Sense-perception has always been an interest of the philosophers. A prominent problem is the problem of perception, which is created by the ideas of illusion and hallucination: if it is possible to have this sort of error, how can perception be what we understand it to be?
When we reflect on the causal facts of perception, it leads to a problem. It’s not clear how perception can yield knowledge of the existence of physical things, considering that any perceptual experience can be caused without an external object stimulating our senses.
Representational Theory of Perception
René Descartes’ representational theory of perception states that our conscious experiences do not reflect the reality of things, rather, we merely see a miniature virtual reality replica of that world in a mental or internal representation.
In other words, we only discern our ideas or interpretations of objects in the world, due to a barrier between the mind and the existing world that prevents first-hand knowledge of anything beyond it.
This theory holds that our ideas come from our sensory perceptions of a real, material, external world, but that the direct object of perception is only a sensory perception that represents the external object. We have no immediate or direct access to things in the world, only to the world of our ideas.
In addition, ideas must be understood broadly to include all the contents of the mind, including perceptions, images, memories, concepts, beliefs, intentions, and decisions. These ideas serve as mental representations of things other than themselves. Much of what these ideas represent, they represent as “out there” or “external” to the mind containing them. It is in principle possible for ideas to represent these things correctly, but they may also be false and misleading.
Do We Get Knowledge From Our Senses?
Descartes, being a skeptic, doubts the possibility of being certain that our knowledge of things actually resemble, in any significant way, the objects to which they are supposed to correspond, since we only have knowledge of the representations of our perceptions. Using sensory perceptions is the only way we learn about the world, because we can’t get information from any other source.
Although our senses are fundamental, they’re not perfect. Sometimes they can delude us. This is evident when we cannot tell whether we are dreaming or not. When we’re dreaming, we have no correct sense of time or substance. We cannot tell whether we’re awake or in a dream. If our senses give us a reason to doubt them once, then we can’t trust or depend on them to provide us with knowledge.
Moreover, there’s nothing about our experiences that assure us that the content we’re learning is factual. We’re habituated to think that every physical object thing we see reflects its true nature, when in fact, we’re only seeing our mental representations of these objects.
Therefore, we can’t depend on our experiences for true knowledge either. This acts as a barrier that prevents us from constructing a solid foundation for our knowledge. Because what we know are just mental representations of things, they are beliefs that we hold true to ourselves. In other words, they are subjective and can be wrong.
Knowledge, on the other hand, requires some sort of certainty. To know something, is to know it with certainty and/or it itself certain. Without a firm foundation, the information we acquire will always be beliefs, rather than knowledge. This prevents us from having an objective view about the world, which could be problematic due to our inability to be certain about the actual reality of things. At the end of the day, we hold responsibility for our beliefs.