CONCEPT OF KNOWLEDGE
The branch of philosophy concerned with the nature and extent of human knowledge is
called epistemology (from the Greek episteme meaning knowledge, and logos
meaning theory). Knowledge seems to come in many varieties: we know people, places and
things; we know how to perform tasks; we know facts. Factual knowledge has been the
central focus of epistemology.
We can know a fact only if we have a true belief about it. However, since only some
true beliefs are knowledge (consider, for example, a lucky guess), the central question
asked by epistemologists is 'What converts mere true belief into knowledge?'. There are
many, and often conflicting, answers to this question. The primary traditional answer has
been that our true beliefs must be based upon sufficiently good reasons in order to be
certifiable as knowledge.
Foundationalists have held that the structure of reasons is such that our reasons
ultimately rest upon basic reasons that have no further reasons supporting them.
Coherentists have argued that there are no foundational reasons. Rather, they argue that
our beliefs are mutually supporting. In addition to the constraints upon the overall
structure of reasons, epistemologists have proposed various general principles governing
reasons. For example, it seems that if my reasons are adequate to affirm some fact, those
reasons should be adequate to eliminate other incompatible hypotheses. This initially
plausible principle appears to lead directly to some deep puzzles and, perhaps, even to
scepticism. Indeed, many of the principles that seem initially plausible lead to various
unexpected and unwelcome conclusions.
Alternatives to the primary traditional answer to the central epistemic question have
been developed, in part because of the supposed failures of traditional epistemology.
These alternative views claim that it is something other than good reasons which
distinguishes (mere) true beliefs from knowledge. Reliabilists claim that a true belief
produced by a sufficiently reliable process is knowledge. Good reasoning is but one of the
many ways in which beliefs can be reliably produced. The issue of whether the objections
to traditional epistemology are valid or whether the proposed substitutes are better
remains unresolved.
- The varieties of knowledge
- Propositional knowledge is not mere true belief
- Warrant
- Foundationalism and coherentism
- Defeasibility theories
- Externalism
- Epistemic principles
- The epistemic principles and scepticism
- The epistemic principles and some paradoxes
- Some challenges to traditional epistemology
1 The varieties of knowledge
Knowledge comes in many varieties. I can know how to adjust a carburettor. I
can know a person. I can know that mixing bleach and ammonia is dangerous. In the
first case, I possess a skill. In the second, I am acquainted with someone. In the third,
I know a fact. Epistemologists have differed on the relationships between these types of
knowledge. On the one hand, it could be held that knowing a person (place or thing),
should be construed as nothing more (or less) than knowing certain facts about that
someone and possessing the skill of being able to distinguish that person from other
objects. On the other hand, it has been held that knowing facts depends upon being
acquainted with particular objects. Whether the reduction of one form of knowledge to
another is ultimately successful is an area of contention among epistemologists (see ACQUAINTANCE AND DESCRIPTION, KNOWLEDGE BY).
Nevertheless, it is knowledge of facts, so-called propositional knowledge, as
opposed to knowledge by acquaintance or the possession of skills, that has been the
central concern of epistemologists. The central question can be put this way: which
beliefs of mine are to be counted as knowledge? This question presupposes that knowledge
is a species of belief, but some might think that knowledge and belief are mutually
exclusive: for example, we say such things as 'I do not believe that; I know
it'. But we also say such things as 'I am not happy; I am ecstatic'. A
suggested paraphrase of this expression seems to capture what is meant without denying the
obviously true claim that ecstasy is a form of happiness. The paraphrase is: I am not merely
happy, I am ecstatic . The parallel is: I do not merely believe it; I know it. Thus, this
type of linguistic evidence does not support the suggestion that belief and knowledge are
mutually exclusive. In general, epistemologists have held that propositional knowledge is
a species of belief.
2 Propositional knowledge is not mere true belief
Propositional knowledge is a species of belief; but which beliefs are knowledge? The
first thing to note is that a belief must be true in order for it to count as knowledge.
But that is obviously not enough. First, true beliefs can be based upon faulty reasoning.
Suppose that I believe that smoking is a leading cause of fatal lung cancer because I
infer it from the fact that I know two smokers who died of lung cancer. The generalization
is true, but my evidence is too meagre for my belief to count as knowledge. Second, true
beliefs can be based on false beliefs. Modifying an example used by Bertrand Russell,
suppose that I believe truly that the last name of the President of the United States in
1996 begins with a 'C'. Also suppose this belief is based upon the false belief that the
President is Winston Churchill. My true belief that the President's name begins with a 'C'
is not knowledge because it is based on a false belief.
Third, even some true beliefs resulting from good reasoning based upon true beliefs are
not knowledge. Suppose that I believe (truly) that my neighbours are at home. My belief is
based upon good reasoning from my true belief that I see lights on and that, in the past,
the lights have been on only when they were at home. But suppose further that this time
the lights were turned on by a guest and that my neighbours had just entered the house and
would not have had time to turn on the lights. In this case, I fail to know that my
neighbours are home. So, the central question becomes: what must be added to true belief
to convert it into knowledge?
3 Warrant
The property, whatever it is, that, if added to true belief converts it into knowledge,
we may refer to as 'warrant'. Knowledge, then, is true, warranted, belief. But simply to
name the missing property does not bring us closer to understanding it and we must be
careful not to think of 'warrant' as a sophisticated synonym for 'justified'. Let us say
that a belief is justified just in case we are entitled to hold it on the basis
of suitable reasons available to us. In the neighbour/lights case mentioned above, we have
already seen that justification is not sufficient for warrant. Whether it is even
necessary will be important in the discussion that follows, especially in §6.
