THE STRUCTURE OF KNOWLEDGE
What has our brief consideration of
scepticism taught us about the nature of
knowledge?
1. S knows that p only if S believes that
p.
 Descartes: I know I exist when I
think I do.
 Knowledge requires taking a
cognitive stance.
2. S knows that p only if it is true that p.
 E.g., I can’t know that I have a body
if I don’t have one.
 Absurd: I know that Santa Claus
exists even though it is false that he
does.
Is more required?
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A third condition
Suppose that S has been drinking.
1. Under the influence of alcohol, S
comes to believe that there is a pink
elephant next door.
2. By luck, a zoologist next door is
examining a rare, pink elephant.
Did S know that P? Clearly not!
Conclusion: belief + truth are necessary but
not sufficient for knowledge.
What else is needed?
 Descartes: Absolute certainty.
Some other well-known suggestions:
 Lehrer: no possibility of falsehood.
 Moore: Common sense evidence.
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Let us employ a neutral word:
3. S knows that p only if the belief that p
is justified.
Where justification = what turns true belief
into knowledge.
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The tripartite definition of knowledge
S knows that p if and only if:
1.
S believes that p
2.
p is true
3.
The belief that p is justified.
Note: you can accept this definition even if
you are a sceptic:
 You might simply deny that we ever
have sufficient justification that p is true.
Either way, we need to determine the nature
of justification.
 How are beliefs justified?
 How much justification is sufficient for
knowledge?
 When is an investigation complete?
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Knowledge and justification
“Justification” is closely related to “reason”.
 To be justified in a belief is to have good
reason or grounds to hold that belief.
So it seems that to be justified in a belief is
to be able (at least in principle) to give good
reasons for holding that belief.
 Okay, but what is it to have good
reasons for what you believe?
Foundationalism is a classic response to
this question.
 We can trace it back to Descartes, but it
has more recent defenders.
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Inferential beliefs
Suppose you believe that
(P) The ground is slippery.
You are asked to justify this. You say:
(Q) There is water on the ground.
Now suppose we want to know why you
believe that Q. You cite reason R:
(R) There is a clear, odourless, tasteless
liquid on the ground.
Can you justify R? Suppose you do a test:
(S1) I don’t smell anything.
(S2) I don’t taste anything.
(S3) I don’t see any colour.
This is an inferential chain.
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Non-inferential beliefs
Could you justify any of these? If asked to
justify (S3) you would probably say,
 “Look, I see that there is no colour.”
But what if we pressed you on it? What
could you say? Perhaps:
(T) I am having a colourless visual
sensation.
Well, we’re being picky here, but what about
this last belief?
 It does not seem to be inferred from
anything else.
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Self-justification
Let’s clarify this. Some propositions have
the following property:
 Necessarily: if they are true, then it is
evident to me that they are true.
Call these “self-justifying” propositions.
(Chisholm: “self-presenting”).
Self-justifying propositions concern:
 Immediate sensory experiences.
o I am feeling pain, I see red…
 Introspective states.
o I am thinking right now …
 Memory-like states
o I recall seeing a cat, …
 “Pure” reason:
o P and (PQ) entail Q …
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Directly evident
Is “I exist” self-justifying?
Chisholm: No; it could be true without being
evident to me (I might be unconscious).
It might, however, be entailed by a selfjustifying proposition: e.g. “I am thinking”.
 This would make “I exist” directly
evident to me but not self-justifying.
There are two ways a proposition can be
directly evident:
1. By being self-justifying.
2. By being impossible to doubt given a
self-justifying proposition.
#2 is the most basic form of justification
transfer.
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The pyramid of knowledge
Foundationalism: At the base of every
inferential chain there must be a selfjustifying proposition.
Visual metaphor:
D
B
Y
U
P
C
Z
V
Q
A
W
R
Justification
X
S
T
Self-justifying (“basic”) beliefs
Why should we believe this picture?
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The regress argument
Consider any inferential (or “epistemic)
chain. It might:
1.
2.
3.
4.
Be circular
Be infinite
Terminate in an unjustified belief
Terminate in a justified belief
1. Circular Chains:
 P is justified by Q, Q by R, R by P.
Problem: the “buck” is always passed.
 Ultimately, P is justified by P.
2. Infinite chains:
 P is justified by Q, Q by R, R by S… 
Problem: requires that humans have infinite
sets of beliefs.
 This is psychologically implausible: we’d
never be able to keep the whole chain in
mind.
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Option #3:
 The chain terminates, but in something
that isn’t itself justified.
Problem:
 How can something that is unjustified be
the foundation of all of my justification?
