Could a philosophical zombie conclude "cogito ergo sum"?

Assume a philosophical zombie which is a hypothetical being that is indistinguishable from a normal human being except in that it lacks conscious experience, qualia, or sentience.

In particular, I mean a behavioral zombie that is behaviorally indistinguishable from a human, regardless of its internal machinery.

I guess it would probably insist there is no such thing as that silly thing philosophers call qualia, but that is OK since most of my good friends insist the same.

I wonder if such a zombie could conclude cogito ergo sum since I believe Descartes really meant (inner) experience entails existence, and that the purpose of I in that statement is simply to point out that first person, direct inner witnessing, rather than some concept of a self.

But, a zombie has no qualia, so...?

EDIT - to clarify, I do not question whether philosophical zombies can reach conclusions in general. I do not mind granting that even AI can be said to reach conclusions. I am asking if it can reach this particular conclusion.

  • You said indistinguishable then it can. You said has no qualia then it probably can not. Your self Contradicting definition means that it is probably impossible to make such a zombie. Or to define well what human behavior actually is. Good news in both cases. Besides <-> great(real) humans were in non of the aspects normal - sO yEAH.
    – Asphir Dom
    Commented Aug 5, 2014 at 23:31
  • @AsphirDom, I do not know that a philosophical zombie is self contradicting, and I do not see how it follows from your argument. Some intelligent people deny cogito ergo sum, or qualia, so a philosophical zombie could as well, without being self contradicting. In addition, philosophical zombies are not made, but conceived. You can alternatively imagine a highly intelligent alien race lacking qualia.
    – nir
    Commented Aug 6, 2014 at 7:16
  • People denying qualia or cogito ergo sum are zombies. Difference is if they are real zombies or they can be awaken. Most of the religions and logical investigations (together with human desires) suggest that they must be not real zombies but rather sleeping beings. Kinda like kids who do not care about philosophy or existence.
    – Asphir Dom
    Commented Aug 6, 2014 at 13:04

4 Answers 4


Cogito ergo sum works, logically, in a generalized form that philosophical zombies can manage.

I have a detector of some sort, D(_). Does anything exist at all? If the detector is passed any argument, then I can say: yes! I might not know what it is, but I surely know it's there. Just one problem: I might imagine a fake argument and pass it instead. Do any non-imagined things exist at all? Oh, but wait, we have a detector, by premise. D(D(_)). Ta-da! We have passed an argument to D, therefore something exists, and it is in fact the detector that we have. I can't be faking D because it is acting as a detector and if it acts as a detector it is a detector. Also, since I am (hypothetically) a philosophical zombie, my D is sophisticated enough to know that that D is me.

I, as the zombie, can't conclude much of anything from this other than that the universe is not the empty set. (Nor can Descartes, actually.)

  • how does doubt fit in this picture?
    – nir
    Commented Aug 5, 2014 at 21:45
  • @nir - It doesn't explicitly. Implicitly (or analogously), unless you pass something into D, the zombie doesn't know about it, so the zombie "doubts" that it exists.
    – Rex Kerr
    Commented Aug 5, 2014 at 21:47
  • I think you are talking about a recursive form of the ultimate machine invented by Marvin Minsky and Claude Shannon :)
    – nir
    Commented Aug 5, 2014 at 22:12
  • I suppose the zombie puts all kind of other arguments, first. It puts in the image of a banana, and the detector says something exists, it puts in the sound of an alarm clock, etc... why would it bother putting D in the detector if it already "knows" something exists?
    – nir
    Commented Aug 5, 2014 at 22:23
  • @nir - I skipped some of the reasoning (where arguments might be imaginary); I've added it in an edit.
    – Rex Kerr
    Commented Aug 5, 2014 at 23:25

A philosophical zombie could not conclude anything inside their mind, because by definition they don't have any minds. They could make it seem like they have made the conclusion, though; but you (again, by definition) would have absolutely no way to tell if this is really so.

The fact that the argument in question is "cogito ergo sum" does not change a single thing.

