▁receive , ▁but ▁is ▁instead ▁filtered ▁sens ory ▁information , ▁where ▁the ▁filter ▁is ▁our ▁existing ▁pre con ception s ▁– ▁a ▁concept ▁later ▁called ▁a ▁' th ematic ▁framework .' ▁He ▁c ited ▁optical ▁ill us ions ▁such ▁as ▁the ▁famous ▁old ▁Paris ienne ▁woman ▁( Pattern s ▁of ▁Disc overy , ▁p .   1 1 ), ▁which ▁can ▁be ▁seen ▁in ▁different ▁ways . ▁Hans on ▁drew ▁a ▁distinction ▁between ▁' see ing ▁as ' ▁and ▁' see ing ▁that ' ▁which ▁became ▁a ▁key ▁idea ▁in ▁evol ving ▁theories ▁of ▁per ception ▁and ▁meaning . ▁He ▁wanted ▁to ▁form ulate ▁a ▁logic ▁explaining ▁how ▁scientific ▁discover ies ▁take ▁place . ▁He ▁used ▁Charles ▁Sand ers ▁Pe ir ce ' s ▁notion ▁of ▁ab du ction ▁for ▁this . ▁ ▁Hans on ' s ▁other ▁books ▁include ▁The ▁Con cept ▁of ▁the ▁Pos it ron ▁( 1 9 6 3 ). ▁Hans on ▁was ▁a ▁sta unch ▁def ender ▁of ▁the ▁C open hagen ▁interpretation ▁of ▁quantum ▁mechan ics , ▁which ▁regards ▁questions ▁such ▁as ▁" Where ▁was ▁the ▁particle ▁before ▁I ▁measured ▁its ▁position ?" ▁as ▁meaning less . ▁The ▁philosoph ical ▁issues ▁involved ▁were ▁important ▁elements ▁in ▁Hans on ' s ▁views ▁of ▁per ception ▁and ▁ep ist em ology . ▁He ▁was ▁intr igu ed ▁by ▁par ado xes , ▁and ▁with ▁the ▁related ▁concepts ▁of ▁uncertainty , ▁und ec id ability / un prov ability , ▁and ▁in comple ten ess ; ▁he ▁sought ▁models ▁of