 Example: I quickly estimate that there
are 50 books in a box.
 From this I conclude: that box is heavy.
Audi: This doesn’t support #3.
 We suppose I have some reasons to
believe there are 50 books there.
 E.g. my visual sensation, past
estimates, etc.
 So justified belief must really at the base
of this reasoning.
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Final option: foundationalism
All inferential chains must terminate in a
belief that is justified, but not by any other
belief.
 We still want to know how we can move
from self-justifying beliefs to empirical
knowledge.
 How do we transfer justification from the
directly evident beliefs to others beliefs?
The four sources of knowledge:
1.
2.
3.
4.
Perception
Memory
Reason
Testimony
Can foundationalism explain how these can
give rise to justified beliefs?
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Perception
Consider this self-justifying proposition: “I
believe that I see a red apple”.
 According to Chisholm, all self-justifying
beliefs are “reasonable”.
 But what else does this belief justify
(other than “I exist”)?
Chisholm: This belief “tends to confirm” the
belief that I in fact see a red apple so long
as:
 There is no ground for doubting my
perception (i.e. no evidence of drugs,
deception, illusion, etc.)
 In this case, the second belief becomes
“acceptable”.
Principle 1: If I believe that I perceive that P,
and I have no ground for doubting my
perceptual faculties, then it is acceptable to
believe that P.
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Memory
A similar principle holds for memory:
Principle 2: If I believe that I remember that
P, and there is no ground for doubting my
memory, then it is acceptable to conclude
that P.
In other words:
 Chisholm assumes that memory and
perception are “innocent until proven
guilty”.
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Achieving knowledge
We might have doubts about what is
“acceptable”. Can we strengthen
justification?
Chisholm: Yes.
 Suppose you have a set of beliefs all of
which are acceptable by Principles 1 or
2.
 Suppose these beliefs are logically
independent and consistent.
 Suppose each belief in the set tends to
be confirmed by all the others.
Then each belief in the set is beyond
reasonable doubt and, therefore, evident for
you.
 “Concurrence” moves a belief from
“acceptable” to “beyond reasonable
doubt”.
 If true, the belief is known.
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Reason and testimony
3. There do seem to be truths of reason:
 [P & (PQ)]Q
 (P v ~P)
These certainly seem to be candidates for
self-justifying beliefs.
 If so, then anything they entail will also
be justified (pure math, logic, etc).
 They can also be applied to the beliefs
of perception and memory so we can
see what they entail—this spreads
justification.
4. What about testimony?
 How can we determine if testimony is
reliable?
 Does it ultimately depend on perception
and memory?
 That’s a homework exercise.
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Summary of Chisholm’s foundationalism
1. Some beliefs are self-justifying.
2. Others propositions can’t be doubted
given a self-justifying belief.
3. These are the directly evident beliefs.
4. Directly evident beliefs are all
reasonable.
5. Directly evident beliefs provide only
very limited knowledge.
6. If one has no belief that casts doubt on
a reasonable belief, it gives rise to an
acceptable belief.
7. Acceptable beliefs become evident via
concurrence with other acceptable
beliefs.
8. If evident beliefs are true, they are
instances of knowledge.
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Foundations and fallibility
Foundationalists agree that self-justifying
propositions ground all knowledge.
However, they disagree over the nature of
these propositions.
Classical
foundationalism
Non-inferential
knowledge is
infallible (or “selfpresenting”)
Descartes,
Chisholm (in some
respects)
Modest
foundationalism
Non-inferential
knowledge is noninferential, that’s all.
Audi
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Classical foundationalism
Axiomatism: Foundations of knowledge
must be impossible to doubt (C & D).
Deductivism: only beliefs that can be
logically deduced from self-justifying
beliefs are justified (D).
But modest foundationalism denies this:
I. Self-justification is defeasible.
 E.g.: one can come to learn that one
was drugged, and so doubt that one
was really in pain.
II. The transmission of justification need not
be deductive.
 Inductive reasoning is justifying as well.
Moreover, something other than
foundational justification can add to
justification:
 E.g., coherence with other beliefs.
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Advantages of foundationalism
1. Answers the regress problem
 The fourth option is the most plausible.
2. Accords with common sense
 We typically think that feeling or seeing
something requires no further backing.
3. Psychologically plausible
 Explains how finite experience could
underlie a wide variety of beliefs.
4. Coheres with biology
 If our basic perceptual, introspective and
memory beliefs were not immediately
justified, we would be at a survival
disadvantage.
5. Tolerant
 Experiences differ; so too may selfjustifying beliefs.
 What follows from them is not dictated
by logic.
 Should expect cognitive pluralism.
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