The external world

Can anyone direct me towards proof that things external to me exist? In addition could someone explain to me what it means for a thing to exist. It came up in a discussion with a fellow student and I was unable to think of a valid argument.

This depends largely on why your fellow student thinks the external world doesn’t exist. Philosophy has no right answers - no one can give you a bullet proof definition of existence. What you CAN do is look at your fellow student’s argument and refute the argument.

Unless you want to kick her/him in the shin and say “if nothing exists, what just hit your shin and made you say ouch?” (Please don’t actually do this)

Is s/he saying “The external world DOESN’T exist” or “we can’t KNOW if the external world exists”?

She seemed to be saying (unless I misunderstood her) that we can’t know if anything exists externally.

Alright! Now we’re onto something. This idea is called External World Skepticism in Epistemology. Epistemology is the area of philosophy concerned with knowledge: what does it mean to ‘know’ something, what can we know, how do we know, those sorts of questions. Usually the External World Skeptical argument boils down to how do we as people know things.

When we’re dreaming, we don’t know that we’re dreaming. Everything we experience inside a dream is false with respect to the world. If you don’t like this idea, a similar one involves a hypothetical used in The Matrix. If we are in The Matrix, we wouldn’t be able to tell. For all our intellect we couldn’t differentiate between reality and what we experience in The Matrix. What this does is create a situation where we can doubt. “Am I typing this post? I don’t know! I might actually be in my bed dreaming!”

The argument then follows like this:

(1) If I can’t tell if I’m dreaming (or in The Matrix or whatever) than I can’t know the external world exists. (Because I might be dreaming it or whatever)
(2) I can’t tell if I’m dreaming. (As I explained in the above)
(3) Therefore I can’t know the external world exists.

You can fight this argument in a lot of ways. You can deny (1) by saying we don’t need to be 100 percent sure of something to know it. For example, we can’t know that ALL ravens are black. We haven’t literally counted every single raven that ever was or will be to be 100 percent sure. But every instance of a raven we have encountered is black. So we for all intents and purposes say we know ravens are black. Science works on this principle - we can never be 100 percent sure of scientific knowledge.

I think the most elegant refutation of External World Skepticism comes from GE Moore. Basically his argument goes like this:

(1) I have one hand.
(2) I have another hand.
(3) We can conclude that there is at least two things in the external world.
(4) Therefore the external world exists.

He appeals to common sense. We as human beings are very sure we have hands. We can feel them, we can use them to feel, we use them to hold and move objects, and we always have them. (Even when we dream - of course barring a terrible trauma). The fact that our hands exist is so overwhelmingly intuitive to us that it goes against common sense to deny they exist.

As far, as I remember, Descartes first argued that God exists (using ontological argument) and then argued that God, being good, wouldn’t let us to be that deceived.

Another option would be a modified Pascal’s Wager: it is more dangerous to be wrong in believing that nothing exists externally than to be wrong in believing that external world does exist.

And a third approach would start with question “Can you prove that we can’t know that?”. I’m pretty sure that will prove to be hard… :slight_smile:

By the way, even if we couldn’t prove something (it might be possible for her to argue that we can’t prove external world exists), it doesn’t yet follow that we cannot know that “something”. For example, we can know that arithmetic is not self-contradicting without a formal proof that that is the case.

Again, though, your refutation depends entirely on your classmate’s argument.

Ask your friend if she believes that water exists in the real world. If she says no, then get a glass of ice cold water and pour it on her head. Then ask a second time. This would be a proof by observational experiment.

Originally I tried to argue something like this.

  1. I seem to experience things in reality.
  2. These things, if they were hallucinations or dreams, would have to be based in things I had experienced before.
  3. If there is no external world than I wouldn’t have experienced them.
  4. Therefore the external world exists

Is this argument fallacious? She claimed I was making a circular argument but I didn’t see how.

I don’t think it’s circular but it doesn’t seem valid either. I could be wrong, it’s late and I’m not going to try and translate and test for validity.

More importantly I don’t think (2) is the whole story. Brain -in-a-vat or Descartes’ evil genius could feed sensory data to your brain and create sensations you’ve never experienced.

I think a better tactic is to make HER justify her assertion. The epistemological skeptic always has to fight an uphill battle trying to explain how it is we cannot know the physical world when our sense data and experiences support a physical world. If reality can’t be known, how is it that what we claim to know about the external world generally is very reliable and generally coheres with the experiences of pretty much everyone? That is a huge bullet to bite for the skeptic.

As a solipsist myself, and specifically a soft solipsist, which is the position that your friend appears to be advocating, perhaps I can offer a helpful perspective. First off, there’s simply no way to refute the solipsistic argument. There’s no way that you can ever know if anything exists outside of your own mind. It’s the inescapable dilemma of the conscious mind. It can never gain a perspective outside of itself. It can never be sure of what’s real.

There’s nothing wrong with believing that the world is real. In fact it’s probably the rational thing to do, so long as one remembers that you can never know. You can never be certain. The question that you may wish to ask your friend is, if this world is only an illusion, then what would she be without it? Everything she knows. Everything she loves, and fears, and hopes, and feels are born of this world. So what would she be without it? The world may not be real, but that doesn’t mean that it’s not unspeakably precious.

