Isagoge Philosophica
Pedro da Fonseca (1528–1599)
First published 1591
Pedro da Fonseca's Isagoge is a scholastic work conceived as a systematic introduction to the doctrine of universals and intended for the general use of the sciences. Fonseca presents it as richer in doctrine, more reliable with regard to truth, and better suited to teaching than Porphyry’s work of the same name. Its first part defines and explains the five predicables, while the second compares them, examining their common features and differences; chapters 7 through 11 are devoted individually to each predicable. Although he acknowledges that much of the material derives from the earlier logical tradition, Fonseca regards chapter 12 as especially original, since it addresses kinds of universals unknown to pagan philosophers and related to the nature of Christ. The work thus combines logic, metaphysics, and Christian theology, offering an orthodox and systematic reworking of Porphyry’s Isagoge while maintaining close thematic ties with the Jesuit philosophical tradition and with the later Conimbricenses Commentary.
Prooemium
Caput I: Quid sit universale
Caput II: Quotuplex sit universale
Caput III: De particularibus
Caput IV: De abstractione universalium a singularibus
Caput V: De triplici consideratione universalium, et particularium, et quo pacto ea ad Dialecticam pertineant
Caput VI: De duplici rerum universalium unitate
Caput VII: De genere
Caput VIII: De specie
Caput IX: De differentia
Difference in one way is called any diversity; by which signification we also say those things to differ among themselves which are diverse in whole genus, as substance and quality. Properly, however, difference is the diversity of those things which otherwise are of one altogether reason: by which difference those things alone are said to differ among themselves which are the same either in genus, or in species, or in number; as man from horse, Socrates from Plato, and the same old man from himself young.
It is noted of difference taken in this pact into common, proper, and most proper distinction. Common is called that which can truly be separated, as to sit, to stand, youth, and similar. Proper, which although truly inseparable is; nevertheless does not pertain to the essence of the thing, as a scar when covered by a callus, the gray color of the eyes, and properties of common natures. Most proper truly is that which makes the essence diverse, as rational; for this is the cause that man is of diverse essence from horse and the other brute animals. Therefore common and proper make the thing otherwise affected, or at least having it in another way; but most proper makes it to be another according to essence.
Difference is also divided first into separable and inseparable: then inseparable into difference per se and per accidens. Difference per se is the same as most proper, and is called difference per se because it is per se divisive of some superior, and constitutive of some inferior; in which way sensitive is divisive of living, and constitutive of animal; rational however divisive of animal, and constitutive of man. Difference per accidens, if taken absolutely, not as a member dividing inseparable difference, comprehends common and proper, and is called per accidens because by accidental alone it divides and makes to differ.
Those things therefore dismissed, difference per se is twofold, one specific, the other individual. Specific is that which with genus constitutes species, whether mediate namely or infima; individual however which with infima species constitutes individual or one in number. Hence it comes about that whatever properly differs from another by difference per se and not per accidens, all that either differs in species or in number alone.
Nor are those to be heard who acknowledge no difference per se among individuals of the same infima species, but wish them to be distinguished only by accidents. For no predicament is there which per se itself and without aid of another predicament is not sufficient for the constitution of its species and individuals, since all predicaments are unmixed from supreme genera to individuals, nor are differences to be sought in one predicament by which species or individuals of another are constituted. But just as from the power of each genus the differences productive of species are in a certain way born, so from the power of each infima species its own differences of individuals arise in its own way.
Specific difference is also said to be that by which species exceeds genus. By the same pact individual difference can be said to be that by which individual exceeds infima species. For just as man in its common essence has this more than animal, that it is participant of reason; so Socrates in his singular essence surpasses the common essence of man, that he is this singular and determinate.
Difference per se is also commonly divided into divisive and constitutive. But these are rather various offices of difference, insofar as difference is (which is already clear from things said) than genera of differences, just as that third which is to make to differ. For no difference per se is there which does not execute these three in that order in which they are numbered, since it both divides something superior, and constitutes something inferior, and makes that differ from this, others of the same division. Although if divisive and constitutive differences are taken with respect to one and the same common nature, no same difference is there which can perform these three, but it is necessary that another or others constitute it and make it differ from another or others, others divide; in which way another is that which constitutes corporeal substance and makes it differ from incorporeal; others which divide incorruptible and exempt from corruption; others also which constitute animal and make it differ from incorporeal substances, incorruptibles, simples, and plants; others which distribute into various species.
Finally specific difference is divided into general and special. General is that which constitutes a species which itself is also a genus; as sensitive. Special which constitutes a species which is not likewise a genus; as rational. But these things are said of difference insofar as it is difference, not insofar as it is the third species of universals, although all things conduce not a little to this posterior consideration.
Difference is also usually described as a certain universal in this manner. Difference is that which is predicated of many differing in species in the question what kind it is; and this (as is understood) according to essence. And this indeed is the explanation of difference drawn from Aristotle, which agrees only in general differences; and this is not given as a fault because special differences are less known and less used. They are called general in this posterior consideration of differences because they are predicated of things differing in species; special however because of things differing in number alone: which genera of differences neither differ in species among themselves, nor are they genera, but are distinguished by more or less universal reason alone.
The common description of all specific differences is nevertheless this: by which difference is said that which is predicated of many in the question what kind it is, according to essence. For it comprehends both general and special differences; and excludes in apt order singulars and other universals. If this is so understood. Difference is a universal which necessarily and according to essence is predicated of many in the question what kind it is. Which all things from those things said above remain clear.
Specific difference is compared with genus; which divides as substantial form with its proper matter; with the species itself which it constitutes, as such form with natural substantial composite; yet neither form nor matter, which are parts truly component of the whole, are predicated of the natural composite. Genus however and difference, which with species are one and the same thing in whatever individual, are said of the species. These are the things concerning universals which are predicated essentially of their particulars.