In thinking about the two kinds of Islamic hermeneutics, the Zahiri and Batini, I have been wondering if there was a neuroscientific basis for this aspect of the hermeneutic tradition in Islam and whether the zahir/batin division reflects the reality of dual brain mental processes. A fascinating text on this topic is "The Dual Brain, Religion, and the Unconscious" by Dr. Sim C. Liddon:
"TWO MODES OF PROCESSING INFORMATION
The experiment with split-brain subjects do have drawbacks: they are few in number, they deal with subjects who already have pathological processes going on (i.e., epilepsy), and the operation interrupts the normal functioning of the intact brain. However, the results of these experiments are supported not only by animal experiments and studies of patients with unilateral brain lesions, but also by experiments with normal subjects using a variety of other techniques. While more study surely needs to be done, some judgments have been made by those working in the field. First there is the obvious thought that the two hemispheres are specialized for different cognitive functions. Second, it has been concluded that the primary factor in hemisphere specialization is not the type of information considered (i.e., words or shapes or sounds) but how the brain processes information.
In trying to interpret this data, however, there is controversy. The anatomical distinctions between the left and right hemispheres are not as clear-cut as they appeared during the first few years of the split-brain research. Indeed, it seems that the way the lay public and popular press "explain" an infinite variety of lifestyles in terms of left/right differences is "simple minded" and a distortion of good scientific research. Let us assume that there are anatomical distinctions that must yet be clarified and that the left/right distinction does represent an oversimplification. With this in mind, and for heuristic reasons, let us go on to look at the differences and distinctions as they appeared during the first years of this research. No matter how anatomical questions are eventually answered, there are distinctions in human mental (or psychological) functioning that are both legitimate and important. In what follows I will speak of left/right differences because that is the easiest way to present the psychological material, but the reader should recognize that the anatomical distinctions are not so clear-cut. The point is, it is vital to distinguish between psychological matters and anatomical matters, and we are primarily interested in the former. Keeping this in mind, let us go on to review some of the results from the split-brain research.
It appears that the left hemisphere processes information in a way that is superior for relating and comparing separate items and for processing information in a linear or sequential mode. It is a far superior mode for language; for the appreciation of time, number, and logic; for the expression of analytic thought; and for the precise discrimination of details and differences. In short, it serves the analytic and scientific "purposes" of humankind. This I shall call the linear mode because it allows us to examine relationships in a linear way. For instance, the equation A + B + C is essentially a way of understanding in a linear form the relationships between the symbols A, B, and C. Its two outstanding characteristics are, first, the appreciation of separateness and discreteness of individual items or facts and, second, the recognition of linear relationships between these distinct items.
Continuing with the "simple-minded" approach of left/right differences, it seems that the right hemisphere synthesizes rather than analyzes. It appears to process information by instantaneously bringing together or integrating different parts into a unified form, or "whole," and is superior in dealing with simultaneous relationships and global properties. It is suited for producing our sensory images of the world as well as the images of our imagination and dream life, and is more suitable for the symbolic expression of the emotional component of our subjective experience. I call the mode of processing associated with the right hemisphere in this "simple-minded" approach the "gestalt" mode, which has two outstanding characteristics. First, there is an instantaneous or simultaneous bringing together of different data or facts into a unified whole, best exemplified by the figures of the Gestalt psychologists. They demonstrated that one perceives a form as a whole and that at the same time there is a lack of awareness of the parts when one focuses on the whole form. The second characteristic is the lack of ability to compare or differentiate which naturally follows from the fact that when one's attention is focused on the whole gestalt, there is a lack of awareness of the parts. While the left hemisphere serves humankind's scientific needs, the right is superior for artistic and religious expression.
For heuristic reasons, I have been talking in anatomical terms about "left" and "right" brain, but let me reiterate that the anatomical distinctions are not so clear as I have suggested. For my purposes, the focus is on identifying the functional aspect of these two modes of mental processing, not their exact anatomical correlations. In other words, each hemisphere shows at least some evidence of both modes of processing, but the split-brain research experiments have made it possible to identify the two functionally different modes of processing information. Thus the important distinction is not so much between the left and right hemispheres as it is a functional distinction between the two modes of mental processing. I shall collectively refer to these two functionally different modes as "bimodal mental processing." (1989, pp. 49-52)
~Excerpted from "The Dual Brain, Religion and the Unconscious" by Sim C. Liddon, M.D.