Gifford Lectures on Natural Theology

In October I had the honor of visiting the University of Glasgow to give the Gifford Lectures on Natural Theology. These are a series of lectures that date back to 1888, and happen at different Scottish universities: Glasgow, Aberdeen, Edinburgh, and St. Andrews. “Natural theology” is traditionally the discipline that attempts to learn about the nature of God via our experience of the world (in contrast to by revelation or contemplation). The Gifford Lectures have always interpreted this regime rather broadly; many theologians have given the talks, but also people like Neils Bohr, Arthur Eddington, Hannah Arendt, Noam Chomsky, Carl Sagan, Richard Dawkins, and Steven Pinker.

Sometimes the speakers turn their lectures into short published books; in my case, I had just written a book that fit well into the topic, so I spoke about the ideas in The Big Picture. Unfortunately the first of the five lectures was not recorded, but the subsequent four were. Here are those recordings, along with a copy of my slides for the first talk. It’s not a huge loss, as many of the ideas in the first lecture can be found in previous talks I’ve given on the arrow of time; it’s about the evolution of our universe, how that leads to an arrow of time, and how that helps explain things like memory and cause/effect relations. The second lecture was on the Core Theory and why we think it will remain accurate in the face of new discoveries. The third lecture was on emergence and how different ways of talking about the world fit together, including discussions of effective field theory and why the universe itself exists. Lecture four dealt with the evolution of complexity, the origin of life, and the nature of consciousness. (I might have had to skip some details during that one.) And the final lecture was on what it all means, why we are here, and how to live in a universe that doesn’t come with any instructions. Enjoy!

(Looking at my YouTube channel makes me realize that I’ve been in a lot of videos.)

Lecture One: Cosmos, Time, Memory (slides only, no video)

Lecture Two: The Stuff of Which We Are Made

Lecture Three: Layers of Reality

Lecture Four: Simplicity, Complexity, Thought

Lecture Five: Our Place in the Universe

  1. In the loophole section for life after death wouldn’t the possibility that we are inside a simulation also be a possibility. Even if core theory is 100% true with its domain, the entity running the simulation could just stop it, then copy your mind as you die and transfer you to an “heaven” and no one inside the simulation would ever know.

  2. Excellent talks, I’ve watched a couple all the way through so far, you’re a very good speaker!

    As to the content itself, well, it starts off very strong, but gets progressively less convincing as the talks go on 😉

    Not much to argue with in (1) and (2), very strong – supurb!

    The problems start to creep in with (3), layers of reality. There’s a question mark as regards ‘leaky abstractions’, where it’s not so clear that layers can be cleanly separated like that. For example, we know that qantum effects can leak through to the macroscopic level in quantum-biology.

    Coming to (4) and consciousness , well here’s where the debating points really start 😉 I don’t think there’s much doubt over naturalism, but there is definitely a doubt about reductionism. As you yourself noted, in *practice*, you always have to use the vocab of (agents, decision, values) to interact with people in daily life, and in cases where agents are completely predictable, the legal system simply doesn’t recognize these agents as moral entities.

    Lecture (5) is the weakest lecture. Even *if* your positions on (1)-(4) were entirely correct, I think sweeping philosophical conclusions about ethics and values are simply premature given our correct level of knowledge about the mind.

  3. slide #19 says that entropy increases because there are more ways to be in a high-entropy state than in a low-entropy state (note: slide #19 is actually a definition of entropy that was previously given by Feynman who said ” We measure “disorder” by the number of ways that the insides can be arranged, so that from the outside it looks the same. The logarithm of that number of ways is the entropy.”) but there is more fundamental question: WHY does nature seek to maximize the number of arrangements? is that a question that physicists should even be asking or is it ‘above our pay scale’ or ‘not in our job description’?

