Solipsism Definition: Your Mind Is the Only Thing that Exists

Have you ever had the feeling that you’re the only person that exists? That other people, life, and the universe are mere figments of your imagination? And that there is no way ‘outside’ your own head to prove otherwise?

If you maintained such views, you’d be what philosophers call a ‘solipsist’.

What is solipsism?

Solipsists believe in an extreme form of skepticism about the external world: namely, that anything ‘external’ doesn’t exist. Everything is an aspect of their own mind.

Taken at face value, this might seem a ridiculous position. How could a single mind possibly conjure up such a rich and endlessly unfolding tapestry of circumstances involving sight, hearing, taste, smell, touch, other people, international events, scientific discoveries, artistic creations, cosmic exploration — cheese?!

That the endless variety of existence has its source in a single mind is a bizarre characterization of reality not worthy of consideration, we might think.

But the solipsist does not appeal to common sense; the solipsist appeals to logic. Consider the following propositions:

1. The only things I have direct access to are the contents of my own mind — sensory experiences, thoughts, memories, and so on.

2. The contents of my own mind are entirely private, and inaccessible to anyone but me.

3. I am unable to access the mind of any other being, and so can only infer the existence of other minds indirectly.

Many people would agree with these propositions (for instance, see Aldous Huxley on the unknowability of other minds). The solipsist simply takes the implications of them to their extreme logical conclusion:

The only thing I can be sure of with certainty is that my mind exists. Therefore, there are no logical grounds for asserting the existence of anything else.

In his 1893 work Appearance and Reality, the British idealist F.H. Bradley characterizes the solipsistic view similarly, writing:

I cannot transcend experience, and experience must be my experience. From this it follows that nothing beyond my self exists; for what is experience is its [the self’s] states.

So, though perhaps ridiculous at face value, solipsism actually provides a surprisingly difficult logical puzzle — one which many philosophers throughout history have wrestled with, perhaps most famously René Descartes with his “I think, therefore I am” statement, which places sustained focus on the problems solipsism raises, as we outline in our short cogito ergo sum explainer piece.

What are some counterarguments to solipsism?

Beyond Descartes, a huge number of philosophers have attempted to refute solipsism over the years, but a universally-accepted logical refutation has proven rather elusive. Many philosophers revert to simply arguing against solipsism’s likelihood, rather than providing logical refutations.

For instance, a common response to the solipsist is to demand exactly how a single mind could conjure up the endless variety of experience.

Is the solipsist really committed to the idea that every ant, every leaf, every grain of sand, every electrical storm, every word in every book and on every page of the internet (including this one!) is conjured up by some inaccessible part of their mind of which they have no conscious awareness?

Surely the mechanistic explanations for such phenomena simply collapse to standard explanations: the ‘mind-generated’ beam of light reflects off the ‘mind-generated’ tomato to hit the ‘mind-generated’ retina. What value, what usefulness or explanatory power does the phrase ‘mind-generated’ actually add here? Is it not just a euphemism for what we’d otherwise describe as the external world?

The solipsist might retort that this is no refutation: solipsism remains a possibility.

The argument from analogy

Historically, the argument from analogy was a very common strategy for avoiding solipsism. A typical occurrence of it can be found in John Stuart Mill’s 1865 work, An Examination of Sir William Hamilton’s Philosophy. In reply to the question of how we can know other people have minds, Mill writes:

First, they have bodies like me, which I know in my own case, to be the antecedent condition of feelings; and because, secondly, they exhibit the acts, and outward signs, which in my own case I know by experience to be caused by feelings.

In other words, other people act like I do in similar circumstances, implying they have similar inner lives.

While the argument from analogy was once popular, it’s now recognized as unfit for purpose. Rather than challenge solipsism, it seems to simply concede the whole argument upon which solipsism rests: that knowing other people have minds is logically unconfirmable. The argument from analogy resorts to insisting that, despite it being unconfirmable, other people must have minds anyway because “they look and act like I do.”

This is far from a refutation. As we discuss in our explainer on the philosophical zombie thought experiment, outward behavior is no logical guarantee of inner life.

So, as before, the solipsist can happily retort that solipsism remains a possibility.

To be is to be perceived

The subjective idealist George Berkeley had a view many equate to solipsism, but he actually offered what he thought was a solid refutation of it. As we outline in our discussion of Berkeley’s philosophy, his metaphysical slogan was esse est percipi: to be is to be perceived.

