It is a well-established fact in various literatures in philosophy that Rene Descartes pioneered the modern philosophy tradition. He was the first one who veered away from philosophic tradition that uses Christian faith as the backbone of philosophizing such that of the minds of the medieval philosophers. Rene Descartes’ main philosophical thesis is derived from his famous approach of methodological skepticism or metaphysical doubt. In this regard, he seeks to arrive at a set of principles that will then lead him to prove the truth without generating any doubt.
According to his thesis, those things that can be doubted should not be considered as genuine knowledge. Consequently those that cannot be doubted in any respect can be the foundation of genuine knowledge. There is a single principle that he uses as the foundation of his philosophy namely the thought exists. Given that a thought cannot be separated from a any person who thinks, then, the thinking person exists. It is in this simplistic manner that we can come to know and, hence, verify our existence.
If a person doubts his existence and, since, nobody can deny the fact that doubting is just another act of thinking, then (by so doing the doubting), the person is in a way asserting his own existence. The very act of doubting your own existence is a proof that you exist. The nature of mind in his writings can be seen to have a distinct function which is to think. It is an indivisible, non-extended thing. But to better understand his propositions in reference to the mind, we must take into account his proposed mind and body problem. The non-thinking thing, he states, is the body.
It is a divisible, extended thing and a material substance that suggests spatial extendedness. The mind and body can so exist independently of each other and while any person can doubt of his own body, he can never doubt his own mind – the thinking thing. It is through apprehension of the necessary existence which is embodied in the clear and distinct idea of the supremely perfect being that we can so acquire knowledge of God. He holds his view that the necessary existence cannot be disconnected to the essence of the supremely perfect being (God) without any form of contradiction.
Moreover, the existence of God is indeed conspicuous and self-evident according to his thesis. The cause that contains much of a reality that the object of the idea has is God. The God put the idea of something that exists clearly and distinctly in our minds. The idea of something draws its reality from the cause. God’s existence is, for Descartes, the most basic mathematical truth. For any person to arrive at genuine knowledge, one has to know the distinction between impulses that lead one to believe and insights to necessary truths. The former implies that it cannot be doubted whereas the latter cannot be doubted at all.
The latter are the principles in our minds by which we acquire knowledge. We must also consider where the errors are coming from in our epistemological pursuit. God, according to him, can never lead people to deception and if only people will use their abilities that they received from God, there will be no chance for any faults. But since people do not easily stay in the narrow realm of truth because of the clashing interests of the will and intellect, people fail to recognize sound judgments. Senses should not be relied upon (in searching for a genuine knowledge); for they only serve confused notions of matter.
Sense perceptions are the results of the body’s influence in the mind not from the mind’s apprehension of the necessary characteristics of matters. Rene Descartes believes that people obtain knowledge through the apprehension of the necessary attributes of beings. The physical world, for Descartes, should be visualized as a complicated machine but not in the manner of using our bodily perceptions; rather by the way it is cognized in mathematical terms. The idea that philosophy should have an exact method like that of the natural science of first came from Franz Brentano.
Franz Brentano is known because of his works in philosophy of psychology and his reintroduction of the concept of intentionality. Unlike Rene Descartes, Brentano does not use the idea of God in his philosophy and his explanations concerning his theses. Intentionality, according to his writings, can be summed up into the relationship of mental phenomena (consciousness) and the physical phenomena, that is, every single mental phenomena or any psychological act has content and is directed towards an object (intentional object).
To signify the status of the object of thoughts in the mind, Franz Brentano uses the term “intentional inexistence”. The mental phenomenon has the capacity to be intentional, thus it can have an intentional object that the physical phenomenon does not have the ability of generating of. Physical phenomenon is deficit of the ability of generating original intentions but can assist in the progress of intentional relationship in a second-hand manner called derived intentionality.
On the other hand, Franz Brentano states that a mental phenomenon is not dependent on the actual existence of an object to be able to form a quasi-relation to it. It should be noted that a thing that does not exist literally in the physical world can be an intentional object of a mental phenomenon. There are criteria to differentiate mental phenomena from physical phenomena. The three most important among those are (1) the exclusive object of inner perception is the mental phenomena, (2) mental phenomena appear as unity and (3) they are directed to an object with a certain degree of intentionality.
Mental acts do not necessary have duration. When we are directed towards an object, the object does not vanish from our consciousness for it remains present but just in an altered state. On the contrary, this is not about the act of remembering per se but rather a kind of memory that keeps “what had been experienced” lively. In the epistemological sense, Franz Brentano states that all knowledge should be from direct experiences that entails the use of first person pronoun, “I”. However, this should not be confused in the idea that Brentano is upholding the standard of empirical science nowadays.
He is introducing here another of approach of performing psychology from an empirical standpoint. This means that those things that one directly experiences in inner perception must be described using the first-person point of view. This then inaugurates another brand of empiricism. Resembling the idea of Descartes, Brentano maintains the idea that perception is erroneous and it could not lead us to de facto existence of the perceived world which could be just an illusion. Moreover, he believes that we can find absolute certainty in our inner perception.
Just like the problem that we can see in Descartes disapproval of the use of bodily senses in approaching knowledge, we cannot deem Brentano’s ideas compatible to the tenets of natural science and its course of experimentations. Reality for Franz Brentano does not reside on the perceived world. As what has been mentioned above, the perceived world can only be an illusion and to properly combat this possible error in our judgment (if we only rely on our senses), we must put in higher regard our introspection of our inner perception.
Following Franz Brentano’s concept of intentionality, Edmund Husserl has formulated another version of the study of the structure of consciousness and its corresponding acts. There is a remarkably similar ideas perpetuating from Brentano’s ideas to that of Husserl notion of the consciousness or the mind. The consciousness acts intentionally toward an intentional object. Consciousness then is always directed toward something, whatever that something is. But then again, the concepts that these two philosophers individually present do not resemble each others in all aspects.
Edmund Husserl proposes that there is a need in pointing out the differences between the act of consciousness and the phenomena at which the act is intentionally directed. We must know the object-in-itself, transcendent to consciousness. Phenomenology does not displace the notion that objects are indeed real but it puts these objects under the method of “bracketing” just so to regard the object as it is and not merely that of the object’s features. It also seeks to pinpoint the constant features that define how objects are perceived.
In a phenomenological standpoint, the object is not regarded based on its external features, it is not its “aboutness” that is being scrutinized, it is the object-in-itself. It is not, therefore, in the business of phenomenology to assume the existence of anything. It is a discipline that means to describe the things in themselves. Edmund Husserl gives a little significance to the perennial metaphysical problem of setting up the whole foundation of material reality of what we constantly perceive. The task of a philosopher, for him, is to look at essences of things.
The knowledge of essences can only be attained by not letting the assumptions of an external world interfere in epistemological pursuit. This is “bracketing” that is entailed in the procedure called epoche. It is through constant act of varying the object in our imagination that we can then arrive at the essences of that object. Husserl’s notion of natural standpoint is marked by a certain belief that there are objects that materially exist and that their properties and characteristics are exhibited by them that we then perceive. He declares that mental and spiritual (mind) realities are not the same.
These two different concepts are independent of any kind of physical evidences. The above paragraph implies that the natural science, in Husserl’s philosophy, is also in a problematic seat just like the problem we see in Descartes and Brentano’s philosophy. The true knowledge is not attainable in the realm of empirical observation however there is rationality involved. The “brand” of reality that these three philosophers advertise is the reality that we cannot grasp in the physical world. Reality does not have a place in the realm of the senses.