Technical Functions as Dispositions: a Critical Assessment

The paper argues that in order to understand the nature of technological knowledge (i.e., knowledge of technical artefacts as distinct from knowledge of natural objects) it is necessary to develop an epistemology of technical functions. This epistemology has to address the problem of the meaning of the notion of function. In the dominant interpretations, functions are considered to be dispositions, comparable to physical dispositions such as fragility and solubility. It is argued that this conception of functions is principally flawed. With the help of Carnap’s analysis of dispositional terms it is shown that there is a fundamental difference between physical dispositional terms and functional dispositional terms. This difference concerns the issue of the normativity; with regard to functional dispositions, it makes sense to construct normative statements of a particular kind, with regard to physical dispositions it does not. Introduction: the dual nature of technological knowledge Elsewhere we have argued for the dual ontological nature of technical artefacts (Kroes 1998). On the one hand, they are physical objects or processes, with a specific structure (set of properties), the behaviour of which is governed by the (causal) laws of physics. On the other hand, an essential aspect of any technical object is its function; think away from a technical object its function and what is left is just some kind of physical object. It is by virtue of its practical function that an object is a technical object. The function of technical objects, however, cannot be isolated from the context of intentional action (use). The function of an object, in the sense of being a means to an end, is grounded within that context. When we associate intentional action with the social world (in opposition to causal action with the physical world), the function can be said to be a social construction. So, a technical artefact is at the same time a physical construction as well as a social construction: it has a dual ontological nature. 1 By using the notion of social construction I am not implying that the context of intentional use of a technical artefact is inherently a social context. I leave that an open question. Techné 5:3 Spring 2001 Kroes. Technical Functions ... / 2 This dual ontological nature has its counterpart at the level of technological knowledge. Technological knowledge also has two faces. On the one hand, it concerns the physical (or structural) properties of technical objects. Consider a car. It has all kinds of physical properties that are of crucial technical importance, such as its weight, the amount of fuel consumption per kilometre, its shape, its air resistance, its breaking power, the shape of its combustion chambers, the temperature and pressure in the combustion chamber during a combustion cycle etc. Knowledge of these physical properties, of how they hang together and of the physical/chemical processes taking place in, for instance, the engine of the car during operation, is part and parcel of standard technological knowledge of cars. On the other hand, technological knowledge also concerns the functional properties of objects. Apart from knowing that a certain object has a round shape, is made of steel etc., we also know that it is a steering wheel, i.e. that it performs a certain function in a car. Car designers, mechanics and users express at least part of their knowledge about technical objects, like a car, with the help of functional concepts. They claim for instance that object X has function Y, and assume that, just as a claim about a physical property, such a claim about object X may be true or false. Technological knowledge, we may conclude, not only consists of statements concerning the physical structure of technical artefacts, but also of statements concerning their functions. From the point of view of engineering design, the idea that technological knowledge involves knowledge of structures as well as of functions is rather obvious. The engineering design process may be interpreted as a problem solving process in which a function is translated or transformed into a structure (Kroes 1996). The process usually starts by gathering knowledge about the desired function, and ends with a design that is a description or blue print of a physical object, system or process that realises the desired function. Various techniques are used by engineers to solve design problems. Some of these clearly illustrate the dual nature of technological knowledge, for instance, the techniques known as structural and functional decomposition of technical objects. In a structural decomposition, an object is decomposed in terms of the physical parts from which it is made or built. In a functional decomposition the overall function of a technical object is decomposed into a number of sub-functions whose composite functionality is the same as the overall function of the object (e.g. Dym 1994, p. 135). Knowledge about how to decompose overall functions into sub-functions is just as well part and parcel of technological knowledge as knowledge about what kind of physical structure realises a certain function. Thus, engineering design requires knowledge of functions and of structures. Techné 5:3 Spring 2001 Kroes. Technical Functions ... / 3 In spite of the obvious importance of knowledge of functions for engineers, technicians and users of technology, little attention has been given to this kind of knowledge in analyses of the nature of technological knowledge. In the standard text on technological knowledge, Vincenti’s What engineers know and how they know it (1990), no systematic discussion of this kind of knowledge is to be found. Vincenti discusses six categories in his anatomy of design knowledge: (1)fundamental design concepts, (2) criteria and specifications, (3) theoretical tools, (4) quantitative data, (5)practical considerations, and (6) design instrumentalities. Remarkably, a special category for knowledge of functions is lacking. The category of fundamental design concepts appears to come most close to functional knowledge. It contains operational principles that explain how a device works, i.e. in the words of Polanyi “how its characteristic parts... fulfil their special function in combining to an overall operation which achieves the purpose” (Vincenti 1990. P. 208). Thus knowledge of fundamental design concepts involves knowledge of functions and purposes. In further discussing fundamental design concepts Vincenti remarks that operational principles provide “an important point of difference between technology and science” (p.209). But a systematic analysis of what kind of knowledge knowledge of functions is and how this type of knowledge is related to knowledge of physical properties of objects is missing. A discussion of these questions has also not been found in the category of theoretical tools. These are tools used by engineers to carry out their design tasks. Under this heading Vincenti discusses intellectual concepts, which provide the language for the structure of thinking in engineering. Here he refers among others to basic ideas from science. But clearly, functional concepts (not borrowed from science since they do not fit into the scientific conception of the world) are as important for thinking in engineering design as are scientific concepts. But Vincenti does not explicitly mention them. The philosophical analysis of knowledge of functions and of the meaning of functional concepts is a rather neglected topic. Particularly this is the case for technical knowledge and technical functions. This is not very surprising in the light of the strong influence of modern science, where the use of functional concepts is generally considered controversial. Within the philosophy of the physical sciences there is a strong tenet to reduce 2 More generally, the philosophical analysis of the nature of technical artefacts and their functions is an almost non-existent field. Preston (1998, p. 215) makes the following observation: “The nature of artifacts generally, and the nature of their functions in particular, is taken to be so transparently obvious, however, that virtually nobody has bothered to examine it at any length.” See also Dipert (1993, p. 8). Techné 5:3 Spring 2001 Kroes. Technical Functions ... / 4 functional concepts to structural ones. A notable exception is the use of functions in biology. This use has been a topic of intense research and debate among philosophers of science (biology), but this debate has not resulted in a generally accepted interpretation of the nature of biological functions. Prima facie, however, there seems to be an important difference between the notions of technical and biological functions; the former implicitly refers to a context of intentional human action, whereas the latter does not. Central issues with regard to knowledge of functions are: What does it mean to state that object X has function Y?; What are the conditions of truth for statements like “Object X has function Y’?; and How can the statement that object X has function Y be justified? Bearing in mind the above remark about the difference between biological and technical functions, the answers to these questions may depend significantly on the kind of functions considered. Here, we are primarily interested in technical functions. A systematic treatment of these questions for technical functions is still missing. The conclusion to be drawn from the foregoing is that in order to understand the nature of technological knowledge, especially in comparison to scientific knowledge, these questions have to be addressed. In other words, it is necessary to develop an epistemology of technical functions as distinct from an epistemology of structures (we will come back to this point later on). As a first step in that direction, we will examine below in detail the idea that technical functions are dispositions. We will start, ho