Principles and parameters

Principles and parameters is a popular framework in generative linguistics. Principles and parameters was largely formulated by the linguists Noam Chomsky and Howard Lasnik, though it was the culmination of the research of many linguists. Today, many linguists have adopted this framework, and it is considered the dominant form of mainstream linguistics.

The Framework
The central idea of principles and parameters is that a person's syntactic knowledge can be modelled with two formal mechanisms: Within this framework, the goal of linguistics is to identify all of the principles and parameters that are universal to human language. As such, any attempt to explain the syntax of a particular language using a principle or parameter is cross-examined with the evidence available in other languages. This leads to continual refinement of the theoretical machinery of generative linguistics in an attempt to account for as much syntactic variation in human language as possible.
 * A finite set of fundamental principles that are common to all languages; e.g., that a sentence must always have a subject, even if it is not overtly pronounced.
 * A finite set of parameters that determine syntactic variability amongst languages; e.g., a binary parameter that determines whether or not the subject of a sentence must be overtly pronounced (this example is sometimes referred to as the Pro-drop parameter).

Language acquisition
According to this framework, principles and parameters are part of a genetically innate universal grammar (UG) which all humans possess, barring any genetic disorders. As such, principles and parameters do not need to be learned by exposure to language. Rather, exposure to language merely triggers the parameters to adopt the correct setting.

Criticism
Criticism of principles and parameters has most often been due to its stance on language acquisition. Although the framework is accepted by most mainstream linguists, it is very controversial amongst psychologists, cognitive scientists, and neuroscientists due to the strong nativism it espouses in relation to language acquisition. For example, the developmental psychologist Michael Tomasello has argued that there is no evidence of innate linguistic knowledge in the early utterances of children. Another source of criticism is the binary nature of parameters in the framework. For example, the linguist Larry Trask argues that the ergative case system of the Basque language is not a simple binary parameter, and that different languages can have different levels of ergativity.

Minimalist program
The influence of principles and parameters is most apparent in the works of linguists who subscribe to the Minimalist Program, Noam Chomsky's most recent contribution to linguistics. This program of research utilizes conceptions of economy to enhance the search for universal principles and parameters. Linguists in this program assume that humans use as economic a system as possible in their innate syntactic knowledge.

Examples
Examples of theorized principles are: Examples of theorized parameters are:
 * Structure preservation principle
 * Trace erasure principle
 * Projection principle
 * Ergative case parameter
 * Head directionality parameter
 * Nominal mapping parameter
 * Null subject parameter
 * Polysynthesis parameter
 * Pro-drop parameter
 * Serial verb parameter
 * Subject placement parameter
 * Subject side parameter
 * Topic prominent parameter
 * Verb attraction parameter