Republic, Plato's allegory of the cave is included as a way of describing the path from ignorance to enlightenment. Plato describes a group of people chained inside a cave, who cannot see anything except for the shadows cast on the wall in front of them by other figures. This represents humanity prior to the development of philosophy, because viewing these shadows dancing on a wall is closest people had previously gotten to real knowledge, which is represented in the allegory as the sun itself, rather than the paltry light offered by the fire.
For Plato, Forms are the essential, real things which human beings may only experience through thought or imperfect representations in physical objects. Because Forms are abstract, universal notions, they reveal the reason behind the similarities and differences among objects, because these objects are merely imperfect representations of a perfect, universalized Form, which is definable only by the features which mark is at distinct from any other Form.
3. Aristotle took a slightly different approach to the theory of the Forms, offering a different interpretation of the connection between objects and Forms as well as the role of the soul. For example, Aristotle rejects Plato's ideas about reincarnation by stating that the soul is merely an effective term for describing what distinguishes a living person from the sum of their physical parts. For Aristotle, the theory is further expanded by adding the idea of matter, which a term which attempts to describe a kind of physical reality that offers a bridge between the abstract world of the Forms and the intelligible world of physical objects.
4. Aristotle describes for causes which explain that explain changes in the world. The first is the material cause, which is the particular matter from which an object or objects are made, followed by the formal cause, which is the shape that matter is in as a representation of an abstract, fundamental form, then moving cause, which is the reason for the initial change, and the final cause, which is a description of the possible end state. In the case of your dog chasing my cat, one could say that the animals' material and formal causes grant the physical ability to chase after one another as well as the inclination, with the moving cause characterized as dogs' tendency to chase animals, and the final cause being the possibility that the dog will catch the cat.
5. According to Descartes, the idea that "I can know for certain that there's a table in the room because I can see and feel it -- and all the other people in the room say that they can see and feel it too" is not valid because of the possibility that I, and everyone else, are being deceived. Descartes would not be convinced by this argument, because all the statement reveals is that people might be in disagreement regarding a deception, and furthermore, those perceived people might themselves be part of the deception.
6. Descartes suggests that the only thing one need not, and cannot, doubt is the notion of "I" itself, because the act of doubting something indicates that there is a "I" to do the doubting. Descartes cannot' reduce or discredit perception and experience to any more of a fundamental point as this, because even if everything one experiences is a deception and removed from reality, there still remains the "I" which thinks and engages with that experience as a separate reasoning force.
7. In his Sixth Meditation, Descartes argues for the existence of a material world outside his body essentially by suggesting that God is capable of making it (after having "proven" the existence of God earlier on). While one cannot know everything about the objects in this material world for certain, According to Descartes one can know that they are distinct from the human mind (once again, simply because God can make things like this).
8. Samuel Johnson's refutation of Berkeley's theory of material things by kicking a rock is enjoyable but does not actually function as a refutation of Berkeley's theory, because it does not challenge Berkeley's claim that these objects, including the foot and the rock, only exist in as much as they are ideas which the mind brings into existence by perceiving them. This is not to suggest that Berkeley's idea is unassailable, but rather that Johnson's critique does not address the underlying problems with it.
9. Berkeley would disagree with Descartes' claim that God is not a deceiver, which underlines his assumption that there are material things outside of the mind, because Berkeley claims that the "imaginary" sensations of the material world which are perceived are generated by God as a means of informing the individual consciousness. Descartes and Berkeley are actually in general agreement regarding the role of God, it is just that they propose slightly different means by which God creates and orders the universe (but both means produce largely the same results).
10. According to Locke, if you were inhabited by the same immaterial, Platonic soul as Alexander the Great, that would not make you the same person, because Locke views the self as constructed through experience and the associations which develop in the mind over time. As the Platonic soul is stripped of these memories and experiences, it would no longer represent Alexander the Great in any meaningful way in relation to Locke's theory of the self.
11. Hume's Philo would likely obviate Descartes' claims regarding the apparent conflict between individual's propensity for mistakes and God's apparent perfection by suggesting that Descartes' argument is irrelevant. This is because in Philo's mind, the very propensity for mistake that Descartes is attempting to reconcile with his idea of God would serve to disqualify any description of God as inherently flawed, thus removing the impetus for Descartes' argument in the first place.
12. There are two premises in Berkeley's argument regarding the possibility of God's influence on sense-perception that Hume would disagree with, both having to do with the ability to instigate or generate ideas in the mind. Berkeley states that no material object or idea can cause ideas to occur in the mind, but he does not offer a reasonable explanation as to why this must be the case, whereas Hume would suggest that it is entirely possible for material objects and ideas to generate new ideas.
13. Hume does not actually claim that one could know for certain that he or she is standing in front of a table, but rather suggests that one can know for certain how much of previous experience suggests that there is a table present. Thus, while Berkeley descriptions of sense as the assumption that these material objects will continue should they continue to be perceived is slightly off in Hume's estimation, it does at least describe how Hume views the construction of the self and its view of the material world.
14. Even if someone reports a miraculous experience supported by numerous simultaneous eyewitness accounts, Hume would not change his opinion regarding the unlikelihood of miracles, because this report does not fundamentally challenge any of his criticisms, such as the fact that people can lie, or can be deceived (even in groups). Even if the event seemed undeniably a supernatural abrogation of the usual rules (such as an eraser that turns into a dove and flies away), for Hume it would still not be productive to call this a miracle until all other possibilities have been rejected.
15. Much more than Plato, Descartes, and Berkeley, Hume would agree with the statement "we can learn a lot of truths about reality by means of sense-perception" because he alone does not attempt to locate sense-perception and the material world to a lower plane than that of ideas or thought. Berkeley and Descartes would agree somewhat less, although they both do suggest that sense-perception can lead one to certain knowledge about the nature of God. For Plato, sense perception, while offering some small insight into reality, can only ever get as close as shadows on a cave wall.
16. Perhaps more than other philosophers, Plato would agree with the statement "we can learn a lot of truths about reality by means of the understanding" because it essentially conforms to his ideas about how one accesses true reality. Descartes would also agree, but Hume and Kant would put far less emphasis on this by acknowledging the importance of other factors on reason, and the impossibility of genuine reasoning.
17. Plato, Descartes, and Berkeley would all agree that "bodies and souls (or minds) can exist apart from one another," because despite their differences, these three have all posited some kind of soul or mind functioning independently of the body, whether that is because the soul is part of the higher plane of Forms, or because sense-perception cannot be trusted, or because the physical world is not real at all, but merely exists in the perceiving. Aristotle and Hume would disagree but for slightly…