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Hello everyone,
Sorry for cross-posting.
The University of Namur's Emergence Seminar is pleased to welcome Johannes Martens (CNRS, SND) on Friday, March 27, 2026, from 11:00 a.m. to 1:00 p.m., to discuss the following topic:
Evolutionary transitions in individuality: one concept, two criteria?
The seminar will be held in English, in person in room L52 of the Faculté des Lettres (rue Grafé, 1, Namur) at UNamur, and remotely via the following link:
Abstract
In this presentation, I shall discuss an important contrast between two (broad) construals of the notion of an
evolutionary transition in individuality (ETI), itself rooted in a more fundamental opposition between two conceptions of a paradigmatic Darwinian individual.
Historically, the concept of
an ETI has been characterized as a
process during which most of the selective forces happen to be “transferred” from the lower to the higher level—such that, at the end, the bulk of the adaptations end up being concentrated at the level of the collectives, and
the entities at the lower level turn out to be largely “de-Darwinized” (Michod 1999; Godfrey-Smith 2009, 2013). Throughout the past decades, the major transitions theory has made possible the organization of much empirical knowledge about the nature and variety
of ETIs. However, an important (though often overlooked) ambiguity persists, in the literature, with respect to the very
scope of this notion due to the existence of two different criteria for identifying the presence of a new Darwinian individual at the collective level. The first relates to a classical trend in the unit-of-selection debate (Williams 1966; Sober and Wilson
2011) and stipulates—very roughly—that a paradigmatic collective Darwinian individual should be the ultimate
beneficiary of the adaptations that it possesses, with the crucial requirement that rb > 0 (Birch 2018). The second derives from the assimilation of the class of Darwinian individuals to a particular subclass of reproducers, and emphasizes the transfer
of the capacity of
reproductive autonomy from the lower level to the organismal level (Griesemer 2000; Godfrey-Smith 2015). In many ways, these two measures represent desirable criteria that a collective Darwinian individual should satisfy; yet they
disagree about the things which fall under the extension of the “ETI” concept, leading to an apparent inconsistency in the very characterization of its domain. More precisely, the “beneficiary requirement”—properly understood—doesn’t allow for the recognition
of any symbiotic (i.e. “egalitarian”) instances of this concept, while the “reproductive autonomy requirement” admits of a non-empty class of egalitarian transitions—though at a parsimony cost.
In this talk, my aim will be to provide a kind of “best-compromise” solution to this puzzle (parsimony vs. generality), by developing a theoretical model which, overall, accommodates the two aforementioned measures of Darwinian individuality, and reconciles
the need to include some egalitarian transitions with the kind of parsimony considerations associated with the beneficiary requirement. To this end, I will argue that these two “measures” should not be envisaged as alternative interpretations of the concept
of a (collective) paradigmatic Darwinian individual, but as representing different “kinds” of such units, which both have to be integrated into a specific, “layered” sort of compositional structure (the units of the first kind being the proper parts of the
units of the second kind) to fully account for the case of egalitarian ETIs.
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Gauvain Leconte-Chevillard
Il/lui (he/him)
Postdoc Université de Namur - SPiN (Sciences and Philosophy in Namur)