Visual Displays of Information and the Practice of SciencePragmatic approaches

Valeria GiardinoUniversità di Roma ‘La Sapienza’

Institut Jean Nicod

valeria.giardino@gmail.comhttp://valeria.giardino.googlepages.com/

Centro de Filosofia das Ciências da Universidade de LisboaJanuary 15, 2008Workshop2

Diagrams and (history of) science

Outline

• I. The dynamics of science: against logical empiricism

• II. Two proposals

• III. A case study: Faraday

• IV. Some remarks on science and art

• Questions for the discussion

I. Capturing the dynamics of science: beyond logical

empiricism

“The primary mode of scientific representation for a logical empiricist is linguistic. [...]. This cognitive authority resonates in standard portraits of the relationships between technology and science”

Baigrie (1996)

Logical empiricist image of science

1. Scientific knowledge consists primarly of what is encapsulated in scientific theories, which are ideally to be thought of as interpreted axiomatic systems;

2. scientific reasoning has the general character of a logic (linguistic entities).

Giere (1996)

Kuhn (1965)

• The relative evaluation of rival paradigms is not something that can be reduced to any sort of logic but a matter of choice by scientists acting as individuals within a scientific community

• Naturalistic account: explaining science in terms of naturalistic categories (psychological make-ups of individual scientists and social interaction)

Nevertheless...- no emphasis on the role of visual or

other non propositional model of representation in science

- no talk about representation - his picture of science as a puzzle-solving

activity was meant to be an alternative to the view of science as producing truth BUT representations are still thought of in propositional terms (see the emphasis on incommensurability in linguistic terms) thus leading immediately to the concept of truth

Giere (1996)

II. How to approach science and the role of the different representations

used by scientist:two proposals.

A common way of describing it: Two different sorts of linguistic entities- Predicates (quite elaborate internal

structure) (ex. ‘pendulum’, ‘two-body Newtonian gravitational system’)

- Statements of the form ‘X is P’ (X = real system, P = one of the predicate)

(ex. ‘The system earth moon is a Newtonian gravitational system’)

Giere (1996) Model-based view of theories

Giere’s criticism and proposal

This way of formulating the statement and the model-based views still overemphasizes linguistic aspects.

His proposal:The predicate ‘pendulum’, as it appears

in classical mechanics, does not apply directly to real-world objects but to a family of idealized models.

the idealized model pendulum in classical mechanics

real swinging weights

a prototype

things sufficiently similar to the prototype to be classified as of that type

Representational devices: language, models, and objects in the real world.

The representational relationship is not the truth of a statement relative to the facts, or the applicability of a predicate to an object, but the similarity of a prototype to putative instances (two NON-LINGUISTIC entities)

A family of models of pendulums radiating out from the model of a simple pendulum

The sketch at the top is a particular embodiment of the abstract model of a simple pendulum

It too can serve as a prototype in judging the similarity of a particular real pendulum to the classical model

One example

• Visual presentations of both models and data can be used in crucial decisions about which models best represent the real world

• A case study: 20th century geology (stabilism vs. mobilism)

Visual models as an organizing template for whatever other potentially relevant information the agent may possess, regardless of how that information was encoded

Nersessian (1996)

Scientists’s problem solving strategies and the representational practices developed over the course of history of science:

very sofisticated and refined outgrowths of ordinary reasoning and representational processes

Beyond the separation between the context of justification (philosophers) and context of discovery (historians and psychologists)

Cognitive-historical analysis A new context : development

Dynamic processes (long period of time and social context) through which a vague speculation gets articulated into a new scientific theory, gests communicated to other scientists, and comes to replace existing representations of a domain.

Ultimate goal: to reconstruct scientific thinking by means of cognitive theories.

At present, cognitive theories are largely uninformed by scientific representational and problem-solving practices: the fit cognitive theories/scientific practices still to be determined!

