Optimality Theory - Criticism

Criticism

Optimality theory has attracted substantial amounts of criticism, most of which is directed at its application to phonology (rather than syntax or other fields).

It is claimed that optimality theory cannot account for phonological opacity (see Idsardi 2000, e.g.). In derivational phonology effects may be seen that are inexplicable at the surface level but which are explainable through "opaque" rule ordering; but in optimality theory, which has no intermediate levels for rules to operate on, these effects are difficult to explain.

For example, in Québécois French high front vowels triggered affrication of /t/, (e.g. /tipik/ → ) but the loss of high vowels (visible at the surface level) leaves the affrication with no apparent source. Derivational phonology can explain this by saying that vowel syncope (the loss of the vowel) "counterbled" affrication - that is, instead of vowel syncope occurring and "bleeding" (i.e. preventing) affrication, we say that affrication applies before vowel syncope, so that the high vowel is removed and the environment destroyed which had triggered affrication. Such counterbleeding rule orderings are therefore termed opaque (instead of transparent), because their effects are not visible at the surface level.

The opacity of such phenomena finds no straightforward explanation in optimality theory, since intermediate forms are not accessible (constraints refer only to the surface form and/or the underlying form). There have however been a number of proposals designed to account for it; but most of these proposals significantly alter optimality theory's basic architecture, and therefore tend to be highly controversial. Frequently, such alterations add new types of constraints (which are not universal faithfulness or markedness constraints), or change the properties of GEN (such as allowing for serial derivations) or EVAL. Some well-known examples of these include John J. McCarthy's sympathy theory and candidate chains theory, and there are many others.

A relevant issue is the existence of circular chain shifts, i.e. cases where input /X/ maps to output, but input /Y/ maps to output . Many versions of optimality theory predict this to be impossible (see Moreton 2004, Prince 2007). It is not certain whether patterns of this sort occur in natural languages.

Optimality theory is also criticized as being an impossible model of speech production/perception: computing and comparing an infinite number of possible candidates would take an infinitely long time to process. Idsardi (2006) argues this position, though other linguists dispute this claim on the grounds that Idsardi makes unreasonable assumptions about the constraint set and candidates, and that more moderate instantiations of optimality theory do not present such big computational problems (see Kornai (2006) and Heinz, Kobele, and Riggle (2009)). Another common rebuttal to this criticism of optimality theory is that the framework is purely representational. In this view, optimality theory is taken to be a model of linguistic competence and is therefore not intended to explain the specifics of linguistic performance.

Another objection to optimality theory is the claim that it is not technically a theory, in that it does not make falsifiable predictions. The source of this issue is terminology: the term "theory" is used differently here than in physics, chemistry, and other sciences. Specific instantiations of optimality theory may make falsifiable predictions, in the same way that specific proposals within other linguistic frameworks can. What predictions are made, and whether they are testable, depends on the specifics of individual proposals (most commonly, this is a matter of the definitions of the constraints used in an analysis). Thus, optimality theory as a framework is best described as a scientific paradigm.

Some criticisms of optimality theory appear to be based on a misunderstanding of how it works. A well-known example of this is Noam Chomsky's widely-repeated assertion that optimality theory would predict every lexical input to be reduced to a single optimal syllable (e.g. every word is realized as ). In fact, under the premises of Optimality Theory universal neutralization of this type would only be predicted if there were no faithfulness constraints (see McCarthy 1997). In a sense, the diametrically opposite kind of criticism comes from Morris Halle: "... the existence of phonology in every language shows that Faithfulness is at best an ineffective principle that might well be done without." By "phonology," Halle clearly means disparity between inputs and outputs of a phonological system. Optimality theory would fail to predict such deviations from an underlying form only if there were no markedness constraints. In OT, input-output disparity is normally understood as the result of markedness constraints being ranked over faithfulness constraints (M >> F).