In his Meditations on First Philosophy René Descartes states that “All that up to the present time I have accepted as most true and certain I have learned either from the senses or through the senses, but it is sometimes proved to me that these senses are deceptive, and it is wiser not to trust entirely to anything by which we have once been deceived.”
For the rational man or woman, the ontological dilemma immediately comes to mind: does the fallibility of the senses then mean that we can never really know what is real or true?
This “question of reality” stems from the age-old epistemological debate which has persisted within the field of philosophy with the aim of understanding the nature and source of human knowledge. There are two main schools of thought that pertain to this issue: rationalism and empiricism. Rationalists are of the belief that the primary source of our knowledge is our reason, as opposed to empiricists, who claim that the primary source of our knowledge is our sense-experience. Although these two approaches are different in many ways, both have made developments over the centuries in their attempts to better understand the concepts of reality and existence.
Aristotle, a 4th-century BC Greek empiricist, claimed that “The senses are gateways to the intelligence. There is nothing in the intelligence which did not first pass through the senses.” Most of his work on metaphysics emphasized trying to explain the meaning of “the real” or “the true” substance. His teacher Plato, a Greek rationalist, had put forward the “Theory of Forms” in which he claimed that there was a metaphysical realm called the World of Forms which contained abstract objects (Forms) which are “universal”, unchanging and which self-predicate objects in the physical world. Plato believed that objects of the physical world are error-prone and defective as they are mere imitations of the Forms — which are real and perfect — from which these very objects derive their names and corresponding qualities. Plato explained this theory using his Allegory of the Cave in which he emphasized his distrust for “illusions” and “mere perceptions”. For Plato, sensory data (which he described as doxa or opinion) held less truth than the Forms (which he describes as episteme or knowledge).
His best student Aristotle was a big critic of the Theory of Forms. Aristotle had proposed the idea of the Four Causes in which he attributed movement and change as the prime explanation for existence. Aristotle argued that the Forms do not address this issue as it is not within their nature to move or cause change. Aristotle went further to contend that the Forms cannot at all explain the existence of particular objects because of a logical paradox in their theory. Plato claims that the Forms cannot exist in the particulars that “partake” in those Forms, but from a logical standpoint the substance of a particular thing cannot be separate from the thing itself: Plato fails to establish a sound relationship between Forms and particulars. Aristotle’s realism is instead based on the concept of the fusion of Mind (Form) and Matter (substance) and argues that the existence of universals (the reality) is dependent on the particulars they exemplify. Aristotle’s empiricist view regards senses as the primary tools for gaining the knowledge of the universe and, hence, manages to explain substance or “essence of reality” as an entity dependent on the human body itself as opposed to a soul having descended from an independent metaphysical realm. This seems to imply that an objective sense of reality cannot exist due to the lack of any empirical connection between our bodies and a larger reality.
René Descartes, a 17th-century French rationalist, argued (contrary to Aristotle) in his First Meditation that the senses are not to be trusted as they can often be tricked (giving the example of simple illusions such as melting candle wax) and can lead us astray. Descartes then embarked on a journey to discover the ultimate truth or certainty on which he aimed to establish his whole philosophy. His search led him to his famous phrase cogito ergo sum: I think, therefore I am. In his Second Meditation, Descartes went on to further explain this statement. He says that if our distrust in our senses meant we could doubt every sensory belief we have we would also have to let go of the belief that we have our own bodies each equipped with sense organs. The question would then arise, “Does that mean I don’t exist?” Descartes argues that the answer is “No.” The mere conviction or belief that “I do not exist” requires an “I” to be convinced, the thinking entity or our rational self. Therefore, the proposition “I exist” is necessarily true when it is conceived in the mind. It then naturally follows that the self is an immaterial substance whose essence is thought. Descartes used this reasoning to argue that humans could, in fact, perceive the nature of reality purely through intellectual perception.
John Locke, a 17th-century empiricist, criticized Descartes’s argument of a thinking being (as evidence for the perception of an independent reality) for relying heavily on the rationalist view that knowledge was somehow innate — a theory more commonly known as nativism. In An Essay Concerning Human Understanding Locke put forward the idea of tabula rasa or blank slate: the mind initially lacks all mental content and it is with the “senses” and the “faculties” that humans are able to gain knowledge of their surroundings and fill that slate over time. Locke is considered to be an adherent of representational realism— an independent reality exists but our perceptions of it are merely inaccurate representations— which is evident from his proposal of the primary-secondary quality distinction. He claimed that the human perception of an object is a “complex idea” made up of many “simple ideas” which are sensory data our mind receives about individual properties of the object in question. These properties or qualities, Locke states, can be divided into two distinct categories: primary and secondary. Primary qualities are those which can be considered to be independent of the observer such as motion, extension, shape, solidity and number. These are intrinsic properties of the object which can be measured with great certainty and do not require subjective judgements to be understood. Secondary qualities, on the other hand, are dependent on the observer such as colour, taste, smell, sound etc. They tend to create sensations in the observer that cannot be empirically quantified. Locke argued that this difference in qualities automatically translated into a difference in perceptions of reality; there is a reality independent of our observations but there is no way of knowing exactly what that reality is as our senses that experience the secondary qualities give conflicting (and, hence, fallible) perceptions.
