(also called "Von Neumann-Wigner interpretation")
I will give here my own exposition of this interpretation
physics, according to which the collapse
(that is the transition from a "state of indetermination" between
several possibilities, to the exclusive realization of only one
possible outcome), is real and accomplished by the perception of
the measurement result by a conscious, immaterial observer; this
is the metaphysical source of the randomness that appears in
physical phenomena, which becomes the interface of expression of
free will when occurring in the brain.
A short version of this with other aspects is available in pdf: A mind/mathematics dualistic foundation of physical reality, written for the fqxi essay contest on the link between maths and physics (where the discussion in comments helps to clarify a few points), but unfortunately dominated by cranks.
Indeed, I guess the lack of available clear and coherent
expression of what this interpretation says, may be the main cause
why this interpretation seemed so unpopular and even rather
ignored until now in academic circles, before the lack of precise
arguments (together with, I would say, the presence of wrong
formulations and wrong arguments). I do not feel satisfied with
the way I saw it done by the few physicists and other people who
tried to express and support this idea of a fundamental role of
consciousness in quantum physics, such as H. Stapp and R. Penrose.
So, I understand why others did not take that view very seriously
in these conditions. What sense can be made of arguing about a
position that is not clearly expressed, or is expressed in a wrong
And of course, any link with religious views and other misuses by New Age writers as a tool of illusion of scientificity to sell a lot of spirituality books full of nonsense to a naive public, gave it a very bad reputation in the eyes of scientists. This is quite understandable. As I commented here :
[My] combination of accurate metaphysics and accurate physics is quite unusual, and may be hard to follow for those who are not familiar with quantum physics, but I think it is necessary, otherwise physicists would again dismiss it a mere poetry having nothing to do with physics... not entering such details would mean telling nothing more than what others suggested before. And for now, as you can see in David Wallace's reviews of the different interpretations of quantum physics, the idea of a role of consciousness was not even included in the list. I'm not sure if he will do it in the future with my contribution but I understand that the vague calls for such an interpretation, or the strange tries of specifications for it, that I saw made by others until now, were not clear and coherent enough to seem deserving a place in some scientific debates on the topic... There are "problems" with the mind makes collapse interpretation, making it a "not very scholarly" topic of discussion. Namely : it only looks like a vague idea ; it cannot be put into equations or other rigorous definitions in order to check it for possible logical flaws ; many of the people who put it forward have no clue about physics and showed their ignorance of physics. The fact that such ideas were used to sell a lot of spirituality books with bullshit claims about how it can change your life by the power of positive hinking, is a very negative point for being taken seriously by physicists, and I perfectly understand such a reaction. One has to go past that and it is not obvious... And finally among the very few physicists who openly supported such an interpretation, the ones kept it trivial (e.g. Richard Conn Henry simply defines it as "the physical world does not exist", which, logically, does not leave any object to be discussed), the most famous one (Wigner) finally rejected it at the end of his life, others did it in wrong ways soon refuted by other works... which many scientists easily mistake as conclusive on the whole issue.
But the usual explicit objection to any idea of involving
consciousness in the foundations of physics, takes the form of an
appeal to Occam's razor : consciousness was not found to play any
fundamental role in the universe, but its presence can naturally
be explained instead as an emergent process by the Artificial
Intelligence thesis. However (and even if we ignore some
observations at the fringe of usual science, such as experimental
results of parapsychology), this nice picture of explanations
by two clouds (and more of course : divergences of the
standard model at high energies ; dark matter and quantum gravity,
that I would guess to be out of subject here):
"Now, people say the reduction of the wavepacket occurs because it looks like the reduction of the wavepacket occurs. And that is indeed true. What I am asking you (...), is to consider seriously, what it would look like if it were the other way round : if all what ever happens were causal evolution according to quantum mechanics. And what I have tried to convince you is that, what it looks like, is ordinary everyday life. Welcome home."
Indeed that use of Occam's razor looks quite elegant, and the
reasoning looks coherent, except, of course, that mathematical
arguments on probabilities always remain hopelessly circular
(since there is anyway no possible other basis for probabilistic
conclusions than circular arguments).
However it also looks like he overlooked the following : as long as he does not include an answer to the hard problem of consciousness in the picture, by which the presence of a conscious observer looking at the world and having any subjective impressions about it, is fully accounted for, how can he explain the possibility for things to look like anything at all ?
The problem is, the AI concept of "consciousness" does not look quite friendly with the many-world's quantitative concept of "existence", in case both are supposed to combine into a coherent concept of "conscious existence".
Now without ignoring the elegance of Sidney Coleman's use of
Occam's razor, I'm going to shamelessly recycle it into a
different and even more radical use, that will explain more from
less. Here will be my question:
What would the laws of physics look like, if physical things were nothing else than their way of looking like something when looked at by observers that cannot be themselves described by any physical laws, but keep some freedom in their way of looking or not looking at things and in their ability of affecting these physical appearances ?
