Creolistics, or Creology, is the scientific study of creole languages and, as such, is a subfield of linguistics. Someone who engages in this study is called a creolist.
Creolistics investigates the relative creoleness of languages suspected to be creoles, what Schneider (1990) calls "the cline of creoleness." No consensus exists among creolists as to whether the nature of creoleness is prototypical or merely evidence indicative of a set of recognizable phenomena seen in association with little inherent unity and no underlying single cause.
Creoleness is at the heart of the controversy with John McWhorter and Mikael Parkvall opposing Henri Wittmann (1999) and Michel DeGraff. In McWhorter's definition, creoleness is a matter of degree, in that prototypical creoles exhibit all of the three traits he proposes to diagnose creoleness: little or no inflection, little or no tone, transparent derivation; In McWhorter's view, less prototypical creoles depart somewhat from this prototype. Along these lines, McWhorter defines Haitian Creole, exhibiting all three traits, as "the most creole of creoles." A creole like Palenquero, on the other hand, would be less prototypical, given the presence of inflection to mark plural, past, gerund, and participle forms. Objections to the McWhorter-Parkvall hypotheses point out that these typological parameters of creoleness can be found in languages such as Manding, Sooninke, and Magoua French which are not considered creoles. Wittmann and DeGraff come to the conclusion that efforts to conceive a yardstick for measuring creoleness in any scientifically meaningful way have failed so far. Gil (2001) comes to the same conclusion for Riau Indonesian. Muysken & Law (2001) have adduced evidence as to creole languages which respond unexpectedly to one of McWhorter's three features (for example, inflectional morphology in Berbice Dutch Creole, tone in Papiamentu). Mufwene (2000) and Wittmann (2001) have argued further that Creole languages are structurally no different from any other language, and that Creole is in fact a sociohistoric concept (and not a linguistic one), encompassing displaced population and slavery. DeGraff & Walicek (2005) discuss creolistics in relation to colonialist ideologies, rejecting the notion that Creoles can be responsibly defined in terms of specific grammatical characteristics. They discuss the history of linguistics and nineteenth-century work that argues for the consideration of the sociohistorical contexts in which Creole languages emerged.
On the other hand, McWhorter points out that in languages such as Bambara, essentially a dialect of Manding, there is ample non-transparent derivation, and that there is no reason to suppose that this would be absent in close relatives such as Mandinka itself. Moreover, he also observes that Soninke has what all linguists would analyze as inflections, and that current lexicography of Soninke is too elementary for it to be stated with authority that it does not have non-transparent derivation. Meanwhile, Magoua French, as described by Henri Wittmann, retains some indication of grammatical gender, which qualifies as inflection, and it also retains non-transparent derivation. Michel DeGraff's argument has been that Haitian Creole retains non-transparent derivation from French.
To the defense of DeGraff and Wittmann it must be said that McWhorter's 2005 book is a collection of previously published papers and that it contains nothing on "defining creole", Manding, Sooninke or Magoua that wasn't already known when DeGraff and Wittmann published their critiques as can be seen from their published debate. As it is, McWhorter's book does not offer anything new by the way of analysis of Manding, Soninke, or Magoua that wasn't already debated on in his exchange with Wittmann on Creolist. The issues in question are, at this point, unresolved as to sustaining McWhorter's hypotheses in any significant way though DeGraff's 2005 contribution addresses their weaknesses as far as Haitian Creole is concerned adding new evidence against. The only conclusion possibly so far as the typological differences between Manding, Soninke, Magoua and Haitian are concerned is that their comparative data do not confirm McWhorter's yardstick approach to defining creole.
The answer might be that creoleness is better described and referred to as a syndrome. In some cases, the modified source language might be the substrate language when warranted by a homogeneous substrate. In other cases, the modified source language clearly is what creolists identify as the superstrate language' and in still other cases, no single source language might be identifiable. The same approach must be applied to identifying individual features as inherited or non-inherited and to distilling the defining grounds which separate creole languages from mixed languages such as Michif, especially when relexification is somehow claimed to be a moving factor.
The answer might also be, however, that creole languages (i.e. like Haitian Creole) are indeed a unique in terms of the perspective that they offer on the human language competence in terms of the nature of their grammars though there have been no new responses to the counter-claims of DeGraff and Wittmann that would warrant the reopening of the debate as for now. However, Ansaldo, Matthews & Lim (2007) critically assesses the proposal that creole languages exist as a homogeneous structural type with shared and/ or peculiar origins.
Though the call for a sane approach to creolistics goes back to Givón (1979), the first unbiased overview of the scientifically meaningful characteristics of creole languages must go to the credit of Arends, Muysken & Smith (1995). In their account of approaches to creole genesis, they group theories into four categories:
Theories focusing on the European input
Theories focusing on the non-European input
Gradualist and developmental hyptheses
The authors also confine Pidgins and mixed languages into separate chapters outside this scheme whether or not relexification come into the picture.