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Optimality theory - Wikipedia, the free encyclopedia

Criticism

Optimality Theory has drawn a good deal of criticism, most of which is directed at its application to phonology (rather than syntax or other fields).

Many criticisms of OT are, according to its proponents, based on fundamental misunderstanding of how it works. A well-known example of this is Chomsky's (1995) assertion that OT would predict every lexical input to be reduced to a single optimal syllable (e.g. every word is realized as [ba]). In fact, 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 Halle (1995): “... 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. OT would fail to predict this disparity only if there were no markedness constraints (see Prince 2007). Input-output disparity is normally the result of markedness constraints being ranked over faithfulness constraints (M >> F).

Another objection to OT 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 OT 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, OT as a framework is best described as a scientific paradigm.

A more serious objection to OT is the claim that it 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 OT, 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/ -> [tspIk]) 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 occuring 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 OT, 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 OT's basic architecture, and therefore tend to be highly controversial. Frequently, such alterations add new types of constraints (which aren't Universal Faithfulness or Markedness constraints), or change the properties of GEN 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 [Y], but input /Y/ maps to output [X]. Many versions of OT predict this to be impossible (see Moreton 2004, Prince 2007). It is not certain whether patterns of this sort occur in natural languages.

OT 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. The most common rebuttal to this argument is that OT is purely representational. In this view, OT is taken to be a model of Linguistic competence, and is not intended to explain the specifics of Linguistic performance. Further, work by Heinz, Kobele, and Riggle (forthcoming) shows that in fact, OT is computationally tractable, under certain reasonable assumptions.

[edit] Theories within Optimality Theory

In practice, implementations of OT often assume other related theories, such as Syllable theory, Moraic theory, or Feature Geometry. Completely distinct from these, there are sub-theories which have been proposed entirely within OT, such as positional faithfulness theory, Correspondence Theory, Sympathy Theory, and a number of theories of learnability. There are also a range of theories specifically about OT. These are concerned with issues like the possible formulations of constraints, and constraint interactions other than strict domination.

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