I argue that a certain appeal to the scenario of a brain in a vat is vacuous. I defend the conceptual coherence of the scenario under the necessary assumption of an infinitely resourceful agent able to functionally replace any causal process of any complexity. I then argue that employing this assumption trivialises any inference to the location of any particular mental process. I conclude by considering various positive and negative implications of the discussion.

In my talk, I will tackle a core problem in the study of one of our most crucial intellectual abilities, the use in reasoning of external cognitive tools such as diagrams. We spontaneously learn and stock in memory information relying on external symbols, pictures, sequences of public actions, and these cognitive tools are all inter-operable and not directly derived from biological evolution. What grounds our semantical and inferential competence with these representations? Why are they so typically human? According to the external connection hypothesis (EC), diagrams have been invented (or discovered) with the function of facilitating and organizing our reasoning and are used dynamically; their use engages the conceptual system, the visuo-spatial system and the motor system. Dynamically interpreted diagrams work at the interface between these three systems to churn out an inference that puts forward a new conclusion.