Reconceiving conceptual vehicles: Lessons from semantic dementia

Abstract

What are the vehicles of conceptual thought? Recently, cognitive scientists and philosophers of psychology have developed quite different theories about what kinds of representations concepts are. At one extreme, amodal theories claim that concepts are representations whose vehicles are distinct from those used in perceptual processes. At the other end of the spectrum, neo-empiricism proposes that concepts are perceptual representations grounded in the mind's sensory, motor, and affective systems. In this essay, I examine how evidence from the neuropsychological disorder semantic dementia bears on philosophical debates about the nature of conceptual vehicles. I argue that the pattern of deficits in semantic dementia undermines recent neo-empiricist predictions about where and how conceptual knowledge is organized in the brain. I do not intend my analysis of semantic dementia to wholly discredit neo-empiricism; instead, I draw lessons for future theorizing about conceptual vehicles.

Keywords::

• Concept Empiricism
• Neuropsychology
• Philosophy
• Semantic Dementia

Acknowledgements

Many thanks to Edouard Machery, William Bechtel, Daniel Burnston, Michael Anderson, Sharon Thompson-Schill, John Michael, Trey Boone, and two anonymous reviewers for the 38th Annual Meeting of the Society for Philosophy and Psychology for helpful advice and comments on earlier versions of the paper.

Notes

^[1] Several theorists (e.g., Barsalou, 2008) argue that concepts can be grounded in numerous kinds of perceptual systems including sensory, motor, affective, and other introspective (e.g., proprioceptive) systems. Throughout this paper, I will use ‘perceptual’ in this capacious sense to refer to the suite of modality-specific representations taken by some to underlie conceptual knowledge.

^[2] Weiskopf (2007) notes that not all concept empiricists endorse the strong, global form of the perceptual vehicles thesis. For instance, pluarlistic theories (e.g., Dove, 2011) propose that only some concepts are perceptual while others are amodal or “disembodied.” On the other hand, hybrid theories (e.g., Malt, 2010) propose that all concepts consist partly of perceptual representations and partly of different kinds of representation.

^[3] Space considerations prevent me from presenting these arguments in detail. For a discussion of whether cognitive psychology supports neo-empiricism (and whether it can adjudicate between different theories of conceptual vehicles), see Machery (2007).

^[4] However, there is room for debate about whether the ATLs should be thought of as a single brain region. Gainotti (2012), for example, argues that the left and right temporal lobes are specialized for different aspects (verbal and pictorial, respectively) of conceptual knowledge.

^[5] Pobric et al. (2010a) found that TMS applied to the left anterior temporal lobe or right anterior temporal lobe caused similar deficits in semantic processing of both words and pictures.

Additional information

Notes on contributors

Joseph McCaffrey

Joseph McCaffrey is a graduate fellow at the University of Pittsburgh.