Knowledge, Truth, and Meaning
An excerpt from the online hypertext Human
Knowledge: Foundations and Limits.
is justified true
belief. Belief in a proposition p is justified if 1) it is developed
though a process that reliably yields truth, 2) it is appropriately
caused by the fact that p is true, and 3) it would generally not be
held if p were false. The reliability criterion entails that
synthetic (i.e. inductive) knowledge is always provisional. The causal
and counterfactual criteria entail that whether a true belief counts as
knowledge depends on inherently imprecise judgments concerning whether
the believer is accidentally right. Operationally, a belief is
justified if and only if it is convincing and defensible.
is logical and parsimonious consistency with evidence
and with other truth. Evidence is
and all perceived circumstances.
The Principle of Parsimony (or Occam's
Razor) is that the simpler of two explanations is to be preferred
they are otherwise equivalent.
Humans have proposed several criteria for truth.
The Correspondence Theory begs
the question by assuming that reality can be known directly and
Depending on the meaning of 'complete', the Coherence Theory either
to the Correspondence Theory, or it makes truth a purely social (or
construct. The Pragmatic Theory either underdetermines the truth
of certain propositions, or it reduces to a variant of the social
of the Coherence Theory. The proper notion of truth is coherence
grounded in correspondence.
The Correspondence Theory of Truth is that the terms of true
map to elements of reality in a way that validates the proposition.
The Coherence Theory of Truth is that true propositions are
in the system of mutually coherent propositions that is more complete
any rival system.
The Pragmatic Theory of Truth is that true propositions are
that are most useful to believe and that are thus "fated to be
agreed to by all who investigate".
Origins of Knowledge
can classified according to the
dependence of their truth value
on their terms:
Provisionality. All synthetic propositions (including this one) can
only be known from experience and are subject to doubt. It is logically
possible that all experience is deceptive and that the world is
The only absolutely certain truths are true analytic propositions and
synthetic proposition that something exists.
Analytic propositions are
whose truth value can be deduced from only the definitions of their
whose truth value cannot be deduced from only the definitions of their
Cogito Ergo Sum. Descartes
argued "I think, therefore I am". However, "I" could be illusory, and
fact of my thinking only warrants the certainty that something exists:
cogito ergo est.
The denotation (or extension)
of a term
is the set of entities
it refers to. The connotation
of a term
is the properties and concept(s) associated
of a term
is the context-sensitive connotation
ultimately established by its relevant denotation
holds that a statement is propositionally meaningless (i.e. states no
if it is neither logically decidable nor empirically verifiable. Positivism
is a stricter form of Empiricism
Theories of Meaning
Humans have proposed three sorts of explanation for meaning:
The Referential Theory is confounded
by terms that have the same referent but different meaning, such as
star' and 'evening star'. The Conceptual Theory reduces to
circularity for many concepts that can only be described by the word(s)
to which they help give meaning. The Behavioral Theory is undermined by
behaviors and dispositions that underspecify the meanings they are
The Referential Theory of Meaning is that the meaning of a term
is the things in the world it refers to.
The Conceptual Theory of Meaning is that the meaning of a term
the properties and concepts associated with it.
The Behavioral Theory of Meaning is that the meaning of a term
of the behaviors and dispositions associated with it.
Theories of Knowledge
Humans fall into two camps depending on whether they believe synthetic
a priori knowledge is possible:
Rationalism incorrectly assumes
that existence arranges for reason to discover the nature of reality
Rationalism is the thesis that
propositions can be known from reason alone and independent of any
Empiricism is the thesis that all
propositions can only be known from experience.