Three Varieties of Early Modern Scepticism

Stephan Schmid Three Varieties of Early Modern Scepticism

Introduction: RichardPopkin on Early Modern Scepticism

Scepticism loomed large in the earlymodern period. In fact,manyphilosophers from the late sixteenth until the midstofthe eighteenth centurygrappled with the problem of how to justify our knowledge claims in amuch more explicit and fundamental waythan theirAristotelian forerunners had.¹ In numerous articles and books, partic- ularlyinthe latest edition of his volume TheHistoryofScepticism from Savonarola to Bayle,Richard Popkin argued that the earlymodern obsession with scepticism was prompted by the rediscovery of SextusEmpiricus’swritingsfrom the second century CE. As Popkin puts it,the reception of Sextus’swritingsled to “an insoluble crise pyrrhonienne,asthe various gambits of Sextus Empiricus are explored and worked out.”² While Sextus’ssceptical considerations were first applied in theological con- texts and religious debates,Popkin explains, they weresoon transferred to other areas as well. In Popkin’sdiagnosis,this led to a nouveau pyrrhonisme,which “was to envelop all the human sciencesand philosophyinacompletesceptical crisis, out of which modernphilosophyand the scientificoutlook finally emerged.”³ It is hard to overstate the importance of Richard Popkin’swork on the history of scepticism. Not onlydid his investigation of earlymodern scepticism bring to the fore authorswho werewidelyneglectedbefore him, but it also pavedthe wayfor arange of outstanding studies in the history of earlymodern scepticism, which would have been plainlyimpossible withouthis pioneering work. All these merits notwithstanding and without denying due credit to Popkin’sex- ceptional historiographical work, Iwant to challengehis main tenet thatthe early

Iamgrateful to discussions with ZevHarvey, Yitzhak Melamed, José María Sánchez de León Serrano, and Máté Veres and the excellent stylistic suggestions by Anthony Paletta and Yoav Meyrav,which improved thischapter.Ialso thank the Maimonides Centre forAdvanced Studies, DFG-FOR 2311, formakingthischapterpossible in the first place.

 This is not to saythat Aristotelian philosophers wereuninterested in sceptical or even epistemological questions.This long-standing historiographical prejudice is finallyabout to be corrected. Fornuanced investigations into medieval or Aristotelian debates about scepticism, see Dominik Per- ler, Zweifel und Gewissheit: skeptische Debatten im Mittelalter (Frankfurt am Main: Klostermann, 2006), and Henrik Lagerlund, ed., Rethinking the HistoryofSkepticism: The Missing Medieval Back- ground (Leiden: Brill, 2014).  RichardPopkin, TheHistory of Scepticism fromSavonarolatoBayle (Oxfordand New York: Oxford University Press, 2003), 5.  Popkin, HistoryofScepticism,59.

OpenAccess. ©2019 Stephan Schmid, published by De Gruyter. This work is licensed under the Creative CommonsAttribution-NonCommercial-NoDerivatives 4.0 License. https://doi.org/10.1515/9783110591040-011 182 Stephan Schmid

modernperiod wasshaken by aPyrrhonian crisiswhich then led to a nouveau pyrrhonisme. Iamnot the first to do so, but my criticism is different from previous ones. In order to clearlyarticulate my objection and to distinguish it from other critiques, it is important to distinguish twodimensions of Popkin’smain tenet. Popkin’sclaim that the earlymodern period was characterised by a crise pyrrhonienne can be read in two ways—and it seems that Popkin is happy to defend it in both. In one reading, which highlights the historicaldimension of Popkin’stenet, he makes aclaim about the historical origin of earlymodern scepticism, stating that it was triggered, influenced, and inspired by the rediscovery and reception of SextusEmpiricus’swritings. In another reading,which emphasises the taxonomical dimension of Popkin’stenet,hemakes aclaim about the nature of earlymodern scepticism, stating thatitisindeed aform or species of Pyrrhonian scepticism and is thereforeaptly described as “new Pyrrhonism” (nouveau pyrrhonisme). While most critics of Popkin focused on the historical dimension of Popkin’stenet and argued that earlymodern scepticism was influenced and inspired by many other writ- ingsand traditions besides thoseofSextus Empiricus,⁴ here Iwant to takeissue with the taxonomical dimension of Popkin’sclaim. More precisely, Iwillargue that understanding earlymodern scepticism as aspecies of Pyrrhonism is misleading at best. Even the two most famous earlymodern sceptics,René Descartes and David Hume,I submit,developed and employed varieties of scepticism which are distinctivelynon- Pyrrhonian.⁵ In addition, Iargue that distinguishing between different varieties of scepticism is of pivotal historicalimportance insofar as appreciating the fact that Pyrrhonian, Cartesian, and Humean scepticism differ in crucial ways from one another is keytounderstanding the historicaldevelopment of sceptical ideas. These three varieties of scepticism differ from one another in that each is in an important sense strongerorbroader than its antecedent versions; in otherwords, each calls into question what had been taken for granted by their antecedents. In particular,itisimpor- tant to distinguish between Cartesian and Humean scepticism in order to understand Kant’sphilosophical project after the earlymodern period. Kant’sproject was developed in response to Hume’sscepticism about causation,which is different from both