  • why did you complicate conclude with "inside their mind"? It seems tangential to the question.
    – nir
    Commented Aug 6, 2016 at 12:09

In Descartes context, the Cogito Ergo Sum is important because you don't necessarily know that anything exists, except yourself. Relates to the Evil Demon thought experiment, with the idea that even if this is the case, you know that you exist because you can doubt your own existence, and that doubt isn't a perception or qualia that can be forced onto you like essentially every other perception is.

This seems to break down in the case of a Philosophical Zombie. The Evil Demon argument doesn't really apply, because if the zombie isn't able to experience sentience and qualia anyways, it can have no doubt that the things it "perceives" are real. Thus I'd be inclined to answer that the zombie can't use Cogito Ergo Sum because it can't doubt the existence of anything, including itself. I guess the zombie knows it exists and has no need of a proof of it, because it cannot be tricked or illusioned the way a sentient human can.

  • 1
    +1 for approaching the idea that a P-Zombie cannot conclude anything.
    – Magus
    Commented Aug 5, 2014 at 23:14
  • 1
    Why can't a philosophical zombie be tricked? Voice recognition software seems to be tricked all the time that I said something that I didn't. Phone support systems even seem to realize that being tricked is possible and sometimes repeat what I (supposedly) said to check.
    – Rex Kerr
    Commented Aug 6, 2014 at 5:24
  • @Magus, a p-zombie can conclude things by definition.
    – nir
    Commented Aug 6, 2014 at 7:18
  • @Cain, First, I think doubt is just a thought process, which an omnipotent demon should be able to make you believe you are having, just as with voices and images. Second, I do not see why qualia is required for having doubt corresponding to the information receives by the senses.
    – nir
    Commented Aug 6, 2014 at 8:13
  • @RexKerr The zombie can be tricked as to the identity of a thing, just not the exist of another thing. VR software can easily identify the wrong voice, but couldn't dream or hallucinate a voice without sentience.
    – Cain
    Commented Aug 6, 2014 at 15:52

They could say the words, but could never believe them because they have no beliefs. They could act like they believe the words but no actual belief. They could act like they have reached such a conclusion, they could act like they believe it.

If by "reach a conclusion" you mean have the subjective experience of reaching the conclusion then by definition (they have no subjective experiences) they cannot reach any conclusion about anything.

If by "reach a conclusion" you mean act just like a non-zombie who has had the subjective experience of reaching the conclusion then yes they can act like they have reached the conclusion. (Also by definition since zombies can act just like non-zombies.)

  • 1
    philosophy.stackexchange.com/users/8556/nir The whole force of your original question is based on the ambiguity of the statement "can a zombie conclude.." You don't specify if you mean behaving like they concluded or have a conscious experience of the conclusion. It s also spurious to bring up the veracity of the conclusion since even incorrect conclusions can be reached, and often are. Your question was whether or not they could conclude not if they would be correct in doing so. Commented Aug 6, 2016 at 6:46
  • 1
    @nir Casual language does not distinguish between someone acting like they are conscious and their actually being conscious. We say that someone is conscious when we see them acting like they are conscious. Of course the whole point of the zombie construct is that these aren't the same. There is no way to determine if another person is actually conscious, this is 'the problem of other minds'. It's a bit like the difference between "seeing a car" and "seeing the light bouncing off the car". Commented Aug 9, 2016 at 10:32
  • 1
    @nir Ordinary language doesn't distinguish between the two but the latter is a more precise description of the situation. Turing was talking about a machine acting in a sufficiently complicated manner that we would say that it was thinking like we say that a person is thinking when they act in particular ways. You need to go over the problem of other minds to learn to avoid use of terms like "conclude" , "think" which presume consciousness thereby conflating observable behavior with actual consciousness. Commented Aug 9, 2016 at 10:42
  • 1
    @nir So you're willing to talk about what zombies think, believe, feel, conclude , etc., because you ignore the problem? You attribute conscious activities to an entity that by definition has no consciousness? Commented Aug 10, 2016 at 16:26
  • 1
    @nir Not this time. You are basing everything on ignoring a contradiction without any argument to the contrary. Is this a technique that you embrace? Your best explanation for assigning cognitive states to zombie is.."I think that it is time to conclude that there is a gap in our understanding of the question and the problem, which prevents us from discussing the them fruitfully, " ? Commented Aug 12, 2016 at 1:01

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