ABSTRACT Multiple realization occurs when a natural kind is variably realized at more basic levels and the common physical structure of the realizers is not essential for supporting nomological statements. It has been suggested that this phenomenon may be an outcome of natural selection acting over multiple realizers that perform an adaptive function. In this paper, we make the following contributions. First, we present a revision of this model, characterized by stricter equilibrium conditions and superior explanatory power. Second, we present (...) a typology of multiple realization that provides a plausible account of the differences between across- and within-species multiple realization. Third, we perform a formal analysis of the dynamics of multiple realization that sheds light on the differences between multiple realization at different levels of organization. (shrink)

The multiple realizability thesis (MRT) is an important philosophical and psychological concept. It says any mental state can be constructed by multiple realizability (MR), meaning in many distinct ways from different physical parts. The goal of our study is to find if the MRT applies to the mental state of consciousness among animals. Many things have been written about MRT but the ones most applicable to animal consciousness are by Shapiro in a 2004 book called The Mind Incarnate and by (...) Polger and Shapiro in their 2016 work, The Multiple Realization Book. Standard, classical MRT has been around since 1967 and it says that a mental state can havevery manydifferent physical realizations, in a nearly unlimited manner. To the contrary, Shapiro’s book reasoned that physical, physiological, and historical constraints force mental traits to evolve in just a few, limited directions, which is seen as convergent evolution of the associated neural traits in different animal lineages. This is his mental constraint thesis (MCT). We examined the evolution of consciousness in animals and found that it arose independently in just three animal clades—vertebrates, arthropods, and cephalopod mollusks—all of which share many consciousness-associated traits: elaborate sensory organs and brains, high capacity for memory, directed mobility, etc. These three constrained, convergently evolved routes to consciousness fit Shapiro’s original MCT. More recently, Polger and Shapiro’s book presented much the same thesis but changed its name from MCT to a “modest identity thesis.” Furthermore, they argued against almost all the classically offered instances of MR in animal evolution, especially against the evidence of neural plasticity and the differently expanded cerebrums of mammals and birds. In contrast, we argue that some of these classical examples of MR are indeed valid and that Shapiro’s original MCT correction of MRT is the better account of the evolution of consciousness in animal clades. And we still agree that constraints and convergence refute the standard, nearly unconstrained, MRT. (shrink)

Multiple realization occurs when a natural kind is variably realized at more basic levels and the common physical structure of the realizers is not essential for supporting nomological statements. It has been suggested that this phenomenon may be an outcome of natural selection acting over multiple realizers that perform an adaptive function. In this paper, we make the following contributions. First, we present a revision of this model, characterized by stricter equilibrium conditions and superior explanatory power. Second, we present a (...) typology of multiple realization that provides a plausible account of the differences between across- and within-species multiple realization. Third, we perform a formal analysis of the dynamics of multiple realization that sheds light on the differences between multiple realization at different levels of organization. (shrink)

Recently, several critics of the multiple realizability thesis have argued that philosophers have tended to accept the thesis on too weak grounds. On the one hand, the analytic challenge has problematized how philosophers have treated the multiple realization relation itself, claiming that assessment of the sameness of function and the relevant difference of realizers has been uncritical. On the other hand, it is argued that the purported evidence of the thesis is often left empirically unverified. This paper provides a novel (...) strategy to answer these worries by introducing a role for multiple realizability in the context of biological engineering. In the field of synthetic biology, bioengineers redesign the evolutionary realizations of biological functions, even constructing artificial chemical surrogates in the laboratory. I show how in the rational design approach to biological engineering, multiple realizability can function as a design heuristic in which the sameness of function and difference of realizers can be controlled. Although practically motivated, this engineering approach has also a theoretical, exploratory component that can be used to study the empirical limitations of multiple realizability. Successful realization of the engineering designs would amount to a concrete demonstration of multiple realizability, taking evidence for MRT beyond what is readily found in nature. (shrink)