Berkeley thought the only things in existence were minds and their potential contents (e.g. sensory perceptions, feelings, thoughts, and so on).

To the question of whether a falling tree makes a noise when there’s no one around to hear it, for instance, Berkeley answers with a definitive no: things only exist if there is some kind of being there to perceive them — all else is superfluous and nonsensical.

Berkeley differs from the solipsist in that — while both deny the world of matter — Berkeley has no issue with some sort of world existing independently of our minds. This world is made up not of physical stuff, Berkeley says, but rather of all the potential ‘mental stuff’ that could fill our minds (sensory perceptions, feelings, thoughts, etc.), and endures only because it is ‘perceived’ by the all-powerful mind of God.

On Berkeley’s view of to be is to be perceived, therefore, solipsism is an impossible absurdity. The solipsist, being the only thing in existence, cannot be perceived — the solipsist cannot ‘step outside’ themselves to perceive themselves. And, if they cannot be perceived, the solipsist thus cannot exist. (One could perhaps counter, however, that on Berkeley’s view, God is a kind of solipsist).

Berkeley’s argument against solipsism is perhaps the closest to a logical refutation so far, but accepting it means committing to Berkeley’s metaphysics of esse est percipi, which many deem undesirable.

We access the world directly

Some philosophers of epistemology and consciousness take issue with a key premise of solipsism: that our sensory perceptions are aspects of our mind, rather than direct representations of the world itself. One route out of solipsism, therefore, is to deny that all we have access to is the contents of our own mind.

This area is hardly settled, however, with epistemological debates about whether perception is reality continuing to rage. The literature here is vast, and analyzing it in detail is beyond the scope of this article. For more here, see our article on whether the world around us is ‘real’.

The private language argument

Another argument against solipsism is inspired by Wittgenstein’s private language argument, as set out in his 1953 work, Philosophical Investigations, which states that a language understandable by only a single individual is incoherent. Public languages, Wittgenstein argues, can only result from public social contexts.

So, that we are able to express solipsism in public language thereby refutes solipsism: the solipsist, thinking solipsistic thoughts in a public language, presupposes the existence of the public, intersubjective world they seek to deny, undercutting their own position simply by expressing themselves.

Can we be certain about anything?

Another point is less a counterargument to solipsism and more a way to defuse its power. Essentially, solipsism, along with any theory that demands certainty, sets unrealistic expectations for knowledge. We may not be able to rule out solipsism with certainty. But we also can’t rule out with certainty that, say, there’s a giant, invisible spaghetti monster in the sky.

There’s hardly anything we can be certain about. That doesn’t mean solipsism is true.

Defenders of solipsism might counter that the analogy of the giant spaghetti monster is unfair. Someone who proposes that a giant spaghetti monster invisibly reigns over us in the sky is making a leap. They’re suggesting the existence of something over and above the immediate evidence. The solipsist, by contrast, makes no such leap: the solipsist in fact rules out the existence of anything for which we do not have direct evidence, leaving us only with our minds.

Nevertheless, we might still think the solipsist is setting too restrictive a requirement for knowledge.

Solipsism might be difficult to refute logically, and might always remain a possibility, but perhaps that’s okay: we live without certainty every day.

Perhaps we can remain open to various possibilities about the true nature of existence. Perhaps we can accept that we know very little about how our rich inner lives are connected to the cosmos, and whether such a connection (between the internal/mental and the external/physical) could ever have a basis in logic.

This acceptance doesn’t mean we must all commit to solipsism.

Where does solipsism leave us?

Solipsism raises fundamental issues in epistemology, metaphysics, and the philosophy of consciousness, and forces us to face up to the limitations of our reasoning — for while solipsism seems utterly absurd, arguably it has never been (and perhaps never could be) unequivocally refuted.

But perhaps the most poignant reaction we might have when considering solipsism — bizarre metaphysics aside — is to the unavoidable and rather lonely fact that, when you think about it, we can never escape our own minds.

Whatever we do, however vivid our imaginations, however determined our efforts to alter our own minds, we cannot step outside ourselves. We will only ever experience life with the minds we have. We will never directly know what other people think, feel, or experience.

This might seem a depressing, even terrifying thought.

But perhaps another view to take would be that the very inescapable nature of our own minds makes any connection we do manage to make to other minds — minds we must believe, rather than know, to exist — ever more precious.

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