Forms of knowledge
Knowledge can be classified in several ways. Firstly, it can be either
explicit (self-conscious) or implicit (tacit, hidden from
self-consciousness). Secondly, it can be either propositional
or non-propositional (something which cannot be represented by
propositions, e.g. knowing how to do something?). Propositional
knowledge can further be divided into empirical or a posteriori
and non-epirical or a priori knowledge. This division is
usually associated to rationalism and empirism: rationalists
like Descartes, Leibniz and Spinoza believed that all knowledge about
real world is a priori, while empirists like Locke, Berkeley and Hume
believed it is a posteriori.
Kant tried to combine the rationalistic and empiristic traditions. He
believed that a priori knowledge is independent of any experience, and
based on pure understanding and reason. It is also necessary, like
logical or mathematical truths (especially tautologies). A posteriori
knowledge is based on experience and thus contingent (we don't have
direct access to material world). The knowledge is represented as
judgements, which can be analytic or synthetic. Analytic
judgements explain, but they don't enlarge our knowledge. Synthetic
judgements really enlarge our knowledge by adding new contents. Kant
argued that mathematical, physical and metaphysical judgements are
synthetic a priori, i.e. they enlarge our knowledge and are based on
reason. (This seems to be the heighest category: new knowledge, which
Locke has constucted a more complex view, which adds intuitive
element to empirism and rationalism. He has distinguished three types
of knowledge: 1) knowledge based on perceptions i.e. empirical
knowledge, which is not necessary but only probable, 2) intuitive
knowledge, which concerns our own being and is doubtless, and 3)
demontsrative knowledge, which is based on proofs, i.e. rational
knowledge. Primary ideas are produced by our perceptions or
self-study, and more complex ideas are derived from them by combining,
abstracting and creating relations between them. (Question: what about
demonstrative knowledge? Is it derived from empirical and intuitive
knowledge? Are all complex ideas demonstrative knowledge?)
The classical definition of knowledge (by
Socrates) as "justified true belief" concerns only propositional
knowledge. However, scientific knowledge is propositional by its
nature (could it be something else?), and thus it is relevant to
consider this definition more carefully. (An interesting question is,
how to define non-propositional knowledge?!)
Crisholm (Theory of knowledge, 1966) has speculated the third
classical criteria of knowledge, namely justification. He argues that
we cannot say that the knower "has adequate evidense", but that
something "is evident" for her/him. He tries to justify this by
explaining that the subject can have adequate evidense, even if s/he
doesn't know that s/he knows. However, his own formulation produces
same problems, as he himself states: some propositions can be evident
to the subject, and still the subject doesn't know that they are
true. He also speculates how to define "evident" and finally selects
"more reasonable" (i.e. if believing is more reasonable than
withholding, it is evident). Crisholm's speculations are so senseless
and self-contradictory that they are not even worth of disarguing here.
- Knowledge is belief: If you know p, you also believe p (but not
vice versa). This hints that the knower has some psychological
relation to known proposition. This psychological state can exist even
if it is not manifested. It is noteworthy that not all beliefs are
knowledge: the beliefs can also be false.
- Knowledge is true belief: Truth seems to be a necessary
condition for knowledge, but it is really hard to define
universally. In correspondence theory truth is defined as
correspondence between the proposition and the actual proposition. But
how to check the actual proposition? Do we have any direct access to
reality? This demostrates that epistemology is strongly connected to
ontology, i.e. what we consider as being or modes of
being. Coherence theory requires only that the proposition is
consistent with the other system (i.e. it doesn't cause
contradiction). Obviously, this is minimal requirement for truth,
but hardly satisfactory. According to pragmatic view truth is
defined as usefulness: truth is what works best in reality. Naturally,
usefulness depends on who has defined it: it can measure economical
profit, or diversity of political opinions. This definition also
holds largely in empirical science: the theory which predict future
events best, is considered the most probable or "true" theory.
- Knowledge is justified true belief: The point is that truth
is not enough - it could be pure guess. The knower must have adequate
indication that the proposition is true - i.e. evidence. Alston
defines justification as "what is epistemically good for maximizing
truth and minimizing falsity". This adds another side to analysis: we
want to get assured about the truth of proposition, but in the same
time eliminate its falsity.
To be scientific the knowledge must be
The scientific methods should also fill some criteria, which try to
guarantee quality of scientific knowledge. (These are important and
quite permanent part of general paradigm of science):
- communicable: It is something which is discussed.
- general: generalized vs. separate fragments of
- conceptual: represented by concepts vs. intuitive ideas (i.e.
explicit and propositional knowledge)
- true or probable
- argumented: It can be proved or demonstrated.
- progressive: knowledge base is expanded by using this method
- self-correcting: the errors get corrected by this method.
- publicity: arguments are public for anyone
- justifiable: the arguments are satisfactory
- The Cambridge Dictionary of Philosophy. 2nd edition. General editor R.
Audi. Cambridge university Press, 1999.
- Crisholm: Theory of knowledge, 1966. Prentice Hall, Inc. Englewood
Cliffs, N.J. Ch 1: Knowledge and True Opinion.
- Saarinen, E.: Länsimaisen filosofian historia huipulta huipulle
Sokrateesta Marxiin. WSOY 1985.