- This article or section should include material from Episteme
Epistemology (from the Greek words episteme=science and
logos=word/speech) is the branch of philosophy that deals with the
nature, origin and scope of knowledge.
Definition of knowledge
Justified true belief
Plato's Theaetetus defined
knowledge as justified true belief.
One implication of this definition is that one can't be said to "know" something just because one believes it and that belief
turns out to be true. An ill person with no medical training but a generally optimistic attitude might believe that she will
recover from her illness quickly. But even if this belief turned out to be true, on the Theaetetus account the patient did not
know that she would get well because her belief lacked justification.
There are, according to this account, three categories of belief which are not knowledge: beliefs which are true but not
justified; beliefs which are justified but not true (sometimes referred to as Justified Error); and beliefs which are neither
justified nor true (sometimes referred to as Unjustified Error).
In the context of epistemology, belief is not used in the everyday sense of having confidence or faith in something. Belief is
used in the sense of asserting the truth of some proposition or statement. Beliefs in this sense are either true or false. If
Jenny believes that x is true, and x is in fact true, then Jenny holds a true belief. But on the Theaetetus
account, if that belief is to count as knowledge, it must also have a suitable justification. Knowledge, therefore, is
distinguished from true belief by its justification, and much of epistemology is concerned with how true beliefs might be
properly justified. This is sometimes referred to as the theory of justification.
The Theaetetus definition agrees with the common sense notion that we can believe things without knowing them. Whilst
knowing p entails that p is true, believing in
p does not, since we can have false beliefs. It also implies that we believe everything that we know. That is, the things we know
form a subset of the things we believe.
The problem of defining knowledge
For most of philosophical history, "knowledge" was taken to mean belief that was justified as true to an absolute certainty.
Any less justified beliefs were called mere "probable opinion." This viewpoint still prevailed at least as late as Bertrand Russell's early 20th century book The Problems of
Philosophy. In the decades that followed, however, philosophers came to think of knowledge as meaning "justified true
belief," and the notion that the belief had to be justified to a certainty was forgotten. In the 1960s, Edmund Gettier criticised this definition of
knowledge by pointing out situations in which a believer has a true belief justified to a reasonable degree, but not to a
certainty, and yet in the situations in question, everyone would agree that the believer does not have knowledge.
The problems show that there are situations in which a belief may
be justified and true, and would not be knowledge. Although being a justified, true belief is necessary for a definition of
knowledge, it is not sufficient. At the least, the set of our justified true beliefs contains things that we would not say that
we know.
Some epistemologists have attempted to find strengthened criteria for knowledge that are not subject to the sorts of
counterexamples Gettier and his many successors have produced. Most of these attempts involve adding a fourth condition or
placing restrictions on the kind or degree of justification suitable to produce knowledge. None of these projects has yet gained
widespread acceptance. Kirkham (see the References section below) has argued that this is because the only definition that could
ever be immune to all such counterexamples is the original one that prevailed from ancient times through Russell: to qualify as
an item of knowledge, a belief must not only be true and justified, the evidence for the belief must necessitate its
truth. But this conclusion is generally resisted since it easily appears to entail a sweeping skepticism.
Justification
Much of epistemology has been concerned with seeking ways to justify knowledge statements.
Irrationalism
Some approaches to justifying knowledge are not rational — that is, they reject the notion that justification must obey
logic or reason. Nihilism started out as a
materialistic political philosophy, but is sometimes redefined as the apparently absurd doctrine that there can be no
justification for knowledge claims — absurd because it appears to be self-contradictory to claim that one knows that
knowledge is impossible, but perhaps for a nihilist, self-contradiction is simply unimportant.
Mysticism is the attempt to arrive at knowledge or belief through
non-rational means such as faith, emotion or intuition rather than employing logic and rationality. An instance of this may be
when one bases one's belief in the existence of a thing merely on one's desire that that thing should exist. Another
example might be the use of a daisy's petals and the phrase "she loves me/ she loves me not" while they are plucked to determine
whether Juliet returns Romeo's affections. In both of these examples, belief is not arrived at through a rational means.