Given the great variety of approaches to an account of warrant, is there any common,
underlying starting point embraced by epistemologists? Yes: a warranted belief is one that
is not held on the basis of mere cognitive luck. Plato appeals to that intuition in the Theaetetus; Aristotle's account of the transition from ignorance of
the first principles in science to knowledge of them in the Posterior
Analytics is designed to demonstrate that there are reliable cognitive mechanisms
whose output is not the result of chance; Descartes (1641) proposes
methods for acquiring beliefs that would necessarily lead to truth;suggests that Locke (1689) even if persons arrive at a true belief by accident, they are
not thereby free from criticism.
Let us start with the assumption that a proposition is known just in case it is not an
accident, from the cognitive point of view, that it is both believed and true. Hence the
task becomes one of developing an account of warrant that accurately portrays what it is
that makes a belief non-accidentally true from the cognitive point of view.
4 Foundationalism and coherentism
There are two main, traditional approaches to the account of justification:
foundationalism and coherentism. Both are normative views about rules in virtue
of which propositions ought to be accepted or ought to be rejected or ought
to be suspended (see COHERENCE THEORY OF JUSTIFICATION AND KNOWLEDGE;
FOUNDATIONALISM; NORMATIVE EPISTEMOLOGY). In
order to characterize these approaches, recall how the ancient Pyrrhonian Sceptics divided
the possible structures of reasons that provide a basis for accepting a belief (see EPISTEMOLOGY, HISTORY OF; PYRRHONISM). Suppose you
hold a belief and offer another belief as the reason for the first – for example,
suppose you believe that Ford cars are generally less expensive than BMWs. Your reason
could be your belief that you were told so by a reliable person. An obvious question
arises: what is your basis for believing that the person is reliable? You could answer
with another reason and that reason could, itself, be supported by a further reason, and
so on.
This process of providing reasons for your beliefs can have only three possible
structures:
Foundationalism: The process of giving reasons could be such that not every
reason is supported by another reason because there are basic reasons which have
no need of further reasons supporting them.
Coherentism: The process of giving reasons could have no reason that is not
supported by another reason, but there is not an infinite number of reasons. Thus, beliefs
are mutually supporting.
Infinitism: The process of giving reasons could have no reason that is not
supported by another reason, but there is an infinite number of reasons.
Foundationalism and coherentism have both been developed and defended, and there are
well-known objections to each view. In contrast, the prima facie objections to
infinitism have seemed so overwhelming that it has not been investigated carefully.
Infinitism seems to require that a person should have an infinite number of
beliefs (which seems on its face to be false). In addition, it seems to
lead inevitably to the conclusion that no belief could ever be justified, since the
process of justification would never come to an end.
The standard objections to foundationalism are several. First, as the Pyrrhonians would
point out, there must be a distinction between what makes a belief properly basic
and what makes it simply one for which no other reason is, in fact, given. Otherwise, the
offered 'basic' reason is arbitrary. But if there is some further reason for thinking that
an offered reason is not arbitrary, then there is a reason for accepting it, and the
offered reason is, thereby, not basic. Hence, there can be no foundational propositions.
Second, some preferred candidates for properly basic reasons seem not to be properly
basic on closer inspection. Consider perceptual judgments – the source of most of our
knowledge of the external world according to many philosophers (see EMPIRICISM; A
POSTERIORI). A reason for believing that there is a tree before me is that I see a tree
before me. But the latter proposition does not appear to be properly basic because one
could be required to explain what it is about what is seen that leads one to believe that
it is a tree that one sees (as opposed to an illusion). Thus, some
foundationalists have retreated to sensation-beliefs (so-called sense-data propositions)
as their candidates for properly basic beliefs: for example, 'I seem to see a green,
brown, tallish object' (see AYER, A.J.; BROAD, C.D.;
MOORE, G.E.). But although these propositions might seem to be
properly basic, there are notorious problems with the sense-data view (see PERCEPTION, EPISTEMIC ISSUES IN; SENSE DATA).
First, the proffered basic beliefs seem to be too meagre to provide a sufficient basis for
the rich scope of things we seem to know. For example, how can my knowledge that objects
persist when not being perceived be traced to particular sense-data? Second, it appears
that our knowledge of the way in which to characterize our sensations (private sensations
accessible only to the individual having them) depends upon our knowledge of public
objects (see CRITERIA; WITTGENSTEIN, L.).
How could we know, for example, that we have a throbbing pain without first recognizing
what it is for a public object (say, a muscle) to be throbbing?
Foundationalists have developed answers to these objections in part by liberalizing the
requirements either for being properly basic or for being an acceptable pattern of
inference from the foundational propositions to the non-foundational ones (see INFERENCE TO THE BEST EXPLANATION). For example, contextualist accounts
of knowledge have been developed that hold that a proposition is properly basic just in
case it is accepted by the relevant community of putative knowers. In a discussion with a
friend I could offer as my reason for believing another moon of Jupiter had been
discovered that 'I read it in the newspaper'. I would not need further reasons for
believing that I read it. In contrast, at a convention of astronomers that reason would
not be accepted. Hence, contextualists claim, what counts as a basic reason is
context-dependent.