 Good examples areJosé Raimundo Maia Neto, “Academic Skepticism in EarlyModern Philosophy,” Journal of the HistoryofIdeas 58, no. 2(1997): 199‒220; Dominik Perler, “WasThere a ‘Pyrrhonian Crisis’ in Earlymodern Philosophy? ACritical NoticeofRichardH.Popkin,” Archiv fürGeschichte der Philosophie 86,no. 2(June 2004), 209‒20;and Ian Maclean “The ‘Sceptical Crisis’ Reconsidered: Galen, Rational Medicine and the Libertas Philosophandi,” Early Science and Medicine 11, no. 3 (2006): 247‒74.  By this restriction Idonot mean to implythat the twovarieties of scepticism developed by Des- cartesand Hume arethe onlyvarieties of scepticism to be found in the earlymodernperiod nor that they wereexclusively and originallydeveloped by Descartes and Hume. My restriction is simply duetothe fact that Descartes and Hume areboth famous and highlyinfluential earlymodernphilos- ophers. Three Varieties of Early Modern Scepticism 183

Cartesian and Pyrrhonian scepticism.⁶ Thus, understandingthe history of scepticism in general—and the proper targetofKant’sphilosophising in particular—requires us to appreciate varieties of scepticism different from the Pyrrhonian scepticism pre- sented by SextusEmpiricus. The paper consists of four sections. In section 1Iprovide abrief characterisation of Pyrrhonian scepticism on the basis of Sextus Empiricus’sdescription of Pyrrhon- ism in his Outlines of Scepticism.This will set the basis for my comparativeanalysis in the two subsequent sections, devoted to the two presumably most famous mani- festationsofscepticism in the earlymodern period: section 2will be concernedwith the “hyperbolic” scepticism of René Descartes,which he famouslydevelops in his Meditations,while section 3will focus on DavidHume’sscepticism about causation. Section 4willsummarise my findings.

1Pyrrhonian Scepticism

We can onlyproperlyassess the taxonomical correctness of Popkin’stenet,according to which the earlymodern period was shaken by aPyrrhonian crisis which led to a new Pyrrhonism, once we clarify the meaning of Pyrrhonian scepticism. Onlythen can we compareitwith earlymodernvarieties of scepticism. At this point,one might raise afundamental objection to my project.Describing Pyrrhonism as avariety of scepticism parallel to earlymodernvarieties presupposes that ancient Pyrrhonism is an intellectual endeavour of the very same form or type as modernscepticism, such that both enterprises are forms of “scepticism” in the same sense. As recent scholarship in ancient philosophyhas shown, however,this assumption is highlyproblematic.⁷ For, unlike modern scepticism, which is concerned with underminingknowledge claims about certain domains by raising doubts about these domains, ancient Pyrrhonism is not particularlyconcernedwith doubtatall. In fact,there is not even an ancient Greek term for “doubt,” and if the Latin term du- bitatio is usedintreatises in the ancient sceptical tradition, it is not wielded in any