In the end it doesn’t matter what’s real. What matters is how one chooses to live their life. You can choose to love, and cherish, and hope, and believe. Or you can choose to hate, and judge, and resent, and punish. Real or illusion it doesn’t matter, these are your choices. These are the choices that you must make, and these are the choices that your friend must make.

If you were an atheist this argument might be a bit more convincing, but seeing as you’re a Catholic, it begs the response: If a conscious being can’t imagine a world for which it has no experience, then where did God get the idea for creation from?

Cognitive dissonance. The mind imagines a world that makes sense, because an irrational world would be logically incoherent, and prone to being torn apart by contradictions and paradoxes. For the conscious mind to exist, it must imagine a world in which its existence makes sense. It must have a framework in which to give itself context, and so it creates reality. Or to be more accurate, it doesn’t create such a reality, but rather it arises within such a reality, because it cannot exist outside of it. Its existence must have context and coherence, or it couldn’t exist. And so the conscious mind arises within a world that is logically consistent.

But unfortunately this reality can never overcome one overarching truth, one question that it cannot answer: Where did I come from? This unanswerable question leads to cognitive dissonance. The mind struggles to find an answer to this question. To imagine a world in which it knows where it came from, and why it exists, but it can’t. And so it exists in a world of conflict. Constantly struggling with the unanswerable questions: where did I come from, and why am I here? The world as I know it may simply be a reflection of that struggle.

I would disagree that such an argument presupposes God not existing. I didn’t say that conscious beings can’t conceive of things they haven’t experienced. I was referring only to humans. Despite this you bring up an interesting point on how God came up with things that had never existed. I will look into the idea further.

Regardless of this, Rhubarb did point out how the argument doesn’t necessarily refute other possible solipsistic views.

I don’t think there is any rational argument you can give to convince someone that idealism is false. Chesterton discusses this phenomenon in Orthodoxy. Contrary to popular belief, a madman is not someone who is irrational but someone who is only rational. Reason is what is diseased in this individual, so using more reasoning is not going to help, because the student has set up an impregnable rational fortress around his beliefs. Try using reason to convince someone who believes that everyone is out to kill him that you do not really want to kill him. Well he logically concludes, quite validly, that this is exactly what he should expect someone to say if there were a universal conspiracy to kill him.

What you need to do is get him to want idealism to be false so his will moves his intellect to see things differently. Apply Pascal’s wager to this issue. So he is quite convinced that all of his experiences are illusory and his mind is just painting coherent, logical occurrences on chaos to make him feel good. Great. But what is the harm in believing that the external world actually does exist and his experiences are actually reflecting reality? It explains all of the data as well as idealism, and is more healthy for him because now his thoughts are actually meaningful so he can actually know real things instead of only being able to know his experiences. So he can gain objective meaning. What is there to lose? That he is convinced idealism is true and so he’s losing truth? But he hasn’t established that idealism is true and idealism leaves no way for you to determine it is true anyway because all of his idealistic experiences are consistent with realism. So he’s not losing anything because he had no truth of idealism in the first place.

I think it is a really interesting question to meditate on. Where do I stop and the other begin?

I suppose you could turn the question around and ask, can I argue that I am everything that exists? If you feel that it can’t be argued intelligently then it suggests there is an external.

For example, is that door part of me? What would be needed for that door to be part of me? Do I have the knowledge and powers to create a world where that door seems external but is really a part of me?

Is it reasonable to believe that I created this world based on scientific law but I have to spend years trying to understand those very same laws?

If I created everything around me, that is, it is part of me, why does it seem that I cannot break the laws that run that world if I created them? Why am I bound by them?

Does it make sense that I learn important life lessons from what appears to be others external to me? Why are others smarter than me? Where does that knowledge come from if I am everything?

Why am I surprised by the actions of others if they are part of me or creations by me?

Why do I lose arguments to people if they are part of me?

If I am everything that exists, what is a reasonable explanation for how I came to be?

Actually, that looks reasonably good. It is definitely not circular. No premise seems to depend on the conclusion and it looks like she didn’t actually argue otherwise. However, she could try to question premise 2.

Well, in “Brain-in-a-vat” scenario there is an external world that includes at least the vat. And in scenario of Descartes there is an external world that includes at least someone that does the deceiving. After all, assertions “External world does not exist.” or even “We cannot know if external world exists.” are much stronger than mere “External world is mostly unknowable.”.

As you can see, some ways have been proposed. :slight_smile:

You already discussed some (and effectively endorsed the Pascal’s wager), but some others are left.

So, how do you know that? You cannot claim that it is “obvious”, as you think you cannot know something that looks far more obvious - existence of external world. Thus you need an actual argument. And it will have to be quite an argument…

For example, it will not be enough to show that ontological argument is wrong (as if it is not, adding some arguments for “I am not God.”, we’ll prove existence of external world that includes at least God). You will have to show that no similar argument can possibly work. And, of course, you cannot show that using what is supposed to be your conclusion (“There’s no way that you can ever know if anything exists outside of your own mind.” and the like).

What objections would you use against such an argument? Maybe I can modify it to make it more convincing.

Well, I don’t think I would use any objections. :slight_smile: But the weakest part is the second premise and it might be possible to say something like “Perhaps you just have a better imagination than you think?” or something. That is not a very strong objection, as it is hard to think of any alternative explanation, but one should be ready for it.

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