George Berkeley, an 18th-century British empiricist, took the empiricist argument to the very extreme with his subjective idealism — a doctrine that denies the knowability of an objective reality and makes the immaterialist claim that matter has no objective existence outside of our perception. Berkeley felt that Locke’s Essay did not carry the principles of empiricism far enough. He used his criticism of Locke’s primary-secondary distinction theory to showcase his own views. He argued that once an object is stripped entirely of its secondary qualities it becomes very problematic to assign any meaning to that object. A mind-independent object, one free of all secondary qualities, still requires to be specified in place and time so that it can be more than just imagination. Many realists forget that place and time are themselves subjective to our experience of them. Furthermore, primary qualities cannot be conceived without the conception of corresponding secondary qualities. For example, one cannot come to the conclusion about the extension or movement of an object without perceiving a change in that object’s colour or shape. Primary and secondary qualities are, hence, logically dependent on one another and so the distinction argument breaks down along with the idea that matter has some sort of objective existence outside of the human mind. Material existence (reality) is entirely dependent on human perception. Berkeley summarised this notion as esse est percipi: to be is to be perceived.
18th-century German philosopher Immanuel Kant is considered to be one of the most influential people in the history of Western philosophy as his work managed to quite beautifully combine both the approaches of rationalism and empiricism. While presenting careful criticism of both views he was also able to have them incorporated into his own take on the epistemological debate. This work of his collectively became known as transcendental idealism. Kant claimed in his Critique of Pure Reason that both rationalists and empiricists considered the mind to be passive as it either finds itself possessing innate knowledge ready for analysis or it receives ideas about objects through the senses onto a blank slate. Kant’s argument follows that the mind provides a systematic structuring to the scrambled bits of experience it gets access to; the mind gets data from the senses which it then combines into a complex representation. Kant called this process the “synthesis” of ideas. However, for Kant, the idea of synthesis required the presupposition that a rational activity is being taken place by a single subject that is, in a way, supervising the combining operation. In order to synthesize sensory input into meaningful experiences, we need to possess a distinctive self-awareness. Kant argues that when joining these pieces of experiential information together, we are aware of ourselves as the agent of a temporarily extended activity. This reasoning suggests that it is our own conscious self that makes experience possible in the first place. Kant claims that this substantiates the belief that our mind exists in some form of reality.
Kant’s idealism, however, greatly differs from that of Descartes which Kant regarded as “problematic”. Kant claimed that the consciousness of one’s own existence proved the existence of objects in space outside one’s self. Therefore, as opposed to Descartes’s belief in the independent existence of self from the surroundings, Kant argues that the self cannot exist independently of the world it perceives. Kant’s phenomenalism differed from that of Berkeley, which Kant described as “dogmatic”, in the sense that Kant did not deny the existence of objects outside of human observation, unlike Berkeley who was a clear immaterialist. Despite this difference, Kant was still a proponent of a somewhat subjective form of reality. Kant argues that space and time are mere mechanisms through which humans perceive and understand the world around them. Human perception is analogous to wearing filtered glasses. We can only see one particular colour through them due to the physical limitation of the filters. If the filters were, say, green, the actual world may not be green at all; it could be red, blue, yellow or maybe even devoid of any kind of pigment. If we were to take the glasses off, however, we would be able to see the true colour, but that is physically impossible as it would strip our visual senses altogether. Our complete understanding of the world is, therefore, through those filtered glasses. Due to the fact that we can never escape the shackles of our own limited experience and fallible senses, we can never really know what its true features are. Kant comes to the conclusion that humans only have access to the “phenomenal world” of experience and can never tap into the “noumenal world” or the world as it is in itself — the reality. This is essentially the crux of Kant’s transcendental idealism.
A more contemporary approach to idealism revolves around the concept of “quantum idealism” which aims to argue in favour of an idealistic or phenomenalist view with the help of quantum mechanics. This notion of science and philosophy going hand-in-hand is widely debated in both the scientific and philosophical communities. However, areas where the two tend to seemingly overlap is still quite an interesting phenomenon even if it comes with its own set of problems. Quantum mechanics focuses on the interactions within the atomic realm and provides us with effective methodologies to make accurate observations. Most research in the field of quantum physics takes into account the limitations and errors of the scientific procedure of measurement and observation. Many quantum idealists like to bring up Heisenberg’s Uncertainty Principle which states that, “The more precisely you measure a particle’s position in space, the less precisely you can measure its momentum.” This implies that particles do not assume a fixed position or velocity in space until they are observed. Although this may seem quite absurd and counter-intuitive at first glance, it does somewhat correspond to the concept of phenomenalism as our ability to observe said particle directly affects the net result of the experiment itself. There are also the quantum physics concepts of superpositions and wave-functions which explain how an elementary particle can exist in more than one state at the same time until its actual state is ascertained by our conscious observation. The fact that the particle is a certain way is entirely dependent on the observer and their senses (heightened only by advanced scientific instruments); the true state remains a mystery.
In short, the strong empirical approaches utilized by philosophers such as Aristotle, Berkeley and Kant in addressing the ontological dilemma help substantiate the conclusion that the fallibility of our senses is indeed a hindrance to our perception of the universe. Reality, as we know it, is nothing more than our mind’s continuous struggle to piece together incoming data using whatever tools and abilities it has been restricted to. Our physical limitations, hence, render it seemingly impossible for us to ever “really” know whether something is real or true.
