Following is the compare/contrast of two philosophers on a single issue.
1.      Aristotle and Plato on the existence of Universals.

Aristotle and Plato on the existence of UniversalsPlato believes that there is a great difference between apparent and real world, one can only get a small knowledge of apparent world but can have perfect knowledge of real world by Philosophical investigations. Plato believes that the essence or common characteristics held by all things of same type is its universal. The Universals are real as they cannot be changed so they are not in this world because this world is constantly changing. They are in a transcendental world. All the things of the world are copies of their respective Universals.The universal of “Absolute Good” is on the top of the arrangement of all Universals and thus all Universals feel attraction toward it. By this, Plato actually told that Universe is not purposeless as it is moving toward Absolute Good “its purpose”. Plato beautifully explains the difference between the real world(of universals) and apparent world (the material world),by his famous example of Cave.


AristotlePlato’s student Aristotle disagreed with his teacher. Aristotle changed Plato’s Universals into “formal causes”, the essences of individual things. Aristotle argues that if Universals are essence of all the things then how it is possible that essence of a thing has a separate transcendental existence outer then that thing. So, Universal are not in a world other than our material world. He said that Universals are the forms the thing must hold so that it can be credited as a specific thing. Thus instead of idealized way of thinking Aristotle adopted the scientific research method.

Consider an example of a particular Palm tree. This is a member of a species and it has much in common with other Palm trees, past, present and future. Its universal, its palmness, is a part of it. A biologist can study Palm trees and learn about palmness and more generally the intelligible order within the sensible world. Thus Aristotle came toward sensible world and was an empiricist. He used the induction method for his scientific research.


2. Locke and Berkeley on Sense Data



LockeLocke said that individuals are born without built-in mental content and they get knowledge from experiences and perceptions. This theory is called Tabula rasa meaning Blank Slate. For example when I was born I was not capable of knowing things. Then I started getting knowledge by my experiences. I saw a table. Then by comparing it with other visible objects, I was able of knowing that the chair has a specific color. By touching it I got the idea of its hardness. And when I became tall enough, I started sitting on it. And today, I have a complete knowledge of Chair. Individuals get all their knowledge in the same manner by their sense data from matter. If there is no sense data then there will be no knowledge. A blind can’t have an idea of appearance of things as he is unable to use the sense data through his eyes. Locke said that Ideas are just the reflections of the things on mind.


Locke and Berkeley on Sense DataAccording to the Berkeley, all the things surrounding us are nothing but our ideas. Sensible things have no other existence then our perceptions. Our mind creates the meaning in the things and then we name that thing. If there is no mind or in better words no perceiver there would be no object. For example, ifI wouldn’t there to perceive a chair, then there will be no chair. Because “Chair”, is an object having meaning and purpose, which are created by my mind. And I am not there or no perceiver or mind is there, then there would be no meaning in Chair. So chair will exist on my perception. If no one is there then the things exist because God is there as a perceiver. So, according to Berkeley, sense data is not important but perceiver is important as perceiver’s mind creates the ideas and chair is no more than a collection of ideas like having color, hardness and could be used as sitting tool.

3. Hume and Kant on the nature of self



Hume and nature of selfHume think that we traditionally divides the perceptions deducted from incidents in such a manner that as they have a relation like cause and effect. And then we think that the joining power that joins the different perceptions and creates the result is self. But that’s our error. Incidents can happen by own. Like, we can’t say that only boiling will make the water hot. Also we interlink the perceptions in spatial or temporal order and then we think that binding power of the perceptions is self. But if any self can exist, then that can only exist is in the very present moment of awareness. As when we even try to recall past or to predict future, we at same time are actually in present.


KantFor Kant, then, the self is an entity that has the specific task of unifying our experience.  That our experience is in fact the very evidence we need to accept the existence not only of a self but of a self which values the relationships of the perceptions it receives and orders its actions in accord with those regularities.  We plan our meals, engage in educational experiences, enjoy associations with other humans, etc., on the basis of this regularity.


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