80
realist perspectives discussed previously, the positivists did not see numbers as
being inherent properties of objects (Carnap, 1966: p. 100):
Let us […] consider the physical magnitude of weight. You pick up a stone. It is heavy. You
compare it with another stone, a much lighter one. If you examine both stones, you will not
come upon any numbers or find any discrete units that can be counted. The phenomenon
itself contains nothing numerical – only your private sensations of weight. […] We introduce the numerical concept of weight by setting up a procedure for measuring it. It is we
who assign numbers to nature. The phenomena exhibit only qualities that we observe.
Since according to this perspective “the phenomena contain nothing numerical”, the
task of measurement is significantly recast (Carnap, 1966: p. 62):
in order to give meaning to such terms as ‘length’ and ‘temperature’, we must have rules for
the process of measuring. These rules are nothing other than rules that tell us how to assign
a certain number to a certain body or process so we can say that this number represents the
value of the magnitude for that body.
In the human sciences, behaviorism (e.g., Skinner, 1971) captured many of the same
intuitions as those behind positivism, such as an emphasis on observables as the
basis for science and an imperative to avoid metaphysical theories and concepts. In
particular, the concept of the human mind was regarded as too unobservable to be a
proper object of scientific inquiry, as opposed to human behavior, which can be
directly observed. Hence, due to its metaphysical grounds, the traditional form of
realism discussed in the previous section was questioned, or simply rejected
(Neurath, Hahn, & Carnap, 1973):
the statements of (critical) realism and idealism about the reality or non-reality of the external world and other minds are of a metaphysical character, because they are open to the
same objections as are the statements of the old metaphysics: they are meaningless, because
unverifiable and without content.
The positivists and behaviorists alike found a kindred spirit in the work of the physicist Percy Bridgman, who, influenced by many of the same cultural and historical
factors that motivated positivism, had proposed a doctrine about the meaning of
theoretical terms that came to be known as operationalism (or “operationism”): “we
mean by any concept nothing more than a set of operations” (Bridgman, 1927: p. 5),
with the corollary that as long as one has a “set of operations” (or “rules”), one has
a measurement, simply by fiat. Thus, according to operationalism, the meaning of
theoretical terms (including property terms) is exhausted by the particular operations undertaken to observe the entities designated by such terms. As Bridgman put
it (p. 5),
the concept of length is […] fixed when the operations by which length is measured are
fixed: that is, the concept of length involves as much as and nothing more than the set of
operations by which length is determined.
Being a semantic (rather than methodological) doctrine, operationalism was not a
theory of measurement per se, but led naturally to the characterization of measurement as simply “any precisely specified operation that yields a number” (Dingle,
1950: p. 11).
4 Philosophical perspectives on measurement
realist perspectives discussed previously, the positivists did not see numbers as
being inherent properties of objects (Carnap, 1966: p. 100):
Let us […] consider the physical magnitude of weight. You pick up a stone. It is heavy. You
compare it with another stone, a much lighter one. If you examine both stones, you will not
come upon any numbers or find any discrete units that can be counted. The phenomenon
itself contains nothing numerical – only your private sensations of weight. […] We introduce the numerical concept of weight by setting up a procedure for measuring it. It is we
who assign numbers to nature. The phenomena exhibit only qualities that we observe.
Since according to this perspective “the phenomena contain nothing numerical”, the
task of measurement is significantly recast (Carnap, 1966: p. 62):
in order to give meaning to such terms as ‘length’ and ‘temperature’, we must have rules for
the process of measuring. These rules are nothing other than rules that tell us how to assign
a certain number to a certain body or process so we can say that this number represents the
value of the magnitude for that body.
In the human sciences, behaviorism (e.g., Skinner, 1971) captured many of the same
intuitions as those behind positivism, such as an emphasis on observables as the
basis for science and an imperative to avoid metaphysical theories and concepts. In
particular, the concept of the human mind was regarded as too unobservable to be a
proper object of scientific inquiry, as opposed to human behavior, which can be
directly observed. Hence, due to its metaphysical grounds, the traditional form of
realism discussed in the previous section was questioned, or simply rejected
(Neurath, Hahn, & Carnap, 1973):
the statements of (critical) realism and idealism about the reality or non-reality of the external world and other minds are of a metaphysical character, because they are open to the
same objections as are the statements of the old metaphysics: they are meaningless, because
unverifiable and without content.
The positivists and behaviorists alike found a kindred spirit in the work of the physicist Percy Bridgman, who, influenced by many of the same cultural and historical
factors that motivated positivism, had proposed a doctrine about the meaning of
theoretical terms that came to be known as operationalism (or “operationism”): “we
mean by any concept nothing more than a set of operations” (Bridgman, 1927: p. 5),
with the corollary that as long as one has a “set of operations” (or “rules”), one has
a measurement, simply by fiat. Thus, according to operationalism, the meaning of
theoretical terms (including property terms) is exhausted by the particular operations undertaken to observe the entities designated by such terms. As Bridgman put
it (p. 5),
the concept of length is […] fixed when the operations by which length is measured are
fixed: that is, the concept of length involves as much as and nothing more than the set of
operations by which length is determined.
Being a semantic (rather than methodological) doctrine, operationalism was not a
theory of measurement per se, but led naturally to the characterization of measurement as simply “any precisely specified operation that yields a number” (Dingle,
1950: p. 11).
4 Philosophical perspectives on measurement