There are two obvious responses to contextualism. The first is that it might be an
accurate description of some aspects of our epistemic practices, but the fundamental
Pyrrhonian question remains: what distinguishes a properly basic proposition from one that
is merely offered and accepted by a community of putative knowers? The issue concerns what
beliefs, if any, ought to be offered and accepted without further reasons. The
question is not what beliefs are offered and accepted without further reason. The
second response is a corollary of the first. Knowledge seems to be a highly prized state
of belief (as PLATO put it). But, if the contextualists were right, I would gain knowledge
by joining a community of rather epistemically gullible and permissive folk. That hardly
seems right! (see CONTEXTUALISM, EPISTEMOLOGICAL)
In sum, it remains a subject of dispute among epistemologists whether the stock of
purported foundational propositions can be made sufficiently rich and abundant without
including too many that clearly require evidential support, or whether the patterns of
inferences can be liberalized sufficiently without allowing patterns that are not
sufficiently truth-conducive.
The historical rival of foundationalism is coherentism. Coherentists deny that there
are basic reasons and claim that all propositions derive their warrant, at least in part,
from other propositions. The fundamental objection is this: Typically, we recognize that
arguing in a circle is not an acceptable pattern of inference, so what makes it acceptable
in some cases? Suppose I believe that apples contain vitamin C, at least in part because I
believe that fruits contain vitamin C. I would surely be appropriately accused of circular
reasoning if I believed, in part, that fruits contain vitamin C because apples do.
Coherentists would be quick to point out that they are not really suggesting that one
should argue in a circle. Rather, they would point to the fact that our beliefs come in
bunches with a web-like structure (see QUINE, W.V.O.). They are
'mutually supporting' just as the poles in a tepee are mutually supporting. A belief is
warranted just in case it is a member of a set of coherent beliefs.
But whether these colourful analogies answer the basic objection is not clear.
Presumably, circular reasoning is not acceptable because although it might be the case
that if you believe b1 it might be reasonable to believe b2, and if
you believe b2 it might be reasonable to also believe b1, their
mutual support gives you no reason for believing them both. Thus, the fundamental question
is this: What makes one total set of coherent beliefs, say T1, any more
acceptable than an alternative total set of coherent beliefs, say T2?
The Pyrrhonian Sceptics would point out that coherentists either have an answer for
that question or they do not. If they do, then they seem to have abandoned their central
view, since there now seems to be a reason for adopting the set of beliefs, T1,
that is not one of the beliefs in T1. Indeed, if they provide an answer, they
have embraced foundationalism. If they do not have an answer, then it seems that adopting
T1 is arbitrary. Coherentists have attempted to answer this objection by giving
a 'meta-justification' for thinking that certain kinds of coherent belief systems are
likely to contain true members. Indeed, some have argued that coherent beliefs are, by
their very nature, likely to be true (see DAVIDSON, D.). But whether that strategy will
suffice to answer the objections remains an open question in epistemology.
5 Defeasibility theories
A basic objection to the foundationalist's and coherentist's accounts of justification
is that neither seems to be able to show that a true belief which satisfied their accounts
would be non-accidentally true. First, as the neighbour/lights case showed, a true belief
could be fully justified on their accounts, but not be knowledge. Second, as the
Pyrrhonians pointed out, either the beliefs seem to rest upon arbitrary foundations or
they seem to be only one of many, equally coherent sets of beliefs. The defeasibility
theory was developed, in part, to address these issues. It holds, roughly, that it is not
only the evidence that one possesses that makes a belief warranted; it is equally
important that there is no defeating evidence that one does not possess. That is, in order
for a belief to be warranted it must not only be justified (in the sense required by
either the foundationalists or the coherentists) but its justification must be such that
there is no truth which, if added to the reasons that justify the belief, is such that the
belief would no longer be justified (see DEFEASIBILITY).
The defeasibility theory can explain why it is not a cognitive accident that the
warranted belief is true. If any of the important supporting reasons (those that if
removed would destroy the justification) were false, then adding the denial of those
reasons (in other words, adding the truth) to one's beliefs would undermine the
justification. In addition, if there is evidence that one does not possess such that it
makes it an accident that the belief is true, the propositions describing that evidence
would undercut the justification.
A well-known case will help to illustrate this (see GETTIER PROBLEMS).
Suppose that I know Tom Grabit well and I see what appears to be Tom stealing a library
book: I come to believe that Tom stole a library book. And, let us suppose that Tom did
indeed steal the book. Foundationalists and coherentists could deploy their accounts in
order to show that the belief is justified. Nevertheless, suppose that, unknown to me, Tom
has an identical twin, John, who is a kleptomaniac and was in the library on the day in
question and stole a copy of the same book. Even though I arrived at a true belief as a
result of good reasoning based upon true propositions, I do not know that Tom stole the
book since it is accidental, from the cognitive point of view, that I arrived at the
truth. I could just as easily have based my belief on having seen John stealing the book.
The defeasibility theorists would point out that the belief that Tom stole the book is
defeated; if the true proposition describing John were added to my beliefs, I would no
longer be justified in believing Tom stole the book. In general, the defeasibility theory
can rule out accidentally true beliefs as warranted because those beliefs would not be
able to stand up to the truth.
Nevertheless, the defeasibility theory has its problems. The primary one is that it
seems to exclude too much from what we know. Returning to the Grabit Case, suppose that
everything is as it was except that Tom does not have a twin but that Tom's mother
sincerely avows the claims about John. Now, there is a true proposition (Tom's mother has
said sincerely that Tom has an identical twin, John) that defeats the original
justification. Hence the belief that Tom stole the book would be defeated. But if Tom's
mother were demented and there never was a twin, it seems that I knew all along that Tom
stole the book.
