65
2012: 1.6). In this context a measurement problem starts from a previously defined
general property and only requires that one identifies the individual property
intended to be measured as an instance of that general property.
18
Of course, as
physics discovers new properties, and seeks to measure them, it may be that at least
initially these assumptions cannot be met.
Thus, things are not always so simple. In the case of physical quantities, interesting examples have been studied of situations in which measurements were instrumental in the very definition of the general property (a well-known case is
temperature, analyzed in particular by Chang, 2007). In these cases the neat sequential procedure—from the assumption of an already defined general property and a
preexisting measuring instrument to the identification of an instance of that property
as the measurand and then the design and operation of a measuring instrument—
becomes a complex loop in which the distinctions between the activities of defining
the property, constructing the measurement system, and performing the measurement are blurred, and one might operate by measuring without a clear idea of what
one is measuring. It may happen—in the words of Thomas S. Kuhn—that “many of
the early experiments involving [a new instrument] read like investigations of that
new instrument rather than like investigations with it” (1961: p. 188).
19
In the context of the human sciences, which currently lack anything like an ISQ,
this situation of general property definition intertwined with measurement is not
unusual. New variables may be readily obtained via computation, and without a
system such as the ISQ to establish that properties are well defined, such variables
are not necessarily the formal counterpart of empirical properties. It is indeed not
hard to provide examples of variables, such as the “hage” of a person obtained as the
product of his or her height and age (Ellis, 1968: p. 31), which can be computed
very accurately, yet nevertheless do not seem to correspond to any property of individual humans. Less trivially, this problem becomes critical in the context of complex concepts such as the social status of an individual, the quality of the research
18 In the context of metrology it is usual to use the expression “measurand definition” (from which,
e.g., “definitional uncertainty”, JCGM, 2012: 2.27). Under the assumption that properties of
objects are empirical, strictly speaking what can be defined is not a measurand but the concept of
it (consider the parallel case of objects: what can be defined is not a rod, but the concept of a rod):
a measurand can be instead identified, through a sufficiently specific definition or, more simply but
less usefully, a direct reference (“the measurand is the length of that rod” uttered while indicating
a rod).
19 The case of temperature is again exemplary of the problems that can be encountered. In the
words of Hasok Chang (2007: p. 4): “How do we know that our thermometers tell us the temperature correctly, especially when they disagree with each other? How can we test whether the fluid in
our thermometer expands regularly with increasing temperature, without a circular reliance on the
temperature readings provided by the thermometer itself? How did people without thermometers
learn that water boiled or ice melted always at the same temperature, so that those phenomena
could be used as ‘fixed points’ for calibrating thermometers? In the extremes of hot and cold where
all known thermometers broke down materially, how were new standards of temperature established and verified? And were there any reliable theories to support the thermometric practices, and
if so, how was it possible to test those theories empirically, in the absence of thermometry that was
already well established?”.
3.4 The conceptual context
2012: 1.6). In this context a measurement problem starts from a previously defined
general property and only requires that one identifies the individual property
intended to be measured as an instance of that general property.
18
Of course, as
physics discovers new properties, and seeks to measure them, it may be that at least
initially these assumptions cannot be met.
Thus, things are not always so simple. In the case of physical quantities, interesting examples have been studied of situations in which measurements were instrumental in the very definition of the general property (a well-known case is
temperature, analyzed in particular by Chang, 2007). In these cases the neat sequential procedure—from the assumption of an already defined general property and a
preexisting measuring instrument to the identification of an instance of that property
as the measurand and then the design and operation of a measuring instrument—
becomes a complex loop in which the distinctions between the activities of defining
the property, constructing the measurement system, and performing the measurement are blurred, and one might operate by measuring without a clear idea of what
one is measuring. It may happen—in the words of Thomas S. Kuhn—that “many of
the early experiments involving [a new instrument] read like investigations of that
new instrument rather than like investigations with it” (1961: p. 188).
19
In the context of the human sciences, which currently lack anything like an ISQ,
this situation of general property definition intertwined with measurement is not
unusual. New variables may be readily obtained via computation, and without a
system such as the ISQ to establish that properties are well defined, such variables
are not necessarily the formal counterpart of empirical properties. It is indeed not
hard to provide examples of variables, such as the “hage” of a person obtained as the
product of his or her height and age (Ellis, 1968: p. 31), which can be computed
very accurately, yet nevertheless do not seem to correspond to any property of individual humans. Less trivially, this problem becomes critical in the context of complex concepts such as the social status of an individual, the quality of the research
18 In the context of metrology it is usual to use the expression “measurand definition” (from which,
e.g., “definitional uncertainty”, JCGM, 2012: 2.27). Under the assumption that properties of
objects are empirical, strictly speaking what can be defined is not a measurand but the concept of
it (consider the parallel case of objects: what can be defined is not a rod, but the concept of a rod):
a measurand can be instead identified, through a sufficiently specific definition or, more simply but
less usefully, a direct reference (“the measurand is the length of that rod” uttered while indicating
a rod).
19 The case of temperature is again exemplary of the problems that can be encountered. In the
words of Hasok Chang (2007: p. 4): “How do we know that our thermometers tell us the temperature correctly, especially when they disagree with each other? How can we test whether the fluid in
our thermometer expands regularly with increasing temperature, without a circular reliance on the
temperature readings provided by the thermometer itself? How did people without thermometers
learn that water boiled or ice melted always at the same temperature, so that those phenomena
could be used as ‘fixed points’ for calibrating thermometers? In the extremes of hot and cold where
all known thermometers broke down materially, how were new standards of temperature established and verified? And were there any reliable theories to support the thermometric practices, and
if so, how was it possible to test those theories empirically, in the absence of thermometry that was
already well established?”.
3.4 The conceptual context