Conférences plénières

Karine Chemla (CNRS, SPHERE, France)

Quantities, standards, measurement and computation. Views from mathematical sources from the ancient world

Quantities can be assessed using either measurement procedures, or mathematical computations, or even a mixture of the two. We are today quite accustomed to equate the expressions of quantities yielded using these various types of procedures. However, these procedures involve operations and entities of very different kinds: concrete, practical measurement procedures involving instruments and standards, on the one hand, and mathematical calculations on the other. As a result, expressions of quantities of the same type are shaped differently, and accordingly present differences.
Building on mathematical sources of the ancient world, my talk will bring forth differences of this kind, and inquire into how actors related different expressions of quantities to one another. I will argue that these distinctions yield interesting tools for analyzing mathematical practices with numbers and quantities. In particular, we will examine the ways in which number systems are put in play in the shaping of expressions of quantities that derive from computation, and also how computation enters in the activity of observing and measuring.
The considerations above mainly deal with the numerical expressions of quantities. However, I will argue that in some cases, actors explicitly chose to establish a semantic distinction between these two types of assessments of a quantity. A case study (the expression of the space occupied by an amount of grain) will enable us to analyze what is at stake when actors choose to express this magnitude, using either expressions yielded primarily by measurement, or expressions yielded by computations. Moreover, I will examine evidence showing how actors organized practices of measurement and computation in relation to one another. In particular, I will focus on the shaping of a standard for this practice of measurement, and show how it likewise brings measurement and computation into play.

Wendy S. Parker (Univeristé de Durham, Royaume Uni)

Measuring via computer simulation?

In a classic paper, Dudley Shapere (1982) argued for extending the philosophical concept of observation beyond its previous associations with perception, to allow for observation by or with scientific instruments. His discussion took as its starting point a somewhat curious claim made by astrophysicists: that they could ‘directly observe’ the center of the sun using complex instrumentation located beneath earth’s surface. Today, scientific discourse once again prompts philosophers to reflect upon the scope of observation and measurement: in various fields – including computational chemistry, climate science and others – scientists now speak of ‘observing’ or ‘measuring’ the world via computer simulation. What are we to make of this? Is it just loose talk? Does it signal a need to further extend our philosophical concepts of observation and measurement? To what extent can ‘observing’ and ‘measuring’ practices involving computer simulation be accommodated by existing philosophical concepts? This talk will explore these questions.

Oliver Schlaudt (Université de Heidelberg, Allemagne)

“Who is there that doesn't calculate?” The homo economicus as a measuring instrument

In this talk, I will provide an overview of questions related to measurement in current economic theory and economics-based policy. I will make the claim that the infamous “homo economicus” does not simply provide a model for economic behaviour, as is usually assumed, but that he is used at many occasions as a measuring device. This is especially the case when there is no market so that prices have to be produced artificially, as for example the prices for human or natural capital in the framework of national accounting and cost benefit analyses (the same holds for non-monetary indicators that are functionally equivalent to prices, such as performance indicators in the framework of New Public Management).
This reading of the use of the homo economicus as a measuring device, and hence of the critical discussion that has been going on for decades as a discussion essentially, though unwittingly, concerned with metrological problems, allows us to rethink the whole issue. Some well known problems of the homo economicus will appear less dramatic, for instance because they can be understood as inevitable, but actually innocuous idealizations that are quite common in measurement. Other problems on the contrary will become much more critical. In particular, I will show that the working of the homo economicus as a measuring device is based on questionable utilitarian and neoliberal premises.

Oliver Schlaudt est professeur associé au département de philosophie de l'Université de Heidelberg, Allemagne. Ses recherches principales portent sur la philosophie des sciences naturelles et sociales, avec un intérêt particulier envers la mesure et la quantification. Il a organisé avec Alfred Nordmann le colloque Dimensions of Measurement qui a eu lieu à Bielefeld en 2013.

Eran Tal (Université McGill, Canada)

Measurement, Prediction and Coherence

Measurement and prediction are traditionally viewed as two distinct kinds of activity: measurement provides answers to questions about actual states of nature, whereas prediction extracts hypothetical consequences from a theory or model. This distinction is overly simplistic, and ignores the central role prediction plays in measurement. Measurement outcomes are selected based on their ability to maximize the predictive accuracy of a model of the measurement process, as well as the predictive scope of background theories. This implies a more nuanced, coherentist picture of the relation between prediction and measurement than the traditional picture suggests.