Different modeling activities (except for (1), rarely present in the philosophical literature)

1. Analogical reasoning2. Imagistic reasoning3. Thought experiment4. Limiting case analysis

Representational and constructive practices of scientists as part of the scientific methodDeveloping criteria for evaluating good and bad uses of heuristics philosophical investigation

Reasoning comprises more then algorithmsThe new problem: how scientists,

individually and collectively, combine their cognitive abilities (their biology) together with the acquired conceptual resources

III. A case study: Faraday

Gooding (2002)

Faraday's notebooks : • a rich mixture of sketches,

diagrams and text

• Oersted’s discovery that a current-carrying wire has magnetic properties

• Many of Faraday’s experiments as showing a temporal slice - a ‘snapshot’- of the effect of some more complex but hidden, physical process

• Electrical and magnetic effects are mixed in a way that the eye simply cannot see

The story of the ‘constructive method’

• By September 1821: Faraday and Davy had developed experimental methods of integrating discrete experimental events (or rather, of integrating the images depicting them)

• Accumulation: “they combined discrete images obtained over time into a single geometrical structure. Conversely they also created a physical structure of sensors with which to record the effects of a single event at different points of space.”

A typical procedure• Positioning one or more needles in the region of a wire,

connecting the circuit to a battery and observing the effect on the needle(s)

• Similarly, continuous exploration of the space around the wire would produce a pattern made up of many discrete observations of needle positions

• These results into a single model, a three-dimensional representation of the magnetic effects of the current

• A structure of needles arranged in a spiral around the wire and examined after discharging a current through it, gave a three-dimensional magnetic ‘snapshot’ of the magnetizing effect of the current

• Another setup, a horizontal disc with needles arranged around its perimeter, emerged from a set of temporally distinct observations, which this setup integrates into a single spatial array

Gooding’s model

2-D pattern >> 3-D structure >> 4-D process >> inference or material derivation

Faraday’s sketches

• not simple records of observations, rather working notes

• tools for thinking, not images of its outcomes

• what they purport to represent both complex and dynamic

• each image itself stands for an accumulation of practical and theoretical knowledge

• Interpretative images

• cognitive (generative) and social (communicative) functions are inestricably linked

• CONSTRUALS or MANIPULATIVE ABDUCTIONS

• proto-representations which merge images and words in tentative interpretations of novel experiences

Other examples of ‘scribbles’ as ‘artifacts’

Galilei’s first notes on the parabolic path of projectiles

Leonardo’s sketch of ball-bearings

Darwin’s third tree of nature diagram

IV. Some remarks on art and science

Focus on processes: art and science

• Distinction emerged during the Renaissance (science domain of fact /arts domain of expression and interpretation)

• Yet many of the technologies of art influenced representational practices in the sciences

One possible way out of this distinction: focus on processes

• The 'two cultures' do not express fundamentally different aspects of human cognitive capability; rather, they express differences between the cultures in which particular cognitive capacities are applied

Topper (1996)

Scientific illustration is customarily viewed as a form of art (supremacy of written words for recording and conveying information)

Only recently illustrations are studied as a means to convey information.

A series of issues - the nature of scientific illustration itself – theory-ladenness and empirical content - the nature of all types of illustration and imagery- the demarcation of science, pseudo-science, and art - the very nature of what we mean by them

An artistic or scientific ‘reading’ of a picture is fundamentally a matter of context, not content: one example.

The work of the eighteenth-century Dutch artist and anatomist Petrus Camper.

His work on physical anthropology later formed the basis of craniometry and, in particular, the racist theory of the so-called facial angle.

• Petrus Camper’s aim: to show artists how to have a schematic means for drawing Africans correctly (not as black Europeans, as it was usually done), especially the black Magus in Nativity scenes.

• Racist (pseudo-)scientists interpreted this artistic artifact as (pseudo-)scientific, expressing the intellectual ranking of human types (in which – not surprisingly – white Europeans were closer to the ideal beauty of Greek sculpture and Africans closer to apes.

Questions for the discussion

I. A (very serious) methodological issue: from case studies to general frameworks?

II. Philosophy of science: truth or reasoning processes (and technology)?

III. Are scientific images used (1) to represent some object or (2) differently?

IV. If (1), what is a difference between different kind of images (e.g. A photography vs. a sketch)? If (2), how are they used?

References

Baigre (1996), Introduction of Picturing KnowledgeGiere (1996), Visual Models and Scientific

JudgementGooding (2002), Visualization, Inference and

Explanation in the ScienceKuhn (1962), The Structure of Scientific RevolutionsNersessian (1996), How do Scientists think?Topper (1996), Towards an Epistemology of

Scientific Illustrations