 or arbitrary decrees of reason" (1913, 233). Marie Gueguen and Stathis Psillos Anti-Scepticism and Epistemic Humility in Pierre Duhem's Philosophy of Science 59 But even a cursory look at the history of science suggests that many, if not most, of actual theories were far from meeting the above ideal standard. Actual theories were such that explanation and representation were intermingled. How can they be disentangled? And if they can be disentangled, what is the argument against theories that have an explanatory part? Let us address these questions by noting that to motivate the distinction between two types (or two parts) of theory, Duhem (1906, 52) took a cue from Rankine's (1855) distinction between "abstractive" and "hypothetical theories". According to Rankine (1855, 209), the difference between the two kinds of theory stems from the first operation we described in section "Abstraction Principles", i.e., the definition of properties. An abstractive theory will consider as its fundamental properties only those that can be "perceived by the senses": properties are introduced in the physical theory only by means of an abstraction. A hypothetical theory, on the contrary, will accept properties "not apparent to the senses" through conjectures about the underlying nature of the perceived objects or phenomena. Thus, explanatory hypotheses will be introduced as soon as the relevant properties have been chosen, bearing consequences on all of the edifice afterwards. However, unlike Duhem, Rankine did not devalue hypothetical theories. He took them as an indispensable "preliminary step" for the reduction of "the expression of the phenomena to simplicity and order, before it is possible to make any progress in framing an abstractive theory" (1855, 213). For him, the contrast between the two types of theory was a contrast between two different modes of unification, of the "tendency (...) to combine all branches of physics into one system". One way is to rely on the axioms of mechanics as "the first principles of the laws of all phenomena-an object for the attainment of which an earnest wish was expressed by Newton", the other being to rely on "propositions comprehending as particular cases the laws of the particular classes of phenomena comprehended under the more extensive classes". Hence, from Rankine's distinction it does not follow that an explanatory theory should be devalued. Is there any other reason that Duhem summons? For Du
or arbitrary decrees of reason " (1913, 233). Marie Gueguen and Stathis Psillos Anti - Scepticism and Epistemic Humility in Pierre Duhem's Philosophy of Science 59 But even a cursory look at the history of science suggest that many, if not most, of actual theory were far from meeting the above ideal standard. Actual theories were such that explanation and theatrical performance were intermingled. How can they be disentangled? And if they can be disentangled, what is the controversy against theories that have an explanatory region? Let us address these doubt by noting that to motivate the distinction between two type (or two character) of theory, Duhem (1906, 52) took a cue from Rankine's (1855) distinction between " abstractive " and " hypothetical theory ". According to Rankine (1855, 209), the difference between the two kinds of hypothesis stems from the first process we described in part " Abstraction Principles ", i.e., the definition of properties. An abstractive theory will consider as its fundamental properties merely those that can be " perceived by the senses ": properties are introduced in the physical theory only by means of an abstraction. A hypothetical theory, on the contrary, will accept properties " not apparent to the senses " through conjectures about the underlying nature of the perceive objects or phenomena. therefore, explanatory guess will be introduce as soon as the relevant properties have been choose, bearing consequences on all of the edifice afterwards. However, unlike Duhem, Rankine did not depreciate hypothetical theories. He took them as an indispensable " preliminary step " for the reduction of " the expression of the phenomena to simplicity and order, before it is possible to make any advancement in framing an abstractive hypothesis " (1855, 213). For him, the contrast between the two types of theory was a contrast between two different modes of union, of the " tendency (...) to combine all branches of purgative into one system ". One means is to rely on the axioms of machinist as " the first principles of the torah of all phenomena - an aim for the attainment of which an earnest wish was expressed by Newton ", the other being to trust on " propositions comprehending as particular case the laws of the finical classes of phenomena comprehended under the more extensive classes ". Hence, from Rankine's distinction it does not follow that an explanatory theory should be devalue. Is there any other reason that Duhem bidding? For Du
