In this thread, I’d like to defend a moderate shape of solipsism. In particular, I’ll try to refute Stephen P. Thornton’s arguments against solipsism and the unknowability of other minds which he sets forth in his article Solipsism and the Problem of Other Minds in the Internet Encyclopedia of Philosophy (IEP).

First off, let me tell you what kind of solipsism I’ll not try to defend, and even try to refute in this paragraph: the view that all that exists is I or a content of my mind. Just as I’m directly aware of myself, I’m also directly aware of abstract things, such as the number (rimetale) 6, the rimetale 5, the property of propertihood, and the kind of mindhood. Since I can directly “see with my mind’s eye” that 5 is not the same as 6, at least one of them must be distinct from me. Hence, I cannot be the only thing that exists. Moreover, I have no power whatsoever over 5, 6, or the relationships between them, and in order for me to exist or be a self at all, I need the (Platonic) Shape (Form, Idea) of Existence and more broadly of Being as well as the Shape of Selfhood. Thus, there must be things outside of, because groundlaying (fundamental) to, my mind and self (I’ll use “mind” and “self” interchangeably here). (By the way, I hold that all things, including all minds, are abstract, and I can justify my claim, but that’s another matter.) So I believe that solipsism in the strict sense has been ruled out.

However, the solipsism whose irrefutability I want to defend in this thread is the position that I’m the only mind in existence, that is, the only thing that has mindhood, and that there’s no physical world. I’m not trying to defend this kind of solipsism itself, but only that it’s irrefutable unless there are thoughtcasters (telepaths), and that the existence of a physical world and other minds can only be inferred on ultimately shaky ground, but not known – that is, again unless there are thoughtcasters.

Thornton claims that it is meaningless to ascribe pain to a table. That claim is totally wrong imho. If some cannot do this, it may be due to too concrete thinking or lack of imagination. I, for one, can perfectly well imagine a table having a mind and so experiencing pain. Thornton claims that the physical manifestations of pain and anger and other mental states belong to the very concepts of those states, but I see no reason to accept this assertion. What, for instance, is about actors who just simulate emotions? How can you claim to see the anger of a person when that person is just behaving in such ways as to simulate anger? What if there’s only a soulless body in front of me displaying what I usually associate with anger due to physical processes in its brain?

Thornton, and also Wittgenstein, who is quoted by him, assert that it only makes sense to attribute mental qualities to things that look or behave like living human beings. At the same time, he seems to claim that normal (non-telepathic) minds can directly observe each other. Isn’t he replacing a well-supported egocentrism by an ill-supported anthropocentrism? How am I to directly be aware of what you think or feel – if you exist at all –, and how are you – if you exist – supposed to truly know what I think or feel? And would extraterrestrials vastly superior to humans in intellect not be regarded as persons just because they look different from us? Isn’t that a laughable supposition? And yet Thorntin makes the false statement that personhood is the same thing as humanhood. I know that it is false because at least my concept of personhood is very much distinct from my concept of humanhood.

Thornton does not at all give me any convincing reason for assuming that there is a necessary link between the mental and the physical.

When I have pain, I most certainly know that I have pain. How can Thornton say that it is nonsense that I know that I am in pain? If anything is nonsense, then that claim of his, I find.

He also makes the false claim that it is a false assertion that other people (unless they’re telepaths) cannot know my experience. Can you know what I’m experiencing right now from what you read on the screen? No, right? Well, that’s because you only see physical manifestations of me, namely activity on this forum, and if we met each other in person, you’d still only see physical manifestations of me. You’d see much more, I grant you, but that’s only a difference in degree and not in kind.

Tell me, how can I know my brain isn’t connected to the matrix, and that all those so-called people are only conjured up in my imagination by the matrix sending appropriated electric impulses to my brain?

In addition, Thornton makes the unsubstantiated claim that logical rules are intersubjective and public. I derive my logical laws from my (admittedly often blurred) “seeing” of propositionhood, propositions, and logical functions, entities that send propositions or indexed families thereof to propositions.

But what strikes me is Thornton’s bold and unjustified claim that a “non-linguistic solipsism is unthinkable and a thinkable solipsism is necessarily linguistic”. With what right does he claim that speech is needed for thought? As a matter of fact, I can think and see abstract things without using speech, and speech is just my private tool for finding my way around in the abstract world and the world of my experiences. I can “look at” principlehood, in my mind “point” at it, and say to myself, “From now on, I’ll use the word ‘principlehood’ to mean that thing”. Basically, speech consists in setting onesself rules that a certain function is to obey which sends abstract objects from a particular set, which is the set of linguistic expressions, to abstract entities broadly. To obey these rules is to be the meaning-mapping used by the mind in question. The goal of speech is to make thinking easier by doing a one-time rule-setting, a one-time representation of a big part of sooth (reality) in the set of expression, and then mostly “looking at” the expressions; this is easier because the expressions are of a particularly easy-to-see kind, e.g. finite sequences over a finite set of abstract entities. But without thought, there could be no meaning-mapping and so no speech. Speech needs thought, not the other way round.

On the whole, I find Thornton’s article thoroughly unconvincing. I’m still sure that I can directly know that I think and therefore am, I have no problems in imagining my or some other soul in a table or disembodied, and I have never “seen” any experience other than my own. (Please tell me if I’ve misunderstood Thornton is some way.)

In particular, I’d like Thornton and Wittgenstein to answer the following challenges:

What if there’s a puppeteer making all the bodies around me behave as if they had minds?

What if I’m connected to the matrix?

Two different minds in two different bodies, e.g. identical twins, can fool me into thinking they are one person. Two different numbers cannot do that. Why? Because I can be directly aware of the latter but not the former. How do you swuttle (explain) that?

By the Law of Self-Identity, for each x, I trivially know that x is the same as x. Moreover, for each x and each y different from x, I trivially know that x is not the same as y. So for any two things, I either know that they’re the same, or I know that ther aren’t. How, then, can it be that I don’t know whether or not King Cniva and King Cannabaudes are the same? How can it be that I don’t know whether a pair of people on this forum are the same person or not? Because I can only hypothesize about them based on their accounts, right?

What’s wrong with my soul having no body?

Any thoughts?