Functional Robustness:A New Framework for Multiple Realization and its Epistemic Consequences
Worth Boone · D-Scholarship@Pitt (University of Pittsburgh) · 2020
In this dissertation, I provide a novel account of multiple realization. My account reframes the concept in terms of causal theories of explanation, in contrast to the original framing in terms of the deductive-nomological theory of explanation. I align my account of multiple realization with the phenomenon of functional robustness, particularly by examining a number of cases of robustness in neural systems. I then explore the epistemic consequences of functional robustness. In particular, I argue that systems that exhibit robustness will tend to violate causal faithfulness, thus posing challenges to causal hypothesis testing and causal discovery. I then consider the proposal that robustness undermines modularity - i.e. the ability of causal relationships within a system to be disrupted independently. I argue that it does not and instead that robustness often is due to feedback control driving systems toward particular outcomes. As a result, robustness will attend failures of acyclicity, not failures of modularity. I conclude by contrasting these epistemic consequences of functional robustness with those traditionally associated with multiple realization.