The Sun as an Equivocal Cause

Well, then, is it equivocal causation, despite its off-putting label, that obtains between universally perfect God and God's necessarily less than universally perfect effects? Aquinas's model of end p.150

Kretzmann, Norman , (deceased) formerly Susan Linn Sage Professor Emeritus of Philosophy, Cornell University, New York

The Metaphysics of Theism

Print ISBN 9780199246533, 2001 pp. [151]-[155]

equivocal agent causation in chapter 29 does seem to provide some of what we'd expect to find in an account of divine causation.

The sun causes heat in terrestrial bodies (corporibus inferioribus) by acting in keeping with its state of actuality. That is why the heat generated by the sun must hold some sort of likeness to the sun's active power, through which heat is caused in terrestrial things. For that reason the sun [also] is called hot, even though not in connection with one [and the same] ratio [as applies to terrestrial things that are called hot]. And in this respect the sun is said to be somehow like all the things in which it produces its effects in the manner of an agent cause (efficaciter). But, on the other hand, it is unlike all of them in so far as such effects do not possess heat (and [other forms] of that sort) in the same mode in which it is found in the sun. (29.270)

'Heat is in the sun in a mode that exceeds the mode in which it is in a fire' (ST Ia.6.2c); and so 'the sun and fire generated by the sun are not called hot univocally' (32.284).

The sand is hot and dry, and so is the sun. It's quite all right to talk that way, but our interest now is in acquiring knowledge about the remote sun on the basis of our familiarity with some of its local effects, not in making conversation on the beach. If we understand the natures of the effected heat and dryness in the sand, then perhaps the first step toward learning about the nature of their agent cause on that basis is to understand that simply in virtue of the structure of agent causation those effects must somehow be fundamentally like their cause, in the sense that there must be some theoretically discoverable way in which the forms of heat and dryness are also in the sun. But then, surely, the very next step toward learning in this way about the nature of the sun as a heating and drying agent is to recognize that since the sun and the sand are not in the same species and so do not share the same ratio, the forms of heat and of dryness must be realized differently in the cause and in its effects: '[S]uch effects do not possess heat (and [other forms] of that sort) in the same mode in which it is found in the sun.'

The forms familiar to us in the effects, Aquinas says, are not realized in familiar ways in their equivocal agent cause, but are in the cause in respect of power, the way heat is in the sun. Now if that sort of power did not belong to the genus of heat somehow, the sun acting through it would not generate anything like itself. It is on the basis of this power, then, that end p.151

the sun is called hot—not only because it produces heat, but also because the power through which it does this is something in con-formity with heat (a liquid con forme calori). However, through the same power through which the sun produces heat it also produces many other effects in terrestrial bodies—dryness, for instance. And in this way heat and dryness, which are different qualities in [a

terrestrial body

24 I'm introducing 'a terrestrial body' here as a replacement for Aquinas's 'fire', which strikes me as accidentally misleading because of antiquated natural science.

], are attributed to the sun on the basis of its single power. (31.280)

'Every effect that is inadequate to the power of its agent cause receives a likeness of the agent not in accordance with the same ratio but in an [essentially] lesser way (deficienter), so that what is in the effects in many different ways is in the cause simply and in [one and] the same mode—as the sun in keeping with its one power produces in terrestrial things many different sorts of forms' (ST la.13.5c). Solar power, understood as nuclear fusion or otherwise, of course produces tremendous heat, but, strictly speaking, that power is not itself hot. Still, this equivocal agent cause of heat is itself appropriately, though non-univocally, called hot for two reasons: first, because solar power produces heat (in the sun as well as in the sand); second, because solar power is 'something in conformity with heat',

something that shares a form with the heat it produces in the sand.

25 The first is the solar power's agent causation; the second is what Aquinas sometimes calls exemplar causation. See e.g. In Sent. IV.43.1.2.1c, where the distinction is drawn regarding a univocal cause.

It is for these two reasons that it is said to 'belong to the genus of heat somehow'.

The example of heat may make these reasons look clearer than they are,

since we know that the sun really is hot,

26 Aquinas believed the contrary. See ST la.13.5, obj. 1: '[T]he sun causes heat even though it is not hot, except equivocally'; and In Sent. 1.8.1.2c: '[T]he sun, which is not hot, produces heat.'

albeit in a mode different from anything terrestrial, short of the explosion of a hydrogen bomb. Solar power really does belong to the genus of heat, even though the way the form of heat is in the power of this agent cause is specifically different from the way it's realized in its terrestrial effects. 'Since every agent does something like itself in so far as it is an agent, but each thing acts in keeping with its form, it is necessary that there be a likeness of the agent's form in the effect. . . . However, if the agent is not included in the same species'with the effect, as in equivocal causation it is not, 'there will be a end p.152

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© Copyright Oxford University Press, 2006. All Rights Reserved likeness, even though not in keeping with the same ratio as is associated with the species. For example, things that are generated by the sun [e.g. heat] do indeed approach a likeness to the sun—not, however, so as to receive a form belonging to the sun in accordance with a specific likeness but [only] in accordance with a generic likeness' (ST la.4.3c).

But dryness, like most other effects of solar power, requires an account different from the one provided for heat. Of course solar power involves no water at all, and the sun must be perfectly dry, in the sense that it could not contain even a single water molecule; but those facts are utterly irrelevant to solar power's generating perfect dryness in a grain of sand. It should be clearer regarding dryness than it is regarding heat that Aquinas's second reason in support of calling the sun hot or dry is fundamentally the con-formity that is essential to his analysis of agent causation, whether or not the equivocal cause and its effect can be correctly called by the same name. If solar power causes hardening of clay and softening of wax, bleaching of cloth and tanning of skin, then solar power has in it hardening and softening, bleaching and tanning. If objects with various passive potentialities are exposed to the sun, solar power will actualize those passive potentialities differently, which makes it appropriate for us to talk as if solar power included various active potentialities: hardening power, tanning power, and so on. But those conveniently discriminated active potentialities don't support calling the sun hard or tan, even generically, because hardening and tanning are effects much more specific than heating or drying, effects that depend on solar power's affecting passive potentialities that we know cannot characterize the sun itself, although they are quite familiar in

terrestrial bodies.

27 ST Iallae.60.1c: 'It is important to consider that the patient's matter'—i.e. its set of passive potentialities—'is related to the agent in two ways. For [1] sometimes it receives a form belonging to the agent in accordance with the same ratio as is in the agent, as happens in connection with all univocal agents. And in that case it is necessary that the matter receive the form of one species if the agent is one in species (unum specie). For instance, only something that is in the species of fire is generated univocally from fire. But [2] at other times the matter receives a form from the agent not in accordance with the same ratio as is in the agent. This is clear in connection with non-univocal generating causes, as [when] an animal is generated by the sun. And in that case the forms received in the matter from the same agent are not of one species but are varied according to the varying proportion of the matter relative to receiving the agent's input (infiuxum). For instance, we see that by the one activity of the sun animals of various species are generated through putrefaction in accordance with the varying proportion of the matter.'

end p.153

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