Rhetoric as the art of persuading has been contrasted with argument and logic since the time of the Greek philosophers. Rhetorical skill consists in getting others to embrace certain beliefs, opinions or judgements which the speaker or writer wishes them to adopt. Both sound argument and rhetorical techniques have usually been used in scientific discourse, and different trends in historiographical analysis tend to emphasise either one or the other aspect of scientific writing. Rhetorical analysis of any type of discourse (including scientific works) may disclose several relevant features that contribute to effective communication of beliefs, such as:

• Attempts (by the author) to convey the impression that he/she is a credible person (good character, honest intentions, competence, devoted to the truth, ...) and that his/her opponent are the converse.
• Attempts to influence the readers by appealing to their emotions (admiration, disdain, hatred, fear, ...), interests, imagination, prejudices (including naive beliefs), etc.
• Persuasive but false or incomplete arguments (use of peculiar examples, analogy, metaphors, authority, etc.).
• A convincing structure of the discourse accompanied by an adequate style, designed to suppress critical thought and leading the readers to the intended beliefs.

This session will be devoted to the debate of specific instances of rhetoric in modern biological thought, dealing with questions such as:

1. Which kinds of rhetorical devices were used by the main biologists in their writings, in defending their own views or criticising opposite opinions?
2. Does the very presentation of biological data (the result of observation and experiment) make use of rhetorical devices?
3. To what extent did prominent scientists of the past use rhetoric as an essential part of their scientific works?
4. Was the use of rhetoric a strategy for convincing readers when sound arguments were scarce?
5. If one attempts to "clean" biological works of rhetorical devices, will they loose their cogency?
6. Was rhetoric replaced by cold arguments as biological theories got stronger arguments and a better empirical foundation?
7. Is rhetoric an essential part of the current controversies in biology?
8. Do present textbooks use rhetoric in presenting accepted theories?

Organized by: Lilian Al-Chueyr Pereira Martins

Joan Steigerwald, York University
"Romantic Phenomeno-technologies: Galvanic Inscriptions around 1800"

The notion of inscription was introduced by Latour to refer to all types of transformations, with the help of instruments and other devices, through which an entity is materialized into a sign, an archive, a document, a trace. Rheinberger extends this notion of inscription, arguing that all instruments in an experimental arrangement are productive of graphemes, of material signifiers, so that the tables and diagrams produced in a lab are but further transformations of graphematic dispositions of pieces of matter. Both elaborate Bachelard's notion of phenomeno-technology, emphasizing the process of producing inscriptions and the dependency of phenomena upon the apparatus producing them, that graphemes cannot be conceived apart from their spaces of representation and the instruments of their writing. This paper will use these concepts in a reading of Ritter's galvanic experiments. Ritter produced particular inscriptions in his nerve-muscle preparations through particular galvanic arrangements. He then translated these into pictorial inscriptions, diagrams, as a form of instrumental language, both abstract and material, which in turn facilitated the writing of his formal theory.

Palmira Fontes da Costa, New University of Lisbon
"The Embellishment of the Singular: Rhetoric and Authority in Eighteenth-century Reports of Extraordinary Phenomena of Nature"

Reports on extraordinary phenomena of nature were frequently read at the meetings of the Royal Society of London or published in the Philosophical Transactions during the first half of the eighteenth century. Cases regularly presented included double children and animals joined in one body, foetuses without brains or without mouths, hermaphrodites, dwarfs, giants, pregnancies which lasted for some years and foetuses which were delivered by the anus or by the navel. This paper is concerned with the particular problems raised by observations of phenomena outside the common course of nature for their validation as knowledge. It examines to what extent the content of the reports and, in particular, their lack of intrinsic plausibility had implications for the literary strategies used in their authentication at this institution. It gives especial attention to the problem of the borderline between factual and fictional accounts and shows why the rhetoric used in the reports such as the display of modesty and difficulties, and the frequent use of extensive descriptions were usually necessary but not sufficient for the validation of these kind of observations. The status of rhetoric in the validation of natural knowledge is also discussed within the context of debates conducted at the Royal Society in the middle of the eighteenth century over the proper locus of authority in the making of knowledge.

Lilian Al-Chueyr Pereira Martins, PontifĢcia Universidade CatŪlica de S“o Paulo
"Morgan„s Strategy: Studies in the Early Dissemination of the Chromosome Theory of Mendelian Heredity"

The Mechanism of Mendelian Heredity, written by T. H. Morgan, A. H. Sturtevant, H. J. Muller and C. B. Bridges is usually regarded as a landmark of "Mendelism" and chromosome theory. Several scholars, including not only some of Morgan's coeval scientists, but also some historians of science, claimed that the chromosome theory of Mendelian heredity was made consistent by the genetic data already presented in 1915 in this book. This paper discusses to what extent The mechanism did really present a solid basis for such a theory at that time and to what extent their authors used convincing communication strategies when there was a scarcity or lack of evidence. This study led to the conclusion that although the theory was well grounded in some features, such as sex-linked inheritance and non-disjunction in Drosophila, there were several vital points that were not so clear, such as the lack of cytological evidence concerning the occurrence of crossing-over in Drosophila or the existence of discrepancies between observation and prediction regarding the facts of linkage. Besides that, in these features and others, Morgan and his colleagues used rhetoric as well as pictorical representational strategies that created the impression that the situation was clear and established. Some of those obscure points as well as the convincing strategies used by the authors will be pointed out and analysed.

Roberto de Andrade Martins, State University of Campinas (Unicamp)
"Natural Selection Versus Use-Disuse: Logic and Rhetoric in the Weismann-Spencer Debate"

The rhetorical features of the scientific discourse appear at their highest power in controversies. This case study examines the debate that occurred in the years 1893-1895 between Herbert Spencer and August Weismann concerning the mechanisms of evolution. In 1886 Herbert Spencer published "The factors of organic evolution", where he claimed that the inheritance of the effects of use and disuse played an outstanding role in evolution. Seven years afterwards he published a series of papers in The Contemporary Review where he criticised the belief in natural selection as the only cause of evolution and directly attacked Weismann's work. A debate soon began, with the appearance of two long papers by August Weismann (1893), followed by two papers by Spencer (1893, 1894), an answer by Weismann (1895) and a short final note by Spencer (1895). Spencer attempted to exhibit phenomena that could be explained by use-disuse and not by natural selection. Conversely, Weismann presented phenomena that, according to him, could only be explained by natural selection and "panmixia", and claimed that all examples presented by Spencer could be accounted without use-disuse. This debate between two able contenders was full of fact descriptions, interpretation of facts, careful arguments and much oratorical show. As usually happens, the dispute was inconclusive. The analysis of this controversy shows that it is possible to identify a "purely scientific" version of the debate, but rhetorical artifices played a strong role in the discussion. Each of the adversaries was able to perceive and to expose most of the other's rhetorical recourses in an attempt to neutralise their effects.