^In philosophy, the view that you only ever perceive the world indirectly is called indirect perceptual realism.
It’s realism because the view doesn’t deny that there really are objects in the world that we’re perceiving; it just holds that whenever we perceive those objects in the world, it’s through the intermediary step of perceiving our experiences.
^One further argument one might point to in order to support the idea that our senses create our mental world is this: Different animals have different perceptual abilities. For example, bats and dolphins use sonar to navigate and to locate and track prey. Given this, it’s not implausible to suppose that different animals have experiences that feel very different.
P hilosopher Thomas Nagel has a celebrated essay entitled “What Is It like to Be a Bat?” in which he argues that the radically different way in which the bat takes in information about the world through sonar means that we humans actually have no way of knowing what it’s like to be a bat.
Theories of Knowledge LECTURE 7 does sense Perception support Knowledge?
^It’s easy, then, to appreciate the popularity of the view that the senses are an obstacle between us and the world—or, at the very least, to appreciate why you might see the senses as potentially unreliable informants. The problem with all of these arguments, however, is that they completely misrepresent what sense perception does.
^The arguments all share two features:
They suggest that what sense perception really gives us is a feeling or experience with a particular phenomenal quality and that this feeling or experience is what serves as evidence for some further belief about the world. But these phenomenal qualities are in our minds. They’re all feelings in the mind, even if they might seem to be located somewhere outside of our heads.
^Furthermore, the arguments also suggest that, because the feeling or experience is obviously distinct from the world, this introduces the possibility that the feeling or experience could actually be misleading us about the true nature of the world. In fact, part of the way that our senses mislead us is precisely by making us think that what is in our heads is actually in the world.
^The first of these features is more fundamental, then. It’s because what sense perception immediately gives us is an experience with its own
particular phenomenal quality—and because this experience is distinct from the world beyond it—that there is the possibility that the experience could be misleading us about the true nature of the world.
^So, the indirect perceptual realist picture of perception is one in which the primary function of the senses is to provide us with experiences with their own unique phenomenal qualities. Then, on the basis of these experiences, we infer the existence of objects in the world that correspond to those experiences or, at the very least, cause them.
^There are two main problems with this picture of perception—problems so central that they make it difficult to see how the indirect perceptual realist picture could be at all plausible.
^The first problem is that this picture of perception, according to which we infer the existence of objects in the world based on our sense experiences, doesn’t fit with our understanding of how the brain actually processes perceptual information.
^There are many stages of perceptual information processing in the brain before that information reaches a stage at which it can plausibly be called an experience. By the time it reaches that stage, however, it is no longer the sort of purely phenomenal experience that the indirect
Theories of Knowledge LECTURE 7 does sense Perception support Knowledge?
perceptual realist is talking about.
Instead, the sort of experience that results from those many earlier stages
of brain processing already contains a great many assumptions about external world objects.
I t’s hard to imagine a more phenomenal kind of experience than a pain experience. But even a pain experience cannot be understood as a pure phenomenon.
For one thing, you don’t experience a pain as being located somewhere in your mind. Rather, you
experience a pain as located somewhere in physical space—it’s a headache or backache.
For another thing, even the way we describe the type of pain generally
refers to the types of external world causes that lead to the
pain. It’s a “stabbing” pain or a
“pounding” pain.
This suggests that even with experiences as raw as
pains, by the time your brain has processed the
information that goes into the experience, the
experience itself already contains a great deal of
information.
Theories of Knowledge LECTURE 7 does sense Perception support Knowledge?
^This is obvious in the case of sense experience. For healthy perceivers, our visual experience, for example, comes to us with a great deal of
information already processed and ready for use, no inference on our part required.
C onsider the case of perceivers who are not healthy.
Certain brain injuries, resulting from tumors or trauma, can affect centers of the brain responsible for processing visual information and categorizing it according to the objects it contains. People with damage to these areas are said to suffer from visual agnosia.
Here’s one of the scenarios that researchers who study visual agnosia have observed.
First, the researchers present the sufferers of agnosia with pictures of common objects, such as pens, and ask them to sketch what they see. They’re able to do so with no difficulty. Then, researchers ask them to label the objects that they’ve drawn. The agnosics are unable to do this.
Furthermore, if you ask agnosics to define those
objects—”What are pens for?”—they are able to do that.
If perception simply involved inference, then this condition shouldn’t exist. Agnosics should easily be able to infer that the experiences they have correspond to these common, everyday objects and then to name those objects they see. Because they cannot do this, this suggests that the brain processes visual information prior to experience—so that healthy perceivers already enjoy experiences of the objects in their environment as experiences of those objects.
Theories of Knowledge LECTURE 7 does sense Perception support Knowledge?
^The second problem with indirect perceptual realism is that it sees the role of the senses as being able to provide us with phenomenal sensory experiences. But this is simply mistaken. Rather, the role of the senses is to provide us with information about the world around us.
^These two problems may seem bad enough for indirect perceptual realism, but there is an even bigger problem for the view, at least from our perspective: According to indirect perceptual realism, all we immediately perceive is our own perceptual experiences, rather than the objects that those experiences are about. But that’s a claim about the immediate objects of our experiences.
^The technical term for that subject matter is metaphysics—the study of the basic building blocks of reality and their relations to each other.
That’s not what we’re primarily concerned with. We’re interested in knowledge and how to get it. So, we’re interested in the building blocks of knowledge, such as beliefs, and what makes some beliefs count as knowledge.
^And the point now is that the beliefs we form on the basis of sense perception are not primarily beliefs about our experiences. They’re beliefs about phenomena in the world that we care about: people, places, and things.
^But indirect perceptual realism is a theory about the objects of our perceptual experiences, not about the objects of the beliefs based on those experiences. So, even if indirect perceptual realism were true, that would have no direct bearing on the relation between sense perception and knowledge.