It would look like, the laws of physics do not uniquely determine
the way things go. It would also look like the straightforward
expression of these laws seemed to fundamentally refer to the way
things are seen or measured. This reference to observers or
measurements would precisely be needed for giving things a shape
that looks like a definite appearance, and also to operate the
"choices" of how things turned out to go among their diverse
But it would also look like, this reference to observers and the related "choices" of how thing go, expressed in the theory, only came in mysterious circumstances that the theory itself cannot describe, since no physical law can describe consciousness.
The theory would seem to describe things as if the alternative possibilities actually keep coexisting as long as the theory is strictly followed without arbitrarily involving this mysterious reference to observers (which describes "what happens when nobody is looking"), since things cannot "know by themselves" whether they are looked at or not, whether they are chosen or not, thus won't restrict their possibilities just because of this.
It would look like, if we tried to take these laws very seriously for what they exactly say while dismissing that mysterious role of observers by lack of a "reasonable way" to physically describe it, the theoretical consequences would look just the same as the particular case of the above when nobody had a look on an outcome yet: it would look like a persisting coexistence of the many possibilities, between which no actual choice ever came to provide to any of the possibilities any more reality than others.
When an undetermined outcome became physically observable (i.e. the possible result physically behaves like an objective fact which can no more be changed by observation, as the theory must be able to allow for that kind of behavior when several observers are present) but still remains unobserved, no physical effect can distinguish anymore whether or not it might be already observed and thus made definite by some spy; therefore, the only thing that would seem formally clear from the theory in this physical circumstance, is that the "choice" between possibilities would have to be fixed no later than when a known conscious observer is looking at the result; but the question of how much earlier would remain unclear.
For physicists looking for a way to complete the picture of effective laws by further hidden physical laws aiming to specify the operation of these "choices", it would look as if any try to settle these choices as predetermined by the hidden laws would run into many problems, while any idea of letting these choices be only settled a bit later, would embarrassingly surprise itself by its mysterious need of expecting this to successfully fix the choice no later than when someone looks at it (as if it ever mattered), which might technically fail to happen since the physical borders of observability remain unclear.
In short : the laws of physics in such a world would look pretty
much like those of quantum mechanics.
Welcome home. ;-)
Henry Stapp proposed the first option : conceiving free will in
the form of measurements done on a quantum system, affecting the
state of this system in the way expressed by the projection
postulate (which is how the effects of measurement are usually
described in courses of quantum physics). He considered this to be
a means to exert free will even if the perceived results follow
the quantum probabilities, because the projection postulate sends
the state to some projected images (depending on result), whose
barycenter, weighted by quantum probabilities, differs from the
initial state. More precisely, he considered this process as
usable in the form of the quantum Zeno effect, to produce a wanted
effect on a physical state.
This can only work if the projection postulate is applied as
describing the effect of a non-physical measurement process on an
elementary quantum system, in the absence of physical interactions
with the environment and their decoherence process. Because if the
quantum Zeno effect came as a consequence of frequent physical
measurements (physical interactions) which then decohere and are
observed in conformity with quantum probability laws, then
non-material free would not have a place to intervene in this
In particular, the projection postulate would not fit if applied to the case of a purely non-physical measurement, as it would enter in conflict with the principle of preservation of the past memory : the new perception negates the part of the density operator that is purely orthogonal to it (that belong to alternative worlds which are incompatible with this one), however the non-diagonal elements of the density operator between the image space (the new world) and its orthogonal, should (metaphysically) "survive" but the projection postulate appears to annihilate them. But when the perception is linked with a physical measurement, these components are not physically annihilated, but dispersed instead into the environment in the form of entropy, so that the applicability of the projection postulate is restored.Now, if we admit on such metaphysical grounds that the physical effects of perception have to fit inside the decoherence framework, thus excluding (?) the first hypothesis on the physical expression of free will, then we must examine the second hypothesis, and explain the following paradox : if all perceptions comply with the same framework (the choice of a world after decoherence), how to explain the discrepancy between the fact that the quantum probability laws seem to have always been strictly respected by the statistics of physical experiments, and the idea of a full expression of free will in the brain based on a wide deviation away from these probabilities.
This objection appears in diverse articles on the subject : "The
kinds of indeterminacies discoverable at the quantum level may not
correspond in any useful way to our ordinary idea of mental
The answer is that quantum randomness is much more pervasive in reality than many people naively imagine when thinking that many phenomena, such as classical chaos and the randomness of statistical mechanics, can be understood without reference to quantum physics. I mean that while, admittedly, the place of not-yet-decohered forms of quantum superposition, that require the quantum mechanical concepts to be understood, seems limited to molecular scales irrelevant for consciousness, quantum randomness is anyway the real source of a large flow of effectively random data (classically probabilistic superpositions produced by decoherence), where free will has a wide margin for possible intervention. More comments on this fact in the text on Bohmian mechanics.
