Perception "knows" particulars, but reason knows only universals. Both an ontological problem as well as an epistemological problem.

Three possibilities: universals exist ante res (before things, as in Plato’s forms), in rebus (in things, as in Aristotle), and post res (after things, as in conceptualism and nominalism).

Read passage from Porphyry (Jones, p. 186).

Universals separated from sensibles? Radical realism, nominalists, and conceptualists.

Universals found in sensibles? Moderate Realists.

Subsisting coporeally? Moderate Realists.

Subsisting incorporeally? Radical Realists.

"Placed in the naked understandings alone"? Nominalists and conceptualists.

Radical Nominalism: universals are merely names. Offered no solution. Roscelin condemned in 1093 for holding that the Trinity was tritheism. (1050-1120)

Nominalism: William of Ockham. Universals are mere words but they are tools for understanding. More specifically, they are identical with the very act of understanding.

Conceptualism: Peter Abelard (1079-1142). The mind abstracts a common likeness. Not a form of realism, because there are no forms, even immanent forms. Unlike Ockham he thought that universals were concepts.

Note: Jones doesn't clearly distinguish between conceptualism and moderate realism.

Moderate realism: Avicenna, Aquinas, Duns Scotus. Immanent forms in each thing. Scotus will argue for a "formal" distinction between general and specific forms.

Radical Realism: John Scotus Erigena, Anselm, Odo of Tournai, and Wm of Champeau. Universal have real independent incorporeal existence.

Problems with Radical Realism

Following implications in John Scotus Erigena, also in Paul and Philo of Alexandria, there was a spiritual creation of pure kinds--one human, one dog, one cow. Initially, is attractive theologically: In one human (Adam), all "humans" (as mere images of Adam) fell, and in one human (Christ, the second Adam) all humanity is redeemed. No real individuals. Karl Barth: Jesus is the only true human being: Loss of individual realities led inevitably to pantheism (no real difference between humans and God), the implication that Creation was the Fall, and that Satan and Hell are mere privation, and ultimately rejection of creatio ex nihilo in favor of Erigena's emanation theory.

Abelard's criticism of realism (including moderate realism) can be explained in the diagram below.  What we see here is the problem of Platonic participation and the absurdity of "fleeing" forms.  We also note the impossibility of a human participating only in the rational part of animality.

Duns Scotus' Formal Distinction

"Real" Distinction - objective difference between Socrates and Plato in the sensible world. Can only be "shown" not "known." THISNESS.

"Formal" Distinction in thought between "Platoneity" and "Zenoneity" - specific universal that allow us (and especially God) to know Plato and Zeno. SUCHNESS. Mere universal "humanity" does not allow that knowledge, and neither does the sensible matter of the two allow for this indubitable objective knowledge.

"Rational" Distinction: distinction between general essences such as humanity and animality. WHATNESS.

Example from Math

Formal distinctions in the number "7," which is quantitatively identical but qualitatively different. The number 7 is the sum of 3+4, 2+5, 6+1, 0+7... ,or the difference of 10-3, 9-2, 8-1, 11-4.... For example, 7 Little Pigs: Porky, Rind, Sweet Lips, Twiggy, Runt, Bacon, and Loin.

Please note that we have reached the limit of division with these particular persons; one simply cannot divide any more, either mentally or physically.

Contra-Aristotle: For him matter was the principle of individuation, but for Scotus form is the principle of individuation. Universal "whatness" cannot make an individual, but "suchness" can. Scotus believes that this is the solution to how God can know individuals.

Scotus' argument against conceptualism and nominalism: Concepts are logical pictures that must correspond to real forms. If something has the ability to cause different concepts in the mind, then the distinctions must be actual and formally existing within the things known.

Contra-Abelard: if the mind abstracts, it abstracts from forms it directly knows in things.

Scotus' moderate realism different from Aquinas' who believed that the mind does not know things directly, but only indirectly through an abstraction of form from sense perception.

Abelard: The mind makes the universal by abstraction, but Scotus believes that the mind finds universals as a singular form in things.


Radical nominalism: there are only individuals and their corresponding names - makes any general knowledge impossible. Logic deals with signs by which the mind knows objects.

Signs: natural and conventional. Those mental processes in the mind when the mind understands.

Abelard: natural signs (concepts) abstracted from common likenesses.

Conventional signs: written or spoken words. Radical nominalists had focused on these signs.

Terms of First Intention - all stand for individual existents. Cows, horses, humans.

Terms of Second Intention - terms that stand for other terms: nouns, verbs, etc. universals.

Universals are signs (terms) used in the second intention. "Humans are mortal" is a shorthand way of saying thet "Socrates is mortal and Aristotle is mortal and Plato is mortal, and so on."

A universal is an "object" only in the activity of thought. It does not exist in things, in God, or in a kosmos noetos.

Realists fail to distinguish between terms of the 1st and 2nd intention. There are some terms that don't refer to things.

Answer to Abelard and others in Jones, p. 322 top.

Ockham should be called something like a "terminist," because he claims that universals are natural signs (acts of the understanding) while a true nominalist would say that a universal is only a name, a conventional sign.

From E. A. Moody, Enc. of Phil., v. 8, p. 308:

"The varieties of. . . moderate realism turned on the answer to the question of whether, in an individual, the common nature is (1) really [i.e., ontologically] distinct from the individuating principle; or (2) "formally distinct," as Duns Scotus proposed; or (3) distinct only according to the mode of consideration, although involving some 'foundation in the thing' for such distinguishability, as Aquinas held.

