Language, although not spatially defined, has a definable structure that demonstrates transition-like behaviour. We suggest that language, like natural materials, can undergo structural changes as the result of phase transition behavior. The structural change from lexical to functional vocabulary has features that resemble structural changes that occur in materials. Structural changes in vocables are syntactic and obviously not spatial but ultimately we assume that these changes have a correspondence in synaptic functions which are spatial in character. At some level of description, our theory of change in syntactic organization is compatible with a physical theory of behavior in synaptic organization. The comparison is of importance since it demonstrates that language shares crucial features with many other physical systems. First and second order phase transitions are striking phenomena that explain spontaneous state changes in multi-constituent systems. They are well understood phenomena that are formally tractable. Also, an explanation that includes the dynamics of phase transitions for a description of change in language may mirror fine grained observations in the dynamics of synaptic functions.
William H. Calvin [11] also describes a model for language involving some first order phase transitions. Calvin has developed a model that suggests, at a meta-level, how schemas are generated within synaptic functions, how concepts, abstractions and metaphor are formed and sustained through a replication process. He also suggests that partial perceptual cues generate competition between schemas and that resolution is reached through first order phase transitions. Calvin's model will be explored in more detail later in this thesis. It is possible that the fine grained description of phase transitions in the dynamics of synaptic functions may have some influence in the generation of linguistic structures within individuals. It also follows that such features may be reflected at a coarser grained level of language evolution in population dynamics.
First-order phase transition is of particular interest because the consequence of the process is irreversible. The irreversibility of the process, that is, the energy required for the transformation, dissipates after the transformation has taken place so it is non-reusable, much like friction in an engine. The transition of lexical to functional vocabulary can be viewed as irreversible as well, which supports the notion that the structural change in vocables may occur through a first order phase transition.