 or arbitrary decrees of rexson" (1913, 233). Marie Guggyen anv Stathjs Psillus Anti-Scepticism and Epistelix Humulity in Pierre Duhem's Philosopjy of Scuenct 59 But even a cursory look at tgc hiscocy of science soggests that many, if not mmsg, lf actual theories were far from meqting tne above ideal sjandagd. Acthal theories were such that explanztion aid representatipn were intermingled. How cwn tjey be disentanglef? And if thgg cwb be disentavgled, what is the argujent against theories that have an erplanatory kcet? Pgt us addresw thefe questions by notitg that to motivate tme divtibction between two ty'es (or two parts) of jheory, Duham (1906, 52) took a cue fron Eankite's (1855) disguncgioh uetseen "ahstcactive" and "hypotheticql theories". Accordimg np Rankine (1855, 209), fhe disfqrence between the two kinds of theory vtejs from the first operarion we described in dection "Afstraction Principles", i.e., the definition of properdies. En abwtvactkce theory will consider as its fundamental propqdtoex only those tmat can be "perceivrd bu the senses": ptopertiza zre introduced in hhe phyfical theory ogly ny means of an abstraction. Q hypotheticcl rheory, on the contxary, will aceept ptopertoes "not apparent to the senaes" through conjectudds about the unddrljing nature of the perceived ofjects or pheuomena. Tfus, gxplanaeory hypotjeses will be introduced as slot as the rflevant properties have been chosen, bearing cpnveqlences on all pf the edificq afterwards. Hpwever, bnlike Duhem, Raniine div not devaluq hypothetican theories. He took thqm aw an indispdvsable "prelimimary step" for the rwduction of "the exiresskkn of the phenonenq to simplicity ana owdvr, ueforq it is possitle go oske avy progress kn ftaming an abstractiva thsory" (1855, 213). For him, the cjntrast vetween ehe two types of theory was a clntravt uetweem tro different modes of unificatjon, of thf "tcndency (...) to cjmbike ajl branchex of physics into one system". One way is to rely on the axuoms of mechanics ax "the first 'rinci[les of tve laws of all phenonena-an object for the attainment of whjch an earnfst wish was expressed by Newton", the other being to rely on "propositions xompreiegding as padticilar baszs che lawf of vhe particular clssses of phenomena comprehended under tve more extensive classes". Hencr, wrom Rankine's distinction it does not follow yhat an explanatory theory shoukd be devalued. Is there sny othee reaaon that Dnhem summons? For Du
or arbitrary decrees of reason" (1913, 233). and Psillos Anti-Scepticism Epistemic Humility in 59 even a cursory at the history science suggests that many, if not of actual theories were far from meeting the above ideal standard. Actual theories such that explanation and representation were intermingled. How can they be disentangled? And they be what the argument against theories that have an explanatory part? Let us address these questions by noting to motivate the distinction between two types (or parts) of theory, Duhem 52) took a cue from (1855) between "abstractive" "hypothetical According Rankine (1855, 209), difference between the two kinds of theory stems from the first operation we described in section "Abstraction i.e., the properties. An theory consider its fundamental properties that can be "perceived by the introduced in the physical theory only by means an abstraction. hypothetical theory, on the contrary, will properties "not apparent to the senses" through conjectures the underlying nature of the perceived objects or phenomena. Thus, explanatory hypotheses will be introduced as the relevant properties been chosen, bearing on of edifice However, unlike Rankine did not devalue hypothetical theories. He took them as an "preliminary step" for the reduction of "the expression of the simplicity order, before it possible to make any in an abstractive theory" (1855, him, contrast types theory a contrast between two modes of unification, of the (...) to combine all system". One way is to rely on the of mechanics as "the first principles of laws of all phenomena-an object for the attainment of which an earnest was expressed the other being to rely on "propositions comprehending particular cases the laws the particular classes of phenomena comprehended under the more classes". from Rankine's it does not that an explanatory should be devalued. any other that summons?
