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Are there any philosophical arguments to disprove or weaken solipsism?

What justification(s) exist for the generally-agreed-upon axiom that a physical world beyond our mind both exists, and is knowable? This seems to be taken for granted, but rarely wrestled with in my experience. If no justification exists, does it not lead to inevitable epistemological agnosticism, removing any basis from which a man may claim to have any knowledge at all?

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    "does it not...[remove] any basis from which a man may claim to have any knowledge at all?" Even if the world only exists in your mind, you can still know a whole lot about this world that exists within your own mind.
    – Ami
    Commented Jun 16, 2011 at 0:55
  • @Ami If the world existed in your mind alone that would change a great portion of my question. The axiom suggests the world exists beyond our minds, and is occupied by other minds. Commented Jun 16, 2011 at 1:11
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    I'm leaning towards concluding that this question is a duplicate of at least one of those that Ami proposed. Any chance that you can explain how what you're asking here is distinct from those questions? Commented Jun 16, 2011 at 4:54
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    @Cody I think the question may indeed be close enough to the solipsism question that it could justifiably be closed. Commented Jun 16, 2011 at 16:42

2 Answers 2


Justifications? Well, yes:

You experience a world, right. It seems to be full of other people, like you. They seem to also experience a world, and by comparing experiences and building machines which measure the world, it seems that our experiences of the world are the same. We can also see how other people stop and start existing without the world doing so.

That leaves us three options.

Option 1: There is a physical, objective world beyond the mind. You are like one of the other people, a part of the world. The world is not a part of you. The world didn't start with you and will not end with you.

Option 2: There is a physical, objective world beyond the mind, but it's not the one you are experiencing. You are in fact being induced to hallucinate this world instead of the real one. Probably because aliens somehow want to use your body as an energy source, even though that claim makes so scientific sense and is about the worst plot device ever. Nothing you do can break this illusion, there is no blue or red pill.

Option 3: There is no physical world outside your mind, there is only you. You are alone and god. For some reason, when you started existing, you for no particular reason started hallucinating that you were human being that was a couple of years old. And for some really inexplicable reason, you hallucinate a reality over which you have no control. Although you can make yourself a rock star with infinite amounts of money and sex, you hallucinate yourself sitting in front of a computer asking interesting philosophical questions on a website. Nothing you do seem to be able to break the hallucination that the world you hallucinate is not a hallucination.

Now, option 2 is clearly absurd, and option 3 doesn't make any sense. If the world really was your hallucination, why aren't you hallucinating something better?

So yes, there is justifications for assuming that there is an objective world outside of your mind: Everything you experience tells you there is, and nothing you do can break that experience. The only reasonable assumption in that case is that the world in fact is objective and exists outside and independently of your mind.

  • I strongly disagree with the way you've characterized #3. You've over simplified and made strange assumptions about the philosophy of idealism. For one, many idealists believed in God. Have a look: en.wikipedia.org/wiki/Idealism
    – Ami
    Commented Jun 16, 2011 at 3:44
  • @Ami: I didn't refer to, much less criticize Idealism. To a large extent because it's a fuzzy concept, and mostly discussed with a lot of hot air. I'm not interested in dead peoples logical mistakes, personally. Commented Jun 16, 2011 at 4:10
  • You experience a world, right. Do I? That was the question I originally asked. I understand you could suggest the potential for the World to exist only in my mind, but then it's no world at all, but a concept. With all due respect, it seems your post assumes a priori the very thing I'm seeking to justify. Commented Jun 16, 2011 at 4:32
  • @Jonathan: No, in my terminology the world you experience is a world, no matter if it exists inside your mind or outside of your mind. I don't see why I should stop calling the world a world just because it is a hallucination. So you most definitely experience a world (assuming you exist), your question is if it is inside or outside of your mind. Commented Jun 16, 2011 at 4:36
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    @Lennart That's a bit of equivocation that I'm uncomfortable using. Clearly a physical world differs a great deal from a sub-conscious concept illustrated merely by my imagination. Assuming the later, Option 1 doesn't render a physical world, nor does Option 2 (I'm not sure what makes it 'clearly absurd', or even Option 3. It's argued that if the world is mental I would be a rock-star, because that's "better". This seems to ignore the possibility that one can be just as much the victim of their own mind as they are the author of their own mind. Have you never had a nightmare? Commented Jun 16, 2011 at 4:42

"What justification(s) exist for the generally-agreed-upon axiom that a physical world beyond our mind both exists, and is knowable?" (I don't know what you mean by "knowable".)

Unfortunately none.

But you might like to see: What is an 'argumentum ad lapidem'?

In an essay titled "Berkeley's Crossroads," Borges formulates the problem with realism:

By general rule, substance is assigned only size, while all other characteristics – color, taste, and sound – are considered beholden to a borderland between the spiritual and the material, an intermediate universe or the outskirts that are forged, in a continual and secret collaboration, between spatial reality and our organs of perception. This conjecture suffers from grave flaws. The pure and simple naked expanse that, according to the dualist and materialists [realist], composes the essence of the world is a useless trifle: blind, vain, formless, without bulk, neither soft nor hard, an abstraction that no one manages to visualize. The act of assigning it substance is a desperate measure of anti-metaphysical prejudice that completely fails to deny the essential reality of the external world and that takes refuge in a shady compromise by tossing it a verbal bit of charity: a hypocrisy comparable to the concept of atoms, imagined solely as a defense against the idea of infinite divisibility.

Borges dismissal of realism isn't particularly interesting because this is a classic application for the identity of indiscernibles. Until a distinction between a real world and an imagined world can be tested, it doesn't matter which one it is...it's like the question: "are other human beings conscious?"

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    @Ami What I mean by "knowable" is that the world beyond our mind exists in such a way that it intelligible and that man contains the capacity understand it. Commented Jun 16, 2011 at 1:16
  • @Jonathan, what is the standard of understanding you're looking for? The world is intelligible enough that I know something will fall if I drop it. It's not intelligible enough that we can know the exact position and velocity of a particle at one time.
    – Ami
    Commented Jun 16, 2011 at 1:18
  • @Ami It would seem you're begging the question to suggest the world is intelligible enough to know that if you drop something, it will fall. Are you not assuming a priori that the world was intelligible during your past experiences of dropping items? How would somebody begin to suggest it is a physical world that they are knowing, rather than the internal operations of their own mind? Commented Jun 16, 2011 at 1:20
  • I hadn't seen the question on Solipsism, but this question definitely seems to be creeping in that direction - thank you for the link earlier. Commented Jun 16, 2011 at 1:22
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    I'm sot sure why you first say no justification exist, and then in the end give a justification. :-) Commented Jun 16, 2011 at 4:17

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