Ontological pluralism

In philosophy the branch called ontological pluralism is the doctrine that there are different ways or modes of being. Technically, ontological pluralism claims that an accurate description of reality uses multiple quantifiers (see below for more on this term) that do not range over a single domain. A very brief outline of some technical terms is proved next to make the second description clearer.

Quantifiers
The word quantifier in the introduction refers to a variable used in a domain of discourse, a collection of objects under discussion. In daily life, the domain of discourse could be 'apples', or 'persons', or even everything. In a more technical arena, the domain of discourse could be 'integers', say. The quantifier variable x, say, in the given domain of discourse can take on the 'value' or designate any object in the domain. The presence of a particular object, say a 'unicorn' is expressed in the manner of symbolic logic as:
 * ∃ x; x is a unicorn.

Here the 'turned E ' or ∃ is read as "there exists..." and is called the symbol for existential quantification. Relations between objects also can be expressed using quantifiers. For example, in the domain of integers (denoting the quantifier by n, a customary choice for an integer) we can indirectly identify '5' by its relation with the number '25':
 * ∃ n; n × n = 25.

If we want to point out specifically that the domain of integers is meant, we could write:
 * ∃ n ∈ ℤ; n × n = 25.

Here, ∈ = is a member of... and ∈ is called the symbol for set membership; and ℤ denotes the set of integers.

Ontology
The term 'ontology' refers to the assembly of objects in a domain of discourse, but more than that, to their properties, to the relations between them, and to the rules governing their use. The subject of ontology also includes its metatheory, meta-ontology. According to Hofweber:

""The larger discipline of ontology can thus be seen as having four parts:


 * °1. the study of ontological commitment, i.e. what we or others are committed to,
 * °2. the study of what there is,
 * °3. the study of the most general features of what there is, and how the things there are relate to each other in the metaphysically most general ways,
 * °4. the study of meta-ontology, that is, saying what task it is that the discipline of ontology should aim to accomplish, if any, how the questions it aims to answer should be understood, and with what methodology they can be answered.""


 * —— Thomas Hofweber, Logic and Ontology in The Stanford Encyclopedia of Philosophy

Comparing ontologies
The question of comparing ontologies arises. Such comparisons can be simple (like comparing the objects in two ontologies) or much more complicated (looking also at the relations between the objects). Such comparisons can be discussed on the basis of quantifier variance.

Carnap
In a number of papers, Rudolf Carnap proposed a difference between "internal" and "external" questions. The internal questions are answered within a framework, for example, a mathematical structure such as Maxwell's equations, while the external questions involve whether or not observation suggests it is practical to adopt a framework, for example, whether Faraday's laws are suitably described using Maxwell's equations. According to Eklund, Carnap holds that argument over the existence of objects involved in the 'internal' framework is nonsense: the only sensible question is whether the terminology is useful. Eli Hirsch, says that “many familiar questions about the ontology of physical objects are merely verbal. Nothing is substantively at stake in these questions beyond the correct use of language [and the claim that] quantifier expressions can have different meaning in different languages”.

The issue is raised, however, that some objects exist in multiple ontologies, and so perhaps they can lay claim to a more general existence than simply within one or another framework. In particular, Hirsch suggests existence within 'common sense' is a more general form of existence than existence inside any particular framework.

Another issue is raised when comparing frameworks as to which is preferable. “Ontological anti-realism is often traced to Carnap (1950), who held that there are many different ontological frameworks, holding that different sorts of entities exist, and that while some frameworks may be more useful for some purposes, there is no fact of the matter as to which framework is correct”