Defeasibility theorists have tried to answer this objection by suggesting ways to
distinguish between so-called misleading defeaters (for example, Mrs Grabit sincerely
avows that Tom has an identical twin, John) and genuine ones (for example, Tom has an
identical twin, John), but there is no agreement among epistemologists that any of these
suggestions has succeeded in correctly capturing the distinction between genuine and
misleading defeaters.
6 Externalism
Partly in response to the difficulties with foundationalism and coherentism even as
supplemented by the defeasibility theory, epistemologists have developed a variety of
alternative accounts of warrant. They have been called 'externalistic' because their
accounts of warrant focus on features of the world other than the knower's reasons for
belief. Two important ones are the causal theory and the reliabilist theory (see CAUSAL THEORY OF KNOWLEDGE; RELIABILISM).
In their purest forms, these accounts begin with the view that knowledge, and hence
warrant, does not require justification. The foundationalists had already conceded that
there are no reasons for properly basic beliefs. This seemed to create a problem for
foundationalism only because it was assumed that all beliefs needed to be justified and
the 'basic' reasons appeared to be arbitrary. But drop the requirement that beliefs need
to be justified in order to be warranted, and this problem immediately disappears.
Roughly, the causal theory of warrant holds that a belief is warranted if and only if
the state of affairs represented in the belief is appropriately causally related to the
belief. For example, suppose I come to believe that there is a bird in a tree as a causal
consequence of seeing the bird in the tree. Sometimes the causal connection is more
complex; but this direct type of causal connection between the belief and what it
represents will suffice for our purposes.
This theory is initially appealing because it appears to satisfy the basic requirement
that a warranted belief be non-accidentally true since the state of affairs represented in
the belief is a cause of my belief. However, it is easily seen to be both too weak and too
strong; and there seem to be some deep problems with it as a general account of warrant.
It is too weak because it would count some true beliefs as warranted that clearly are not
known. Recall the Grabit case. My belief that I see Tom stealing the book is caused by
Tom's stealing the book, but if he has an identical twin, I do not know that Tom stole the
book. It is too strong because there seem to be many beliefs that count as knowledge which
can not be appropriately causally related to what they represent. Suppose I know
that there is no elephant smaller than a kitten: what possible causal connection
could there be between there being no elephant smaller than a kitten and my belief? In
addition, potential difficulties arise about knowledge of a priori propositions (such as 2
+ 2 = 4) and counterfactuals (such as, if it were raining today, we would have called off
the picnic). It looks as though there is no possible way to produce a causal connection
between my belief and what is represented in the belief – at least as 'cause' is
usually understood (see A PRIORI).
Nevertheless, a basic tenet of the causal theory might still be correct: Not all
beliefs need to be based on reasons in order to count as knowledge. The reliabilist theory
of warrant can be seen as the successor of the causal theory. Instead of requiring an
appropriate causal connection between the states of affairs represented in the belief and
the belief itself, a typical form of reliabilism holds that a belief is warranted just in
case the process resulting in the belief produces true beliefs sufficiently often.
Thus, the non-accidental nature of the true belief receives a very straightforward
analysis. The belief is non-accidentally true because the process that produces the belief
produces true beliefs sufficiently often. This view has many advantages over the causal
theory. My belief that elephants are larger than kittens need not be caused by that state
of affairs. All that is required is that the process by which I come to believe that
proposition typically (often enough) results in true beliefs. A priori or ethical
propositions present no problem since there could be reliable processes that produce those
beliefs.
Nevertheless, there are problems confronting this view. Suppose that you require that
the process should produce true beliefs on 100 per cent of the occasions on which it
arises. That is a very stringent condition; but it is not stringent enough! For if the
belief that Tom Grabit stole a book arises only once in the history of the world –
the time I saw him stealing the book – the actual process produced a true belief 100
per cent of the times it arose; but it is not knowledge. The obvious move for the
reliabilist is not only to include the actual occasions when the particular belief is
produced but rather to consider whether the type of process that produced this belief
would produce true beliefs of this type sufficiently often. But correctly characterizing
those types has not proved easy. Is the type of belief one in which Tom is involved? Or
identical twins? Or libraries? That seems too narrow. Is the type of process one in which
there is first a perception and then some inferences? That seems too broad. It remains an
open question whether reliabilism can produce an acceptable account of the types of
processes and the types of beliefs.
Finally, there is one further objection that some epistemologists have brought against
reliabilism. Perhaps it is best illustrated in a case presented by Keith
Lehrer (1990: 163) that can be summarized as follows: a certain Mr Truetemp has a
thermometer-with-temperature-belief-generator implanted in his head so that within certain
ranges of temperatures he has perfectly reliable temperature beliefs. When it is 50
degrees, he comes to believe that it is 50 degrees. When it is not 50 degrees, he does not
come to believe that it is 50 degrees. He holds these beliefs without knowing why he does.
Such beliefs would satisfy all of the requirements suggested by the reliabilists, but
many epistemologists would hold that although Mr Truetemp has true beliefs and they are
not accidentally true because his thermometer-with-temperature-belief-generator is
reliable, they are accidentally true from the cognitive point of view, as he has
no reasons at all for his beliefs. Indeed, some would say that what Mr Truetemp possesses
is a skill (of telling the temperature) and not propositional knowledge at all.
