The Simulation Argument, Brains in Vats and Digital Physics


Hello, my name is Cosmyk, and this is my first post.

One thing that I find very disturbing is the Simulation Hypothesis (SH). The SH is basically the idea that I am either a brain in a vat, or a simulated person (a “sim”) who is being fed sensory data from some kind of artificially-generated simulation. In my opinion, the two best arguments for the SH are Nick Bostrom’s Simulation argument and the argument from Digital Physics, made by Edward Fredkin, Brian Whitworth, and others. To find Bostrom’s argument, Google “are you living in a computer simulation” and click on the first result. To find Whitworth’s argument, Google “the physical world as virtual reality” and click on the first result. To find Fredkin’s website, Google “Edward Fredkin” and click on the second result.

I don’t believe that the arguments from Digital Physics hold much force. Digital Physics is a minority position. Current scientific evidence does not give any reason to favor it among other theories, since DP is only one interpretation among many superior ones.

Bostrom’s argument, by itself, can be avoided if once accepts dualism. Humans have an immaterial nature, while sims are purely material, so no human is a sim. But I believe his argument can be reformulated to include “neural simulations”, which are “brain-in-vat” scenarios, like in the movie The Matrix. Given the rise in popularity of video games, it is not unreasonable to think that in the future, many “matrices” will be created. If 50% of humans are plugged into such matrices, and we cannot tell whether or not we are in one, the probability of us being in such a matrix is 50%.

Digital Physics also supports the argument. Let’s say one accepts that brains-in-vats (BIVs) outnumber humans, but for whatever reason still believes that one is real. In that case, one is believing an unlikelihood, namely that one was “born out of the matrix”. We should lose credence in theories that posit improbable events, so realist theories would lose credence.

My main questions about all of this are:

  1. Are these arguments sound, or flawed? If they are flawed, how so? Are there any good objections to them?
  2. How would these arguments affect Christianity? Do you think Christianity or theism in general can still be defended even if it turns out we live in a simulation? For example, do the Five Ways still work?



The brain in vats assume super advanced and complex tech that never suffers catastrophic failures. Having done various types of computer support, trying to keep 7 billion connected devices up at all times is a problem.

The simulation arguments are more plausible but are untestable. A properly designed sim would never let the sims detect it. Also, sufficiently advanced civilizations would have reasons for such simulations as well.

Simulation or not this world is effectively real to us. Even the language used wouldn’t be negated by simulation. The level of simulation implies a creator, that exist outside of our existence, who has unlimited power, for whom time flows differently, etc.


Why do you say brain in vat theory and Bostrom’s argument are nonsense?


I don’t have time to review it all right now, but yes, the Five Ways would still work. There’s nothing new introduced in the simulation scenario that would undermine the lines of argument. As for Christianity in particular, that needs more thought.


I’ve started perusing the forst article. As I said before, even if we are in a simulated reality, it wouldn’t impact the Five Ways, and monotheism would be true. However, I have reason to think that we do not.

Suppose that these simulated people are conscious (as they would be if the simulations were sufficiently fine‐grained and if a certain quite widely accepted position in the philosophy of mind is correct).

That’s a big if. I don’t know if I have time for a philosophy of the mind discussion, but I reject the notion that any artificial intelligence could have a mind at all. AIs would necessarily be (philosophy of the mind) zombies. I will keep reading, though.


AIs would necessarily be (philosophy of the mind) zombies.

I also reject the assumption of substrate independence. The argument can be reformulated as to include people whose bodies are literally plugged into the simulation, like the the movie The Matrix.


The main problem is they require a deterministic universe, that is, you have to be able to describe reality with precision in order to “simulate” it. Gödel would be the first objection, that there would be truths that cannot be anticipated, but I suspect the theorists have addressed that. Basically, reality is too complex to simulate. Read some scifi to find out about unintended consequences.

I will have to look more closely at the theories to address the second question. Do the sims interact? Is there faith and hope and love? How does the simulator behave? Is it different from any other god?


The problem with these kinds of theories (brain in a vat, Last Thursday-ism) is that they are specifically designed to not give us any epistemic handles. That is, we explicitly do not have any way to establish the truth-or-falseness in an objective way.

Now some simulation theories are actually “physical” in the sense that science can, in principle, establish their falseness. And so the right response to those kinds of claims is to wait until they have actually been tested.

I think the discomfort that people feel about these theories is that they expose that the metaphysical emperor has no clothes. We don’t have a good way to objectively decide between any metaphysical theories beyond a certain point. The only “bar” a metaphysical theory needs to clear is that it be:

  1. Logically self-consistent
  2. Not contradicted by actual physics
    On top of that people will sometimes add simplicity preferences, which assert that we should prefer metaphysical theories with fewer “moving parts.”

And so, because these theories aren’t too complex, we can’t just reject them out of hand, and they clearly explain real physics without logical contradiction.

Dualism is just one kind of metaphysics, it doesn’t somehow automatically trump these views. You can’t say “well we can’t be brains in vats because we are dualistic” anymore than someone who believes in brain-vats could reject dualism by saying “well we’re brains in vats, there is no duality of substance”


How do you know failures do not occur all the time? For all you know, there are exceptions being throw and caught constantly.

I don’t necessarily agree. In a simulation, physical dimensional properties must be finite (ie, a shortest distance, a minimal time period, a maximal distance, a maximal time period, a minimal speed, a maximal speed, etc). For example, in a simulation, there must be a maximum speed of information propagation.
Physics has shown this to be true - the speed of light. There is also Planck length, Planck time, etc.

