136
indistinguishability of properties of objects in a simple way: two properties of
objects are indistinguishable if they identify the same universal property, or if
they identify distinct universal properties which prove to be indistinguishable
according to the available empirical means. This is an instance of a position that
in the philosophical tradition is often called realism.
The two positions share the common condition that properties of objects are particular entities, spatiotemporally situated. Whether things such as lengths and reading
comprehension abilities are concepts, as nominalists assert, or entities that exist in
the world independently of the knowledge that we have of them, as realists assert, is
an ontological alternative that affects the interpretation of some key components of
measurement, in particular the meaning of the Basic Evaluation Equation, but cannot be decided by experimental activity.
35
Each position can be translated into the
other one safely (and usually unproblematically, though sometimes in a cumbersome way—see the examples in Footnote 35; see also Mari & Giordani, 2012:
p. 762).
We believe that most scientists, technologists, and practitioners, in both the physical and human sciences, are (perhaps unconsciously) at least moderate realists
about properties, in that they consider individual properties such as lengths and
reading comprehension abilities to exist in some sense (see also the discussion in
Sect. 6.6). If explicitly asked, they might plausibly accept the more complex ontology in which properties are considered to be universals, given that the adoption of
the more complex ontology does not affect day-to-day practice, and simplifies the
reporting of experimental results by at least provisionally accounting for the
observed indistinguishability of properties of objects in terms of their equality, such
that properties of objects can be included in relations interpreted as actual equalities. Furthermore, this ontology allows for a more flexible treatment of properties,
in particular by admitting the possibility of formally handling properties that might
currently not be instantiated by any existing object (and maybe even properties that
35 The alternative between realism and nominalism relates not only to properties, as realism and
nominalism clash about the existence of universals as such. Take these two examples: “the steam
engine was invented at the end of the seventeenth century” and “the tiger is an endangered species”. For a nominalist they cannot be literally true, because “the steam engine” and “the tiger” do
not refer to anything in the world, but only to concepts we adopt to organize our knowledge. He or
she would explain the meaning of the two sentences by considering them to be shorthands for
something like “the first object that we presently conceptualize as was invented at
the end of seventeenth century” and “the current number of objects that we conceptualize as
is less than a given threshold”, or even more explicitly “the extension of
was empty before the end of seventeenth century” and “the cardinality of the current extension of
is less than a given threshold”. This reduction strategy may become cumbersome. For
example, in the case of “Shakespeare’s works include 39 plays”, the nominalist would claim that
the quantification is on concepts, so that, e.g., A Midsummer Night’s Dream does not exist as such
but it is only a concept by means of which we identify a subset of the objects (paper volumes, digital files, theater performances, etc.) with the property of having Shakespeare as their author.
Assessing the truth of the sentence would then require first of all assessing an equivalence criterion
between such disparate entities, and then counting the number of the so obtained equivalence
classes.
5 What is measured?
indistinguishability of properties of objects in a simple way: two properties of
objects are indistinguishable if they identify the same universal property, or if
they identify distinct universal properties which prove to be indistinguishable
according to the available empirical means. This is an instance of a position that
in the philosophical tradition is often called realism.
The two positions share the common condition that properties of objects are particular entities, spatiotemporally situated. Whether things such as lengths and reading
comprehension abilities are concepts, as nominalists assert, or entities that exist in
the world independently of the knowledge that we have of them, as realists assert, is
an ontological alternative that affects the interpretation of some key components of
measurement, in particular the meaning of the Basic Evaluation Equation, but cannot be decided by experimental activity.
35
Each position can be translated into the
other one safely (and usually unproblematically, though sometimes in a cumbersome way—see the examples in Footnote 35; see also Mari & Giordani, 2012:
p. 762).
We believe that most scientists, technologists, and practitioners, in both the physical and human sciences, are (perhaps unconsciously) at least moderate realists
about properties, in that they consider individual properties such as lengths and
reading comprehension abilities to exist in some sense (see also the discussion in
Sect. 6.6). If explicitly asked, they might plausibly accept the more complex ontology in which properties are considered to be universals, given that the adoption of
the more complex ontology does not affect day-to-day practice, and simplifies the
reporting of experimental results by at least provisionally accounting for the
observed indistinguishability of properties of objects in terms of their equality, such
that properties of objects can be included in relations interpreted as actual equalities. Furthermore, this ontology allows for a more flexible treatment of properties,
in particular by admitting the possibility of formally handling properties that might
currently not be instantiated by any existing object (and maybe even properties that
35 The alternative between realism and nominalism relates not only to properties, as realism and
nominalism clash about the existence of universals as such. Take these two examples: “the steam
engine was invented at the end of the seventeenth century” and “the tiger is an endangered species”. For a nominalist they cannot be literally true, because “the steam engine” and “the tiger” do
not refer to anything in the world, but only to concepts we adopt to organize our knowledge. He or
she would explain the meaning of the two sentences by considering them to be shorthands for
something like “the first object that we presently conceptualize as
the end of seventeenth century” and “the current number of objects that we conceptualize as
was empty before the end of seventeenth century” and “the cardinality of the current extension of
example, in the case of “Shakespeare’s works include 39 plays”, the nominalist would claim that
the quantification is on concepts, so that, e.g., A Midsummer Night’s Dream does not exist as such
but it is only a concept by means of which we identify a subset of the objects (paper volumes, digital files, theater performances, etc.) with the property of having Shakespeare as their author.
Assessing the truth of the sentence would then require first of all assessing an equivalence criterion
between such disparate entities, and then counting the number of the so obtained equivalence
classes.
5 What is measured?