Here we can detect a fundamental clash of intuitions. The reliabilists would hold that
Mr Truetemp does know; the traditional normativists would hold that he does not. There
appears to be no way to satisfy both. But this much seems clear: There are some situations
in which the steps in the process that brings about a belief include the holding of
reasons. In those cases in which there is no automatic true-belief-generator (as in the
Truetemp case) and in which we must rely upon our reasoning to arrive at a belief, the
questions asked by the traditional normativists are crucial: what must the structure of
our reasons be so as to make a true belief acceptable? Are there foundational reasons? Can
mutually supporting reasons be offered without begging the question? (Could reasons be
infinite in number?) And need those reasons be such that they are not undermined by the
truth, as the defeasibility theorists would hold? At least in some cases, it seems that
normative standards for belief-acquisition apply and their satisfaction will determine
whether a belief ought to be accepted. Thus, it appears that an evaluation of the
conditions under which beliefs ought to be accepted, denied or suspended is inescapable
(see INTERNALISM AND EXTERNALISM IN EPISTEMOLOGY; JUSTIFICATION,
EPISTEMIC).
7 Epistemic principles
Epistemic principles describe the normative epistemic status of propositions under
varying conditions (see EPISTEMIC LOGIC). It is generally agreed
that if a person, S, is justified in believing any proposition, x, then S is not at the
same time justified in believing that not-x. Foundationalists and coherentists alike can,
and typically do, accept this principle. Other principles are more controversial. They are
intuitively plausible but they seem to provide a basis for scepticism and for some deep
epistemic puzzles. Here are three of the more interesting principles.
Conjunction principle (CON-P): If S is justified in believing that x, and S is
justified in believing that y, then S is justified in believing that (x
and y).
Closure Principle (CLO-P): If S is justified in believing x, and
x entails y, then S is justified in believing that y.
Evidence Transfer Principle (ET-P): If there is some evidence, e, that
justifies S in believing that x, and x entails y, then
e justifies S in believing that y.
In each principle and with suitable grammatical modifications 'justified' could be
replaced by other epistemic terms, such as 'reasonable', 'plausible', 'evident',
'certain'. Furthermore, each principle is designed to capture a basis upon which a
positive normative epistemic status of a proposition can be transferred to another
proposition. As a corollary, 'S is justified in believing x' is not
taken to entail 'S does believe that x, justifiably'. For S may
not form the belief because of a failure to see the connection between the propositions.
Finally, with regard to CLO-P and ET-P, since a tautology is entailed by every
proposition, the entailment must be restricted to some form of relevant entailment and/or
the range of propositions must be restricted to contingent ones (see RELEVANCE
LOGIC AND ENTAILMENT). Other restrictions are no doubt necessary; but these three
seemingly intuitive principles have been challenged at their core.
It is important to see some of the relationships between these principles. CLO-P does
not entail CON-P since the CLO-P is about one proposition that S is justified in
believing, not sets of propositions. In addition, CLO-P does not entail ET-P because CLO-P
does not require that it is the very same evidence, e, that S
has for x that justifies y for S. Thus, one can accept CLO-P
without accepting either of the other principles.
8 The epistemic principles and scepticism
Scepticism – the view that we lack knowledge in those areas commonly thought to be
within our ken – comes in many varieties. The most extreme view is global scepticism.
It holds that we have very little, if any, knowledge. That view seems preposterous at
first glance. Indeed, some epistemologists think that any theory that leads to global
scepticism should, ipso facto, be rejected (see COMMONSENSISM; SCEPTICISM). Yet there are many arguments for global scepticism that are
difficult to answer. In addition, more modest forms of scepticism about particular subject
matters (for example, other minds or the future) have been developed. But since the more
modest sceptics employ strategies similar to those employed by the global sceptics, I here
consider only the most extreme form of scepticism – global scepticism (see OTHER MINDS).
We have already seen the basis for one such argument for global scepticism that can be
gleaned from the Pyrrhonians, namely:
(1) All knowledge requires having reasons that are neither arbitrary nor
question-begging nor infinitely many.
(2) The only structures for reasons are such that reasons are either arbitrary
(foundationalism), question-begging (coherentism) or infinitely many (infinitism).
Therefore, there is no knowledge.
There are at least four possible responses to this argument: (1) the foundational,
basic propositions are not arbitrary; (2) coherentism does not necessarily lead to
question-begging arguments; (3) requiring infinitely many reasons for a belief does not
entail that a belief cannot be justified; (4) not all knowledge entails having reasons.
All but (3) have been systematically developed by epistemologists.
Pyrrhonism does not rely directly upon the epistemic principles discussed in the
preceding section. But there are other important forms of scepticism that do. Consider
this argument that can be traced to Descartes (see DESCARTES, R.
§4):
(1) If I am justified in believing that there is a table before me, then I am justified
in believing that I am not in one of the sceptical scenarios (evil demon worlds, for
example) in which there is no table but it appears just as though there were one.
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(2) I am never justified in believing that I am not in one of the sceptical scenarios
in which there is no table but it appears just as though there were one.
Therefore, I am never justified in believing that there is a table before me.
Premise 1 is a clear instance of CLO-P. Since the argument is valid (if the premises
are true, the conclusion must be true), there are only three plausible responses: (1)
CLO-P is false; (2) the second premise is false; (3) the argument begs the question.
Responses (1) and (2) are relatively easy to envisage; the third is not so obvious.
