SOPhiA 2013

Salzburgiense Concilium Omnibus Philosophis Analyticis

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Programm - Vortrag

Externalism, Enactive Approach and Canonic Neurons
(Erkenntnistheorie, Englisch)

I will focus on the relation among the Enactive Thesis, Externalism and the recent discovery of Canonic and Bimodal neural systems. According to Enactive Thesis our knowledge, emerging from cognitive structures based on recurring sensory patterns, is physiologically connected with our capacity to conduct actions thanks to perception and vice versa. The sensory-motor system is fundamental to embodied-cognition experiencing the external world. The coupling between the bodily cognitive processes and the environment is basic. Enactivism inherited some (proto externalist) intuitions by James J. Gibson and Maurice Merleau-Ponty, suggesting that the mind depends on world/agents interactions. According to environmental theory by Gibson, animal behavior is based on a single movement/perception system. The concept of affordance, the environmental function that an object offers to an individual, or the sum of its practical uses, is primary. Also O'Regan and Noe claim that the mind is constituted by the sensory-motor interaction between the agent and the world. The set of actions results from the matching between environment and body.

Furthermore, the Extended Mind model (Clark, Chalmers, 1998) suggests that cognition is larger than subject's body, and that its boundaries aren't always inside the skin. The mind uses objects in the external environment as extensions of itself. Andy Clark states that cognition leaks out into body and world.

A related doctrine is Externalism, according to which in order to have certain types of intentional mental states, it is necessary to be correctly related to the environment. Externalist (e.g., Putnam) have claimed that meanings and thoughts aren't in the mind, and quite similarly Noe states that perception isn't a process in the brain, but the skilful activity of the animal as a whole. Some externalists affirm that phenomenal content are partially external to the body of the subject.

In ''Proof of an external world'' (1939) G.E. Moore gave a common sense argument against scepticism by raising his right hand and saying ''Here is one hand'', and then raising his left and saying ''And here is another'', then concluding that there are at least two external objects in the world, and therefore that he knew (by this argument) that an external world exists. It is not by chance that I will focus on hands, precisely, on touch sense and affordances in their enactive dimension. Recently neuroscience brain imaging experiments using functional magnetic resonance imaging (fMRI) have discovered the canonic-neurons system, which give us a better founded idea of the relations between our perception/action system and the cognitive processes behind our knowledge of the external world. The working hypothesis of the present paper is to show: a) that the discovery of canonic neurons supports the thesis of cognition as strictly based on enactive processes; b) that the discovery of bimodal neurons supports the Extendend Mind model; c) that according to results obtained in point a) and point b), we can argue, against anti-realistic representationalism and sense-data theory, that it is possible to know the external world.

In the first section I show how the discovery of canonic and bimodal neurons strengthens the Enactive Thesis and the Gibson's intuition about the concept of affordance: neurophysiological studies, confirm that motion and perception cannot be divided in their cortical aspects (at least in regions involving canonic phenomenona). I illustrate experiments (Rizzolatti, Gentilucci 1988) showing that at brain level there is a strong correlation between the way of grasping and the codification of the object. Cognition is attuned with the pragmatic use that external objects ''mean'' for the acting subject. In the brain dimension visualizing an object means understanding what we can really do with that object, how can we precisely catch it, or what kind of object we are in front of, we have to be aware of, or we can interact with. Seeing means realizing the way we can grasp, for example, the object. We cognitively catch it in a way defined by Dretske as non-epistemic (Dretske, 1979). It is not a chance that both actions, catching the object and seeing it, activate the same cortical regions (many of which in motor cortex).

Then, I'll talk about bimodal neurons. They are similar to pure somatosensory neurons, that fire only to somatic stimuli. Moreover, bimodal neurons are more complex. They fire also thanks to visual stimuli, but only when the visual stimulus comes near their tactile receptive field (Fogassi et al., 1992), a particular space determined by their visual receptive field as an extension of somatosensory receptive field regardless the direction of the glance (Gentilucci et al., 1988) or stimulus across the retina (Gentilucci et al., 1983; Fogassi et al., 1996).We can define the surrounding space thanks to our organ in relation with the external objects. Thanks to this relation there are different bodily reference systems, because there are different body parts. Cognitive structures emerge from sensory recurring patterns, allowing to guide actions thanks to perception.

In the second section I argue that some experiments by Atsushi and Iriki on bimodal neurons (Iriki et al., 1996) support the Extended Mind model, showing that if we use a tool to catch an object, visual receptive field includes the tool, that becomes at brain level, a body part, changing the extrapersonal space in peripersonal space.

In the third section I use these results to criticize anti-realist representationalism and sense-data theory, holding that what is given in our experience is not non-physical entities (sense-data): these experiments show that we don't build arbitrary images, but isomorphic mappings of the external objects.

Finally, I analyze neuroscientific data, in relation with the Enactive Thesis, Externalism and Extended Mind in order to explore the possibility of Direct Realism, according to whom, when one perceives the world, the mind-indipendent object of perception are constituents of one's experience. In other words, we can directly perceive the external world as it really is.

Chair: Sebastian Kletzl
Zeit: 15:30-16:00, 13. September 2013 (Freitag)
Ort: HS 105

Gabriele Ferretti
(Urbino, Italien)

Gabriele Ferretti. Date of Birth: 14/11/88. Place of Birth: L'Aquila. Nationality: Italian. Address: Via Mazzini no30, Roseto degli Abruzzi (TE), Italy. Email: fairg@live.it

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