Table of Contents
Links

[2. The Main Philosophical Tenets of Logical
Positivism.]
c. The Language of Science.
According to logical positivism, a scientific
theory is an axiomatic system that acquires an
empirical interpretation only by means of
appropriate statements called rules of
correspondence, which establish a correlation
between real objects (or real processes) and the
abstract concepts of the theory. Without such type
of statements a theory lacks of a physical
interpretation and it is not verifiable, but it is
an abstract formal system, whose only requirement
is axioms consistency.
The language of a theory includes three kinds of
terms:
 Logical terms, which include all
mathematical terms.
 Observational terms, which denote objects
or properties that can be directly observed or
measured.
 Theoretical terms, which denote objects or
properties we cannot observe or measure but we
can only infer from direct observations.
According to this distinction, the statements of a
theory are divided in three sets:
 Logical statements, which include only
logical terms.
 Observational statements, which include
observational and logical terms.

Theoretical statements, which include
theoretical, observational and logical
terms. Theoretical statements are divided
in:
 Pure theoretical statements, which
do not include observational
terms.
 Mixed theoretical statements, which
include observational terms. Rules of
correspondence belongs to this set of
statements.
The following table represents the diverse kinds of
statements.
Statements

Lstatements

Ostatements

Tstatements

Pure Tstatements

Mixed Tstatements

Lterms

Lterms

Oterms

Lterms

Tterms

Lterms

Oterms

Tterms

(Abbreviations:
L=Logical, O=Observational,
T=Theoretical)
With respect to the method of ascertaining their
truth or falsity, the statements of a scientific
theory are divided in two sets:
 Analytic a priori statements, whose truth
is based on the meaning of the terms of the
language. They include logical statements,
whose truth is based only on the rules of logic
and mathematics.
 Synthetic a posteriori statements, which
are the notanalytic statements.
Another distinction is between:
 Axtrue or Axfalse statements, which are
either a logical consequence of the axioms of
the theory or incompatible with the
axioms.
 Contingent statements, which are
independent from the axioms of the theory.
The following table represents the diverse kinds of
statements.
True

False

Axtrue

Contingent

Axfalse

Analytic a priori true

Synthetic a posteriori

Analytic a priori false

Logical true

Possible

Logical false

The main points of this thesis about the structure
of scientific theories are:
 The distinction between observational and
theoretical terms
 The distinction between synthetic and
analytic statements
 The distinction between theoretical axioms
and rules of correspondence
 The deductive nature of scientific
theories.
These four points are linked together. Rules of
correspondence give an empirical meaning to
theoretical terms and are analytic, while
theoretical axioms express the empirical portion of
the theory and are synthetic. A theory must be a
deductive system; otherwise, a formal distinction
between the various kinds of sentences and terms is
impossible.
