Exploring the Boundaries of Human Knowledge
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The question of the scope of human knowledge has been a longstanding preoccupation of philosophy. And that question has always had a special intensity where philosophical knowledge itself is concerned. ... It is not merely that we are a tiny speck in a vast cosmos; that speck also has its own specific cognitive orientation, its own distinctive architecture. The human mind conforms to certain principles in forming concepts and beliefs and theories, originally given, and these constrain the range of knowledge to which we have access. We cannot get beyond the specific kinds of data and modes of inference that characterise our knowledge-acquiring systems – however paltry these may be. The question has been what the operative principles are, and where their limits fall. How limited are we, and what explains the extent and quality of our limits? Can we, indeed, come to understand the workings of our own epistemic capacities?
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The most recent major theorist in this tradition is Chomsky. According to him, the mind is a biologically given system, organized into discrete subsystems or modules, which function as special-purpose cognitive devices, variously structured and scheduled, and which confer certain epistemic powers and limits on their possessors. The language faculty is one such module: innately based and specifically structured, it comes into operation early in human life and permits the acquisition, or emergence, of an intricate cognitive system in a spectacularly short time – this being made possible by the antecedent presence of the principles of universal grammar in its initial design.
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As Chomsky observes, the knowledge so generated is no simpler than knowledge of advanced mathematics or physics; but the human mind is so adapted that it yields this knowledge with comparative ease – somewhat as we effortlessly develop a complex physiological structure in a pre-programmed way. (Compare the ease with which our visual system converts two-dimensional arrays into three-dimensional percepts, but the difficulty we have in making even simple two-dimensional drawings on the basis of our three-dimensional visual experience.) As a corollary, however, this faculty is poorly adapted to picking up conceivable languages distinct in grammatical structure from that characteristic of human speech. Its strength is thus also its weakness; in fact, it could not be strong in one way without being weak in another…
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The human mind is a biologically given system with certain powers and limits. As Charles Sanders Peirce argued, "Man's mind has a natural adaptation to imagining correct theories of some kinds...If man had not the gift of a mind adapted to his requirements, he could not have acquired any knowledge". The fact that "admissible hypotheses" are available to this specific biological system accounts for its ability to construct rich and complex explanatory theories. But the same properties of mind that provide admissible hypotheses may well exclude other successful theories as unintelligible to humans. Some theories might simply not be among the admissible hypotheses determined by the specific properties of mind that adapt us "to imagining theories of some kinds," though these theories might be accessible to a differently organised intelligence. Or these theories might be so remote in an accessibility ordering of admissible hypotheses that they cannot be constructed under actual empirical conditions, though for a differently structured mind they might be easily accessible.