S-ANU 2014, Semester 2

26-28 November 2014
Bundanoon

Program

Thursday 27

Abstracts

Maureen O’Malley (Sydney): Evolution from complex to simple: empirical cases and philosophical reflections

Evolution as a historical trend of increasing complexification is usually taken for granted. I will challenge this assumption with some cases that show how major phylogenetic groups have evolved via the decomplexification of genomes, intracellular structures and functional capabilities. Some very thought-provoking episodes have occurred during eukaryote evolution. These episodes have attracted scientific attention because eukaryotes are standardly understood as the most complex cells and organisms on this planet, and their evolution normally discussed as one of increasing complexification. The examples I will focus on occurred during the early evolution and diversification of eukaryotes, and in relation to the evolution of metazoans (there are further excellent examples in the fungi, but I won’t have time for them). I will put these particular eukaryote examples into a larger context of ongoing processes of decomplexification in prokaryote evolution, in which genome reduction and other simplification processes are very common. What are the philosophical implications of such cases? I will explore what they mean for understanding general trends in evolution, suggest ways of conceiving the relationship between simplification and complexification, and discuss the explanatory payoff of including simplification in evolutionary scenario-building. The presentation is part of a project that is very much in the initial stages, so philosophical feedback will be much appreciated.

Kim Shaw-Williams (ANU): The Australopithecines: Why We Should Love Them and Leave Them

I will present new evidence that indicates the australopithecines were a gorilla-like lineage that specialized in a mainstay diet of corms and rhizomes of sedges; they are probably not the direct Pliocene ancestors to early humans; but are still worth studying because they provide a well recorded evolutionary example of incremental over-specialization. In the process I reveal the Pliocene hominins who probably were our ancestors.

Karl Rollings (Sydney): Unifying evolutionary explanations of morality

This talk is a modification and representation of work presented more than 3 years ago at SANU, exploring how the motivation to act according to a cooperative morality could have evolved by natural selection. The fundamental challenge is to outline selective regimes under which cooperative dispositions within a group would not be undermined by cheating. I find that both intrademic group-selective accounts of morality (eg. those appealing to indirect reciprocity) and interdemic group-selective accounts (eg. those appealing to punishment-facilitated ‘multiple stable equilibria’) illuminate mechanisms that seem capable of solving a part of this riddle. However, each fails to explain the evolution of a fully-fledged morality on its own terms. I speculate that it may be possible to link these two approaches to yield a complete evolutionary account of morality.

Jessica Isserow (ANU): Putting Pressure on the Evolutionary Hypothesis: another challenge for evolutionary debunking arguments

Evolutionary debunking arguments comprise an empirical, a metaethical and an epistemological component. The first puts forward an account of moral evolution, the second embraces a particular understanding of moral facts and the third offers an inference to the effect that moral beliefs lack epistemic justification. Philosophers typically resist evolutionary debunking arguments by attacking one of the latter two components. In this paper, I pursue a different tactic by putting pressure on the empirical component of Richard Joyce’s debunking thesis—in particular, upon the account of moral judgment which it assumes. Joyce understands the human capacity to make moral judgments as a biological adaptation which enforced a more robust disposition for cooperation and other fitness-enhancing behaviours within early hominins. For Joyce, moral judgments make for more effective commitments devices than mere prosocial emotions or desires and accordingly, are better positioned to undergird evolutionarily important behaviours such as cooperation. Contra Joyce, I argue that the presumption that moral judgments offer a distinctive evolutionary edge in conferring a capacity for behavioural commitment is unsupported.

Pierrick Bourrat (Sydney): Two kinds of drift: deterministic and probabilistic drift

Drift is commonly defined in statistical terms as the result of deviations from expected reproductive outputs. I argue that this definition is ambiguous, for it underlies at least two possible causal interpretations. As a result, I show that at least two different concepts of drift can be distinguished: one I call deterministic drift, the other I call probabilistic drift.

Christopher Lean (ANU): Hierarchy in Ecology and its implications for Biodiversity

The hierarchical structure of biological entities has received considerable philosophical attention since William Wimsatt’s influential discussion of how organisms can be multiply decomposed along different ‘theoretic perspectives’ (Wimsatt, 1972). This enquiry has yielded considerable advances in our understanding of the relationship between the entities studied by different biological disciplines. However, there has not been a similar examination of the ways ecologists describe ecological systems. I aim to rectify this omission by outlining how the different research programs in ecological science yield different non-isomorphic sets of variables. Crucially, there are distinct explanatory variables within ecological science; for example the movement of energy and material resources in a system (ecosystem ecology), functional compositional relations of assemblages (community ecology), and spatial configuration of organisms (population ecology). These variables have a nested structure within their local disciplines (vertical composition) and we can attempt to translate the identity relations of variables between disciplines (horizontal identity). Understanding the relationship between the variables of ecological science impacts both our concept of biodiversity and ability to preserve biodiversity.

Griffiths, P.E., Pocheville, A., Calcott, B., Stotz, K., Kim, H., and Knight, D.: Causal specificity, Invariance and Stability

Several authors have argued that causes differ in the degree to which they are ‘specific’ to their effects. Woodward has used this idea to enrich his influential interventionist theory of causal explanation. Here we propose a way to measure causal specificity using tools from information theory. We show that the specificity of a causal variable is not well-defined without a probability distribution over the states of that variable. It has been suggested that specificity can be assessed in light of actual or relevant variation in causes, as well as all possible variation. We show that these options correspond to different probability distributions, and lead to different conclusions about specificity. ‘Minimal invariance’, the basic criterion of causation in the interventionist approach, is shown to be equivalent to non-zero specificity. The range of invariance of a causal relationship can be measured by its degree of specificity. The ‘background variables’ for a causal relationship are additional variables that have some degree of specificity, either for the effect variable or for the relationship between the cause and effect variables. We show that these two are not equivalent. We show how to measure the effect of a background variable on the relationship between a cause and its effect, and suggest a measure of the stability of a causal relationship with respect to background. We demonstrate the tractability and interest of our proposed measures by measuring the specificity of coding DNA and other factors in a simple model of the production of mRNA.