Table of Contents
Suárez: The Soul’s Powers
Following Aristotle, Suárez holds that every living being is endowed with a soul, which is a substantial form. He emphasizes that there is just one soul for each living being, thereby rejecting the pluralist position, which posits several substantial forms and hence several souls (De anima, d. 2, q. 5; Des Chene 2000: 155-169). In defending this unitarian position, Suárez can easily explain the unity of a living being: if there is just one soul that structures all the parts of a living being, they form together a single, well-defined thing that is distinct from all other things (Rozemond 2012, Shields 2013). However, the unitarian position gives rise to a serious problem. How can a living being engage in different types of activities if it has just one soul? Are not different principles of activity and hence different souls required for a plurality of activities? Suárez solves this problem by referring to the powers of the soul: every individual soul has different powers or faculties (potentiae), and each of them makes a certain type of activities possible (De anima, d. 3, q. 1). Thus, a human soul has vegetative, sensory and rational powers and can therefore produce a large number of activities, ranging from breathing and digesting up to perceiving and thinking.
This solution, which has a long tradition (Biard 2008, King 2008, Perler 2015), is clearly inspired by Thomas Aquinas, who insisted that the soul has an internal richness; its simplicity does not rule out the presence of various powers (ST I, q. 77, art. 1). But how exactly are the powers present in the soul? Suárez answers this question by critically examining the nominalist position. Ockham and his followers claimed that each soul is really identical with its powers; a power is simply a way of acting of the soul (Reportatio II, q. 20, 435-443; Perler 2010, de Boer 2013: 227-252). But this cannot be a convincing position, Suárez objects, because every power has its own definition, which differs both from the definition of another power and from the definition of the soul. For instance, the intellect is defined as the power that is responsible for acts of thinking, whereas the will is defined as the power that is responsible for acts of willing, and the soul as a whole is defined as the basic principle of life and unity. Given this definitional difference, there must be a real difference both between the two powers and between the powers and the soul. Otherwise one could say that it is the intellect that produces acts of willing or the will that produces acts of thinking, because one and the same thing would produce all these acts (De anima, disp. 3, q. 1, n. 6). To avoid this consequence, one needs to acknowledge that powers are special entities or things (res) that exist in the soul. Of course, they are always bound to the soul and must therefore be understood as dependent entities. Nevertheless, each of them is a real and irreducible entity with its own causal domain.
In making this claim, Suárez rejects a reductionist theory of powers and replaces it with a realist theory. But how should powers be classified as entities? Clearly, they cannot be substantial forms; otherwise they would have the status of souls and the unity of a human being would be threatened. So, they must be accidental forms. However, they cannot belong to the same type of accidental forms as colors or other externally caused forms. They are rather internally caused and should therefore be understood as intrinsic accidental forms (De anima, d. 3, q. 3, n. 6). Moreover, they do not change or disappear but constantly remain in the soul; hence they are stable forms. And they only exist as long as there is an underlying substantial form. Suárez even claims that this form, i.e. the soul, produces them. Just as every creature is made by God, so “a power is a new effect that is produced by the soul” (De anima, d. 3, q. 3, n. 7), and the production at stake here is an instance of efficient causation. This is a remarkable thesis. Unlike many predecessors, Suárez does not simply claim that the soul includes the powers or that it is their formal cause (Corcilius & Perler 2014). He characterizes it as their efficient cause, thereby turning the soul into some kind of basic power station that produces other entities, which then also act as powers. Obviously, there is a complex network of powers that is hierarchically ordered.
In a normal situation, the powers naturally come into existence and cannot be separated from the soul in which they are anchored. However, God could intervene in nature and prevent the powers from coming into existence (De anima, d. 3, q. 3, n. 12). This means, of course, that we would then have a human being with a “naked” soul. To be sure, this is only a hypothetical scenario. Suárez does not claim that God really intervenes and that he really prevents a human soul from producing powers. Like most scholastic scenarios that appeal to God’s omnipotence, this scenario is only intended to illustrate what is metaphysically possible (Courtenay 1990). But it should not be overlooked, because it makes clear that there is no necessary production of powers. Or to be precise, there is no absolute necessity, but only conditional necessity: the powers will necessarily come into existence only if the natural order will not be changed.
In the case of human beings, the powers depend on the soul not just for their existence, but also for their activity. The soul is the primary causal principle that is involved in every activity (DM 15, 1, 7). Suárez even holds that it is the causal principle that coordinates all the powers in their activity (DM 18, 5, 2-3). For instance, a human being could not perceive an object and then immediately think about the very same object without having well-coordinated perceptual and intellectual powers. It is precisely the underlying soul that is responsible for this coordination. In fact, thanks to the soul there is a “harmony” or “sympathy” between all the powers (DM 18, 5, 3; De anima, d. 2, q. 5, n. 5; d. 9, q. 2, n. 12; Ludwig 1929, Tropia 2014). That is why the presence of a single soul is not only indispensable for the unified existence of a human being, but also for unified cognition and agency.
Suárez’s appeal to the coordinating function of the soul has an important consequence for his account of the relationship between the powers. Unlike Thomas Aquinas and other predecessors, he does not claim that they causally interact (Spruit 1995: 294-307). For instance, when explaining the process leading to cognition he does not hold that the sensory power first produces a material cognitive device, a so-called “phantasm,” and that the intellectual power then abstracts an immaterial cognitive device, a so-called “intelligible species,” from it (De anima, d. 9, q. 2, n. 6-10). There is no abstraction in the strict sense, because the intellectual power cannot act upon the sensory one and take something from it. Nor can the sensory power act upon the intellectual one and send something to it. Causal relations in both directions are ruled out, since a power can only act in its own realm, which is either material or immaterial; hence it can only produce a cognitive device in that realm. But thanks to the underlying and unifying soul, the activity of the intellectual power is perfectly coordinated with that of the sensory power. So, whenever the sensory power produces a material phantasm, the intellectual power produces an immaterial species that has the same cognitive content (De anima, d. 9, q. 2, n. 12). This means that there is no relation of efficient causation between the two powers, but only a relation of occasional causation. That is, the presence of the material phantasm in the sensory power is nothing but an occasion for the intellectual power to produce an immaterial species, and the coordinating soul guarantees that it produces the right kind of species.
In rejecting causal interaction between the powers, Suárez avoids the vexing problem of how an immaterial power can act upon a material one. But there is a prize to be paid. The soul needs to be accepted not just as the basic principle of life and unity, but also as the basic cognitive principle that somehow monitors all the activities of the powers. For if the soul did not know the cognitive content of the phantasm that is present in the sensory power, it could not make the intellectual power produce a corresponding device with the same content. In any case, powers are dependent not just from a metaphysical point of view, since they need to be produced and maintained in existence by the underlying soul. They are also dependent from a cognitive point of view, since they could not produce a set of unified, well-arranged perceptions and thoughts without the aid of the soul. This conception of the soul became influential in early modern debates on causation and cognition (Schmaltz 2008: 129-177, Nadler 2011).
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