Roughly, the argument goes as follows: since one of the potentially available grounds for
my being justified in believing that I am not in a sceptical scenario is any proposition
that entails that I am not in such a scenario, every good argument for the second premise
would have to establish that I am not justified in believing that there is a table before
me. But that, of course, is the very conclusion.
It is important to note that there is an apparently similar argument for scepticism
employing the stronger epistemic principle, ET-P:
(1) If the evidence, e, that I have for believing that there is a table before me is
adequate to justify that belief, then it is adequate to justify the belief that I am not
in one of the sceptical scenarios.
(2) The evidence, e, is not adequate to justify that I am not in one of the
sceptical scenarios.
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Therefore, the evidence, e, is not adequate to justify that there is a table
before me.
Of course, it is open to epistemologists to deny ET-P. Since one can deny ET-P without
abandoning CLO-P (because CLO-P does not entail ET-P), that certainly seems to be a
strategy worth considering. The discussion in the next section provides additional reasons
for considering that strategy.
9 The epistemic principles and some paradoxes
There are many epistemic paradoxes (see PARADOXES, EPISTEMIC). I
here consider two in order to show how they depend upon some of the epistemic principles
considered earlier.
The Lottery Paradox: Suppose that enough tickets (say n tickets) have
been sold in a fair lottery for you to be justified in believing that the one ticket you
bought will not win. In fact, you are justified in believing about each ticket that it
will not win. Thus, you are justified in believing the following individual propositions:
t1 will not win. t2 will not win. t3
will not win.… tn will not win.
Now if the conjunction principle is correct, you can conjoin them, ending up with the
obviously false but apparently justified proposition that no ticket will win. So, it seems
that you are in the awkward position of being justified in believing each of a series of
propositions individually, but not being justified in believing that they are all true.
Some philosophers have thought that this seemingly awkward position is not so bad after
all, since there is no outright contradiction among any of our beliefs as long as the
conjunction principle is rejected. But others have thought that making it rational to
hold, knowingly, a set of inconsistent beliefs is too high a price to pay.
Others have suggested that we are not actually justified in believing of any ticket
that it will lose; rather what we are justified in believing is only that it is highly
likely that it will lose. But the lottery can be made as large as one wants, so that any
level of probability (below 1) is reached. Thus, this suggestion seems to rule out our
being justified in believing any proposition with a probability of less than 1. That is a
very high price to pay! There is no generally agreed-upon solution for handling the
Lottery Paradox (see PROBABILITY THEORY AND EPISTEMOLOGY; CONFIRMATION THEORY).
The Grue Paradox: The so-called 'Grue Paradox' was developed by Nelson Goodman and has been recast in many ways (see GOODMAN, N.). Here is a
way that emphasizes the role of ET-P:
All of the very many emeralds examined up to the present moment, tnow, have
been green. In fact, one would think that since we have examined so many of them, we are
justified in believing that (G): all emeralds are green. But consider another proposition,
namely that all emeralds examined up to tnow are green, but otherwise they are
blue. Let us use 'grue' to stand for the property of being examined and green up to tnow
but otherwise blue. It appears that the evidence which justifies us in believing that all
emeralds are green does not justify us in believing that (N): no emerald is grue.
What are we to make of this version of the paradox? First, note that it depends upon
ET-P. Although (1) our inductive evidence (the many examined green emeralds) justifies
(G), and although (2) (G) does entail (N), the inductive evidence does not justify (N). In
other words, this version of the paradox arises because the evidence does not transfer as
the principle would require. Second, note that CLO-P is not threatened by this paradox
since it is the evidence for (G) that is inadequate for (N). (The issue is not whether we
are justified in believing (N) whenever we are justified in believing that (G).)
But if ET-P were not valid, then the sting of this version of the paradox can be
pulled. Recall the original Grabit case. In that case, I had adequate evidence for being
justified in believing that Tom stole the book, that is, the person stealing the book
looked just like Tom. It seems clear that this evidence is not adequate to justify the
proposition that it was not Tom's identical twin who stole the book. If it were the twin,
things would appear to be just as they did appear to be. But this tends to show that we do
not typically impose ET-P on our evidence. There are other versions of the Grue Paradox
that do not make explicit use of ET-P. For example, since 'all emeralds are green' and
'all emeralds are grue' are alternative hypotheses, it seems paradoxical that the very
same evidence that justifies believing the first alternative also seems to support the
second. But perhaps, like the version considered above, this apparent paradox rests on a
mistaken intuition. Consider the Grabit Case once again. Here, the evidence which
justifies the belief that Tom is the thief would also support the claim that Tom's
identical twin stole the book. To generalize further, consider any hypothesis, say h,
that is justified by some evidence that does not entail h. It is always possible
to formulate an alternative hypothesis that is supported by that very evidence, namely
(not-h, but it appears just as though h because of…). Thus, an intuitively
plausible epistemic principle similar to ET-P might be invalid. That principle is: if
there is some evidence, e, that justifies S in believing that x,
and x is an alternative hypothesis to y, then e does not
support y.
To sum up, if ET-P and similar epistemic principles do not accurately capture our
normative epistemic practices and if the argument for scepticism that depends upon CLO-P
begs the question, then the sting of Cartesian scepticism (considered in the previous
section) is numbed and the Grue Paradox can be addressed. But those are big 'ifs', and the
issue remains open (see INDUCTION, EPISTEMIC ISSUES).
A traditional question asked by epistemologists is 'what ought we to believe?'