 This is meticulouslydefended by Michael Forster, Kant and Skepticism (Princeton: PrincetonUni- versity Press, 2008).  See for instanceMichael Williams, “Descartes’ Transformation of the Skeptical Tradition,” in The CambridgeCompanion to Ancient Scepticism,ed. RichardBett (Cambridge and New York: Cambridge University Press, 2010), 289‒91,who lists altogether nine differences between Pyrrhonian and Des- cartes’sscepticism. Other enquiries intothe differencebetween ancient and (early) modern scepticism areMyles Burnyeat, “Idealism and Greek Philosophy: What Descartes Sawand Berkeley Missed,” ThePhilosophical Review 91, no. 1(January 1982):3‒40;and José Luis Bermúdez, “The Orig- inality of Cartesian Skepticism: Did It Have Ancient or Mediaeval Antecedents?” HistoryofPhilosophy Quarterly 17,no. 4(October 2000): 333‒60. 184 Stephan Schmid

technical sense.⁸ The Greek word skeptikos simplymeans “seeker” or “investigator.” This is exactlyhow ancient sceptics conceivedofthemselves: as investigators interested in the very questions of physics, ethics, and logic addressed by theirdogmatic opponents. Unliketheir opponents, however,they recommended suspending judgment about these matters since they did not find conclusive evidence to decisively answer these questions.⁹ What is more,ancient sceptics advertisedtheir scepticism as ameans for happiness or an untroubled life. By contrast, modernscepticism is and wasconsidered mainlyasathreat,which not onlyundermines the endeavour of scientific research but is also at odds with our self-understanding as cognitive agents living in amaterial world. Idonot want to question these findings; especiallyinlight of the fact that they are grist for the mill of my case against Richard Popkin’sidentification of a crise pyrrhonienne in the earlymodernperiod. However,these findings provide such afundamental refutation of Popkin’sidentification of a crise pyrrhonienne in the earlymodern period that it is hard to believethat he reallywanted to claim that earlymodern sceptics were in fact Pyrrhonists in the sense portrayedbySextus Empiricus. Instead, Iwill assume that Popkin construed “Pyrrhonism” as aposition one can come to adopt on the basis of Sextus’sviews if one is interested in the typicalmodern epistemological project of exploring the limits of our knowledge by raising specific doubts. Accordingly, my sketch of Pyrrhonian scepticism is not to be read as an adequate representation of ancient Pyrrhonism, but as asystematisation of the sorts of doubts that Pyrrhonians would have launched had they engagedinakind of project typicallypursued by their earlymodernsuccessors. That said, what does (a “modernised” version of)Pyrrhonian scepticism consist of?Towardswhat kind of epistemic state does aPyrrhonian aim, and which types or domains of knowledge does s/he undermine? In responsetothese questions, the openingparagraph of Sextus Empiricus’s Outlines turns out to be particularlyrevealing.Inthis passage, Sextus distinguishes three schools of philosophersconcerned with findingthe truth. One school of thought—which Sextusassociateswith Aristotle, Epicurus, and the Stoics—believes that they have actuallydiscovered the truth. Sextus calls adherents of this school dogmatists. Another school—which Sextus associates with “Clitomachus and Car- neades, and other Academics”—asserts thatwecannot arrive at the truth. In making such adefinite assertion, adherents of this school alsoqualify as dogmatists in Sex- tus’sview.They are,asitwere, negative dogmatists.¹⁰ Finally, followers of the third

 Katja Vogt, “From Investigation to Doubt: The Beginnings of Modern Skepticism,” in Roman Reflec- tions:EssaysonLatin Philosophy,ed. by Gareth Williams and Katharina Volk (Oxford, New York: Ox- fordUniversity Press,2015), 262‒64.  Vogt,262.  It should be notedthat,asamatter of historical fact,Sextus’scharacterisation of the Academics is probablywrong: as Ciceroreports(in his Acad. 45 and Luc.28), both Arcesilaus and Carneadesde- claredthat they did not even know whether they know anything. Foraninvestigation into the real Three Varieties of Early Modern Scepticism 185

school—whom Sextus identifies with the (Pyrrhonian) sceptics—have yettocome to a conclusion about the truth. They are still investigating—and are for that matter true “sceptics” in the original sense of the Greek term, or “seekers.” Lacking aconvincing resolution of the question as to what the truth is, Pyrrhonian sceptics withhold their judgmentsabout the truth of thingsorevenabout our capacity to know the truth. Pyrrhonian scepticism, then, is aphilosophicalstance that —unlike the one Sex- tus attributes to the Academics—is entirely anti-dogmatic. Pyrrhonian sceptics are opposed to two dogmatic camps of philosophyinthat they neither claim to know the truth nor definitelydenyour capacity to know it.Rather,they suspend theirjudg- ment about the nature of thingsand our capacity to (eventually) know it.Thisanti- dogmatic nature of Pyrrhonian scepticism is reflected by Sextus’sofficial definition of Pyrrhonism:

