My finished final for Modern Philosophy, PHIL 220 at UNC.

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1.	Compare and contrast Descartes’ proof of the existence of material things with Berkeley’s proof of the existence of God. 

Berkeley’s proof of the existence of material things relies heavily on his worldview, now known as idealism, being the actual structure of our universe and the sentient things contained therein. His idealism, at this point in the Dialogues, is incomplete, as all that exists in this mind-space are ideas and spirits. Taking this worldview to be true, he rules out by case each possible origin of the idea of sensation, and concludes that the addition of an infinite, all-perceiving mind (God) is required to finally and fully match this idealistic worldview with reality. This contrasts with Descartes’ proof, even in class, which is a proof by contraction. Descartes has shown that God is no deceiver, that he (Descartes) has been instilled with the inclination to believe that the sensible properties he experiences originate from something external to him, and thus if these sensible properties did not originate from something external to him, then God would be a deceiver, therefore material things (things external to the meditator) must exist. 

This is a heavy contrast, as the requirements for Berkeley’s proof are in a great sense more substantial and less substantiated than Descartes’: Descartes’ proof requires that meditators follow along, and clearly and distinctly perceive a variety of truths, and from these truths and inferences, the existence of material things will emerge. This proof appears in many ways more grounded in certainty than Berkeley’s, as Berkeley requires that followers begin by abandoning a well-regarded worldview (that material things exist as entities separate from a perceiver; albeit, this abandonment is guided through a careful dialogue and assured to be in better accordance with Berkeley’s guiding principle: common sense), but also that followers adopt a proposed idealistic worldview in which there are only two entities: ideas and spirits. In a sense, the construction of this idea-space did not give much consideration to uniqueness: there could, for instance, be many more idealistic worldviews that satisfy Berkeley’s abandonment of real existence. This uniqueness is an essential property if the worldview to be used as the basis for further deductions.

A rather remarkable and interesting similarity is that Descartes’ argument for the existence of material objects relies on the existence of God, while Berkeley’s proof of the existence of God is derived from the necessity for an explanation of the apparent existence of material objects. This sort of suggests that these two notions: the existence of God and the existence of material things, are linked in terms of derivability. That is, there is some sort of codependence between the two, which could exist due to a certain idea of God that both Berkeley and Descartes hold. 

Another similarity which becomes apparent is that in order for both of these proofs to be possible, much setup had to be done. That is, these proofs are by no means standalone or easily extractable and come with the luggage of a lot of assumptions and intermediary conclusions of the works within which they each reside. 

2.	One might object to Berkeley’s theory because it seems to make it impossible for two people to see the same object. Explain this objection. What is Berkeley’s response to the objection? 

The grounds for this objection are as follows: two individuals are capable of an interaction in which they, for instance, exchange comments on some nearby sensible object. Some disagreement may arise as to the object’s hue or pigmentation, however, surely, it should not the case that the sensible object they are perceiving are in fact different. That is, they should be perceiving the same thing. Hylas says that surely if Philonous’ (Berkeley’s) principles are to mandate that no two individuals (finite spirits) could see the same thing, then his worldview would be “highly absurd”. 

We see that this is an apparent problem with Berkeley’s idealism proposal. In Berkeley’s idea-space, when a spirit perceives an object, the spirit conceives the idea (recall that this idea, in the case of what would conventionally be referred to as an “object”, is simply a collection of sensible traits bound together). However, now consider, in this idea-space, the case where two spirits are to encounter the “same” idea (again as before, an idea which would conventionally be a material object). Well, it is certainly not the case that the same idea exists in both the spirits (as the spirits are, certainly, distinct). That is, the same idea (existential identity “same”) may not exist in two locations, spirits, or any other state, if those states are not coincident. Thus, the two spirits must not be perceiving the same idea; there is no way one, the same, thing could be simultaneously present in two distinct things. Of course, it should be recognized that this question of “sameness” and identity could simply only be a valid concern in a materialistic worldview (and only appears to be a concern here because most are so accustomed to thinking in its terms), and no such consideration is reasonable in an idealistic space. 

Berkeley counters, explaining that the words one uses to describe the ideas in such a situation are, like all words, arbitrary, and have possibly misleading and misappropriated consequences. The question of whether or not the two spirits (people) perceive the “same” object, is surely and exclusively a matter of semantics. Essentially, this abstract notion of identity, which is primarily only the concern or consideration of philosophers, seems to have no bearing or little importance to what one should consider to be the “same”. Philonous uses the example of a house: the internals of the house are demolished and replaced with new internals, while the outside of the house, the “shell”, remains unchanged. Even if Hylas were to claim this construction were not the same house, while Philonous encouraged it was, they certainly would still “perfectly agree in [their] thoughts of the house” as it is considered in itself. Berkeley concludes that it is not he who must make this worldview agree with the abstract idea of identity, it is the abstract idea of identity whose worth that needs to be reconsidered. 

Moreover, Berkeley explains, materialism falls victim to the same non-issue. As materialists claim that when a person observes matter, they form their own idea of this matter from their immediate perceptions. Thus, when two minds attempts to tackle the inspection of an object, they are in fact not examining the “same” object, as each of them are examining their own perception-derived idea of that object. 