Typically, the answer is given by (1) describing the types of reasons that contribute to
warranting a belief, and (2) developing a set of necessary and sufficient conditions for
knowledge in which the types of reasons depicted in (1) play a prominent role. But there
are many challenges to this answer.
We have already seen the challenge developed by the causal theorists and the
reliabilists. Roughly, they hold that our beliefs need not be the result of proper
reasoning to be counted as knowledge. Sufficiently reliable belief-acquisition methods are
all that is required. Indeed, some have held that epistemology, when done correctly, is a
branch of psychology because the primary issue is the study of reliable belief-acquisition
methods. This programme has often been referred to as 'naturalized epistemology' and, in
one form, its basic tenet is there are no a priori knowable epistemic principles (see NATURALIZED EPISTEMOLOGY; QUINE, W.V.O.).Another
challenge to traditional epistemology comes from `virtue epistemology', which makes the
primary object of epistemic evaluation traits of persons rather than properties of beliefs
or belief-forming processes. The virture approach has been taken farthest by Linda
Zagzebski (1996) who proposes an epistemic theory modelled on virtue ethics and argues
that such a theory permits the recovering of such neglected epistemic values as
understanding and wisdom (see VIRTUE EPISTEMOLOGY).
A further type of challenge is that of Edward Craig (1990). While
allowing that the debate has been shaped by real features of the concept of knowledge, he
rejects the project of analysing it in necessary and sufficient conditions. Instead, he
tries to 'synthesize' the concept by deriving these features from a pragmatic hypothesis
about its purpose, thus explaining the debate rather than joining it.
Even more radical challenges have been developed. First, some have argued that there is
no unique method of acquiring and revising beliefs that ought to be employed by all people
(see COGNITIVE PLURALISM). Second, it has been argued that the
proposed conditions of good reasoning (for example, objectivity and neutrality) tacitly
aim at something other than truth. They are developed to prolong entrenched power (see FEMINIST EPISTEMOLOGY). Finally, it has been argued that successful belief
acquisition occurs when the future can be adequately anticipated and controlled (see PRAGMATISM).
The defenders of traditional epistemology have two basic types of reply. First, they
can examine the particular arguments developed by the critics to determine whether any one
of them is sound. Second, they can point out that the critics will have to defend the
reasonableness of their views by at least tacitly employing the very principles of good
reasoning investigated by traditional epistemologists. Of course, this would not show that
the critic's position is false, but it does at least illustrate the universality of the
question `what ought we to believe?'.
References and further reading
Alston, W. (1989) Epistemic Justification, Ithaca, NY: Cornell University
Press. (Develops and defends a theory of knowledge containing elements of internalism and
externalism.)
Annis, D. (1978) 'A contextualist theory of epistemic justification', American
Philosophical Quarterly 15 (3): 213–19. (A non-technical contextualist account
of justification.)
*Aristotle (3rd century BC) Posterior Analytics, ed. and
trans. J. Barnes, Oxford: Clarendon Press, 1975. (Aristotle proposes and defends an
empirical foundationalist account of knowledge. It can be viewed as containing a basis for
a reliabilist account of knowledge of first principles in science.)
Armstrong, D. (1973) Belief, Truth and Knowledge, Cambridge: Cambridge
University Press. (One of the first carefully developed reliabilist accounts of
knowledge.)
Audi, R. (1993) The Structure of Justification, Cambridge: Cambridge
University Press. (Develops and defends a version of foundationalism.)
Ayer, A.J. (1940) Foundations of Empirical Knowledge, London: Macmillan.
(Develops and defends a foundationalist account of the structure of reasons.)
Bonjour, L. (1985) The Structure of Empirical Knowledge, Cambridge, MA:
Harvard University Press. (Contains a sophisticated defence of coherentism.)
Broad, C.D. (1965) 'The Theory of Sensa' in R. Swartz (ed.) Perceiving, Sensing and
Knowing, Berkeley, CA: University of California Press. (Develops the sense-data
theory of knowledge. The collection contains many of the most important papers on
perception written in the early- and mid-twentieth century.)
Chisholm, R. (1966) Theory of Knowledge, Englewood Cliffs, NJ: Prentice Hall,
2nd edn, 1977; 3rd edn, 1989. (The successive editions contain increasingly complex
foundationalist accounts of knowledge along with versions of the defeasibility account.)
Code, L. (1991) What Can She Know? Feminist Theory and the Construction of
Knowledge, Ithaca, NY: Cornell University Press. (Contains a sophisticated feminist
challenge to traditional epistemology.)
*Craig, E. (1990) Knowledge and the State of Nature, Oxford: Oxford
University Press. (The concept of knowledge approached by asking 'why do we have it?'
Assumes some familiarity with the current debate. Mentioned in §10above.)
Davidson, D. (1983) 'A coherence theory of truth and knowledge', in E. LePore (ed.) Truth
and Interpretation: Perspectives on the Philosophy of Donald Davidson, Oxford:
Blackwell, 1986 . (Contains an account of the coherence theory of knowledge, as well as
arguments for the claim that coherent beliefs must be true in the main.)
DeRose, K. (1995) 'Solving the Skeptical Problem', Philosophical Review 104
(January): 1–52. (Develops a contextualist theory of knowledge and uses it to address
the problem of scepticism.)
*Descartes, R. (1641) Meditations on First Philosophy, in E.