Quine
In a very influential series of papers and books, Willard v.O. Quine argued against the position of Carnap. In his view, the distinction between internal and external questions and objects was not sharp. Although a particular object within a conceptual framework can have properties and connections with other objects in that framework that are fundamentally decided by the rules of the framework itself, there are interactions between the framework and the 'real' world that cannot be discounted. On one hand, the objects of the framework can be suggested as abstractions from the 'real' world, which might be viewed as the 'muse' leading to the framework. (This view resembles somewhat that of Aristotle, that idealized concepts like 'circle' are abstractions from observations of real objects that approximate a circle.) A classic example is Euclidean geometry, initially thought to express the way the world worked, and later considered to be a 'model' suggested by 'reality', but that applied only approximately to reality under strict limitations. On the other hand, and more significantly, the application of the framework to the real world is very strongly colored by the framework itself; the framework suggests the direction that observations should take, what connections should be looked for, what properties are to be expected. ""Rather than being divided between contingent synthetic claims and indubitable analytic propositions, our beliefs constitute a continuous range from a periphery of sense-reports to interior concepts that are comparatively theory-laden and general.""


 * —— Frank X. Ryan, discussing Quine's position in Analytic: Analytic/Synthetic; American Philosophy: An Encyclopedia

Of course, observations may prove surprising and suggest the application of the framework has discrepancies with reality. But the application of the framework to the real world is a continuing process, with our 'interpretation of what we see' and 'what we see' related as inseparable partners in a dance.

The key objection made by Quine was that no clear definition of a 'framework' can be found. In trying to establish the meaning of a term within a framework, its analytic or tautological meaning, one is caught up in a process that inevitably involves real objects, 'synthetic' objects. "It begins to appear, then, that Carnap’s dichotomy of questions of existence is a dichotomy between questions of the form “Are there so-and-sos?” where the so-and-sos purport to exhaust the range of a particular style of bound variables, and questions of the form “Are there so-and-sos?” where the so-and-sos do not purport to exhaust the range of a particular style of bound variables. Let me call the former questions category questions, and the latter ones subclass questions. I need this new terminology because Carnap’s terms ‘external’ and ‘internal’ draw a somewhat different distinction which is derivative from the distinction between category questions and subclass questions. The external questions are the category questions conceived as propounded before the adoption of a given language; and they are, Carnap holds, properly to be construed as questions of the desirability of a given language form. The internal questions comprise the subclass questions and, in addition, the category questions when these are construed as treated within an adopted language as questions having trivially analytic or contradictory answers."


 * —— Willard v. O. Quine On Carnap’s Views on Ontology

Quine's chief objection to analyticity is with the notion of synonymy (sameness of meaning), a sentence being analytic, just in case it substitutes a synonym for one "black" in a proposition like "All black things are black" (or any other logical truth). The objection to synonymy hinges upon the problem of collateral information. We intuitively feel that there is a distinction between "All unmarried men are bachelors" and "There have been black dogs", but a competent English speaker will assent to both sentences under all conditions since such speakers also have access to collateral information bearing on the historical existence of black dogs. Quine maintains that there is no distinction between universally known collateral information and conceptual or analytic truths.

Another approach to Quine's objection to analyticity and synonymy emerges from the modal notion of logical possibility. A traditional Wittgensteinian view of meaning held that each meaningful sentence was associated with a region in the space of possible worlds. Quine finds the notion of such a space problematic, arguing that there is no distinction between those truths which are universally and confidently believed and those which are necessarily true.

Wittgenstein
Wittgenstein is credited as the originator of the internal/external contrast. It is suggested that although Carnap acknowledged his indebtedness to Wittgenstein, in fact a closer understanding by Carnap would have provided a better foundation for Carnap's philosophy: "All that Carnap had to do was to take a good hard look at his state-descriptions and to ask: what are they supposed to be descriptions of in some realistic, down-to-earth sense? One natural answer is that they are descriptions of the different possible states of affairs or courses of events (in short 'possible worlds') in which the speaker of a language could possibly find himself and which he could in principle distinguish from each other. From this answer it is only a short step to the crucial idea that the rules for using the language will have to be shown - in principle - by the way a well-informed speaker would use it in these different circumstances according to the rules, i.e. by the extensions which the expressions of the language would have in those several 'possible worlds'. This is all we need to arrive at the basic ideas of possible worlds semantics."


 * —— Jakko Hintikka as quoted by Bradley Carnap's Semantics in Retrospect, p. 375