does　not　understand　or　suppose　it　to　have　them；　surely　the
  questioner　here　has　directed　his　argument　against　his　thought！　Or
  how　else　ought　he　to　put　his　question　except　by　suggesting　a
  distinction…suppose　one's　question　to　be　speaking　of　the　silent
  possible　or　not？'…as　follows；　'Is　the　answer　〃No〃　in　one　sense；　but
  〃Yes〃　in　another？'　If；　then；　any　one　were　to　answer　that　it　was　not
  possible　in　any　sense　and　the　other　were　to　argue　that　it　was；　has　not
  his　argument　been　directed　against　the　thought　of　the　answerer？　Yet
  his　argument　is　supposed　to　be　one　of　those　that　depend　on　the
  expression。　There　is　not；　then；　any　definite　kind　of　arguments　that　is
  directed　against　the　thought。　Some　arguments　are；　indeed；　directed
  against　the　expression：　but　these　are　not　all　even　apparent
  refutations；　let　alone　all　refutations。　For　there　are　also　apparent
  refutations　which　do　not　depend　upon　language；　e。g。　those　that
  depend　upon　accident；　and　others。
  If；　however；　any　one　claims　that　one　should　actually　draw　the
  distinction；　and　say；　'By　〃speaking　of　the　silent〃　I　mean；　in　one
  sense　this　and　in　the　other　sense　that'；　surely　to　claim　this　is　in
  the　first　place　absurd　（for　sometimes　the　questioner　does　not　see
  the　ambiguity　of　his　question；　and　he　cannot　possibly　draw　a
  distinction　which　he　does　not　think　to　be　there）：　in　the　second　place；
  what　else　but　this　will　didactic　argument　be？　For　it　will　make
  manifest　the　state　of　the　case　to　one　who　has　never　considered；　and
  does　not　know　or　suppose　that　there　is　any　other　meaning　but　one。
  For　what　is　there　to　prevent　the　same　thing　also　happening　to　us　in
  cases　where　there　is　no　double　meaning？　'Are　the　units　in　four　equal
  to　the　twos？　Observe　that　the　twos　are　contained　in　four　in　one
  sense　in　this　way；　in　another　sense　in　that'。　Also；　'Is　the
  knowledge　of　contraries　one　or　not？　Observe　that　some　contraries　are
  known；　while　others　are　unknown'。　Thus　the　man　who　makes　this　claim
  seems　to　be　unaware　of　the　difference　between　didactic　and　dialectical
  argument；　and　of　the　fact　that　while　he　who　argues　didactically　should
  not　ask　questions　but　make　things　clear　himself；　the　other　should
  merely　ask　questions。
  11
  Moreover；　to　claim　a　'Yes'　or　'No'　answer　is　the　business　not　of　a
  man　who　is　showing　something；　but　of　one　who　is　holding　an
  examination。　For　the　art　of　examining　is　a　branch　of　dialectic　and　has
  in　view　not　the　man　who　has　knowledge；　but　the　ignorant　pretender。　He；
  then；　is　a　dialectician　who　regards　the　common　principles　with　their
  application　to　the　particular　matter　in　hand；　while　he　who　only
  appears　to　do　this　is　a　sophist。　Now　for　contentious　and　sophistical
  reasoning：　（1）　one　such　is　a　merely　apparent　reasoning；　on　subjects　on
  which　dialectical　reasoning　is　the　proper　method　of　examination；
  even　though　its　conclusion　be　true：　for　it　misleads　us　in　regard　to
  the　cause：　also　（2）　there　are　those　misreasonings　which　do　not　conform
  to　the　line　of　inquiry　proper　to　the　particular　subject；　but　are
  generally　thought　to　conform　to　the　art　in　question。　For　false
  diagrams　of　geometrical　figures　are　not　contentious　（for　the　resulting
  fallacies　conform　to　the　subject　of　the　art）…any　more　than　is　any
  false　diagram　that　may　be　offered　in　proof　of　a　truth…e。g。
  Hippocrates'　figure　or　the　squaring　of　the　circle　by　means　of　the
  lunules。　But　Bryson's　method　of　squaring　the　circle；　even　if　the
  circle　is　thereby　squared；　is　still　sophistical　because　it　does　not
  conform　to　the　subject　in　hand。　So；　then；　any　merely　apparent
  reasoning　about　these　things　is　a　contentious　argument；　and　any
  reasoning　that　merely　appears　to　conform　to　the　subject　in　hand；
  even　though　it　be　genuine　reasoning；　is　a　contentious　argument：　for　it
  is　merely　apparent　in　its　conformity　to　the　subject…matter；　so　that　it
  is　deceptive　and　plays　foul。　For　just　as　a　foul　in　a　race　is　a
  definite　type　of　fault；　and　is　a　kind　of　foul　fighting；　so　the　art
  of　contentious　reasoning　is　foul　fighting　in　disputation：　for　in　the
  former　case　those　who　are　resolved　to　win　at　all　costs　snatch　at
  everything；　and　so　in　the　latter　case　do　contentious　reasoners。　Those；
  then；　who　do　this　in　order　to　win　the　mere　victory　are　generally
  considered　to　be　contentious　and　quarrelsome　persons；　while　those
  who　do　it　to　win　a　reputation　with　a　view　to　making　money　are
