Next we must consider the cause of habitudes. And first, as to their generation; second, as to their growth; third, as to their diminution and corruption. About the first, four questions are asked. First, whether any habitude is from nature. Second, whether any habitude is caused by acts. Third, whether habitude can be generated through one act. Fourth, whether any habitudes are infused into human beings by God.
To the first one proceeds thus. It seems that no habitude is from nature. For of those things that are from nature, the use is not subject to will. But habitude is that which one uses when one wishes, as the Commentator says on De Anima III. Therefore habitude is not from nature.
Further, nature does not do by two what it can do by one. But the powers of the soul are from nature. Therefore if the habitudes of the powers were from nature, habitude and power would be one.
Further, nature is not defective in matters of necessity. But habitudes are necessary for working well, as was said above. Therefore if any habitudes were from nature, it seems nature would not be defective in causing all necessary habitudes. But this is obviously false. Therefore habitudes are not from nature.
But contrariwise is that in Ethic. IV, among other habitudes is put understanding of principles, which is from nature, whence also first principles are said to be naturally cognized.
I reply that it must be said that something is able to be natural to someone in two ways. (1) In one way, according to the nature of the species, as it is natural for a human being to be risible, or fire to rise. (2) In another way, according to the nature of the individual, as it is natural for Socrates or Plato to be illness-prone or health-prone, according to his temperament [complexionem]. Again, according to both natures, something is able to be said to be natural in two ways, (i) in one way, because it is wholly from nature, (ii) in another way, because according to something it is from nature and according to something it is from an external principle; just as when someone is healed through himself, health is wholly from nature, but when someone is healed through the help of medicine, health is partly from nature and partly from external principle.
So, therefore, if we speak of habitude according as it is a disposition of a subject ordered to form or nature, in any of the aforesaid ways habitude can happen to be natural. For there is some natural disposition that is due to human species, outside of which no human being is found. And this is natural according to the nature of the species. But because such a disposition has a certain latitude, it happens that diverse gradations of this sort of disposition can be appropriate to diverse human beings according to the nature of the individual. And this sort of disposition is able to be either wholly from nature or partly from nature and partly from exterior principle, as was said of those who were healed through art.
But habitude that is a disposition to working, whose subject is a power of the soul, as was said, is able to be natural both according to the nature of the species and according to the nature of the individual: According to the nature of the species, according as it is held on the part of the soul itself, which, as it is the form of the body, is a specific principle; but according to the nature of the individual, on the part of the body, which is the material principle. But in neither way does it happen in human beings that there are natural habitudes so that they are entirely from nature. (In angels this does happen, in that they have naturally innate [inditus] intelligible species, which do not belong to the human soul, as was said in the first place.)
There are therefore in human beings some natural habitudes as it were existing partly from nature and partly from external principle, in one way in the apprehensive powers and in another in the appetitive powers. For in apprehensive powers there is able to be natural habitude according to incipience [inchoationem], both according to the nature of the species and according to the nature of the individual: according to the nature of the species, on the part of the soul itself, as the understanding of principles is said to be natural habitude. For from the nature of the intellectual soul itself, it is appropriate that a human being, cognizing what is whole and what is part, cognizes that every whole is greater than its part, and likewise in other things. But what is whole and what is part, he is not able to cognize save through intelligible species received from phantasms. And because of this is the Philosopher, at the end of the Posterior [Analytics], shows that cognition of principles comes to us from the senses. But according to the nature of the individual, there is some cognitive habitude according to natural incipience, inasmuch as one human being from the disposition of organs is more apt to understand well than another, inasmuch as we need sensitive virtues for the working of the intellect.
But in the appetitive powers, there is no natural habitude according to incipience on the part of the soul itself according to the substance of the habitude itself, but only as to certain principles of it, as principles of common right are said to be seminal virtues. And this is because inclination to proper objects, which seems to be incipience of habitude, does not pertain to habitude, but pertains more to the very notion of powers. But on the part of the body, according to the nature of the individual, there are some appetitive habitudes according to natural incipience. For some are disposed from their own bodily temperament to chastity or gentleness or to some such.
To the first, therefore, it must be said that this objection proceeds from nature as divided over against reason and will, whereas reason and will themselves pertain to human nature.
