Solipsism is the view that only the individual exists. In that respect, the precise content of solipsism shifts with respect to every individual who holds it. If I am a solipsist then I believe only I exist and everything else I experience (including you) are contents of my mind and nothing more. If you are a solipsist then you believe that only you exist and everything else you experience (including me) are contents of your mind and nothing more.
Solipsism is a standard skeptical stop on the mainline of the skeptical epistemology train (along with idealism, brains-in-vats, and no-other-minds). In each case, by contemplating the views of the skeptic, the epistemologist is challenged to fine-tune justifications for “commonsense” beliefs she accepts without question.
This suggests that solipsism is, by and large, a philosopher’s mental exercise, a fanciful what-if scenario, a thought-experiment. But is it something more? Are there solipsists in the world? People who genuinely believe it is really all about them — and generated by them?
Here’s a practical way to put the question: have you ever met a solipsist? Alvin Plantinga has. In his autobiographical essay in the book Alvin Plantinga (Profiles, Vol. 5; ed. James Tomberlin and Peter van Inwagen; University of Warsaw, 1985), Plantinga recalls a memorable experience during his tenure at Wayne State University when he met a genuine solipsist, a professor who was teaching in another university department. Let’s call him Dr. X. After their pleasant visit as Plantinga turned to go, one of Dr. X’s colleagues quipped, “We treat Dr. X really well here because when he goes, we all go!”
[Cue the laugh track.]
It isn’t surprising that Plantinga still recalled that anecdote twenty years later because meeting a genuine solipsist is a truly rare occurrence. Idealists are, by comparison, a dime a dozen.
So it was noteworthy when I was contacted the other day by a person expressing concern that solipsism might indeed be true. I assured this person (via email) that I did, indeed, exist. But of course, once a person has bought into solipsism, it becomes a universal skeptical acid in which any possible defeater (such as my testimony that I exist independent of the solipsist’s perception of me) can be explained away as yet another permutation of the individual whose mind is generating all reality.
In short, once a person’s epistemological Jeep is stuck in the solipsist bog, how do you ever winch them out?
My second — and more serious — approach went like this. “Solipsism shouldn’t bother you because there is absolutely no reason to believe that thesis is true.” To unpack that point, note that there is an infinite number of equally implausible “global skeptic theses” which (1) can be reconciled to any data we experience but which (2) are all utterly implausible just the same, including the thesis that we’re all regularly deceived by a Cartesian demon, or that we’re dreaming our existence, or that the universe was created five minutes ago with apparent age. If we don’t worry about these global skeptic scenarios, why select solipsism for particular concern? My point, in short, is that concern about (or belief in) solipsism is hopelessly arbitrary.
At that point, I moved from comparing solipsism to other global skeptic theses and on to a final line of critique in which I compare it to known risks which, though minimal, are still far more prima facie likely than solipsism. “Indeed,” I continued, “there is far better evidence prima facie that an undetected asteroid will annihilate life on earth tomorrow, but I don’t worry about that possibility and I suspect you don’t either. But then it is irrational to worry about a far less plausible thesis [e.g. solipsism].”
I’m not sure if that reasoning made a dent in this individual’s lingering solipsism, but I did my best. How would you seek to rebut the global skeptical acid of solipsism?