Also, mathematically, certain numbers cannot exist in a simulation. For example, a circle would be impossible. In our universe, perfect circles do not exists - not because perfection is impossible, but because PI (3.14…) is an irrational number. Zeno’s paradox (and many other problems, like squaring the circle) is resolved if we live in a simulation. I think the evidence that we live in a simulation is quite overwhelming.


I think the evidence that we live in a simulation is quite overwhelming.

How can we still be Christians if we live in a simulation? How do we deal with the nagging threat of being shut down? In fact, we can’t be confident in any of our beliefs. The Simulation Hypothesis is a complete epistemological disaster. Do you have some way of dealing with these questions? If you do, I’d love to know.


Why is it such a “disaster”? Don’t you believe as a Christian that God could instantly bring the world to an end right now?
Perhaps the issue is with “eternal souls”? If we are in a simulation, then what are we really? Just and information pattern? In many ways, that is EXACTLY what we are. For example, it is estimated that after 8 years, not a single molecule of your body is the same. The information pattern is what makes you “you”. According to Christian doctrine, a soul exists outside of the worldly bounds. Well, if this world is a simulation, our information pattern could be transferred out of the simulation and ‘used’ elsewhere.

In many ways a simulation is far more reconcilable with Christianity than not.


If we’re in simulation , Jesus was in simulation which is impossible if he’s Son Of God.


Why not? If being human implies living in a simulation, Jesus became part of our simulation in order to become “human”.


Because it means God (Jesus) can be manipulated by a non-God entity


Don’t worry. Mulder and Skully debunked this theory in Season 7 Episode 13. :sunglasses:


I see what you are saying, but I don’t think it’s limited as you imply. Consider, for example, the similar ‘theory’ that we are living in a dream, a la the Inception movie. How do you know we are not in a dream? On the surface, there appears to be no “handle” as you say.

But if we think deeper, I think we can make some progress. Consider in this reality that I can change a state according to rules, and the reality stays consistent. For example, say I currently live in Delaware. Here, I can move a stone perhaps 2 inches to the left. I then go to California for 10 years. I return to Delaware, I find the stone still there. In other words, there are consistent, stable physical “rules” that this reality follows, and a consistent, stable “memory” of states. The key is that, in this reality, I can extrapolate the Delaware rock example to every molecule in the Universe. No matter where I look, these rules and states are consistent and present. This means this reality cannot possibly be a dream, for by definition, a dream is subset of the true reality. In other words, until we “wake up”, you could not define the concept of a “dream” that differs in any way from actual reality.

The interesting thing about a simulation is that the above does NOT apply at the quantum level. As I mentioned in another post, if we live in a simulation, there must be a minimal distance and time. This is the definition of a simulation, more or less (in terms of information theory, an approximate of a reality). In other words, if we were in a simulation, there must be some limit to the accuracy of this reality in terms of measurement. There must be some significant digit such that we can no longer define accurate measurements. Surprise, this is EXACTLY what happens at the quantum level. I think if you make an effort to define “simulation”, you will find that our reality ends up matching exactly that definition.


Perhaps aliens, ghosts, etc are glitches? What if blindness is an interface glitch? Maybe the Bermuda triangle is an error in the terrain map?

Simulations need not progress in real-time. Simulations progress one “tick” at a time. In games there’s typically 15-60 per second. Elements of the virtual world do not sense the ticks. Also, we would be unable to determine if the rules of physics were altered to work with the simulation, simplifications If you will. If something complex happens, there would be a long pause between ticks, but being sims we would be unaware.


Right, thats why I said:

So yes, if we had a metaphysics that denies physics, we can reject it. I was talking about the set of metaphysics that meet those requirements. So if you defined a dream to have consistent physics, we’d be right back in business.


Do enough hallucinogens and you’ll have experiences or ideas of this nature but whatever that altered state is is probably more organic in design… or possibly might not even exist as it is just big imagination on drugs.

Christian mystics have had various divine revelation and experiences through prayer and meditation and divine intervention that defy much modern thought rational thought or laws of reality yet are perfectly explainable in light of the Catholic faith or are miraculous in nature. These interpretations of God or his kingdom I think are much more worthy of belief than some of these other philosophical ideas.

As someone who enjoys sci fi… I remember the days of Dos and Basic. I just don’t think computers are that smart. I think if we were in the sort of spiritual prison defined by op it would have to be natural in design or in liberation so Christianity seems to be a more acceptable view of reality.

If I had to live in fear I’d say Aldous Huxleys Brave New World or George Orwells 1984 are much closer to the times we live in.

Should fear the secular non believers more than anyone who has any spectacular philosophies. We are limited and enslaved by false sense of normality and conformity more than anything spectacular or supernatural because I think transcendent things tend to be things that liberate us rather than enslave us.

To many questions like these we don’t have answers… but they can often be proven true or false using reasoning of ancient philosophy and logic.

Christianity seems pretty solid to me… though today I feel quite jaded and disappointed for emotional reasons… I cannot disprove any hope I have out of logic or reason and that gives me some strength.

I would also think that dark things such as demons or witchcraft may seriously exist as well in light of this deduction…

But they are not seen by secular standards as part of normal life…

Which this normality I think is false sense of security… that is our prison that dulls the intellect and shadows the faith.

There is simply more to life than what we can sense.


Map is not territory.

Our definition of reality may match our definition of simulation, but reality is more than our definition of reality. Our definition of reality can never be complete.

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