Bridgman's and Agazzi's Operationalism

According to the main principle of Bridgman’s “operational analysis”, empirical concepts generally mean nothing more than a set of operations: a scientific con­cept “is synonymous with the corresponding set of operations”.¹ A body has a position only in so far as this position can be measured; if a body’s position cannot be measured in principle, then that body’s position does not exist.

I wish to thank Dr. Paolo Baracchi for valuable stylistic suggestions.

¹Bridgman (1927: 5).

should be “uniquely” defined and intersubjectively repeatable; that is, different scientists must be able to perform the same operations with reasonable agreement in their results. As Bridgman says, operations should be such that they “can be repeated by the same person or different persons under the same or different con­ditions without hesitation and with the accompaniment of no phenomena which demand the assertion that there has been failure to repeat”.^[11]

Operationalism in the form it takes in Bridgman’s writings, incurs serious diffi­culties; this fact has induced many authors to dismiss operationalism per se. Since the meaning of a physical term is nothing but the operations leading to its meas­urement, different measuring operations define different physical magnitudes, so that we end up with an implausible proliferation of physical magnitudes. According to Bridgman, the operations by which length is measured should be uniquely specified. Lengths measured by a ruler and lengths inferred from the time that light takes to travel a given distance and return are to be considered as differ­ent physical magnitudes and, strictly speaking, they should have different names: since we have more than one set of operations, and therefore we have more than one concept of length.^[12]

Bridgman was well aware of this consequence,^[13] but the identity of the measure­ment results of lengths that are ‘different’ because they are measured by different instruments remains for him an unexplained accident.

Agazzi’s philosophy of science is decidedly operational in character yet avoids such difficulties. Like Bridgman, Agazzi holds that scientific concepts are inti­mately connected with instrumental operations, but he strongly disagrees with Bridgman as to how experience and theory are to be understood.

On the one hand, for Agazzi it is doing, not sense-data, that is the basis of expe­rience. He insists on the fact that there are meaningful statements that are accepted or rejected on the basis of non-linguistic conditions, that is, of conditions which concern the sphere of “doing something” rather than that of “saying something”.^[14] Building on Poincare and the later Wittgenstein, Agazzi claims that people’s agreement about cognitive content does not hinge on their ‘private’ data but on determinate actions that they perform:

Is such an agreement possible? It is, through operations. This fact is very general and is not limited to scientific practice: When we wish to test whether we agree with someone else about a certain notion (that is, about any content of knowledge) the only means at our disposal is to see whether we both make the same use of that notion. It is not apprehend­ing the same thing in applying the notion that can demonstrate agreement about the notion, but applying the notion in the same way in what are otherwise the same circum­stances. [...] If I have certain reasons to be doubtful about my interlocutor’s having the same notion of red as mine, I could, for example, invite her to select from a bundle of pen­cils a red one. If the person’s way of operating is the same as that which I should have adopted in all circumstances of this kind, I am fully justified in concluding that ‘red’ is an intersubjective notion for us.^[15]

On the other hand, Agazzi differs from Bridgman not only in his view of expe­rience, but also in his view of theory.

if we take a watch and ask what the area of its face is, we are considering it as an object of topology; if we ask what its mass is, or what the laws are that regulate the motion of its balance wheel, or what its influence would be on the magnetic field inside the room where it is located, we are considering it as an object of physics; if we ask what the composition of the alloy is out of which its case is made, or what the degree of purity is of the rubies that are inside it, we are considering it as an object of chemistry; if we ask its price rela­tive to other watches and in relation to the present conditions of world watch production, we are considering it as an object of economics; if we ask whether wearing a watch of a certain kind might be an indication of its owner’s having a certain sort of temperament, we are considering it as an object of psychology; or if our watch is rather old and we ask whether it once belonged to a certain prime minister whose biography we are writing, we are considering it as an historical object.^[16]

The two characterizations of objectivity are intimately connected with each other because the operations by means of which the objects of a given science are “extracted” from reality are the same as those by means of which it is possible to reach an intersubjective agreement among researchers.

In general, we may say that Agazzi’s view of operations, in comparison with Bridgman’s, is closer to that of Hugo Dingier and of German “methodical con­structivism” in maintaining that doing is the basic condition for us to have an epis- temic access and theoretical-perspectival reference to reality.^[18] Together with German “methodical constructivism” Agazzi anticipated the “new experimental­ist” turn, which in the 1980s stressed the importance of experimenting and, more in general, of acting and operating in science. A comparison with Hacking’s enti­ties realism will enable us to better understand Agazzi’s operationalism.

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