 or arbitrary decrees of reasoN" (1913, 233). Marie GuegUen anD StAthIs psilLos ANti-Scepticism aND EpiStemic Humility in Pierre duhem'S PHIlosOPhY of ScIence 59 BuT EvEN A cuRsOrY loOk AT tHe hisTorY of scieNce suggestS thAt Many, if not mosT, Of Actual theoRieS were far from MeeTing thE aBovE Ideal StaNdard. actual THeorieS were such ThAT explaNAtion anD REpReseNtation were intermINgLEd. How can they be DisentAnGLeD? aNd iF thEy can be disEnTanglED, what is THe ARGUmeNT against theorIes that have AN exPlanatOrY paRT? Let us AddreSs THesE questions bY notIng that to MotivaTE the disTInction BetweeN twO tyPes (oR TwO pArtS) oF TheORy, duhEM (1906, 52) toOk a cue frOm raNkine'S (1855) disTINCTion BetWeen "AbstrActive" and "hypoTheTicaL TheOries". accorDing To rankiNe (1855, 209), the dIfferEnCe between the two KindS of theory SteMs FroM tHe firST operaTioN we DescribEd in secTIon "abSTRAcTion Principles", i.e., thE dEFInItion of pRopertIEs. an ABstractiVe TheOry wILL consIder AS iTs fundamEntal pROpErTies onlY tHose thAt Can Be "pErceiVEd by The senSes": propeRties ARe introduced in THe physical theORy ONLy BY meaNs oF an abstractIon. A HYpotHetiCAl TheORy, on tHe conTrARy, WIll accept properties "NoT apparEnt to The senses" throUgh conjectURES about thE undERlYIng nature of the PerceIved objectS Or phenomEna. ThUs, explanAtory hypoTHEses will Be iNtrOduCed AS SoOn as the relevaNT PropErTies havE beEn choseN, beAriNg cOnsEqUences on aLl of the eDiFiCe AfTerWards. hOwever, unLiKe DUhEm, RAnkinE Did not DevalUe hyPoThETicAl theorIEs. hE Took ThEm As an IndIsPensaBle "pREliMinary sTep" for the RedUCtioN oF "tHe expreSsion of the pheNoMena to simpLiCitY and orDER, before iT is possible to make any proGRess in fRamIng an AbstRactive thEorY" (1855, 213). For hiM, thE ContraSt betwEen thE tWo tYPEs of tHEOrY waS a Contrast beTWEen Two diFfErenT modes oF unification, of the "tENdeNcy (...) to combine aLl bRancHES oF phYSiCS inTo ONe sYSTem". One way is to reLy on the axiOmS Of Mechanics aS "The FiRst prinCiples oF the lAWs of all Phenomena-An object fOr The aTTAinMent of whicH an earneSt wish was EXpresSEd By NewTon", The othEr BeiNg to rEly on "pROpoSitioNs compReHendinG as paRtIcular caSes the laws of the particulAr clasSes of PheNomena comPreHEndEd under thE morE extensive ClaSseS". HencE, frOM RankIne's DIsTinCTion iT doeS Not follow THaT an EXPlAnatory theoRY SHouLd be dEvaLUed. Is tHere Any other reason thaT duhem summons? FoR Du
 or arbitrary decrees of r eason" (19 13, 2 33) . M ar ie G uegu en and Stathis Psil los Anti-Scepticism an d Epi st e micH um ility  in Pie r re D uhe m' sPhi lo s op hy of  Sc ience 5 9 But even  acu rsory look a t  t he history  of  science sug ges ts tha tman y , ifnot  most , of a c tual t heories w er e  far f r om meet i n gtheabove ideal stand a rd .  Actual theori es wer es uc h tha t e xplanation  a nd re p resenta t io n w ere intermingled.  How can th e y b e dise nt ang l ed? An d ifth e y c an be disen tang led, what  is th e  argume n t again st the ori esthat ha ve  an  e x pla n at ory par t? Let u sad dress  the s e q uest ion s by  noti ng that to mo tiv atet hedisti nctio n be tw een t wo typ es (o rtwo parts) of t heor y, Duhem(19 06 , 5 2)  took a cuefro m R ankine' s (1855 )  di st i n c ti on between "abstra ct i v e"  and "hy pothet i ca lt heories" .Acc ordi n g  to R anki n e(1855, 2 09), t h edi fferenc ebetwee nthe  tw o kin d s of  theor y stemsfromt he first opera t ion we descri b ed i ns ecti on"Abstractio n Pr i ncip les" ,  i .e. ,  thedefin it i on of properties. An a bs tracti ve th eory will con sider as i t s fundamen talp ro p erties only th ose t hat can be "perceiv ed by  the sen ses": pro p e rties ar e i ntr odu ced i nthe physicalt h eory  o nly bymea ns of a n a bst rac tio n.  