Scepticism is an ability to set out oppositions amongthings which appear and are thought of in anyway at all, an ability by which, because of the equipollenceinthe opposed objects and ac- counts,wecomefirst to suspension of judgement and afterwards to tranquillity (PH 1.4.8).¹¹

APyrrhonian sceptic, Sextus explains, is able to counter every argument for aputa- tive knowledge claim with an equallystrongorconvincing counter-argument.Inlight of these conflicting arguments for and against acertain view,aPyrrhonian sceptic will suspend judgment.Asitturns out,this suspension of judgment resultsinthe sceptic’stranquillity or peace of mind. This is, Sextus explains, because the dogmat- ics “who holdthe opinion that thingsare good or bad by natureare perpetuallytrou- bled” (PH 1.12.27); as long as they lack what they take to be good, they feel thatthey are victims of some natural evil, and when they have reached it they are in constant fear of losing it.Pyrrhonian sceptics,bycontrast, “who make no determination about what is good and bad by nature neither avoid nor pursue anything with intensity; and hence they are tranquil” (PH 1.12.28). Due to their suspension of judgment about the truth of the matter,Pyrrhonian sceptics are less troubled than their dogmatic opponents, and acquire—albeit accidentally—the desired peace of mind, in hope of which philosophers come to philosophise in the first place. Sextus’sdefinition of Pyrrhonian scepticism hints at another essential element of Pyrrhonism: ThePyrrhonian sceptic comes to withhold her or his judgment about the nature of thingsbysetting out “oppositions among thingswhich appear and are thought of in anyway at all.” In doing so, the Pyrrhonian sceptic does not call into question that there arethings that appear to us in acertain wayand differencebetween historical Pyrrhonists and Academics, see Gisela Striker, “On the Differencebe- tween Pyrrhonists and the Academics”,inEssaysonHellenistic Epistemology and Ethics (Cambridge and New York: Cambridge University Press, 1996), 135‒49,and Striker, “Academics versus Pyrrhon- ists,Reconsidered,” in TheCambridge Companion to Ancient Scepticism,ed. RichardBett (Cambridge and New York: Cambridge University Press, 2010), 195‒207.  All references fromSextus,abbreviatedasPH, arecitedinparentheses and taken from Outlines of Scepticism,trans. Julia Annas and Jonathan Barnes (Cambridge:Cambridge University Press, 1994). 186 Stephan Schmid

are thought of in many ways.Sextus is explicit about this point,writing that “no-one, presumably, will raise acontroversy over whether an existing thing appears this way or that; rather,they investigate whether it is such as it appears” (PH 1.11.22).The scepticism launched by aPyrrhonian sceptic, then, is of arestricted scope: it is restricted to the true nature of things, leaving untouched the fact that there are things, which appear to us in various ways.¹² In sum, we should note two corefeatures of Pyrrhonian scepticism: First,Pyr- rhonism is anti-dogmatic in nature. As opposed to positively denying that we can know the true nature of things, aPyrrhonian sceptic simplysuspendsjudgment and is silent about the true nature of things. Whether we can, in principle, know the true natureofthingsornot,the Pyrrhonian merelyobservesthat thereare as manyconvincing arguments for agiven position about the nature of thingsas there are arguments against it and thus refuses to take astance on the question, withholdingjudgment.For all that—and this marks the second core-feature of Pyr- rhonism—aPyrrhonian sceptic is arealist of acertain stripe: the Pyrrhonian does not doubt or question the very reality of thingsthat appear in acertain way. He or she onlyquestions whether the thingsinthemselves really exist in the waythey appear to us. There is much more to be said about Pyrrhonian scepticism. This should be enough,though, for my present purpose of assessingPopkin’sclaim that the early modernperiod was shaken by a crise pyrrhonienne.