  4. I am quite astonished by hearing in the lectures that the Core Theory prevents the statements like “yogic flying is possible” or “the soul does survive the body” etc. from being true. The Core Theory is not the ultimate theory of nature, it is still a classical theory (since GR is a classical theory). Each classical law of nature is only a statistical law, emerging as a most likely upshot from vast number of microscopic events from the more fundamental level. Being such, each classical law of nature is only an approximate law, having no absolute character, and therefore can be defeated.
    If our mind/awareness/nervous system (call it whatever you wish) is so subtle and sophisticated to enjoy the presence of the most fundamental levels of nature, it can (mimicking the acting of the Maxwell’s demon) upset the abovesaid statistical averaging law, to come up with something surprising on the surface of the life (possibly beating the predictions of the Core Theory).
    You can not prove that such a mind drill is not possible, after all, it is only a matter of practice (for the time being you are probably not able to perform 100 push-ups in a row, but with some practice you could).
    Quantum Gravity tells that nowhere in space a definite configuration of gravitational field does exist, on the contrary it is a wave-function containing all possible configurations that matters at that fundamental level. Again, if our mind is so sophisticated, it can pick up a configuration different from the most probable one, for instance, the one which does not pull
    our bodies towards the centre of the Earth.
    The death will get rid us of our bodies and personality, but certain patterns from the deeper level (soul?), where there are no particles, atoms and fields and where everything is dissolved to energy and information, easily survives.

  5. Musings on consciousness:

    – I am of the opinion that property dualism should be regarded as the “default” form of dualism, the type we should think of every time someone uses the term “dualism” without differentiating context. Substance dualism is, to my mind, more of a special case.

    – The term “qualia” does not add anything to the conversation that is not already intrinsic in the term “consciousness”. I believe it is the same kind of semantic inflation whereby, if it becomes customary to tell a speaker that they gave a great lecture, it soon becomes necessary to tell them that they gave a wonderful lecture if we genuinely liked it. Likewise, when a dualist is annoyed at a naturalist for using the word “consciousness” in a way that seems to miss the very essence of what that term denotes, the dualist might try to introduce a new word, even though the new word is really no different from the old one. Hence, “You can’t explain consciousness” is replaced by the entirely synonymous “You can’t explain qualia”.

    – The argument of the philosophical zombie (as opposed to the presentation and terminology) is not original to Chalmers. It’s one of those arguments that is so fundamental that it is reformulated periodically when people try to articulate the problem of consciousness. Heck, I came up with it myself once, as a teenager, quite independently. That’s probably why it’s popular: it evokes the response “I remember thinking that”.

    – If a naturalist says “Consciousness is intrinsically unmeasureable, therefore I can dismiss it”, a dualist will say, “No, the fact that it is intrinsically unmeasurable is precisely why you CAN’T dismiss it”. The idea that consciousness can in principle be explained by underlying non-mental physics appears to violate something analagous to a mathematical invariant, like claiming that there is some special way to jiggle two linked rings that will somehow unlink them. This aspect of reality which my intuition insists must be invariant is the (potential) existence of intrinsically subjective experiences.

    – I sometimes wonder if I might be a superposition of many consciousnesses sharing a single physical substrate, each aware only of itself, and each giving rise to exactly the same behaviour.

    Haven’t watched lecture five yet.

  6. @Adrian

    I’m a fan of Chalmers for taking consciousness seriously, but at the end of the day, I have to go with Sean on this one and agree that zombies don’t really make sense. Thinking of consciousness as ‘non-physical’ is simply the wrong way of looking at things.

    My current position would be for the weak form of dualism (property dualism), or ‘non-reductive physicalism’. Consciousness is *composed* of physical processes, but not *reducible* to them. Consciousness is a computational processes, but if the only way to predict what a computation is going to do is to actually run it (what Stephen Wolfram defines as ‘computational irreducibility’), then I think a reasonable case can be made against reductionism. I do think ‘qualia’ is a valid concept (qualia are real), but they are physical.

