Today's Philosophy Mondays will be an interlude from our exploration of knowledge and values. I just finished reading Erik Hoel's wonderful book "The World Behind the World," which I highly recommend reading (I may write a short review). One of the concepts in the book is that of "scientific incompleteness." This is the idea that while science has proven extremely powerful there are some areas of understanding that will remain forever elusive. We of course have a hint of this already from mathematics and computer science in the form of Goedel's incompleteness theorems and Turing's halting problem.

I am convinced that qualia are another example of where science cannot go. Not because we don't have the right tools yet, but because it is fundamentally impossible. For me, qualia means "what it feels like to experience x" where x could be a taste, a sound, a thought, a feeling, etc. This is the truly subjective aspect of existence. Here we need to get a little more precise though and separate out two questions: first, how do qualia occur and second, what do they feel like? The former may turn out to be amenable to scientific inquiry, the latter not.

How come? Here a simple thought experiment will suffice. Consider two people, Alice and Bob. Alice wants to know what it feels like to Bob to have a taste of Alice's home baked muffins. Bob turns out to be amenable to having his brain state recorded at some pretty high resolutions. Brain computer interfaces have made enough progress to not only read the state of Bob's brain but also write some version of this state to Alice's brain. Does this mean Alice can now feel what Bob is feeling? No. Because Alice's brain is wired differently, has a different set of experiences, and is connected to a different body.

The only way to guarantee that Alice can experience Bob's subjective experience would be to rearrange all of Alice's atoms (maybe shedding some and recruiting a few new ones) and turn her into Bob. Of course now we run into a new problem. Now Alice is Bob. There is nothing of Alice left. To be nice to Alice we keep a backup copy of her around so we can restore her. When she is restored, however, she has no memory of what she experienced as Bob.

In summary then, we may get hints of someone else's subjective experience in some hybridized state where we are partially ourselves and partially them but it will never be fully their experience. This being true among humans means it is ever more so true across species and vastly more so across different substrates (biology versus silicon).

This fundamental inaccessibility of qualia happens to provide a beautiful reason for maintaining a high degree of diversity of species. We value our own personal subjective experience and we should allow the same for other beings. A world with many different subjective experiences is thus in an important way a richer world.

PS I will explore consciousness further in future posts. For now I want to point out that much of the philosophy and research I have read on consciousness suffers from confusion about the particularly complex relationship between map and territory that it engenders.

Illustration by Claude 4.0 based on this post.