In this paper I review some of the theoretical issues surrounding metaphor, and trace them through the context of the cognitive neuroscience debate. Metaphor, like all figurative language, has typically been explained as a secondary linguistic process which is a function taking place on literal language. However this explanation does not fit well with some of the recent work on right hemisphere processing of language or recent cognitive studies, both of which suggest that the figurative and literal language are processed simultaneously and share much substructure. In seeking ways to operationalize the Lakoff and Johnson view of conceptual metaphor as a constitutive cognitive phenomenon, I begin to spell out what kinds of theoretical predictions the Lakoff Johnson model would make on the neurophysiological levels af cognitive investigation. I conclude by offering some thoughts on new directions of research using these methods, and by reassessing the philosophical basis of these matters.