Abstract
Suárez held that the vital faculties of the soul are really distinct from the soul itself and each other and that they cannot causally interact. This means that he needed to account for the connections between the activities of the faculties: they both interfere with and contribute to each other’s activities. Suárez does so by giving the soul a direct causal role in these activities. This role requires the unity of the soul of a living being and Suárez used it to argue against the view that a living being, in particular a human being, has more than one soul. This line of thought displays some affinity with arguments for the simplicity of the soul from the unity of consciousness. One important difference is that Suárez was talking not just about mental activities but about all vital activities.