  sophistical。　For　the　art　of　sophistry　is；　as　we　said；'　a　kind　of　art
  of　money…making　from　a　merely　apparent　wisdom；　and　this　is　why　they
  aim　at　a　merely　apparent　demonstration：　and　quarrelsome　persons　and
  sophists　both　employ　the　same　arguments；　but　not　with　the　same
  motives：　and　the　same　argument　will　be　sophistical　and　contentious；
  but　not　in　the　same　respect；　rather；　it　will　be　contentious　in　so
  far　as　its　aim　is　an　apparent　victory；　while　in　so　far　as　its　aim　is
  an　apparent　wisdom；　it　will　be　sophistical：　for　the　art　of　sophistry
  is　a　certain　appearance　of　wisdom　without　the　reality。　The　contentious
  argument　stands　in　somewhat　the　same　relation　to　the　dialectical　as
  the　drawer　of　false　diagrams　to　the　geometrician；　for　it　beguiles　by
  misreasoning　from　the　same　principles　as　dialectic　uses；　just　as　the
  drawer　of　a　false　diagram　beguiles　the　geometrician。　But　whereas　the
  latter　is　not　a　contentious　reasoner；　because　he　bases　his　false
  diagram　on　the　principles　and　conclusions　that　fall　under　the　art　of
  geometry；　the　argument　which　is　subordinate　to　the　principles　of
  dialectic　will　yet　clearly　be　contentious　as　regards　other　subjects。
  Thus；　e。g。　though　the　squaring　of　the　circle　by　means　of　the　lunules
  is　not　contentious；　Bryson's　solution　is　contentious：　and　the　former
  argument　cannot　be　adapted　to　any　subject　except　geometry；　because
  it　proceeds　from　principles　that　are　peculiar　to　geometry；　whereas　the
  latter　can　be　adapted　as　an　argument　against　all　the　number　of
  people　who　do　not　know　what　is　or　is　not　possible　in　each　particular
  context：　for　it　will　apply　to　them　all。　Or　there　is　the　method　whereby
  Antiphon　squared　the　circle。　Or　again；　an　argument　which　denied　that
  it　was　better　to　take　a　walk　after　dinner；　because　of　Zeno's　argument；
  would　not　be　a　proper　argument　for　a　doctor；　because　Zeno's　argument
  is　of　general　application。　If；　then；　the　relation　of　the　contentious
  argument　to　the　dialectical　were　exactly　like　that　of　the　drawer　of
  false　diagrams　to　the　geometrician；　a　contentious　argument　upon　the
  aforesaid　subjects　could　not　have　existed。　But；　as　it　is；　the
  dialectical　argument　is　not　concerned　with　any　definite　kind　of　being；
  nor　does　it　show　anything；　nor　is　it　even　an　argument　such　as　we
  find　in　the　general　philosophy　of　being。　For　all　beings　are　not
  contained　in　any　one　kind；　nor；　if　they　were；　could　they　possibly　fall
  under　the　same　principles。　Accordingly；　no　art　that　is　a　method　of
  showing　the　nature　of　anything　proceeds　by　asking　questions：　for　it
  does　not　permit　a　man　to　grant　whichever　he　likes　of　the　two
  alternatives　in　the　question：　for　they　will　not　both　of　them　yield　a
  proof。　Dialectic；　on　the　other　hand；　does　proceed　by　questioning；
  whereas　if　it　were　concerned　to　show　things；　it　would　have　refrained
  from　putting　questions；　even　if　not　about　everything；　at　least　about
  the　first　principles　and　the　special　principles　that　apply　to　the
  particular　subject　in　hand。　For　suppose　the　answerer　not　to　grant
  these；　it　would　then　no　longer　have　had　any　grounds　from　which　to
  argue　any　longer　against　the　objection。　Dialectic　is　at　the　same
  time　a　mode　of　examination　as　well。　For　neither　is　the　art　of
  examination　an　accomplishment　of　the　same　kind　as　geometry；　but　one
  which　a　man　may　possess；　even　though　he　has　not　knowledge。　For　it　is
  possible　even　for　one　without　knowledge　to　hold　an　examination　of
  one　who　is　without　knowledge；　if　also　the　latter　grants　him　points
  taken　not　from　thing　that　he　knows　or　from　the　special　principles　of
  the　subject　under　discussion　but　from　all　that　range　of　consequences
  attaching　to　the　subject　which　a　man　may　indeed　know　without　knowing
  the　theory　of　the　subject；　but　which　if　he　do　not　know；　he　is　bound　to
  be　ignorant　of　the　theory。　So　then　clearly　the　art　of　examining　does
  not　consist　in　knowledge　of　any　definite　subject。　For　this　reason；
  too；　it　deals　with　everything：　for　every　'theory'　of　anything
  employs　also　certain　common　principles。　Hence　everybody；　including
  even　amateurs；　makes　use　in　a　way　of　dialectic　and　the　practice　of
  examining：　for　all　undertake　to　some　extent　a　rough　trial　of　those　who
  profess　to　know　things。　What　serves　them　here　is　the　general
  principles：　for　they　know　these　of　themselves　just　as　well　as　the
  scientist；　even　if　in　what　they　say　they　seem　to　the　latter　t