SENSIBLE AND NONSENSICAL QUESTIONS OF
Theories propounded under the heading of ontology have
often been full of whimsical, metaphysical inventions and the
source of much confusion. Ontology has been defined as the
study of what is the case as contrasted with epistemology: the
study of what one can know to be the case. It has also been
contrasted with axiology or normative philosophy: the study of
what is the case versus of what ought to be the case.
'Ontological' problems of that sort have thus been posed on the
same level, and side by side, with those of epistemology and
axiology or normative philosophy.
Recommending themselves as 'specialists in the nature of being' the
'ontologists' concerned purported to be searching for what there (really)
is, as opposed to what can be known to be the case, and to what should be
Antimetaphysicians who have always repudiated the belief
in some 'nature of being' or an 'ultimate reality' have
indicated that this kind of 'ontology' is an exercise in
futility. With it, however, they have traditionally also repudiated
all theories about kinds of existence or about the
ontological status of existents. It seems like they have
wrongfully equated the idea of an ultimate reality with the idea
of an ultimate conceptual framework or constructional system
used when speaking or thinking about reality. But it is exactly
this which is the primary task of a sensible ontology: to make
explicit the fundamental, conceptual or constructional categories
and presuppositions of a particular system of language or
thought, and to examine what are the primitives and hypothetical
entities in this system. Ontology in this sense is, then,
concerned in the first place with the question whether such a
system does indeed make a distinction between:
- what is the case, and what is known to be the case;
- what is the case, and what is believed to be the
- what is the case, what can be the case, and what
should be the case; and
- what was, what is, and what will be the
The subject of ontology is therefore not what is the case as
distinct from what is, can, or should be known or believed to be
the case, or as distinct from what ought to be the case, but the
subject of ontology is first of all the question whether the
distinction between the factual and the epistemic or doxastic,
and between the factual and the normative, is actually drawn in
a particular system.
Some of the above distinctions correspond to a difference in
ontological status, some do not, but also in 'one and the same'
sphere of what was, is and will be the case some entities may
have another ontological status than other entities. Immediately
following is therefore the question of what is explicitly or
implicitly taken to be existing in a certain language or system
- only 'i' or 'my' mind (in solipsism)?
- only mind (or the human mind), or only matter, or
- only abstract entities such as attributes, or only concrete
things, or both?
- sets, classes, functions and/or numbers (in logics and
- one or more gods, demons and/or other supernatural entities
(in religious thought)?
- (a) supreme being (in more general, denominational thought)?
The crux of the matter is, of course: what does
If we do not make use of a synonym like being, it
is not possible to define this term (or these terms) without
referring to entities whose (purported) existence is required
for the definition itself, if only by means of giving examples
of existence. This implies that the term existence may have
different meanings in different systems, dependent on what kind
of entities are said to 'exist' in these systems. (Compare the
meaning-variance thesis in logics: the meaning of logical
constants wholly depends upon the axioms or rules of the system
in which they occur.)
Thus, solipsists who believe that only they themselves exist, or
idealists who believe that only mind exists (that is, who use the
word exist so that only mind 'exists') give another meaning to
existence than materialists who believe that only matter
The same does not apply to the existence or nonexistence of the supreme
being and entities with supernatural qualities like gods and demons,
because the suggestion is that they have an ontological status no
different from that of human beings or people and the other things of the
After having made these inventories the next step is to lay bare the
possible inconsistences in the constructional or ontological system, and
to consider the possible elimination of certain categories, postulates,
primitives or hypothetical entities.
Underlying this activity is the conviction that every theory or conceptual
system must be free from superfluous conceptual ballast.
The criterion of consistence is an essential element of the coherentist
theory of truth, the criterion of simplicity or parsimony
is a principle of conceptual minimization, that is, of fewest
conceptual entities (categories, postulates, primitives, and so
on). A problem with regard to the latter criterion is that it is
not that simple to determine the general, formal simplicity of
an ontological system (if possible at all), even not in only one
For example, the simplicity of the basis of primitive predicate
expressions is not fixed by merely counting the number of primitives, or
of primitive predicate places (because —as has been argued—
predicate expressions can be compounded into other predicate expressions
having more places, or can be replaced with other predicate expressions
having fewer places).
Another question is the number of nonprimitive expressions.
We shall see that our own ontological system has many more individual
expressions, because it accepts the names of attributes, such as
happiness, as individual expressions where other, formal systems
have only -- is happy as a predicate
On the other hand, the latter systems need many more predicate
expressions, and the total number of individual and attributive
expressions remains the same in these two types of system.
If individual expressions should not be multiplied
'beyond necessity', then neither should attributive expressions.
-- is happy and the other expressions
designate only one-place predicates or attributes, the primitive two-place
predicate expression -- has .. needed in
addition to the individual expressions is always the same one, and cannot
be dismissed anyhow in any system which recognizes the relation of
having-as-an-element or being-an-element-of (which is its inverse).
As to relations it is inevitable that we must use individual
expressions besides the relational ones. These individual expressions
are reduced or 'derelativized' one-place predicate
expressions of the two- or more-place corresponding ones. (In
combinatory logic such 'derelativization' is done by means of a
predicate operator 'Der'.)
Friendship in the sense of having (someone as) a friend,
for instance, corresponds to the one-place --
has (someone as) a friend which is a reduction of the two-place
-- has .. as a friend (the inverse of
-- is a friend of
This recognition of individual relations is necessary, because when
relations become the focus of attention, and when we start talking about
their attributes and/or relations (with other attributes and/or
relations), they become things themselves, albeit in a different domain
Relations (such as friendship) cannot have the same ontological
status as the things (such as friends) they relate to each
other, otherwise we would be stuck with a loose, unconnected set
of objects with parts and purely nonrelational attributes at the
most. Thus, when we talk about relations, we make use of
individual expressions corresponding to reduced, one-place predicates,
and when we talk about the things being related, we
make use of two- or more-place predicate expressions. Attributes
are limit cases of relations: one-place predicates as it were.
They have the same ontological status and behave very much like
them, especially when looked upon as things in a separate (the
so-called 'secondary') domain of discourse.
This is the reason that we shall employ the term predicate
as common denominator of both attributes and relations, while using the
phrase predicat(iv)e expression for an
expression which designates an attribute or relation.
(In other systems such an expression itself is often called "a predicate",
while attributes may be called "internal" or "intrinsic properties" and
relations, "relational" or "extrinsic properties".)