2Cartesian Scepticism

Descarteswas no sceptic. To the contrary, he was convinced that we can achieve ab- solutelycertain knowledge (scientia)about ourselves, God, and the nature of bodies. In fact,hetook great pains in defending his epistemological optimism, but in the course of doing so, he famouslyemployed sceptical strategies and doubts. Far from defending scepticism, Descartes was onlyamethodological sceptic who con- sciouslyinvoked doubts in order to laybare an unshakable and firm foundation for certain and stable knowledge.¹³ But what is the nature of the scepticism that Des- cartes employs in his search for certain knowledge?

 This “realist character” of Pyrrhonism has been convincinglypointed out by Burnyeat, “Idealism and Greek Philosophy,” and Stephen Everson, “The Objective Appearance of Pyrrhonism,” in Psychol- ogy(Companions to Ancient Thought 2),ed. Stephen Everson (Cambridge:Cambridge University Press, 1991), 121‒47.Cf. the critical remarks by Gail Fine, “Sextus and External World Skepticism,” Oxford Studies in Ancient Philosophy 24 (2003): 349‒52.  See the openinglines of Descartes’ Meditations,whereheexplains that “onceinthe course of his life” he wanted to “demolish everythingcompletely and start againright from the foundations.” See Oeuvres de Descartes,ed. Charles Adam and Paul Tannery (Paris:Vrin, 1974‒1989;henceforth AT), 7:14; Philosophical Writings of Descartes. Editedand translated by John Cottingham, Robert Stoothoff, Three Varieties of Early Modern Scepticism 187

It is well known thatDescartes develops his methodologicaldoubtinthree stages, each of which is strongerthanits preceding stagetothe extent thatitcalls into question what was left untouched in the previous stage. ConcerningPopkin’s tenet,the crucial question is whether these three forms of doubt are indeedPyrrho- nian in nature. Popkin himself had no doubts about this. Or so it seems, when he characterises Descartes’sthree stages of doubt:

By movingfrom[1] the partial Pyrrhonism of doubtingthe reliabilityofour senses to [2]the metaphysical Pyrrhonism of the dream hypothesis,doubtingthe reality of our knowledge,to[3] the total Pyrrhonism of the demon hypothesis,doubtingthe reliabilityofour rational faculties, we finallydiscover the cogito,atruth so subjectively certain that we areincapable of doubtingitat all.¹⁴

Let us have abrief look at Descartes’sthree stages of doubt in order to see whether Popkinwas right in describing them as three forms of Pyrrhonism. Descartesbegins his sceptical “demolition” of beliefs by casting doubt on his sensorybeliefs, that is, those beliefs he “acquired either from the senses or through the senses.” Noting that he has often found that “the senses deceive,and it is pru- dent never to trust completelythosewho have deceivedusevenonce” (AT7:18; CSM2:12),Descartes findsdoubtinall our sensory beliefs at once and consequently rejects them as uncertain. At the sametime, Descartesisclear that just pointing out that the senses some- times deceive us is not sufficient for undermining our confidence in sensory beliefs in general. As he remarks,sensorybeliefs might be problematic with respect “to objects which are very small or in distance,” but he admits that “there are manybeliefs about which doubt is quite impossible, even though they are derived from the senses,” citing examples likehis belief that he is “sitting by the fire,wearingawinter dressing-gown” (AT7:18; CSM2:12),and so forth. Descartes’sfirst stageofdoubt,based on the occasional deceptiveness of our senses, does not venture very far.Itdoes not even undermine our perceptual beliefs in general, as it leavesuntouched our beliefs about objects that are neither very small nor distant. Descartes’ssecond stageofdoubt, which he induces by his famous dream hypothesis,ismoreambitious. It might well be,Descartesconsiders,thatweare asleep and that we just dream about the thingsthatweseem to perceive. “How often, asleep at night,amIconvinced of just such familiar events,” he remarks, “thatIam here in my dressing-gown, sitting by the fire—when in fact Iamlying undressed in bed!” (AT 7:19;CSM 2:13). However,aslongasIcannot reject the hypothesis thatIam just dreamingwhat Iseemtoperceive,mysensory beliefs become dubitable. Unlike

