an epistemology of apl  epistemology is the study of what we know and how we know it. inevery day life this usually means trying to understand how we builda mental model which seems to correspond to the reality of theworld around us. from the dot matrix of our retinas, with theirmillion or so pixels, our brains recognize as units such objects asstraight lines, curves, and human faces. from vibrations of nearbyair molecules we hear conversations and c major triads. ordinarypeople simply consider what we know about our surroundings, asinterpreted by our senses, to be what we can know about theworld.  humans do not have ways of knowing possessed by other creaturesin the world. dogs hear sound frequencies beyond the range of humanears. some insects can directly sense ultra-violet light. these andother animals with various modalities of perception experienceworlds that may be quite different from the one that humans know.uv sensitive insects use their eyes to find the flowers they needfrom which to grab pollen. conversely, the flowers are pollinated.one can wonder who is using whom.  philosophers like to muse about such things. what do we reallyknow? how do we create symbolic constructs in our brains? irismurdoch [ref 1] puts it this way:  the idea of a self-contained unity or limited whole is afundamental instinctive concept. we see parts of things, we intuitwhole things. we seem to know a great deal on the basis of verylittle. oblivious of philosophical problems and paucity of evidencewe grasp ourselves as unities, continuous bodies and continuousminds. we assume the continuity of space and time. this intuitiveextension of our claim to knowledge has inspired the reflections ofmany philosophers & the urge to prove that where we intuitunity there really is unity is a deep emotional motive tophilosophy, to art, to thinking itself. _intellect naturallyone-making._ [emphasis added]  murdoch has distinguished two levels of understanding, callingone of them intuitive. the other one we shall call logical. withinthe ellipsis in the quotation above, murdoch suggests hume and kantas spokesmen respectively for two views:  [hume said that] if a fiction is necessary enough, it is not alie.  [kant said that] we could not infer reality from experience whenthe possibility of experience itself needed to be explained.  the division is between laws and customs, between logic andintuition, between analysis and synthesis, between rules andjudgment, between the engineer and the poet. one might describephilosophy as the art of logical analysis of the intuitive.  epistemology is not static. the ways in which we view the worldchange as our perceptions change. for hundreds of thousands ofyears our five senses were the only windows of perception.gradually, mental models became more important. who has ever seen,smelled, or touched a positron or a black hole? these and even moremysterious phenomena --- from the cosmological construct on thelarge scale to quarks on the small --- are not only the primarystudies of physics: they also appear regularly in the _new yorktimes science times._  the physical universe became a different place with thecopernican revolution. it wasn't much of a revolutionscientifically; it was little more than a change of origin. it did,however, shake up the religious establishment a bit. as theheliocentric view took hold it diminished the long assumedcentrality of humanity, but, curiously, enough it also madepossible not only seeing the earth as a minor bit of the solarsystem but also seeing the solar system as a trivial item in anordinary galaxy, and the galaxy as part of a galactic group, and soon to higher levels of cosmic organization.  the sky today is generally believed to be full of neutrinos,entangled quantum states, and dark matter. this newly clutteredcosmos has led to wonderful new structures in our brains,particularly in the brains of cosmologists, of course, but also ---and more important --- to readers of the daily news. perception istranslation from sensory inputs to what pinker [ref 2] callsmentalese.  apl epistemology has its own history. since its beginnings aplhas extended the perceptual field which characterized many earlylinear languages. in succeeding section several stages of thisdevelopment will be discussed.  j. philip benkard