Scott Sullivan’s An Introduction to Traditional Logic
Chapter 3
Substance
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Primary substance is an individual existent, e.g., Socrates
Primary substance is not a category
Primary substance does not exist in something
Secondary substance is universal or nature, e.g., human being
Secondary substance is a category
Secondary substance is predicated of a primary substance
Accident
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Modify the way a primary substance exists
Exist only in primary substances
Categories
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Ten categories = secondary substance + nine accidents
Is a secondary substance an accident, i.e., does a secondary substance modify the way
something exists?
o
o
No, because an individual existent (a primary substance) has the kind of existence which
it has as a specific kind of existing being only through a secondary substance.
This is perhaps the sense in which we should take Sullivan’s assertion that the secondary
substance is the main category (existing as a universal predicate)
Predicables
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If categories are the predicates of a subject, then the predicables are the ways in which the
predicates are related to a subject
Genus + specific difference = species
Is every species a secondary substance?
Is a genus ever a secondary substance?
o
o
o
o
o
Sullivan characterizes both species and secondary substance as the “nature” of a thing
Sullivan also characterizes “living” as a species (of corporeal things)
But “human being” and “living” are not species in the same sense or to the same degree
“living” doesn’t get as close as “human being” to revealing the reality of Socrates
Is Sullivan using species in an equivocal way?


To refer to the nature of an existent (i.e., a primary substance) AND
To refer to a subclass of a larger class?
Property
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Characteristic that always accompanies a particular nature
Distinguished from accident, which is a characteristic that can be said of things with different
natures