Dugald Murdoch (vols.1and 2; henceforth: CSM), and AnthonyKenny(henceforth: CSMK) (Cam- bridge and New York: Cambridge University Press, 1984‒1991), 2:17.References to Descartes’swritings aregiven in parentheses.  Popkin, HistoryofScepticism,156‒57 (numberingadded). 188 Stephan Schmid

the observation that our senses are sometimesdeceptive,then, Descartes’sdream hypothesis can undermine all our sensory beliefs. Giventhe possibility of dreaming, it might well be that his formerlyunquestioned beliefs—“that my eyes are open, that I am moving my head and stretching out my hands—are not true. Perhaps,indeed, I do not even have such hands or such abodyatall” (AT7:19; CSM2:13). But the doubtinduced by the dream hypothesis goes farther than just affecting our beliefs in the qualities of external things. It also undermines our confidencein the very existenceofthese things. As for the dream hypothesis,itisnot onlythe case thatextra-mental thingsmight in fact be quite different from the waythey appear,but alsothat they maynot exist at all. Giventhat he might justbedreaming, Descartesponders, he might “not even have such hands or such abodyatall.” Forall this,Descartes’ssecond stageofdoubt leavesmanyother beliefs unaffect- ed. In particular, it does not undermine non-empirical beliefs. “Forwhether Iam awake or asleep,” Descartesargues, “two and threeadded together are five,and a square has no more than four sides” (AT7:20; CSM2:14). It is onlyDescartes’sthird and last stageofdoubt,which is induced by the evil demon hypothesis, that undermines non-empirical beliefs as well. Giventhat it is (epistemically) possiblethat we are all victims of an evil demon thatpersistentlyde- ceivesusand interferes with our cognitive faculties,almostall our beliefs can be doubted. As Descartesvividlyputs it:

HowdoIknow that he [i.e., an evil demon] has not broughtitabout that thereisnoearth, no sky,noextended thing,noshape, no size, no place, while at the same time ensuringthat all these things appear to me to exist just as they do now?What is more, sinceIsometimes believe that others go astrayincases where they think that they have most perfect knowledge,may Inot similarlygowrong every time Iadd twoand threeorcount the sides of asquare, or in some even simpler matter,ifthis is imaginable? (AT7:21; CSM2:14)

To the extent that Icannot rule out the possibility thatall of my thoughts—together with theirappearance of certainty—could have been instilled by an evil demon (and how could Iknow for certain that Iamnot avictim of such apervasive deception), pretty much everythingthat Iusually accept as true could be false.Evensuch simple non-empirical beliefs as that 2+3=5orthat squares have four sides could have been instilled in me by an evil demon together with the conviction that these facts cannot be otherwise. As it is well known, there is onlyone belief thatsurvivesthis third stageofdoubtaccording to Descartes. This is the cogito,Descartes’sinsight that “this proposition, Iam, Iexist,isnecessarilytrue whenever it is put forward by me or conceivedinmymind” (AT7:25; CSM2:17). So much about Descartes’sthree stages of doubt.Are they aptlydescribed as forms of Pyrrhonism, as suggested by Popkin?Ashas become plain in this brief sketch of these three stages already, this question is clearlytobeanswered in the negative.Asseen above, Pyrrhonian scepticism is committed to acertain sort of re- alism:the Pyrrhonian does not doubt the reality of thingsthatappear in acertain way, but onlyquestions whether the thingsare by nature the waythey appear to Three Varieties of Early Modern Scepticism 189

us. Descartes’ssecond and third stages of doubt,bycontrast,undermine such arealist commitment: As long as we cannot rule out the possibilityofdreamingorbeing deceivedbyanevil demon, we cannot be certain whether there are in fact external thingsthatappear to us in acertain way—or whether we are simplyhallucinating. UnlikePyrrhonian scepticism, the scepticism raised by Descartes’slast two stages of doubt, which Popkin describes as “metaphysical” and “total Pyrrhonism,” concerns our beliefs in the existence of extra-mentalthings, of which there is “no controversy” according to Sextus. In fact,undermining our confidence in non-empirical beliefs (such as our beliefs that 2+3=5orthatsquares have four sides), Des- cartes’sthird stageofdoubt even undermines our beliefs in what we usuallytake to be necessary truths.¹⁵ Forifwemight be mistaken in thinkingthat squares have four sides, squares with five,six,seven, or anyother number of sides might well be possible, after all—and the same holds for the rational square root of 2orthe largest prime number. Relying on the criterion of scope, onlyDescartes’sfirst stageofdoubt,which concerns the reliability of our senses and which leavesour confidenceinthe existenceof extra-mental thingsuntouched, retains alegitimate claim to count as aform of Pyr- rhonism.But when we also take the first core-feature of Pyrrhonism into account—its anti-dogmatic nature—even the scepticism induced by Descartes’sfirst stageof doubt fails to be Pyrrhonian. Thisisdue to the strongepistemologicaluse Descartes makes of his methodologicallyemployed doubts. As he writes in the second Meditation:

