, you have to assemble a string quartet to perform the music. And the way that I would know this is that I would look at the sheet music and that knowledge would become a physical brain state. And then I would hear the music performed and discover that I had learned something new about the music — what it sounds like. But this is an interesting observation about the nature of information. It is not a statement about the nature of reality. Everything the string quartet does in performing the music is physical — all the sound waves are physical entities. There's nothing spooky going on here. Nothing about either the sheet music or the performance in any way calls into question whether the laws of physics are capable of accounting for all observable phenomena in the universe.A problem exists only if I make the claim that the sheet music encodes "everything there is to know about the music." We know it does not.

The way this discussion of music is set up, it's an entirely materialist inquiry into how physical (musical) information is encoded. It's not going to reveal anything about the metaphysical nature of reality.I am asserting that if you want to instead have a discussion about the nature of music, and whether there is some magical quality that music has over and above the physical, you would have to first eliminate any semantic messiness and questions of encoding, so that all that is left is the question of whether there is any magic special sauce in addition to the physical facts. You would have to imagine a "perfect" piece of sheet music that encodes not just the written music, but also all the sound waves produced by the instruments in perfect fidelity. We would have to say that the brain state you have when you hear the music performed is the same as the one you would have after reading the "perfect" piece of sheet music. And then and only then could you ask the question, "does the person who heard the music performed know something new that the person who only read the 'perfect' sheet music does not?" Any other version of this argument is an argument about encoding and information — not physicalism.

There is a lot of other stuff in Jackson's paper that is ill-defined such as terms like, "learn" or in the concept of knowing. These seem to be higher level descriptions, but the conclusion about physicalism as about as low-level as you can get.

For example Jackson is positing that Mary knows a bunch of stuff about redness. What does it actually mean to know something? There are probably a few definitions, but any would necessarily include memory. To know something is to remember it. Even if you just experienced it a millisecond ago, for you to "know" it, you must be recalling it. And by "recall" we mean "tell a story." Your brain cobbles together a set of symbols and ideas and associations into something like a sufficiently internally coherent story, which for humans includes the memory or association of relevant qualia.

Jackson (who was a dualist at this point) seems to be suggesting that the human mind stores all its memories of physical facts in the brain, but somehow stores "experiential facts" elsewhere, to be retrieved alongside the merely physical when remembered/known? That indeed leads us to dualism, with all its interactionism problems, right? I don't see how there is a compatibilist version of this but maybe I'm wrong.

I would argue that "knowing" something isn't a coherent, definable state of being that you can talk about sensibly at this low level of inquiry. We could translate this into something about brain states, but that is exactly what Jackson objects to. For the purposes of the thought experiment, we can make up what Jackson might describe as a "convenient" definition of knowing, but once we are making stuff up, why not just assert that "knowing" about red includes its qualia? Why not say that if Mary knows all the physical facts about red, that would necessarily include the physical sensation of seeing red. What are we really learning here?

There is also a debate about imagination since using Churchland's formulation all the physical information about red would by definition include every possible brain state that could in principle be associated with the color red. Brain states are physical. Mary knows all the physical information. That means whatever brain state would be associated with leaving her room and seeing a fire engine — she remembers it. Mary isn't colorblind. She is theoretically perfectly able to imagine colors, she just can't label them. If Mary were colorblind, or unable to imagine colors, then once again by implication she cannot "know" every physical fact about red. For the argument to work, she must in principle have all the sensations and knowledge available to her. She just hasn't physically ventured outside her B&W room. Jackson objects to this, but the problem is semantic. Since human beings can't have "all the physical information" downloaded into their brains, we're forced to use terms like "imagine." But what Churchland describes isn't imagination in the tradition sense. The distinction is better described as, "is there a difference between typing a long post into reddit one character at a time, or pasting all the text in at once?" Mary leaving her room is typing. Mary "knowing" all the physical facts/brain states is "pasting." The result is identical, and Jackson's objections don't really make sense.

Again, my conclusion is that Mary's Room and by extension the knowledge argument (if Mary's Room is in fact the correct realization of it) may be an interesting inquiry into how certain types of information are expressed or encoded, but they have nothing to offer a metaphysical inquiry into subjects such as dualism, panpsychism, idealism, etc.

My caveat is that I am not a trained philosopher and therefore probably wrong.

Welcome to this week's Open Discussion Thread. This thread is a place for posts/comments which are related to philosophy but wouldn't necessarily meet our posting rules (especially posting rule 2). For example, these threads are great places for:

• Arguments that aren't substantive enough to meet PR2.

• Open discussion about philosophy, e.g. who your favourite philosopher is, what you are currently reading

• Philosophical questions. Please note that /r/askphilosophy is a great resource for questions and if you are looking for moderated answers we suggest you ask there.

This thread is not a completely open discussion! Any posts not relating to philosophy will be removed. Please keep comments related to philosophy, and expect low-effort comments to be removed. All of our normal commenting rules are still in place for these threads, although we will be more lenient with regards to commenting rule 2.

Previous Open Discussion Threads can be found here.