    I do like Sean’s claim that consciousness is based on ‘mental time travel’, I think it’s definitely on the right track- we can consider the past (memory) and the future (imagination). Consciousness is strongly related to working memory, and I think it involves constructing an image of ‘the present’ via memory (it doesn’t neccesserily need long-term memory, but definitely some sort of short-term working memory is required).

    I think that consciousness could be explained through a generalization of the notion of ‘entropy’, and I’m currently tentatively defining consciousness as ‘a symbolic representation of the arrow of time’. However, I’m suspecting a major shift in perspective would be required for proper understanding, as big as the shift between Newtonian physics and general relativity. That is to say, I think consciousness is ultimately rooted in fundamental physics, not neuroscience or biology.

  7. Sean,

    In your Lecture 2, QFT says a “particle” is some local excitation of a universe-size field. Or, “At any instant in time, a particle can be represented by the local excitation of a field”.

    When we start a clock ticking, we then make statements such as “The LHC found a particle making a track in a bubble chamber” (over several consecutive instants).

    A question that arises is, “How certain are we that the LHC statement refers to the one and same particle?”

    A related question is, “Could that be the result of repeating a great number of measurements, the aggregate result of which then yielded the impression of a track made by one particle?”


  8. Wow, what a deep, articulate thinker you are (no need to be self depreciating with respect to Penrose).

    I was left wanting more discussion about the nature of emergence (I have read Holland, Kaufman, etc.) rather than it just being a way to describe things you see at higher levels of aggregation. Conjecture: it’s symmetry breaking/phase transitions “all the way up” (as opposed to “turtles all the way down”). It seems that information gets created when this happens, and new layers of organization “emerge”, which can be described with their own dynamics. Whereas the highest levels can’t directly influence the lowest levels, they can influence one layer below them (e.g. hormones impacting human behavior).

    I was somewhat saddened that you made the (personal) decision to not have children (my brother made this decision also). I have 5 kids, all PhD’s and one MD, and I feel I probably did more for the world being a parent than in my field of computational molecular physics (previously, plasma physics).

  9. Robbert Dijkgraaf likes to say that what the Dutch and QM have in common is tolerance. Anything is allowed if you do it fast enough. A similar point was made in my last comment about the LHC. Namely, reality description may be more demanding, less tolerant, when a clock is running.

    On the tolerant side, without clocks ticking, standard QFT says a particle can be viewed as a local excitation of an underlying quantum field. That is actually another way to describe quantum fluctuations (with clocks ticking).

    What if we view quantum fluctuations in the context of measurement? When left alone, we say there are random fluctuations of the underlying quantum field over time. Equivalently, we could say some random observer, unbeknownst to us, is measuring that field, thus leading to random fluctuations being revealed.

    When the random observer is a human (stationary), then we go back to the standard QFT statement above. But what if we apply this same concept to other “observers”?

    When an observer accelerates through space, the underlying quantum field shows Unruh radiation. When the observer is a black hole, Hawking radiation is revealed (Paul Sutter in When the “observer” consists of two parallel plates, Casimir effect is noted, all from the same field.

    What the above suggests is that the quantum field itself is indifferent. What is observed or revealed depends on what tools are applied to that field. The tool could be a stationary human, an observer accelerating, a black hole, or simply a pair of parallel plates.


  10. Disagree with the idea that philosophy has anything left to offer. I think philosophy is a dying field and people in it are just trying to keep it alive because it is their living or source of income. The reason simply is that if the mind is the brain (or something natural) then everything produced by the mind was just produced by the brain. Studying the brain is what science does so it follows that the most comprehensive level for the mind, psychology, sociology, ethics, morals, mathematics, logic, philosophy, theology and so on are brain related phenomena. In other words, philosophy is just a temporary stop on the road to scientism. The project really is to fully naturalize philosophy and in the process, retire a field that has a lot of baggage left in it from bygone days.