Descartes has a dream, and when he wakes up he has a problem in front of him. He wants to know how to tell the dream world and the real world apart. This is what Descartes sets to do and derive a conclusion about the external world and how man perceives it. This leads ultimately to the study of self. Without knowing self Descartes can never conclude how the self differentiates between the dream world and the real world. When he begins thinking on this matter Descartes plans to remove all the things from his external world. He begins doubting the existence of the chair in front of him, the table, the book, everything. He looks at the real world and doubts everything because he thinks that he cannot tell if he is in the real world or the dream world. So he begins doubting all the apparent things around him. This makes him conclude one thing; one and the most important thing that is taken as a milestone in modern philosophy. He derives that he can doubt the existence of everything except that he doubts. He cannot doubt that he is doubting; which means some sort of ‘I’ exists that doubts. By rationality and reason Descartes has concluded self’s existence. Existence of self for Descartes becomes necessary because the self thinks. Because I am the one doubting, it rationally means that all can be doubted except me. Now the self that logically exists for Descartes is the thinking element and not the body. Self is reason or consciousness. This is where Descartes rationalism turns to idealism. He replaces human matter and puts reason there. For Descartes self is limited to this extent that it can know of nothing but its own existence. It is a prisoner of itself and the external world may just be an illusion to self. There is nothing self can do to justify the existence of the external world. However, one possible thing is to justify the external world as it exists to me by a God. This God can bring in me the illusion of an external world. However, the world has flaws and the good being I perceive would not create in me illusions of something. Hence, maybe god did not create in me the illusion of an outside world but Satan did. But the external world has so many relationships amongst things and order in nature which cannot be the work of Satan or a malignant being. Hence, the world is my last alternative that might have created the illusion of it in me. Descartes says that I have an idea of a God, an omnipotent, all-knowing, higher authority. But I am so weak and full of doubts I cannot cause something this powerful. Maybe God caused in me the idea of himself. I possess the idea of the perfect entity therefore it exists. Hence, through self Descartes proves God and he proves that the external world is present. For Descartes his ego and his soul are different from his body. His ego is linked to all other substances in natre because his ego or self is what justifies their existence for you. Descartes thinks that there needs to be a connection between thought and extension. Reason alone cannot produce ideas which means that self is not sufficient for ideas. There needs to be a substance of thought and a substance of extension and at their base is the presence of the substance of infinity (God). God can make the ideas of self clear and distinct so they become innate ideas that are true and reflect reality.
Next comes Locke, a British philosopher and politician. He is not just a rationalist but an empiricist which means that his origin of knowledge is experience. Locke rejects Descartes innate ideas and believes that ideas are representations or perceptions. He is of the view that soul is clear and empty at birth. Ideas come from our experience and that is what fills the soul. These ideas come into us through our sense apparatus and they come in the form of sense data. He is a political man unlike Descartes. The sense data can be categorized and Locke does that by putting them in the primary qualities which have objective validities. These include number, figure, solidity, motion that belong to the body and cannot be separated from the body. Secondly, there are the secondary qualities that include colour, odour, taste, temperature and all the things that man perceives differently. Their validity is subjective. It will be different for different people. This was Locke’s way of justifying why the ‘self’ me takes something as rectangular whereas from where the ‘self’ you is standing it may look square. Locke is taking further Descartes study and changing in to fit better to the subjectivity of human beings. As it is, Descartes has completely neglected the perceptions that are different with respect to people. Locke proceeds and he thinks memory is the basis of every idea. There are simple ideas in brains that form impressions that are associated with other ideas and complex ideas are formed. Notion of substances and relations amongst things are complex ideas that form from minds activity. Locke rejects thinking, learning or knowledge. The self Locke has perceived is one with complex ideas, perceptions and things being perceived by different sense data. This is how ideas form when it comes to Locke.
Berkeley continues Locke’s thinking and arrives at the most extreme form of idealism. Berkeley rejects the notion of generalizing things and takes subjectivity of self even higher. He does not believe in universal concepts of anything. For Berkeley primary qualities are as subjective as secondary. Here he completely rejects Locke’s idea. He thinks extension is an idea and so is colour. They are all contents of the self and they are perceptions. They are from self and there is no material world says Berkeley. It’s just self and the delusion that there is an external world. Rationally an external world can never be proven. Hence there isn’t one. There is an intuitive certainty of self (he is agreeing with Descartes) but there is nothing else except self. Berkeley also rejects that there are any causes and effects. He believes that there are just relations between ideas that we perceive. There are not causes or effects. God made the self by making these ideas in the self. Hence God caused us and we cause the material world through God.
Hume takes empiricism even further, so far that it becomes sensationalism. He takes it further from Berkley. According to Hume ideas are all necessarily based on intuitive impressions. They are based on direct copied of impressions. Perceptions give us what we use to give attributes to substances. Therefore we do not know the impressions; we just have tools to attribute them. Notion of the substance is only perceivable after the associative process in self. Hume says ego is a bundle of perceptions which means this is how he defines self; a bundle of perceptions of consciousness. Ego has no reality it is just an imagination. Therefore Hume, in his theory has gone far from Berkeley. He thinks that it is not just that the external world is a delusion but I am a delusion too. This is where scepticism starts. He does not even agree with Descartes with ‘I doubt therefore I am.’ He is even suspecting that I am. Something Descartes said was not to be questioned at all. Hume says self has perceptions and self is a perception; a bundle of it. It perceives other things by giving these perceptions attributes. He doubts causal relation, the external world ad he doubts self. When it comes to Hume science ceases to exist. For causal relation he says that no matter how many times X occurs after Y we cannot logically infer that Y causes X. We cannot prove causal relation and therefore. Hume has deducted that knowledge cannot lead to metaphysical truth. Therefore alls science can go down the drain. Reality becomes perception and ideas and therefore subjective. The self for Hume is a bundle of perception conceiving one after another so rapidly that it is not understandable.
I remember from my class of PHIl101 that Kant thought Hume woke him up from his dogmatic slumber. Hume criticised everything and proved science and maths false. This brought Immanuel Kant to rescue. For Descartes self is God creating unity in thought and extension and the formation of innate ideas but for Kant self is transcendental. Being is not in the body for Kant, it is out of the body and it is out of the qualities of the body. Body and the qualities are rooted in the self but the self does not mingle with them. Kant uses knowledge to bridge self and material things together. What Kant says is that there is nothing but my ideas and the knowledge of my ideas. These ideas are what I perceive through self. Kant does not reject knowledge like Hume did. Things I see are not external; a part of them is joined to me through my ideas. My ideas are what connect me and the external world. Now the ideas that are in me come through the sensory apparatus. We all have the same apparatus and so we have same ideas. This means there is a unity. This he calls the Transcendental Unity of Apperception. Now Kant explains his theory by asking us to eliminate everything from the world but the only thing you won’t be able to eliminate from your mind is going to be space. Space or location always remains. The other thing you will never be able to remove is time. It cannot stop no matter what. These things make Kant’s perception for him. They are not in the world but they are a part of the self. The spatial temporal world is inside us and not outside. All things are in themselves and a part of them in is us. Our minds possess the order, unity to sequence the raw sensations. The part that is in them cannot cause the unity. But the spatial temporal part that is in us is what makes the unity. It sets all things right. It sets science right. There is a unity on experience rationally proven and this transcendental unity of experience is what makes science, cause and effect, stand. Hence, Kant solves the problem of self perceiving the world