Mysticism need not be an intentional process; one may engage in mysticism without being aware of it.
Rationality
If one does not reject rationality, but still wishes to maintain that knowledge claims cannot be or are not justified, one
might be termed a skeptic. Here we are on firmer
philosophical ground; since skeptics accept the validity of reason, they can present
logical arguments for their case.
For instance, the regress argument has it that one can ask for
the justification for any statement of knowledge. If that justification takes the form of another statement, one can again
reasonably ask for it to be justified, and so forth. This appears to lead to an infinite regress, with every statement justified
by some other statement. It would be impossible to check that each justification is satisfactory, and so relying on such a series
quickly leads to scepticism.
Alternately, one might claim that some knowledge statements do not require justification. Much of the history of epistemology
is the story of conflicting philosophical doctrines claiming that this or that type of knowledge statement has special status.
This view is known as Foundationalism.
One can also avoid the regress if one supposes that the assumption that a knowledge statement can only be supported by another
knowledge statement is simply misguided. Coherentism holds that a knowledge
statement is not justified by some small subset of other knowledge statements, but by the entire set. That is, a statement is
justified if it coheres with all other knowledge claims in the system.
This has the advantage of avoiding the infinite regress without claiming special status for some particular sorts of statements.
But since a system might still be consistent and yet simply wrong, it raises the difficulty of ensuring that the whole system
corresponds in some way with the
truth.
Synthetic and analytic statements
Some statements are such that they appear not to need any justification once one understands their meaning. For example, consider: my father's brother is my uncle. This statement is true in virtue of
the meaning of the terms it contains, and so it seems frivolous to ask for a justification for saying it is true. Philosophers
call such statements analytic. More technically, a statement is analytic if the concept in the predicate is included in
the concept in the subject. In the example, the concept of uncle (the predicate) is included in the concept of being my father's
brother (the subject). Not all analytic statements are as trivial as this example. Mathematical statements are often taken to be analytic.
Synthetic statements, on the other hand, have distinct subjects and predicates. An example would be my father's brother is overweight.
Although anticipated by David Hume, this distinction was more clearly
formulated by Immanuel Kant, and later given a more formal shape by
Frege. Wittgenstein noted in the
Tractatus that analytic statements "express no thoughts", that is, that
they tell us nothing new; although analytic statements do not require justification, they are singularly uninformative.
Epistemological theories
It is common for epistemological theories to avoid skepticism by adopting a foundationalist approach. To do this, they argue
that certain types of statements have a special epistemological status — that of not needing to be justified. So it is
possible to classify epistemological theories according to the type of statement that each argues has this special status.
Rationalism
Rationalists believe that there are a priori or innate
ideas that are not derived from sense experience. These ideas, however, may be justified by experience. These ideas may in some way derive
from the structure of the human mind, or they may exist independently of the mind. If they
exist independently, they may be understood by a human mind once it reaches a necessary degree of sophistication.
The epitome of the rationalist view is Descartes' I think therefore I am, in which the skeptic is invited to consider that
the mere fact that they doubt implies that there is a doubter. Spinoza derived a
rationalist system in which there is only one substance, God. Leibniz derived a system in which there are an infinite number of substances, his Monads.
Empiricism
Empiricists claim knowledge is a product of human experience. Statements of observations take pride of place in empiricist theory. Naïve empiricism holds simply that our ideas and theories need to be
tested against reality, and accepted or rejected on the basis of how well they
correspond to the facts. The central problem for epistemology then becomes explaining this correspondence.
Empiricism is associated with science. While there can be little doubt about the
effectiveness of science, there is much philosophical debate about how and why science works. The Scientific Method was once favoured as the reason for scientific success,
but recently difficulties in the philosophy of science
have led to a rise in Coherentism.
Naïve realism
Naïve realism, or Common-Sense realism is the belief that there is a
real external world, and that our perceptions are caused directly by that world. It has its foundation in causation in that an object being there causes us to see it. Thus, it follows, the world
remains as it is when it is perceived - when it is not being perceived - a room is still there once we exit. The opposite
theory to this is solipsism. Naïve realism fails to take into account the
psychology of perception.
