In this essay I present Descartes’ view of the self and the world around him, and look at how Wittgenstein’s work, particularly his private language and rule following arguments, can be used to challenge the solitary view presented by Descartes.
To arrive at his conclusions, Descartes used the method of doubt. He looked at everything he thought he knew, and asked himself whether he can be absolutely certain of each of those pieces of information. If not, he would discard this piece of knowledge, and continue to look for something he could know with absolute certainty. Descartes is considered the initiator of the “Scientific Revolution”, and since he was a scientist and mathematician, it is clear why he adopted this method - he was not satisfied with taking things for granted and wanted aboslute certainty about what he thought he knew. Descartes’ first part of his mission was, in his words in the “Meditations”, to “withhold assent from propositions that are obviously false” and “withhold it from ones that are not completely certain and indubitable”.
In his second meditation, Descartes sees that “I am nothing while I think I am something” is a contradictory statement - either he is nothing but then he cannot think that he is something, or he thinks he is something, but then he can’t be nothing. For Descartes, it made no sense to claim “I am nothing”, since what is the “I” referring to? With this, Descartes famously concludes his cogito argument - “I am thinking, therefore I exist”, which is a proposition difficult for even the most committed skeptics to dismiss.
Next, Descartes seems to get stuck. All he can be certain of is that he is a thinking “thing”, but is not sure what exactly. Descartes believed that the mental and physical are separate, made from different substances, with the mental not having an extension into the physical. The “I” in the cogito argument is a mental “I”, something that doesn’t need a physical substrate - “I am simply a thing that thinks — a mind, or soul, or intellect”. For Descartes it was improper to believe otherwise. He imagines himself as a thinking thing, able to get sense impressions about what is around him, but it could all be non-existent, a figment of the imagination of the mental “I”.
To rescue himself out of solipsism (belief that only one’s mind is sure to exist), Descartes saw he needed to prove the existence of a benevolent God. His argument is that an omnipotent, omniscient, benevolent God would not deceive him, and from that it would follow that his sense perceptions are not deceiving him - they represent real things - and hence there exists an external world. If Descartes gets to that, he claims “whatever I perceive very clearly and distinctly is true”1. Descartes has two proofs for the existence of a benevolent God: the ontological argument, and the trademark argument. I do not explore further the details of these or the arguments for and against (the main one against being that Descartes uses circular reasoning - he deduces the existence of God from clear and distinct perceptions, and then deduces the reliability of his clear and distinct perceptions from the existence of God). Many later philosophers, especially empiricists such as Locke and Hume, were left unconvinced by Descartes’ proofs of existence of God, and how it should follow from it that an external world exist. They were inclined towards skepticism about the external world.
At what view of the self has Descartes arrived? He deduces that he is a thinking thing, a mental intellect, that inhabits a physical body, and that there exists a real physical world of which the body he is attached to is a part of. Furthermore, his senses provide him with clear and distinct perceptions, and these he deems to represent true things. Descartes, the intellect, is very alone in the world - he is exploring the real world from within his physical vehicle, his body, but he is still left unsure of many things, for example whether other conscious beings exist, or if they are merely zombies simply looking like they exhibit consciousness. I present Figure 1 as a simple picture of how I understand Descartes view of the self and the world he inhabits. The important part of the picture is to see that Descartes requires nothing but himself to exist to form all the ideas that he is able to form.
I now present Wittgenstein and show how his work challenges that of Descartes’. Even though Wittgenstein occasionally worked in logic and mathematics, his works are more dense and less accessible than the philosophy of Descartes which follows step-by-step patterns with clear application of rules of inference and conclusions. There are no conclusions, and both the “Tractatus” and “Philosophical Investigations” (main works of Wittgenstein) are numbered aphorisms meant to present to the reader a different point of view. Wittgenstein does not argue with any previous philosopher per-se, but instead presents the overall problems with approach to philosophy. Wittgenstein is concerned with the role of language and rule-following, and how philosophical issues arise because of misunderstanding, or lack of expressiveness of language and rule-following.
Regardless of whether there is or isn’t an external world, we agree that the language you use is meaningful. If there is no external world, it still holds that the language we use for our experiences and sensations must still be meaningful without this external world. In “Philosophical Investigations”, Wittgenstein develops the private language argument, which shows that it is not possible for a “private language” to exist - otherwise it would be meaningless and hence not a language. Looking at the contrapositive of the above, if we can show that we can’t have a “private language” (a meaningful language system without an external world), it follows that an external world exists.
We can interpret “private language” as something akin to being trapped in subjectivity, like in Descartes’ case. What is not meant by “private language” is for example, what a baby who grows up on a deserted island could possibly develop for its own use. In that case, an outsider could theoretically learn that language (possibly via interactions, watching, or provided ostensive definitions), and hence it wouldn’t be private. With this definition, if we show that if a “private language” cannot exist, then being trapped in subjectivity like in Descartes’ view, is impossible.