"Ockham considered all forms of this doctrine of common natures in individual things to be self-contradictory and irrational. If the human nature of Socrates is really distinct from Socrates, then it is not Socrates' nature or essence, for a thing cannot be said to be essentially something that it really is not. If the common nature is anything at all, it is either one thing or many things; if one and not many, it is not common but singular, and if not one but many, then each of the many is singular and there is still nothing common."


a = Zeno’s "suchness" represented, let's say by 111 + 1111 = 1111111

b = Plato's "suchness" represented by 11 + 11111 = 1111111

Proof: Since a is not formally distinct from a, it follows that if a is identical with b, then b is not formally distinct from a.

Since a is not formally distinct from a, then if b is formally distinct from a, then b is not identical with a.

Ockham anticipates Leibniz's principle of the identity of indiscernibles. a and b are indiscernible, therefore they are identical and the concept of suchness is superfluous. Ockham's razor strikes again!

Ockham (herewith spelled Occam) on Universals by Michael Howard, "Star" Phil 309 Correspondent Student

    Occam, in attempting to uphold man's ability to acquire scientific knowledge naturally, was however reluctant to incorporate anything of realism in his theory. For Occam, realism in any form pre-empted the possibility of not only natural scientific knowledge, but any knowledge begotten via sense experience, as all sense objects are merely imperfect representations of the eternal archetypes, or universals. In this scenario truthful knowledge can be possible only by way of extranatural illumination. Occam was unable to accept this conclusion, firmly holding that man's finite mind was capable of acquiring knowledge solely by natural sense experience.

    In outlining his theory, Occam was careful to remain at least one step from nominalism, wishing to avoid the logical nominalist conclusion which follows from their rejection of universals in any form. If, as nominalism claims, no universals exist in any form, then what is the nature of the general assertions of scientific inquiry. It would seem, if only the particulars actually exist, that science's general conclusions are in actuality empty of meaning.

    Occam's theory begins with the assertion that the universals are tools which we use to think about the particulars, emphasizing that the true objects of thought are the individual particulars of sense perception. Only in the science of logic do universals themselves become objects of thought. Logic differs from the "real" sciences in that it is concerned not with real objects themselves, but rather solely with the "signs" which are the "means by which the mind knows real objects." Logic seeks to discover the method and means by which we can use these signs to express ourselves. To understand this concept we must delve deeper in Occam's logic, beginning with the exact nature of these signs.

    "Signs" are means by which the mind knows the particulars of sense perception, and Occam proposes two types of signs, the natural and the conventional. The natural sign is the actual [mental] process undergone in the mind in the action of perception or understanding. The conventional sign is simply the written or spoken word which denotes a given object. Among the conventional signs, we have a further distinction between signs used significantly and signs used nonsignificantly. The sign "trees" is used significantly in the sentence, "Trees have roots," as in this instance "trees" represents specific existing objects such as maples, oaks, and pines. "Trees" can also be used nonsignificantly in the sentence, "'Trees' is a word containing two vowels and three consonants," as in this case "trees" represents only itself. A sign or term is used nonsignificantly when what is being said concerns only the sign itself, and not those real things which "the sign is the sign of."

    One last distinction must be made in rounding out our discussion of Occam's logic, that between signs or terms of real existent objects, which he called "terms of first intention," and terms which stand for other terms, which he called "terms of second intention." Man, for example, can be either a first or second intention term. If I say, "That man possesses a heart," I use "man" as a first intention term explicitly because in this sentence it is a term which stands for a particular individual object. However, if I say, "Man possesses a heart," I have used "man" as a second intention term. It is a second intention term because upon analysis I will see that "man" in this case stands not for a specific individual object, but rather for the signs or terms of the many individuals such as Thatcher, Mitterand, and Twain.

    To clarify this rather complicated matter, and uncover how this relates to universals and objects of scientific knowledge, we must first establish that for Occam, "all natural knowledge is knowledge of individuals." Occam further maintains that among the many terms are those terms which signify a particular individual, and those which signify a multitude of individuals. Returning to our example of "Man possesses a heart," we find "man" to be one of those terms which is a sign of many individuals. "Man possesses a heart," is in effect a convenient shorthand method of saying "Thatcher possesses a heart and Mitterand possesses a heart and Twain possesses a heart etc." This answers our question as to the nature of universals. They are those terms which are signs of many individuals. The universal is merely a tool which is used for scientific reasoning, and cannot be considered a thing at all. It is further not an object of thought except in logic, and her it is no more than a term of second intention.

    It is this distinction between first and second intention which was not recognized by the realists, and consequently they erred in thinking universals to be actual things. In other words, the realists failed to see that the term man was fundamentally different from the term Twain. "Twain" is in fact a sign of a true existent object, although not itself a thing. Man on the other hand, is a sign of a group of signs, it represents no real object.

    Finally, we recall that Occam does theorize besides the conventional sign a natural sign, and this distinction prompts Jones to call him a terminist rather than a nominalist. Nominalism would not have admitted the existence of any but conventional signs. The universal could be no more than a verbal sound or written symbol. Occam states that although the universal sign is not an actual entity thought or created by the mind, it does have an objective existence. It is the activity of thinking itself, that physical process of brain activity which occurs during perception or understanding. For Jones, this qualification is enough to distinguish Occam from the nominalists.