Representationalism
Representationalism or Representative realism, unlike Naïve Realism,
Representationalism proposes that we cannot see the external world directly, but only through our perceptual representations of
it. In other words, the objects and the world that you see around you are not the world itself, but merely an internal
virtual-reality replica of that world. The so-called veil of
perception removes the real world from our direct inspection.
Idealism
Idealism holds that what we refer to and perceive as the external world is in
some way an artifice of the mind. Analytic statements, for example, mathematical truths, are known to be the case without
reference to the external world, and these are taken to be exemplary knowledge statements. George Berkeley, Immanuel Kant and Georg Hegel held various idealist views.
Phenomenalism
Phenomenalism is a development from George Berkeley's claim that to be is to be perceived. According to phenomenalism, when you see "a
tree" you see a certain perception of a brown shape. On this view, one shouldn't think of objects as distinct substances, which
interact with our senses so that we may perceive them; rather we should conclude that all that really exists is the perception
itself.
Contemporary approaches
Much contemporary work in epistemology depends on the two categories: foundationalism and coherentism.
Recently, Susan Haack has attempted to fuse these two approaches into her
doctrine of Foundherentism,
which accrues degrees of relative confidence to beliefs by mediating between the two approaches. She covers this in her book
Evidence and Inquiry: Towards Reconstruction in
Epistemology.
Reliabilism involves making predictions from what usually happens (e.g.
claiming to speak Russian can be proved by a Russian speaker). There are two methods of reliable justification: External
(Reliable, e.g. a doctor diagnosing me); and Internal (Unreliable, e.g. relying on sensations from my internal organs). But how
do we know that something that is reliable is right? A computer with a bug in it is reliably incorrect.
In the aftermath of the publication of the Gettier problem and
other similar scenarios, a number of new definitions were formulated. While there is general consensus that truth and belief are
two necessary facets of knowledge, there is a debate about what needs to be added to the true beliefs to make them knowledge, and
a debate about whether justification is necessary in the definition at all.
Some examples of these new definitions include (where S is the belief holder and p is the belief):
- Peter Unger's "No accident account of knowledge", which defines
knowledge as "S knows p if and only if it is not at all accidental that S's belief in p is
true".
- The "Defeasibilty account of knowledge", where "There is no other proposition (q), such that if S became
justified in q, S would no longer be justified in p". Under this account, q is known as the
"defeater".
- The "Causational Account", where "The fact of p causes S's belief in p"
- A problem with the Causational account is that deviant causal chains can emerge. Philosopher Alvin Goldman added that "Fact that
p, causes fact that q, causes S's belief in q is not knowledge, but belief in q, from which
p is inferred, is knowledge". However, there must be an awareness of the causal chain.
- The Conditional Account associated with Robert Nozick.
S believes in p, p is the case, and if p were not the case, then S would not believe it.
- The "Reliable Analysis" account, which adds to the "justified true belief" definition that "S arrived at
p by a reliable method, or S is a reliable judge in such matters".
Epistemic theories
Epistemic philosophers
Related topics
External links and references
- Is
Justified True Belief Knowledge? (http://www.ditext.com/gettier/gettier.html)
from Analysis, Vol. 23, pp. 121-23 (1963) by Edmund L.
Gettier, transcribed by Andrew Chrucky (Sept. 13, 1997).
- Richard Kirkham, "Does the Gettier Problem Rest on a Mistake?" Mind, 93, 1984.
- Bertrand Russell, The Problems of Philosophy Hackett Pub Co Inc, Hardcover ISBN 087220099X, Paperback ISBN 0879754974 plus many others
- Groovyweb (http://www.groovyweb.uklinux.net/?page_name=philosophy%20of%20knowledge&category=philosophy)
- Philosophy online (http://www.philosophyonline.co.uk/tok/tokhome.htm)
- The
Epistemology Page (http://pantheon.yale.edu/~kd47/e-page.htm) by Keith
DeRose
- An
Introduction to Epistemology (http://www.galilean-library.org/int5.html) by
Paul Newall, aimed at beginners.
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