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Functions in MindA Theory of Intentional Content$

Carolyn Price

Print publication date: 2001

Print ISBN-13: 9780199242009

Published to Oxford Scholarship Online: October 2011

DOI: 10.1093/acprof:oso/9780199242009.001.0001

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(p.254) Appendix

(p.254) Appendix

Source:
Functions in Mind
Publisher:
Oxford University Press

In Chapters 4 and 5, I argued in support of the claim that the content of the frog's visual signal is (something like) ‘Catchable fly within range now!’ (The term ‘fly’ here is being understood as shorthand for a catchable item having just those biochemical properties that make flies nutritious to frogs.) In order to make this claim I have had to rule out an array of rival content ascriptions. In this appendix, I would like to summarize the different elements of the account in order to provide a consolidated statement of my view. I will focus on the example of the frog's visual system rather than the slightly more complex case of the bee dance mechanism, where we have to appeal not only to the function of the system but to the rules by which the system normally works.

The account that I offered in Chapters 4 and 5 can be summarized as follows: the content of the frog's visual signal concerns the presence of a fly nearby because (i) signals of that kind normally carry the information that there is a fly within range, (ii) the fact that in the past signals produced by the system carried that information helps to provide a suitable abstract and immediate explanation of the fact that snaps prompted by those signals coincided with the presence of a fly within range, and (iii) the fact that those snaps coincided with the presence of a fly within range helped to explain their success.

In the course of Chapters 4 and 5, we encountered a number of rival content ascriptions. I will list them and explain briefly how each one is excluded by the account.

  1. (1) ‘The content of the visual signal concerns the absence of a predator close to the frog.’ This ascription violates (i)—the signal does not normally carry this information.

  2. (2) ‘The content of the visual signal concerns the fact that the sun is shining’ This ascription violates (iii)—the fact that the sun is shining is irrelevant to the success of the frog's snaps.

  3. (3) ‘The content of the visual signal concerns the fact that acceleration due to gravity at the earth's surface approximates 9.81 metres per second.’ This proposal violates (iii)—the fact that the signal carries information about the condition does not help to explain the fact that the frog's snaps coincide with it.

  4. (4) ‘The content of the visual signal concerns the presence of something small and dark within range.’ This ascription violates (iii)—the fact that the signal carries information about this condition does not provide a suitably abstract explanation of the success of the frog's snaps. It is equivalent to the claim that the function of the heart is to make squeezing motions.

  5. (5) ‘The content of the visual signal concerns the arrival of a certain pattern of light at the frog's retinae.’ This ascription can be excluded for exactly the same reason as (4).

  6. (6) ‘The content of the visual signal concerns the presence of something less than 1 centimetre across and moving at less than 50 kilometres per hour.’ Again, this violates (iii)—the fact that the signal carries information about this condition does not (p.255) provide a suitably abstract explanation of the success of the frog's snaps. It is equivalent to the claim that the function of the heart is to move blood that is free from clots. Note the distinction between this rival ascription and the one that I have proposed, on which the content of the signal concerns the presence of a catchable fly. My proposed ascription contains no allusion to specific features of the frog's fly-catching equipment.

  7. (7) ‘The content of the visual signal concerns the presence of a fly in the area a few second ago.’ This proposal violates (iii)—the fact that the signal carries this information fails to provide a suitably immediate explanation of the success of the frog's snaps. It is equivalent to the claim that the function of the chameleon's pigment-arranging mechanism is to ensure that the colour of the chameleon's skin matches the chemical composition of the surface on which it is standing.