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Dreaming Spiders? My Disagreement with Michael Egnor

Günter Bechly
Photo credit: Victor Grabarczyk, via Unsplash.

My colleague Michael Egnor wrote here yesterday about new research suggesting that spiders dream. I remain very skeptical of this claim. We know that consciousness and dreaming is correlated in humans with neocortical activity. The rare brain anomaly of hydranencephaly is sometimes mentioned as evidence against this, but awareness in the vegetative states of such patients without a cortex is still a disputed question among experts (e.g., Merker 2007 v. Berlin 2014).

Therefore, I tend to concur with those neuroscientists who doubt any organisms possess phenomenal consciousness that lack a neocortex (found only in mammals) or a comparable structure (in birds and maybe cephalopods). Rapid eye movement may indicate neural activity, but the concept of dreaming for me implies a conscious awareness of the dream state, which I consider as highly unlikely in spiders. Spiders definitely are capable of remarkably sophisticated and seemingly intelligent behavior in their web building activity, but that behavior seems to be preprogrammed and not an achievement of their individual intelligence. But this is of course just my educated guess or gut feeling about the subject. I am open to the possibility of consciousness in lower animals but not convinced on the basis of the current evidence.

Dr. Egnor writes that “the precondition for a mental state is to have a sensory organ. Spiders, for example, have sensory organs such as eyes so it makes sense to infer that they have mental states.” If sensory organs were sufficient for mental states, then even protists could be conscious, as there are protists with lens eyes. If a protist can be conscious because of a sense organ, then why not a thermostat or a smartphone?

The Aristotelian View of Nature

Egnor’s view is explicitly influenced by his Aristotelian metaphysics. Likewise, my friendly disagreement in the current question is facilitated by the fact that I no longer embrace an Aristotelian view of nature. For a while I very much sympathized with panpsychist and Aristotelian-Thomist metaphysics. However, I came to realize that both are untenable in the light of modern physics, especially the growing consensus that spacetime (and thus also matter/energy) is not fundamental but emergent from entangled quantum information. If matter is not fundamental, then panpsychism is obsolete: we cannot solve the hard problem of consciousness by adding consciousness as another state of matter additional to its physical properties. Furthermore, at least those versions of Aristotelian-Thomist metaphysics (e.g., Edward Feser’s view) that rely on an A-theory of time (presentism) are in my view definitely refuted by new scientific arguments like that of Gustavo Romero:

The argument goes like this:

P1. There are gravitational waves.

P2. Gravitational waves have non-zero Weyl curvature.

P3. Non-zero Weyl curvature is only possible in 4 or more dimensions.

P4. Presentism is incompatible with a 4-dimensional world.

Then, presentism is false.

The logic is sound, so let us review the premises of the argument to see whether there is some escape route for the presentist. The truth of P1 is accepted by the vast majority of scientists working on gravitation. Gravitational waves are a basic prediction of General Relativity (Einstein 1916, 1918b). Large gravitational wave detectors such as LIGO — the Laser Interferometer Gravitational Wave Observatory — have been constructed and are now under a process of upgrading to meet the required sensitivity for effective wave detection. A space-based observatory, the Laser Interferometer Space Antenna or LISA, is currently under development by the European Space Agency (ESA). All this activity shows the confidence of the scientific community in the existence of gravitational waves. Indirect evidence for such existence is found from the orbital decay of the binary pulsar PSR B1913+16, discovered by Hulse and Taylor in 1974. The decay of the orbital period is in such accord with the predictions of General Relativity that both scientists were awarded the Nobel Prize in Physics in 1993 (see, for instance, Taylor and Weisberg 1982). So, P1 can be considered true within the context of our present knowledge of the universe. 

Premises P2 and P3 are necessarily true. Gravitational waves propagate in empty space, where Einstein’s field equations are reduced to: 

Rab = 0.

This expression means that the 10 coefficients of the Ricci tensor are identically null in vacuum. But the full Riemann tensor has 20 independent coefficients since it is a rank 4 tensor. The remaining 10 components are expressed by the Weyl tensor. Then, since the gravitational waves are disturbances in the curvature, the Weyl tensor must be non-zero in their presence. If the dimensionality of the world were 3, as proposed by the presentists, the Riemann tensor would have only 6 independent components, and since in 3 dimensions Einstein’s equations in vacuum are reduced to 6, the Weyl tensor must vanish. Only in 4 or more dimensions of gravity can propagate through empty spacetime (see Hobson et al. 2006, p. 184; Romero and Vila 2014, p. 19). 

Then, the presentist should either deny that presentism is incompatible with 4-dimensionalism or accept that presentism is false. But presentism is essentially the doctrine that things do not have temporal parts (Heller 1990). Any admission of temporal parts or time extension is tantamount to renouncing the basic claim of presentism: there are no future or past events. I conclude that presentism is utterly false. I shall ignore this position in what remains of this article. 

Since P2 and P3 are necessarily true, and P1 is meanwhile established by numerous empirical confirmations (including Nobel Prize-winning research), it looks to me like presentism is utterly and irredeemably destroyed by modern physics. The thrust of this argument cannot be avoided by appealing to a Neolorentzian interpretation of relativity that William Lane Craig has suggested against claims that special relativity refutes presentism. Only a mere instrumentalist view of the mathematical laws of physics could shield presentism from falsification by Romero’s argument, but this seem to me a very desperate move that I am not willing to entertain.

Therefore, I have reluctantly changed my views towards an eternalist metaphysics in the form of Neoplatonist Objective Idealism, which can be compatible with Christianity (and arguably Judaism) as demonstrated by many idealist Christian thinkers (e.g., Jonathan Edwards).

To Make a Long Story Short

Thus, I disagree that all organisms with sensory organs necessarily possess individual consciousness, but I am fine with the idea that like everything else, they exist within consciousness (the mind of God). I consider individual consciousness as a kind of dissociation from universal consciousness (in the sense of Bernardo Kastrup’s view). But in contrast with Kastrup, who considers biological physiology and metabolism as crucial, I think that sophisticated information processing (likely related to Giulio Tononi’s Integrated Information Theory) is correlated with this dissociation. This either requires or implies a sufficiently complex biological brain or an AGI of comparable complexity and function. But of course, I am aware that this may represent a fringe view in the ID community and even a quite heterodox view among Christians. I think it is one of the great strengths of the “big tent” of ID that it is very undogmatic and pluralistic and therefore is refreshingly open to very different views on important questions.