Editing Ontological commitment (section)

==Quine's criterion<!--'Ideological commitment' redirects here-->==

[[Willard Van Orman Quine]] provided an early and influential formulation of ontological commitment:<ref name=Quine2/>
{{quote|If one affirms a statement using a name or other singular term, or an initial phrase of 'existential quantification', like 'There are some so-and-sos', then one must either (1) admit that one is committed to the existence of things answering to the singular term or satisfying the descriptions, or (2) provide a 'paraphrase' of the statement that eschews singular terms and quantification over so-and sos. Quine's criterion can be seen as a logical development of the methods of [[Bertrand Russell]] and [[G.E. Moore]], who assumed that one must accept the existence of entities corresponding to the singular terms used in statements one accepts, unless and until one finds systematic methods of paraphrase that eliminate these terms.<ref name=Loux/>|Michael J. Loux & Dean W. Zimmerman|''The Oxford Handbook of Metaphysics'', 2003, p. 4}}

The purpose of Quine's strategy is to determine just how the ''ontological commitment'' of a theory is to be found. Quine argued that the only ontologically committing expressions are variables bound by a first-order existential quantifier, and natural language expressions which were formalized using variables bound by first-order existential quantifiers.<ref name=Quine0/><ref name=Dejnozka/>

Attempts have been made to argue that [[predicate (grammar)|predicate]]s are also ontologically committing, and thus that subject-predicate sentences bear additional ontological commitment to [[abstract object]]s such as [[Universality (philosophy)|universal]]s, [[set (mathematics)|sets]], or [[class (philosophy)|classes]]. It has been suggested that the use of meaningful names in nonexistence statements such as "Pegasus does not exist" brings with it an ontological commitment to [[empty name]]s like Pegasus, a quandary referred to as [[Plato's beard]] and escaped by using quantifiers.<ref name=Fogelin/>

This discussion has a connection to the Carnap–Quine argument over analytic and synthetic objects.<ref name=Ryan/> Although Quine refers to 'ontological commitment' in this connection,<ref name=Quine3/> in his rejection of the analytic/synthetic distinction he does not rely upon the formal translation of any particular theory along the lines he has suggested.<ref name=Quine1/>  Instead, Quine argues by using examples that although there are tautological statements in a formal theory, like "all squares are rectangles", a formal theory necessarily contains references to objects that are not tautological, but have external connections. That is, there is an ''ontological commitment'' to such external objects. In addition, the terms used to interpret the application of the theory are not simply descriptions of sensory input, but are statements in a context. That is, inversely, there is an ''ontological commitment'' of these observational objects to the formal theory. As Ryan puts it: "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."<ref name=Ryan/>  Thus we end up with Quine's 'flat' ontology that does not see a distinction between analytic and synthetic objects.<ref name=Schaffer/><ref name=Putnam/>

Quine further made a distinction between the ontological commitments of a theory (what the theory says exists) and the '''ideological commitments'''<!--boldface per WP:R#PLA--> of a theory (those concepts, logical or non-logical, that are expressible within the theory).<ref>[https://plato.stanford.edu/entries/ontological-commitment/ "Ontological Commitment"]. ''[[Stanford Encyclopedia of Philosophy]]''.</ref>

===Ontological parsimony===
Whatever process one uses to determine the ontological commitments of a theory, that does not prescribe what ontological commitments one should have. Quine regarded this as a matter of [[epistemology]], which theory one should accept. "Appeal is made to [concerns of] explanatory power, parsimony, conservatism, precision, and so on".<ref name=Routledge/>

Ontological parsimony can be defined in various ways, and often is equated to versions of [[Occam's razor]], a "rule of thumb, which obliges us to favor theories or hypotheses that make the fewest unwarranted, or ''ad hoc'', assumptions about the data from which they are derived."<ref name=Henke/> Glock regards 'ontological parsimony' as one of the 'five main points' of Quine's conception of ontology.<ref name=Glock/>

Following Quine,<ref name=QuineW/> Baker states that a theory, ''T'', is ''ontologically committed'' to items ''F'' if and only if ''T'' entails that ''F′''s exist.  If two theories, ''T<sub>1</sub>'' and ''T<sub>2</sub>'', have the same ontological commitments except that ''T<sub>2</sub>'' is ontologically committed to ''F′''s while ''T<sub>1</sub>'' is not, then ''T<sub>1</sub>'' is more parsimonious than ''T<sub>2</sub>''. More generally, a sufficient condition for ''T<sub>1</sub>'' being more parsimonious than ''T<sub>2</sub>'' is for the ontological commitments of ''T<sub>1</sub>'' to be a proper subset of those of ''T<sub>2</sub>''.<ref name=Baker/>

These ideas lead to the following particular formulation of Occam's razor: 'Other things being equal, if ''T<sub>1</sub>'' is more ontologically parsimonious than ''T<sub>2</sub>'' then it is rational to prefer ''T<sub>1</sub>'' to ''T<sub>2</sub>''.'  While a common formulation stipulates only that entities should not be multiplied beyond necessity, this version by contrast, states that entities should not be multiplied ''other things being equal'', and this is compatible with parsimony being a comparatively weak theoretical virtue.<ref name=Baker/>