To the second it must be said that something is able to be naturally superadded to power that nevertheless is not able to pertain to the power itself, as in angels it is not able to pertain to some intellectual power that it be through itself cognizant of everything, because that would need to be the act of everything, which is God's alone. For that by which something is cognized needs to be the actual similitude of what is cognized, whence it would follow, if the power of the angel through itself cognized everything, that it would be the similitude and act of everything. Hence it needs to be the case that some intelligible species, which are the similitudes of intellectual things, be superadded to the intellectual power itself, because through its participation of divine wisdom, and not through its own essence, their intellects can be actual for those things which they understand. And so it is obvious that not everything that pertains to natural aptitude is able to pertain to power.
To the third it must be said that nature does not equally have itself to causing all the diversity of habitudes, because some are able to be caused by nature, some not, as was said above. And thus it does not follow that if some habitudes are natural, all are natural.
[Thomas Aquinas, ST 2-1.51.1. The Dominican Fathers translation is here, the Latin is here.]
So this mazy article is a partial taxonomy of habitudes. We are considering only those habitudes in some way caused by nature, and we have to consider a prior distinction in habitudes, namely, habitudes insofar as they are ordered to nature or form, and habitudes insofar as they are ordered to operation. The classification looks something along these lines:
NATURAL HABITUDES INSOFAR AS THEY ARE ORDERED TO NATURE
(1) According to the nature of the species
--- --- (i) as wholly from nature (e.g., natural disposition pertaining to human species, presumably those natural balances that are necessary for vital human functions)
--- --- (ii) as partly from nature, partly from external source (e.g., one's vital functions as restored or corrected by medicine)
(2) According to the nature of the individual
--- --- (i) as wholly from nature (e.g., variant forms arising from the latitude of the natural disposition pertaining to human species, such as sickly or healthy physical temperament)
--- --- (ii) as partly from nature, partly from external source (perhaps as examples we could include healthiness in part from dietary regimen, or physical fitness, which refine the natural health of the body)
NATUR AL HABITUDES INSOFAR AS THEY ARE ORDERED TO OPERATION
(1) According to the nature of the species (in human beings, on the part of the soul)
--- --- (i) as wholly from nature (do not exist in human beings, although angels have them, e.g., innate intelligible species through which the angel understands by nature)
--- --- (ii) as partly from nature, partly from external source (in natural incipience or inchoation)
--- --- --- --- (a) in apprehensive powers (e.g., understanding of first principles)
--- --- --- --- (b) in appetitive powers (do not properly exist, although in a loose sense seminal virtues in the apprehensive powers, insofar as they prepare for appetitive operation, can be considered as standing proxy for them)
(2) According to the nature of the individual (on the part of the body)
--- --- (i) as wholly from nature (do not properly exist)
--- --- (ii) as partly from nature, partly from external source (in natural incipience or inchoation)
--- --- --- --- (a) in apprehensive powers (e.g., sensitive virtues, i.e., better disposition of the physical organs so as to facilitate understanding, like quickness of imagination or clarity of memory)
--- --- --- --- (b) in appetitive powers (e.g., bodily temperaments facilitating character)
So since 1.i, 1.ii.b, and 2.i of those ordered to operation are empty classes for human beings, there are seven kinds of natural human habitudes. This is, of course, not a complete taxonomy of habitude, but only covers natural habitudes; there are other habitudes that are acquired in ways that make them not natural in any of these senses, which the next articles will go on to discuss. From what we see here, the natural habitudes insofar as they are ordered to nature are the principal foundation for health and medicine; the natural habitudes insofar as they are ordered to operation are the principal foundations for human social and cognitive life; but we should not consider this as a sharp separation (e.g., since we are naturally social, there could be socially-oriented natural habitudes ordered to nature, and 2.ii.a and 2.ii.b clearly intersect with medical concerns).
An interesting question for understanding how natural habitudes work in principle is how many kinds of natural habitude angels have. As far as I know, St. Thomas never addresses this, but I am inclined to say four: they can have all of the natural habitudes insofar as they are ordered to nature, but there is no distinction between individual and species at the angelic level, at least in St. Thomas's account -- every individual angel just is its own species of angel, carrying everything that is possible to that species. Thus these collapse to two. The same occurs for natural habitudes according to operation, but the reason for denying the existence of 1.ii.b to human beings seems quite general and thus would apply to angels. So of those natural habitudes, angels would have at least innate innate intelligible species (1.i) and innate apprehensive habitudes for understanding (1.ii.a). One could perhaps argue that these latter also collapse in angelic intellects; but I think both angelic self-knowledge and angelic communication, as St. Thomas characterizes them, allow for 1.ii.a that is not 1.i.