Making sense of the senses: Individuating modalities in humans and other animals
How ought we differentiate the senses? For example, what distinguishes vision from audition from olfaction, and how many senses are there, exactly? I argue that these questions come in two versions. First, there is the traditional problem of individuating the senses in humans, which goes back to Aristotle's solution that we have five senses. Second, there is also an important question about what sensory modalities we ought to attribute to non-human animals, a version of the question that has been virtually ignored by philosophers. In this paper, I argue that modality ought to be construed as an “avenue into” an organism for information external to the nervous system. I examine a collection of seven proposed criteria found in the philosophical literature concerning the senses. Initially, the four criteria I support—physics, neurobiology, behavior, and dedication—are shown to be individually necessary and jointly sufficient. Next, three criteria—Aristotle's proper objects of sensation criterion, Grice's sensation or qualia criterion, and Nelkin's belief criterion—are considered and rejected. However, one overall goal of this paper is to show that there is interesting contemporary work left to be done on this ancient philosophical question.