The knowledge modality of normativity

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CHE MEng

182 In the context of the study normativity refers to evaluative and deontic aspects of the use of concepts. As discussed in chapter two, various philosophers of technology argue for a strong normative aspect of engineering science knowledge. The functionality and intentionality of engineering systems play an important role to explain this, and were evident in the data. Considering the typical fundamental values in the sciences (explanation and description), it would be reasonable to expect more value-neutral and descriptive knowledge in the sciences. In the light of the anticipated importance of normativity in engineering, the mode ends developed for the normative modality continuum of the knowledge were ‘constitutive’ and ‘incidental’. This was done to reflect that at the one end normativity is an intrinsic quality of the knowledge, whereas at the other end normativity, when present, it seems almost peripheral.

The normative knowledge modality is unmistakeable in the engineering sciences, and is especially well-developed in the mechanical engineering textbook. There were numerous and varied examples of normativity in the mechanical engineering textbook data, and as a

consequence knowledge is coded ‘constitutive’. Normativity is an intrinsic quality of thermodynamics knowledge in the mechanical engineering text. Some of the instances of normativity found in the data were more implicit, as in the cost calculations in the problems set, and in the choice of terminology employed, like ‘steam quality’ to refer to the moisture content of steam in power generation, and the ‘dumping’ and ‘wasting’ of energy in heat engine cycles. In other cases the normativity is more explicit: there is an extended discussion on the quality of energy, with some forms of energy (eg. electrical energy) more valuable than other forms of energy (eg. heat energy). Efficiency is an important topic, and both First Law efficiencies (the performance of a machine or process) and Second Law (thermal) efficiencies are covered in detail. Second Law efficiency (the formulation that thermal efficiency is intrinsically lower than unity), expressed in the equation = 1 −𝑄𝐿

𝑄𝐻 , is dealt with across all disciplines, as would be expected in textbooks that cover the Second Law. However, the normative aspect of this concept is particularly strong in the mechanical engineering textbook where it is emphasised as the fixed theoretical upper limit for the efficiency of a heat engine. In the mechanical engineering text this limit provides a standard against which actual devices can be compared and improved. A starkly different emphasis is particularly evident in the physics textbook where the author talks about the equation as a purely mathematical construct, and considers how to how to produce a less efficient engine (as though this could be conceived of as equally desirable) by generating extra entropy in a process, dumping more energy to leave less energy to convert to work (see the discussion under 6.3.2). The mechanical engineering textbook also carries examples where the authors quantify the error margin introduced by approximation. Although approximation is a simplification (and therefore refers to idealisation), the focus here is on

183 quantifying the inaccuracy introduced by this type of idealisation. This is an instance where an idealised deliberation (the approximation) is given a normative inclination.

Normativity is also evident in the chemical engineering text, but to a lesser degree, and more implicit (this could perhaps partly be explained by Alexander’s (2009, p. 1008) observation that that the notion of efficiency has been historically more prominent in mechanical engineering than in other engineering professions). An interesting example of normativity at work in the chemical engineering textbook is found in the discussion of the mechanical explosion of an over- pressurised vessel (high pressure vessels are typical in the chemical engineering industrial environment). Here the simplifying assumption made (neglecting the generation of entropy in the explosion) is justified by the over-riding safety concerns of engineers. The approximation gives an over-estimate of the damage rather than simply a less accurate solution. Therefore the motivation for coding the normative modality as principal (rather than the idealisation

modality) with a mode of constitutive normativity is found in the abiding engineering concern for safety.

Normative aspects are virtually absent in the thermodynamics knowledge in the sciences: there is no discussion of First Law efficiency in either the chemistry or the physics text. The

theoretical limit on Second Law efficiency is briefly mentioned as a consequence of entropy generation in both cases, but the implications in real-life applications are not explored. The chemistry textbook briefly mentions some efficiency issues in the introduction to the textbook, but this is not taken up anywhere beyond the introduction to thermodynamics. The way the physics text deals with Second Law efficiency has already been discussed above, and therefore the absence of normativity in both chemistry and physics results in a coding of the normative modality as incidental.

Figure 7.3 illustrates clearly that the engineering science knowledge as displayed in the engineering textbooks has a much stronger normative orientation than the science knowledge

in the physics and chemistry textbooks. Furthermore, the normative mode of the knowledge in mechanical engineering is noticeably stronger and more explicit than is the case in the chemical engineering text.

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