Descartes argues that whenever he thinks, he exists. The context for this argument is that the person has no senses and no body, so everything in his/her imagination is false. He moves on to ask the question: Then what is real before we conclude that everything is fake? The answer to this question leads to the following argument: (1) I exist because I can think of something, regardless of the truthfulness of my thoughts; (2) someone manufactures all my fake sensory experiences and thoughts, but this someone cannot make me nonexistent as long as that “I think I am something (Descartes).” (1) and (2) imply that this person at least possesses the abilities to be aware of being aware of thoughts, to have beliefs and to be deceived. A being that possesses all these three traits must be alive because no men have seen/heard otherwise. This allows Descartes to conclude: (3) Therefore I exist.
Chatelet claims that Descartes uses the principle of contradiction in this argument. I will explain her definition of it and show why she thinks Descartes utilizes it. She defines contradiction as accepting and denying the same thing at the same time. Following from this, her principle of contradiction states that if something is A, it cannot be A and not-A simultaneously. A true statement will always be consistent with the principle of contradiction, which is “the foundation of all certainty (Chatelet),” and thus never be contradictory. This principle is the basis for all necessary truths (a truth that only exists in one way).
Descartes, in her opinion, is assuming that the behavior of thinking necessitates existence. Existence is a necessary quality for thinking. If one thinks, one must exist, although it may not be true the other way around. A thinking thing must be alive, so denying the existence of a thinking thing is saying that a thinking and therefore existing thing is not existing. This contradictory denial is similar to denying that a rectangle has four sides, which are a necessary quality of the rectangle.
I personally completely agree with Chatelet because even if one accepts Descartes’ assumptions, without the principle of contradiction, his argument will not be valid because the principle of contradiction is the basis for the validity and logic of Descartes’ argument and its methodology. If one grants his assumptions but not the principle of contradiction, one can criticize: “I can be thinking and not thinking at the same time, so I can be dead and alive simultaneously.” This way of thinking without the principle of contradiction is absurd and demonstrates that no one will agree with any logical argument if they don’t accept the principle of contradiction.
After Chatelet analyzes Descartes’ most famous argument, she starts criticizing his discussion about one’s inability to distinguish dreams from reality by using the principle of sufficient reason (PSR). She interprets PSR as “the principle on which all contingent truths depend,” which is just as fundamental as the principle of contradiction. I will first define contingent truth so I can explain her version of PSR and finally her criticism. A contingent truth can exist in several versions, which are equally necessary, whereas a necessary truth will only exist in one version. The principle of sufficient reason states that if a contingent truth is existing in one way, out of its many ways, this particular version of this contingent truth must be preferable to others for an adequate reason.
She believes without PSR, events will happen haphazardly without a sufficient reason and reasonable pattern because all reasons are equally preferable. Also, nobody can be psychologically sure for a prolonged period of time about reasons behind the occurrence of events because they don’t have sufficient reasons for occurring, and behave in a random manner. For example, if PSR applies, the Duke admission office accepted me into Duke, it is sure that I am accepted for a sufficient reason and that my acceptance is preferable to putting me on the waitlist or rejecting me, so they will maintain the acceptance if they don’t hear anything about me in the future. If PSR doesn’t apply, it will be sure only at the moment of its decision to accept me, but because they don’t have a sufficient reason to maintain the decision, the next second they can randomly waitlist or reject me because the alternatives are equally preferable.
To criticize Descartes, the key point Chatelet is attempting to make is that in dreams, how events come to be don’t depend on PSR and don’t happen for the best, or sufficient, reason. In dreams, scenarios like the second PSR-less and inconsistent Duke admissions event constantly happen. However, in real life, they’re unlikely. PSR always applies in reality and in how the Duke admissions operate. It has a sufficient reason to choose to accept me and thus will maintain the acceptance, unless a more sufficient reason to reverse the decision appears in the future. The fundamental difference between dreams and reality is whether PSR is always effective. It implies that events in reality have an underlying character of consistency by happening for the best reasons and that those in dreams don’t.
She does presuppose her criticism on principle of contradiction. She is claiming that PSR is a necessary quality that dreams don’t have for constructing reality. To her, the principle of contradiction has differentiated dreams and reality based on whether each possesses PSR. Although it’s basic, it is turned into this form in her argument: Dreams, or the reality, cannot always have and never have PSR, a necessary quality, simultaneously. Thus it will only be valid to define either dreams or the reality as only always possessing PSR, or never possessing PSR. It is crucial to her argument because it reduces the complexity of her project to differentiate the two into proving that dreams have no PSR and the reality always does. It makes her demonstration, that dreams don’t have PSR supported by the PSR-less dream examples of her riding the unicorn and teleporting, relevant and significant, so she successfully marks their fundamental difference. Therefore, it’s false to say dreams and reality are not differentiable if one admits to Chatelet’s illustration of their foundational difference.
I disagree with Chatelet on this point. Dreaming doesn’t have a consistent definition as science progresses because humans were never able to define it properly. If one assumes dreaming is a state when people become unaware of the physical reality, it’s possible that dreams can always possess PSR. This is the ideal of virtual reality. If certain measures are implemented, like scientists constantly stimulating the relevant brain regions in specific ways, to utilize reason to construct imaginative events when people are dreaming, the imagination they experience will always follow PSR and thus indifferentiable from reality. One flaw with my disagreement is that this consistent PSR-enabled state of dreaming can only be achieved artificially with future advances in neuroscience. Also, another flaw is that if I grant her premise that the definition of dream is being unaware and having a series of random events and thoughts, her argument is valid because her form of dreaming doesn’t contrive imaginative events with PSR. I cannot criticize her criticism’s internal logic if I grant all her premises. Nevertheless, I hold that advances in neuroscience will re-understand dreaming with empirical evidence and render her definition of dreams, her argument’s cornerstone premise, obsolete.
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