Multiple realisation prompts the question: how is it that multiple systems all exhibit the same phenomena despite their different underlying properties? In this paper I develop a framework for addressing that question and argue that multiple realisation can be reductively explained. I illustrate this position by applying the framework to a simple example – the multiple realisation of electrical conductivity. I defend my account by addressing potential objections:contra Polger and Shapiro, Batterman, and Sober, I claim that multiple realisation is commonplace, (...) that it can be reductively explained, but that it requires asui generisreductive explanatory strategy. (shrink)

Polger and Shapiro argue that their official recipe, a criterion for judging when the phenomenon of multiple realization exists, renders MR less widespread than its proponents have assumed. I argue that, although Polger and Shapiro’s criterion is a useful contribution, they arrive at their conclusion too hastily. Contrary to Polger and Shapiro, I claim that the phenomenon of multiple realization in the biological world, judged by their criterion, is not as scarce as they suggest. To show this, an updated official (...) recipe, namely a multiple mechanistic realization thesis, integrating Polger and Shapiro’s criterion with a compositional conception of realization, is developed. Then, three examples of varied kinds are examined, showing that cases of MR are not so hard to find in the biological world. (shrink)

Thomas Polger and Lawrence Shapiro claim that unlike human-made artifacts cases of multiple realization in naturally occurring systems are uncommon. Drawing on cases from systems biology, I argue t...

Biochemical kinds such as proteins pose interesting problems for philosophers of science, as they can be studied from the points of view of both biology and chemistry. The relationship between the biological functions of biochemical kinds and the microstructures that they are related to is the key question. This leads us to a more general discussion about ontological reductionism, microstructuralism, and multiple realization at the biology-chemistry interface. On the face of it, biochemical kinds seem to pose a challenge for ontological (...) reductionism and hence motivate a dual theory of chemical and biological kinds, a type of pluralism about natural kinds. But it will be argued that the challenge, which is based on multiple realization, can be addressed. The upshot is that there are reasonable prospects for ontological reductionism about biochemical kinds, which corroborates natural kind monism. (shrink)

Multiple realizability says that the same kind of mental states may be manifested by systems with very different physical constitutions. Putnam ( 1967 ) supposed it to be “overwhelmingly probable” that there exist psychological properties with different physical realizations in different creatures. But because function constrains possible physical realizers, this empirical bet is far less favorable than it might initially have seemed, especially when we take on board the richer picture of neural and brain function that neuroscience has been uncovering (...) over the past forty years, in which all sorts of brain activities play crucial roles beyond all-or-nothing electrical signaling. Because of its evolutionary history, the brain’s metabolic and informational processes are inextricably intertwined. The resulting complex integrated functions impose more constraints on possible realizers than the clean, single-purpose functions usually cited as examples in discussions of multiple realizability—with ramifications for the functionalist and computationalist foundations of cognitive science, artificial intelligence, and the philosophy of mind. (shrink)

One might have thought that if something has two or more distinct realizations, then that thing is multiply realized. Nevertheless, some philosophers have claimed that two or more distinct realizations do not amount to multiple realization, unless those distinct realizations amount to multiple “ways” of realizing the thing. Corey Maley, Gualtiero Piccinini, Thomas Polger, and Lawrence Shapiro are among these philosophers. Unfortunately, they do not explain why multiple realization requires multiple “ways” of realizing. More significantly, their efforts to articulate multiple (...) “ways” of realizing turn out to be problematic. (shrink)

This paper has two principal goals. The first is to set out a bit of conceptual cartography, mapping out a number of distinct conceptual issues that are frequently conflated in the vast literature on multiple realization. The second is to review very briefly how work by Carl Gillett and myself attempts to address a few of the many problems of multiple realization. One of these is explaining what Jerry Fodor apparently took to be mysterious, namely, how multiple realization of properties (...) is possible. (shrink)