A hypoth etical t he or y,  o n t he co n trary, w il l a cc ept  prop e rties"notappa re nt tothe sen s es " thro ug hconj ect ur es ab outt heunderly ing natur e o f  the  p er ceivedobjects or ph en omena. Thu s,  ex planat o r y hypoth eses will be introduced as soon  as  therele vant prop ert ies ha veb een ch osen,beari ng  co n s equen c e sonal l of the e d i fic e aft er ward s. Howe ver, unlike Duhem, Ran kine did notdev alue h yp oth e ti c alth e ori e s . He took themas an indi sp e ns able "prel i min ar y step"  for th e red u ction o f "the ex pressionof  the p hen omena to s implicit y and ord e r, be f or e itispossib le  to  make  any p r ogr ess i n fram in g an a bstra ct ive theo ry" (1855, 213). For hi m, the  cont ras t between  th e  tw o types o f th eory was a  co ntr ast b etw e en tw o di f fe ren t  mode s of unificati o n,  of t he  "tendency( . . .)to co mbi n e allbran ches of physics i n to one system" . On e way  is to r el y on the axiom s o fm e chanicsas  "the first  princip le s  of t he law s of a ll phen o m en a -an ob ject  fo r the att ain me n t of wh ic ha n earn estwi sh was  expre s sedb y  Newton", the ot her b e i ng to rel y on"p roposit i onscomprehend ing as part icular  cas es th e lawsof  the p art ic ular class e s of phen omena  compre he nded  un der th e mo r e  exte nsiv ecla sses". He n c e, fr om Ran kine 's di st inct ion it do e s not fo llo w  that a nexp l a natory th e o ry shouldbedeval u e d. Is ther e  any ot h er re ason t hat Du hem sum m ons ?For Du
 or_arbitrary decrees_of reason" (1913, 233)._Marie Gueguen_and_Stathis Psillos_Anti-Scepticism_and Epistemic Humility_in Pierre Duhem's_Philosophy of Science 59_But even a_cursory_look at the history of science suggests that many, if not most, of actual_theories_were far_from_meeting_the above ideal standard. Actual_theories were such that explanation_and representation_were intermingled. How can they be disentangled? And_if_they can be_disentangled, what is the argument against theories that have_an explanatory part? Let us address_these questions by_noting_that_to motivate the distinction_between two types (or two parts)_of theory, Duhem (1906, 52) took_a cue from Rankine's (1855) distinction between_"abstractive" and "hypothetical theories". According to_Rankine (1855, 209), the difference_between the_two kinds of theory stems_from the first_operation we_described in section_"Abstraction Principles", i.e., the definition of_properties. An abstractive_theory will consider as its fundamental_properties_only those that_can_be_"perceived by_the senses": properties_are_introduced in_the_physical theory only by means of_an_abstraction. A hypothetical theory, on the contrary,_will accept properties "not_apparent_to the senses" through_conjectures about the underlying nature_of the perceived objects or phenomena._Thus, explanatory_hypotheses will_be introduced as soon as the relevant properties have been chosen,_bearing consequences on all of the_edifice afterwards. However, unlike_Duhem, Rankine_did_not devalue hypothetical_theories._He took_them as an indispensable "preliminary step" for_the reduction_of "the expression of the phenomena_to simplicity and order,_before_it is possible to make any_progress in framing an abstractive theory"_(1855, 213). For him, the_contrast_between_the two types of theory_was a contrast between two different_modes of unification,_of the "tendency (...) to combine all_branches_of physics into one system". One_way_is to rely on the axioms_of_mechanics_as "the first principles of_the laws of all phenomena-an object_for the attainment of which an earnest wish was_expressed by Newton",_the other being to rely_on_"propositions_comprehending as particular cases the laws of the particular classes_of phenomena_comprehended under the_more extensive classes". Hence, from Rankine's distinction it does not_follow that an explanatory theory should be_devalued. Is there any other reason that Duhem summons? For Du