One explanation I said above : it requires to clearly specify its
principles and their exact connections with physics, which was not
properly done by previous supporters.
The other explanation : since consciousness is not physical, it cannot be "explicitly found" when strictly focusing the study on properties the physical world.
If consciousness is needed to collapse the wavefunction, did the
Universe exist, either precisely or in potential (in a large
superposition of states) until some intelligent life appeared on
Earth to observe it and do the collapse ?
I was surprised to see that some of the physicists who support the mind makes collapse interpretation, actually also support that idea. What is strange here, is that for this conclusion to be "deduced" from its explicit premise, it needs to assume another premise that, I would say, contradicts the first premise, so I wonder why it is so often implicitly taken for granted without justification : the materialistic principle that (the presence of) consciousness is produced by the structure of biological systems (and more precisely some brains), so that consciousness cannot observe the universe from outside these systems, and thus could not be present in the Universe before they appeared in the course of evolution.
I find it quite a strange assumption. I would just dismiss it as
ridiculous and not deserving attention, together with its
resulting Participatory Anthropic Principle itself, if it did not
seem to have that number of supporters. But since it appears to be
part of the landscape of opinions, I will develop here the
One argument against it, is the data of parapsychology, especially NDE and OBE: many of the near-death and out-of-body experiencers first have (mainly visual) perceptions of our physical reality from outside their bodies before eventually exploring other realms. Some other testimonies such as haunted houses or the Faustina diary, suggest in other ways the actual presence of unincarned spirits as well. So, if some minds can be present outside bodies to observe us now, what could be the problem in the idea that such minds (just less anthropomorphic) could be present to observe the Earth and other parts of the Universe before "intelligent" animals appeared during evolution ? I understand it would may have been "less interesting" for more rudimentary biological systems, but...
For example some NDE testimonies here and there tell about afterlife of animals (see the whole debate for which I initially found these links).
Now what about earlier times, when there were only unicellular organisms, or even before, were there any souls on Earth or in other "lifeless" parts of the Universe ? It could have been very boring for these minds to wander here trying to play with mere unicellular organisms, or no biological system at all. Still some sould could have been here to stare at the landscape, the sky or such (and others spending time in more interesting realms as suggested by NDEs).
But our initial question, in fact, can be split into 2 questions to be discussed separately:
Can we locally consider a total absence of souls on Earth for a very long time, such as the first 2 or 3 billion years of its history, letting it split into very many parallel worlds, until some soul just suddenly came to select and give existence to one of these many worlds, precisely because of some "interesting" organisms it contains, therefore creating the past evolution retrospectively ?
I don't see this as reasonable, and here is why:
To find out whether some conditions on a planet and the organisms
present on a planet are suitable for hosting consciousness, cannot
be done at first site. Because the property for an organism to be
a comfortable host for consciousness and that can work in the long
term in the face of all kinds of events, is a complex problem. It
cannot be found without doing some experiments with it. So,
imagine that you let a planet without any mind for millions of
years, it divides itself into an extremely wide diversity of
parallel worlds, then, in mysterious ways you manage to browse
through this unthinkable diversity and feel that one of the
possibilities may be nice. They you do it a try. You enter some
organisms there and bring your friends with you. But finally you
find yourself very uncomfortable. Will you leave ? Or, you disturb
the behavior of your body so badly that it dies. Or, you play it
so well with your friends, that the host specie becomes too
strong, disrupts the ecological equilibrium of the planet (driving
its predators and then its food to extinction) and finally
disappears due to this disruption. What can you do then ? You have
collapsed the wavefunction, it is too late to un-collapse it now.
The planet is corrupt and not suitable for conscious life anymore.
I would rather guess that consciousness was always there from the beginning of evolution, first in disembodied forms, then progressively playing with organisms in more and more committed and elaborate manners. Then "completely embodied" but still intelligent configurations progressively came to dominate, due to their selective advantage (as they "force the mind to cooperate" by their intelligence for the survival of the body).
Reference : The
Watchmaker by James Huber.
See my site against spirituality and religion, with summary of my rationalist position ; how I separate metaphysical and religious issues; and my comments on the unfortunate practical division between science and the sense of life (or "fundamentally interesting issues" for the public) here and there.
By other authors :
Debunking the Law of Attraction and "Thoughts Create Reality" Religion
New Thought : Problems
The debate on quantum idealism (other possible name for the mind makes collapse interpretation)
Many references on consciousness and quantum physicsIntroduction to quantum physics (notions of states and measurements)
Many Worlds(I also have a page on metaphysics, strongly connected with this issue of interpreting quantum physics, though it may be not so clean, I will consider to revise it later.)
The de Broglie-Bohm interpretation