Abstract
Teleosemantics explains mental representation in terms of etiological history: a mental state’s representational contents are the result of natural selection, or some other selection process. Critics have argued that the “swampman” thought experiment poses a counterexample to teleosemantics. In several recent papers, Papineau has argued that a merely possible swampman cannot serve as a counterexample to teleosemantics, but has acknowledged that actual swampmen would pose a problem for teleosemantics. In this paper, I argue that there are real-world cases of swampman-like representation, in the form of functional tetrachromacy. People with functional tetrachromacy are born with four types of cones in each eye, rather than the usual three, and as a result can represent a wider variety of colors than the average person. I argue that the functional tetrachromat’s additional color representations are not the result of a selection process. Functional tetrachromacy is therefore a real-world case of mental representation without an etiological history, and therefore poses a genuine counterexample to teleosemantics.
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Notes
Roughly, the difference between consumer and producer teleosemantic theories is this: consumer teleosemantics takes the contents of a signal to be fixed by the function of the system that consumes the signal, while producer teleosemantics takes the contents to be fixed by the system that produces the signal. Both versions accept the core claim that any representational state must be the result of a selection process, and that is the claim that the existence of tetrachromacy seems to challenge.
Different theories impose different conditions on function-generating selection processes. For example, Millikan (1984) requires that the selected trait be reproduced; Papineau (1984) does not. The description of teleosemantics that follows should apply to each of the main versions of teleosemantics, as should the arguments involving tetrachromacy in later sections.
It is worth noting that this account does not only apply to naturally occurring functions, but other functions as well. For example, an artificial heart has roughly the same function as a biological heart. The artificial heart’s function is not the result of natural selection, but the result of an intentional design process. This design process is what gives the artificial heart its function, just as the “design” process of natural selection gives the biological heart its function.
This allows teleosemantics to account for mental representations of objects and phenomena that are too novel to have played any role in natural selection. This will be discussed in more detail in section six.
Papineau’s response to the swampman objection is not the only response that the teleosemanticist can take. As mentioned above, Millikan (1996, 2010) denies that swampman has any mental representations. Neander (1996) argues that even actual swampmen would not show that teleosemantics is a bad theory of broad content. Each of these responses is open to the teleosemanticist, but they are not targets of this paper. Millikan would need to deny that the tetrachromat’s novel color representations are true representations, and Neander would have to deny that the tetrachromat’s color representations have any broad contents. Each of these claims strikes me as unappealing, but I will not argue against them in this paper.
Millikan may disagree here. Millikan (1996, 2010) denies that swampman has any mental representations, and would likely deny that the tetrachromat’s color perceptions are representational. Millikan might argue that since they are not selected for any particular purpose, the tetrachromatic color perceptions have no normal or abnormal function, and can therefore neither represent nor misrepresent. However, the tetrachromat’s color perceptions do seem to be able to function normally or abnormally, and they do seem to be able to represent and misrepresent. The tetrachromat’s color perceptions therefore do seem to be representational, despite the lack of selection history. Nevertheless, it should be noted Millikan may be willing to bite this bullet.
Or at least a large portion of the visual system that includes the retinas, LGNs, and much of the visual cortex. Not all areas of the visual cortex are involved in color perception, and those areas will not be part of the system that has as its function the production of color representations. The important point is that color representations are produced by a system that includes areas of the visual cortex, but also includes the retina and other precortical components.
For example, a population of synapses sending signals to a target neuron could “compete” for a nutritive substance that is made available by the target neuron (Garson 2011). This would be competition for a proximal reward, not needing the dopamine-dependent reward signals of organism-level behavioral success (Garson 2011).
There is one respect in which this may in fact be good news for the teleosemanticist. As Bence Nanay (2014) worries, teleosemantics can seem to be a degenerative scientific research program, in the sense of Lakatos (1970, 1974): it purports to be a genuine scientific research program, but it “makes no (or hardly any) new predictions or new explanations” (Nanay 2014). However, if teleosemantics is expanded to include neural selection, then it does in fact make genuine empirical predictions. Namely, teleosemantics predicts that our color-representing mental states—apparently corresponding to neural codes in hV4 (Bannert and Bartels 2018)—are the result of neural selection, rather than the result of neural construction. Although there is some evidence pointing to neural construction as the basis for much of the neural development of color vision, many aspects of neural development are still unknown. It is an open question whether or not neural selection processes are involved in the development of color representing mental states. Teleosemantics, if expanded to include neural selection, makes the testable scientific prediction that color-representing mental states (or their neural correlates) are the result of neural selection, not merely neural construction.
This is a somewhat simplified version of Abrams’s account. Abrams does not explicitly discuss contributions to an organism’s overall fitness, but instead focuses on one collection of properties being “fitter” than another, and of causing events of a certain type more often being fitter than causing them less often (2005). This is a minor point; the important thing for my purposes here is Abrams’s requirement that there be ancestors that have the trait.
This ignores the relatively small chance that the tetrachromat could have a colorblind daughter, who would have to inherit her tetrachromatic mother’s anomalous cone and inherit a second anomalous cone from her father. But this only increases the odds of the tetrachromat having a colorblind child, and so does nothing to help the teleosemanticist.
Many thanks to an anonymous reviewer for pressing me on this point.
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Acknowledgements
I would like to thank David Papineau, who read multiple drafts of this paper and provided very helpful comments and discussion throughout the writing process. I would also like to thank the anonymous reviewers; their insightful comments lead to many significant improvements in the paper, and I am very grateful for their efforts. I would also like to thank Maureen O’Malley, whose helpful comments and guidance were of great help in revising the paper. Many thanks to Dongwoo Kim and Becky Keller, who read earlier drafts of the paper and gave many useful suggestions, and to Susan Erck, Maggie Fife, Becky Keller, Dongwoo Kim, Jacob Martin, Callum MacRae, Pedro Miguel Monque López, and Sai Ying Ng for helpful discussion of the paper.
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Porter, B. Teleosemantics and tetrachromacy. Biol Philos 35, 10 (2020). https://doi.org/10.1007/s10539-019-9732-9
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DOI: https://doi.org/10.1007/s10539-019-9732-9