I now paraphrase and analyze PI§258, where Wittgenstein provides an example of a private language. Assume you want to keep a diary about the recurrence of a certain sensation \(S\), and in it, you will write “S” whenever \(S\) occurs to you. The assumption is that it’s not possible to define \(S\) normally. You can try to provide yourself with an ostensive definition, try to inwardly point to what \(S\) is. A definition is supposed to provide meaning, a connection, an immutable mapping between \(S\) and the symbol “S”. You now take this definition, and will write “S” at a future time if \(S\), according to your definition, occurs.
Wittgenstein pinpoints an issue. See the above in terms of rule-following and the rule: if \(S\) occurs, per the definition, note “S”, or symbolically, \(S \rightarrow W\) where \(W\) denotes the action of writing down “S”. In PI§202, Wittgenstein remarks “Thinking to obey a rule is not to obey a rule” which can be justified as follows. If we have the rule \(S \rightarrow W\), then at any future point in time when any sensation \(T\) occurs, we cannot be sure that \(T=S\) because we lack any independent checks and only have the contents of our own mind to check if \(S=T\). Even though we are thinking we are following the rule \(S \rightarrow W\), we are also aware that it is impossible for oneself to assert without aid that \(S=T\). We understand what following the rule involves, but because of our uncertainty in the statement “S=T”, we are not able to follow the rule \(S \rightarrow W\).
This means that if if a sensation \(T\), objectively different from \(S\), occurs at a future time, you might easily mistake it for \(S\) and still note down “S” in your notebook. From this point on, for you, \(T = S\). This is a kind of “private language”, but it is meaningless since the definitions of everything are free to change. It is not possible to correctly assert to yourself the validity of some statement having only at your disposition your own mind and memory. This is like buying a newspaper, and then buying extra copies of the same newspaper, to convince yourself that what is written in the first copy is correct2. A correct justification requires an independent source.
A “private language”, then, cannot exist. How does this apply to Descartes? Descartes is trapped in subjectivity, he is a lone mind, and all he has is that he thinks he is obeying rules correctly. How does he know that he is using them in the same way as beforehand? He cannot. Descartes’ world is then completely meaningless - an impression he associates with the color “red”, can be associated with “blue” in the very next moment. Wittgenstein showed us that if all you have is one closed system, for example the contents of your mind, then the meaning of anything can never be fixed. Descartes would not be able to form any rational thoughts if the concepts he had, had no meaning.
By the private language argument, the idea that a person could describe their own sense impressions without any connection to the outside world is impossible. This is contradictory to how Descartes’ sees himself as a single mind receiving sense impressions. Both Wittgenstein and Descartes show that an external world exists, although Wittgenstein does it differently, more convincingly, without relying on shaky proofs of God’s existence.
Wittgenstein’s view can also be used to show how there is no distinction between the mental and the physical like in Descartes’ picture. What Descartes suggests is that it’s possible to have a purely subjective language operating in the mental space. Such a language would have to be a “private language” (since it’s subjective, it does not use external justifications), and hence impossible. But then Descartes would not be able to form rational thoughts, and he appears to do. So there must exist something else in the same strata as Descartes’ “I” that’s doing the introspection.
It is certainly not easy to understand Wittgenstein’s arguments. Descartes’ method, up until proving existence of God and hence the external world, is easy to follow and appears sound. Descartes has a bottom-up approach, approaching it from the lonely self, pondering about its sensations. Wittgenstein approaches the problem from the other side, looking at everything as a community, and showing that there is no private meaning and how we are what we are only because of our shared life and language. Following step-by-step Wittgenstein’s arguments, we can see though how it leads to a view that contradicts that of Descartes. It is indeed very hard to imagine an entity existing by itself with no relation to anything whatsoever, and still be able to form rational, meaningful thoughts. All of Wittgenstein’s arguments revolve around language, so one could ask whether something without language, say an animal or a baby, can form any meaningful thoughts. The question is misguided, since both the baby and an animal, interact with their environments, their own worlds, and hence are using a kind of objective language usable in their own worlds. Wittgenstein said “If a lion could speak, we could not understand him”, and this is precisely because a lion, surely able to form rational thoughts, inhabits a different conceptual world, and as language is a product of the inhabitants and the world they inhabit, our languages will be different. Many have argued, or interpreted in a certain different way, the work of Wittgenstein. For example, the logician Saul Kripke in “Wittgenstein on Private Language” shows that it appears to be impossible to follow any rule, since you would need a rule to follow that rule, ad infinitum. Nevertheless, presented as it is in Philosophical Investigations, we can use use Wittgenstein’s private language argument to challenge the view of Descartes.
We have seen how Descartes presents his view of a solitary mental self, and how Wittgenstein’s private language argument leads to conclusions contradicting those of Descartes. It follows from Wittgenstein’s work that there is no distinction between the inner and the outer, and that it is not possible for Descartes to exist just by himself as a mind - an external world must exist, as otherwise Descartes’ thoughts would be meaningless.
0.1 Sources
René Descartes, Meditations on First Philosophy. Jonathan Bennett, 2004
Ludwig Wittgenstein, Philosophical Investigations. G.E.M Anscombe, Basil Blackwell, Oxford 3rd Edition, 1958.
Saul Kripke, Wittgenstein on Private Language. Harvard University Press, 1982
Film, Wittgenstein. Director: Derek Jarman, 1993