Haldane and G.R.T. Ross (eds) The Philosophical Works of Descartes, vol. 1, Mineola, NY:
Dover Publications, 1955. (Contains a classic formulation of rationalistic
foundationalism. Meditation I contains the 'Cartesian' argument for scepticism which he
rejects in the following five meditations; Mediation IV employs the notion of warrant
requiring non-accidentally true beliefs – see especially paragraphs 11–13 on
page 176 of this edition.)
Dewey, J. (1929) The Quest for Certainty: Gifford Lectures 1929, New York:
Capricorn, 1960. (Contains a contextualist account of doubt and justification.)
Dretske F. (1981) Knowledge and the Flow of Information, Cambridge, MA: MIT
Press. (Contains a reliabilist account of knowledge employing information theory.)
Foley, R. (1987) A Theory of Epistemic Rationality, Cambridge, MA: Harvard
University Press. (Develops and defends a sophisticated version of subjective
justification.)
Gettier, E. (1963) 'Is justified true belief knowledge?', Analysis 23 (6):
121–3. (This article was responsible for focusing attention on the inadequacies of
characterizing warrant in terms of justification alone.)
Goldman, A. (1967) 'A causal theory of knowing', Journal of Philosophy 64 (12)
357–72. (The first careful statement of the causal theory of warrant.)
—— (1986) Epistemology and Cognition, Cambridge, MA: Harvard
University Press. (Contains a sophisticated development and defence of reliabilism.)
* Goodman, N. (1965) Fact, Fiction and Forecast, New York:
Bobbs-Merrill, 2nd edn. (Contains the formulation of the Grue Paradox discussed in§9 above.)
Klein, P. (1981) Certainty: A Refutation of Scepticism, Minneapolis, MN:
University of Minnesota Press. (Examines various forms of scepticism and develops the
defeasibility theory of knowledge as a response to scepticism.)
—— (1996) 'Skepticism and closure: why the evil genius argument fails',
Philosophical Topics 23 (1) spring 1995: 215–38. (Develops the 'question-begging'
reply to scepticism briefly discussed in §8 above.)
*Lehrer, K. (1990) Theory of Knowledge, Boulder, CO: Westview
Press. (An accessible introduction to the fundamental questions in epistemology that
defends a version of coherentism and contains arguments against externalism including the
TrueTemp example cited in §6 above; see especially pages 163–75.)
*Locke, J. (1689) An Essay Concerning Human Understanding, ed.
A.C. Fraser, Mineola, New York: Dover Publications, 1959. (Contains the classic defence of
empirical foundationalism conforming to the constraint that knowledge cannot be
accidentally true belief. See especially Book XI, chapter 23, section 28 – pages
413–14 of this edition.)
Lucey, K. (1996) On Knowing and the Known, Buffalo, NY: Prometheus Books. (A
comprehensive and accessible collection of essays on the concept of knowledge.)
Moore, G.E. (1953) Some Main Problems of Philosophy, New York: Collier Books,
1962. (The text of lectures given in 1910–11. See especially chapter 2 which develops
the sense-data foundationalist theory of knowledge.)
Moser, P. (1989) Knowledge and Evidence, Cambridge: Cambridge University
Press. (Contains a sophisticated development of foundationalism.)
Nozick, R. (1981) Philosophical Explanations, Cambridge, MA: Harvard
University Press. (Develops and defends a reliabilist account of knowledge.)
Plantinga, A. (1993) Warrant: The Current Debate, Oxford: Oxford University
Press. (A good source for discussions of various accounts of warrant.)
*Plato (4th century BC) Theaetetus, in The Collected Dialogues of
Plato, ed. E. Hamilton and H. Cairns, Princeton, NJ: Princeton University Press,
1961. (Suggests that knowledge cannot be mere true belief even with a justification; but
Plato does not suggest what the missing feature is.)
Pollock, J. (1986) Contemporary Theories of Knowledge, Totowa, NJ: Rowman
& Littlefield. (Examines various contemporary accounts of knowledge and justification
and develops a sophisticated version of the defeasibility theory.)
Prichard, H.A. (1950) Knowledge and Perception, Oxford: Clarendon Press.
(Defends the view that knowledge is not a species of belief. See page 88 and following.)
Quine, W.V.O and Ullian, J. (1978) The Web of Belief, 2nd edn, New York:
Random House. (A very accessible defence of coherentism.)
Radford, C. (1966) 'Knowledge – by examples' Analysis 27 (1): 1–11.
(Defends the view that belief is not a necessary condition of knowledge.)
Sextus Empiricus (c.200) Outlines of Pyrrhonism, trans. R.G. Bury, Cambridge,
MA: Harvard University Press and London: Heinemann, 1976. (See especially book I, chapter
15, for the argument that the three logically possible theories of justification lead to
scepticism.)
Shope, R. (1983) The Analysis of Knowing, Princeton, NJ: Princeton University
Press. (A thorough discussion of the Gettier Problem and the various approaches to solving
it.)
Sosa, E. (1991) Knowledge in Perspective, Cambridge: Cambridge University
Press. (Contains an interesting version of reliabilism that is designed to address issues
generated by traditional normative epistemology.)
—— (ed.) (1994) Knowledge and Justification, vols 1 and 2,
Brookfield, VT: Ashgate Publishing Company. (Contains a comprehensive set of essays on
knowledge and justification.)
* Zagzebski, L. (1996) Virtues of the Mind, Cambridge:
Cambridge University Press. (Contains a fully developed account of virture epistemology.)
PETER D. KLEIN
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