PHIL2606: Knowledge, Reason and Action
Week 11: Sources of Knowledge
Sources of knowledge
Let's set aside skeptical concerns and take it that we do have at least some knowledge, and can get more of it. This raises a question: how do we get knowledge? (Is this a philosophical question?)
Suppose that a certain bottle is white but I do not yet know that it is. Here are some ways that I might come to know:
- By perception (e.g. by seeing that it is white).
- By testimony (i.e. by being told that it is white).
- By reason. (e.g. deducing that it is white, or inferring (to the best explanation) that it is white).
- By memory (i.e. remembering that it is white).
Here are some other ways of getting knowledge (although perhaps not knowledge that the bottle is white):
- By introspection (e.g. of our mental and bodily states).
- By intuition (e.g. that Smith in the Gettier case does not have knowledge).
What about the following - how do we get knowledge of these?:
- Mathematical truths
- Modal truths
- Truths about the past
- Truths about the future
- Moral truths
- Truths about other people's minds
The following are not ways to get knowledge:
Are there any truths that we have no way of getting to know? There is good reason to think yes.
It is natural to think that we don't know everything - that there are some truths that we do not know. Suppose that is right. Let p be one of them. Then we have the following truth:
p': p is an unknown truth
The curious thing is that p' is an unknowable truth - it is impossible for us to come to know p'. Not just practically impossible, but logically impossible.
So we have the following result: If there are unknown truths then there are unknowable truths. If there are actually some unknown truths (as seems very likely), then we have this result: There are some unknowable truths.
Things, of course, are not as simple as they might at first seem.
Testimony. We can get to know p by being told p (via utterances, postings on blogs, newspaper articles, books, tv, radio, cds, etc). But only if the person who tells us knows p. Are there any other conditions? Do we have to know that the person knows?
Memory. Is this a source of knowledge at all? What do we remember? Past events, present facts (someone’s phone number), future events (the date of the 2012 olympics)(?). We say that memory is fallible, but what does this mean? That we can remember things that did not happen? Or that we can seem to remember things without actually remembering them? In that case, is it misleading to say that memory is fallible? How does remembering p differ from perceiving p?
Introspection. Is this different from perception, or just a special case?
Intuition. Is this a source of knowledge? If I have an intuition that Smith does not know that the man who will get the job has ten coins in his pocket, is this knowledge that he does not know? Or does it give me knowledge of something else?
Deduction. The idea is this: If I know p, and I know that p entails q, then I can, on this basis, come to know q. What reason do we have for thinking that this is right? It seems that appealing to deduction to justify this belief just begs the question. Do we just take it on faith?
Induction. Example: These ten crows are black, therefore all crows are black. What reason do we have for thinking that this is an ok form of reasoning? If we argue by induction that it's ok then we just beg the question. We also have a couple of paradoxes: the paradox of the ravens; the grue paradox.
Perception as a source of knowledge
We will spend some time considering in detail the question:
EQ: How do we get knowledge via visual perception?
The question presupposes that we do get knowledge via visual perception - we may, of course, end up wanting to reject this when we think things through more carefully.
We can get knowledge via perception via any of the five sense modalities:
- I know that the bottle is white because I can see that it is white.
- I know that the bell is ringing because I can hear that it is ringing.
- I know that the liquid is beer because I can smell that it is beer.
- I know that the milk is sour because I can taste that it is sour.
- I know that her bra is silk because I can feel that it is silk.
But we shall focus mainly on visual perception (seeing).
Note that although the two typically go hand-in-hand, there is a difference between seeing and having a visual experience:
- Blind sight
So is it seeing or having a visual experience that is a way to get knowledge? How do you know that the bottle is white? Because I can see that it is white? Because it looks white to me? Or some combination?
Note also that there is a difference between seeing a bottle, or seeing its whiteness, and seeing that the bottle is white. I might see a bottle without seeing that the bottle is white (e.g. by seeing it in odd lighting conditions); I might see a bottle's whiteness without seeing that the bottle is white (e.g. by seeing just a small part of the bottle, not enough to see that it is a bottle).
EQ is an epistemological question. It is intimately connected with another, a metaphysical question:
MQ: What is the nature of visual perception?
The two are connected, as follows. First, an answer to MQ might give us an answer to EQ. Second, EQ presupposes that we can get knowledge via visual perception. If that is right, then only answers to MQ that allow that we can get knowledge via visual perception can be right.
No exercise this week - time to catch up/polish up.