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Why Don’t Changes to Our Bodies Create a Different Consciousness?

The sense of consciousness remains single and united despite ceaseless bodily change

In the third podcast of the “Unity of Consciousness” series, Walter Bradley Center director Robert J. Marks interviews Angus Menuge, professor and chair of philosophy at Concordia University, on unique features of human consciousness, including the question of why there really can’t be two of you. But Dr. Marks asks one final question: If consciousness is simply generated by the body, as materialists think, why don’t changes to our bodies create different consciousnesses?

This portion begins at 11:06 min. A partial transcript, Show Notes, and Additional Resources follow.

Robert J. Marks: There are cells that change quite a lot. And then there are cells that don’t change a lot, for example, neurons. That is, you keep the same neurons. And the fact that you remain still the same person is frankly astonishing.

Note: “our skin cells are known to constantly be shed and then renewed. Red blood cells make their repetitive journey through our bloodstream with a lifetime of about 4 months (BNID 107875, 102526). We can connect this lifetime to the fact calculated in the vignette on “How many cells are there in an organism?” that there are about 3×1013 red blood cells to infer that about 100 million new red blood cells are being formed in our body every minute! Replacement of our cells also occurs in most of the other tissues in our body, though the cells in the lenses of our eyes and most neurons of our central nervous system are thought to be special counterexamples.” – “How quickly do cells in the human body replace themselves?”, BioNumbers

From the chart available at the site, we learn that central nervous system cells and ova last a lifetime but — for example — stomach cells last 2-9 days, taste buds 10 days, and skeleton cells are replaces at 10% per year. The information available to our consciousness from these sources is mediated by constantly changing “personnel” but we perceive ourselves as single persons.

Angus Menuge: If a hundred percent of your neurons are sufficient to generate consciousness and so on, 99.9% and 99.8%, when you look at all of those subsets, why doesn’t each one of them generate a different consciousness?

Over time, lots of parts are being changed in various ways. Why don’t they keep generating different consciousnesses? Instead of what we see is continuity. And we notice that from our own experience. When you’re listening, for example, to a phrase in a symphony, you have the sense, here is that theme coming around again. That presupposes that you are the same person who heard that theme the first time.

Angus Menuge (pictured): Likewise, when you do a demonstration in mathematics or logic, you rely on the fact that you’re arguing from premises that you previously understood. And you know where you are in the proof based on lines that you have already proved and know what you’re moving on to. All of those kinds of thinking presuppose that you’re the same person from beginning to the end of the proof.

Otherwise, you wouldn’t really be the one drawing the conclusion. It would be like one person was studying the problem and the conclusion occurred to another person but that person didn’t reason from the premises to the conclusion.

Same with our actions. I mean, what’s the point of doing all that work in pre-med or pre-law, if it’s somebody else who goes to a law school or med school? That’s not actually how we think. We are planning our own future based on our current actions, assuming all the while that is going to be us that does these things. If we can’t account for that kind of identity over time properly, we actually undercut the rationality of human action. Why is the scientist bothering to do these experiments to confirm or refute a theory if it’s not going to be him or her who ends up discovering the results?


Here are the five earlier portions of this six-part discussion:

Part 1: Mystery: Our brains divide up events but we experience them whole That’s one of the conundrums of consciousness. Philosopher Angus Menuge notes that something that is not just our brains unifies our experiences from the partial information scattered across many neurons.

Part 2: How split-brain surgery underlines the unity of consciousness. At one time, some thought that if the brain were split, consciousness would be too, but that did not turn out to be true. Philosopher Angus Menuge thinks that “split personality” doesn’t mean two consciousnesses but loss of access to the information that integrates mental states.

Part 3: Why do we stay the same person over time? Why not split up? It would be a total fluke if all the different clouds of atoms that produce your brain would always produce the same consciousness. But they do. Philosopher Angus Menuge argues that you have one soul, at and over time. And that explains why, despite changes, you are one consciousness, at and over time.

Part 4: Life in the plural: If there were two of you, would “you” exist? According to philosopher Angus Menuge, there can’t be two of you, because two things cannot be one thing. The case of conjoined twins who share a body but perceive life as separate individuals provides a model for understanding.

Show Notes

  • 00:30 | Introducing Dr. Angus Menuge
  • 01:04 | Unity of consciousness
  • 03:04 | Split-brain operations
  • 04:55 | Split personalities
  • 06:49 | Too many thinkers problem
  • 11:06 | Why don’t bodily changes generate a different consciousness?
  • 14:28 | Elon Musk’s Neuralink

Additional Resources

Podcast Transcript Download


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Why Don’t Changes to Our Bodies Create a Different Consciousness?