3.	Compare and contrast the attitudes of Descartes and Berkeley regarding commonsensical things believed by people untrained in philosophy and science. 
Both Berkeley and Descartes were concerned that the commonsense men and women, those not well trained in science and philosophy, would adopt principles of skepticism and doubt and, unguided and untrained, lose trust in areas such as God and religion. Berkeley goes so far as to open the Dialogues with this concern explicit: Hylas expresses worry when encountering Philonous in the garden that individuals will follow the teachings of those philosophers who proclaim notions of universal doubt and questioning and thus launch them into suspicion of “the most important [sacred] truths”. While Descartes did not explicitly express these concerns in the Meditations, it is certainly the case that Descartes had some reservations regarding skepticism directed at religion, as, similarly to Berkeley, there was concern that the commonsense meditators would become skeptical of religion. Despite Descartes’ effort, some of Descartes’ work, in fact, was banned by the Church as a precaution to ensure that individuals did not turn their skepticism toward religion and God. 

In the meditations, Descartes begins with universal doubt, which involves stripping away all existing notions and prior beliefs, including the eradication of commonsense knowledge. However, in rebuilding these, Descartes appeals to even untrained individuals’ intuition, or “clear and distinct perceptions”, which can certainly be considered “common sense”, as one would likely define “common sense” to be understanding common to all humans, and in fact clear and distinct perceptions are, according to Descartes, embedded in each human’s mind. This is a similarity to Berkeley, as Berkeley also relies heavily on commonsense principles in guiding his Dialogues, and considers the commonsense of people to be an ideal measure of validity. For instance, Philonous uses as a fulcrum to eject materialism the claim that Hylas’ materialistic viewpoint actually contains “more paradoxes and repugnances to Common Sense” than his idealistic view. 

Ultimately, however, Descartes’s meditations result in a worldview not much different from what he and his fellow meditators started with. Only more sure is the meditator that her beliefs are grounded in certainty. This contrasts with Berkeley, who concludes with a very different worldview. He begins by claiming that the common sense believed by the masses, and even many philosophers, is wrong. Later, he shows that in fact, common sense had been tricked into adhering to a worldview that really had not been demonstrated correct, and this revealing is guided by other basal common sense. Although, even with this worldview it can still be concluded that sensible things exist (they simply exist in a very different manner than previously thought) that is, they exist in God’s mind and are a collection of ideas rather than objects in space.  

Based on the meditations, it appears as though Descartes has more trust in the ability of those untrained in philosophy and science than does Berkeley. This can be seen as Descartes instructs the reader, specifically themselves to follow the method of the meditations, the first step of which is to apply universal doubt, a risky request, while Berkeley begins with a warning to ensure avoidance of skepticism involving “those which are most sacred [God and religion]”.

4.	Compare and contrast the attitudes of Descartes, Berkeley, and Hume regarding skeptical arguments and skepticism. 

Descartes fully embraces skepticism, as it is the the driving force behind the primary step of the meditations. Without skepticism about all that the meditator has come to believe they know, Descartes believes they would be in no position to achieve any perfect knowledge. Thus, the entire premise, the most crucial point of the meditations, is actually to be a “skeptic”. Even the use of Berkeley’s definition (“one who denies the reality of sensible things, or professes of the greatest ignorance of them”) seems somewhat fitting during the first stage, upon which even very minuscule doubts warrant the abandonment of well-evidenced principles. Descartes begins with denying what most reasonable individual would consider as the most sensible things, in order to achieve a more sure understanding of the universe, even at first the denial of self. 

From this, we see that Descartes embraces doubt far more than Berkeley, who is in many ways weary of being called a skeptic and ensures that throughout his Dialogues, a skeptic is well-defined and only his opponent in argument is ever classified as such. At all costs, throughout the Dialogues, Berkeley insists that his (Philonous’) argument is guided by common sense (we can equivalently think of a skeptic as one who has no regard for common sense), and that nothing more is required to follow his argument. Moreover, that his argument contains fewer “repugnances to Common Sense” than the popular alternative that he is attempting to overcome: materialism. 

However, it is important to note that Berkeley and Descartes’ share (even if concealed) an employment of a skeptical method: Berkeley’s worldview of idealism was likely generated by skepticism, although he does not reveal or consider this directly in the Dialogues. That is, Berkeley surely must have started with a materialistic view of the world, similar to Hylas, and only arrived at his conclusion of idealism after first questioning the, to him at one time, “common sense” principles that he had taken for granted. The difference between Descartes and Berkeley being, Berkeley mostly focuses on the construction of his idealism via “common sense” in his Dialogues rather than the deconstruction of what most would have considered to be common sensical (and consequently, skeptic-rendering); unlike Descartes, he is not momentarily lost in certainty in nothing, having doubted all that exists. 

Hume actually directly considers skepticism in his “Enquiry Concerning Human Understanding”, with even a formal classification. Hume is accepting of Descartes' skepticism, but only to a moderate degree: Hume does not believe there exists such a first principle that is so self-evident that it may be used as an immaculate starting point from which the rest of knowledge may be reasoned; he also believes that even if such a point existed, one couldn’t advance at all beyond this first point because they have no capacity to be sure that the deductions they make are sound. The more moderate degree of skepticism that Hume is accepting of has strong hints of Descartes’ skepticism: start with clear and self-evident principles, progress cautiously and constantly check conclusions and consequences of the deductions made. 

The skepticism that Hume seems to prefer is in a sense less “prior” than Descartes’ (which is more of a bottom-up approach). Rather than building up knowledge, Hume prefers to be skeptical about our existing, common conclusions and judgements, and ensure a solid basis for each. This is, in essence, a top-down approach, which is more similar to Berkeley’s reasoning his Dialogues.