Anythingwhich admits of the slightest doubt Iwill set aside just as if Ihad found it to be wholly false; and Iwill proceed in this wayuntil lrecognize somethingcertain, or,ifnothingelse, until I at least recognize for certain that thereisnocertainty (AT7:24; CSM2:16).

In employing his scepticism as amethodfor revealing an indubitable foundationof knowledge,Descartesuses his doubts not onlytoincite suspension of judgment,but as an immediate reason for denying claims of true knowledge or certaintyabout a particulardomain. This is quite different from the Pyrrhonian, who would always re- main open to the possibilityofovercoming these doubts and thereforerefuse to adopt the negative epistemologicalverdict announcedbyDescartes. Hence, far from yielding an anti-dogmatic state of universal suspension of judgment,Descart- es’sscepticism, if successful, helps us “to recognize for certain” that we do not have anytrue or certain knowledge after all. In his quest for certain knowledge,Des-

 This result is closelyrelated to another famous and widelydebated view of Descartes: his conviction that necessary and eternal truths depend on the will of God (and aretothis extent not ultimately necessary insofar as God could have chosen adifferent set of necessary and eternal truths). As an entry point intothe debate, see his Letter to [Mersenne], 27 May1630(AT 1:152; CSMK 25)and David Cunning, “Descartes’ Modal Metaphysics,” in TheStanfordEncyclopediaofPhilosophy,ed. Ed- wardN.Zalta (Spring2014Edition), https://plato.stanford.edu/archives/spr2014/entries/descartes- modal/. 190 Stephan Schmid

cartes takes the possibilityof(the slightest) doubt about the belief that p to immedi- atelyestablish the (dogmatic) epistemological verdict that we do not have anycer- tainty or true knowledge as to whether p.¹⁶ Starting from the textuallywell-founded premise that Pyrrhonian scepticism is essentiallycharacterised by that fact that it is (1) anti-dogmatic in nature(and merely aims at our suspension of judgment) and (2)restricted in scope to the extent that it does not question the existenceofextra-mental thingsthat appear to us in acertain way, we have to conclude that, pace Popkin, none of the scepticisms invoked by Des- cartes’sthree stages of doubtqualifyasgenuine formsofPyrrhonism. As an instru- ment for laying bare asecureand lasting foundationofknowledge,Descartestakes his scepticism to be sufficient to refuteour claims of certain knowledge about apar- ticular domain and for this reason it is clearly dogmatic in nature. Furthermore,the forms of scepticism invoked by Descartes’sdream and evil demon hypothesis go far beyond the restricted scope of Pyrrhonism in thatthey undermine our beliefs in the existenceofextra-mentalthingsingeneral. Descartes’sscepticism is distinctively non-Pyrrhonian.¹⁷

3HumeanScepticism (about Causation)

In fairness to Popkin, it is important to note that he did not classify David Hume¹⁸ as aPyrrhonian sceptic in the traditional sense, though he argued that “Hume, himself, actuallymaintained the only ‘consistent’ Pyrrhonian point of view.”¹⁹ In fact,Popkin identifiestwo aspects in Hume’sscepticism that he takes to be different from Sextus Empiricus’sstandard formulation of Pyrrhonism.²⁰ First,Popkin contends that Hume’sscepticism is more dogmatic than Pyrrhonism in that Hume assertorically

 Notethat even if we takeDescartes to articulateonlyamaxim of assent here, according to which we should not accept what can be doubted, this maxim is stronger than the ancient sceptic’sprecept to onlyaccept aproposition for which there is moreevidencethan counter-evidence. Foradiscussion of this point,see Janet Broughton, Descartes’ Method of Doubt (Princeton:Princeton University Press, 2002), 43‒49.  This is not changedbythe fact that Descartes’ contemporaries (like Hobbes; see AT 7:171; CSM 2:121) as wellasDescartes himself (AT7:171‒72,CSM 2:121; AT 5:147, CSMK 333) denied that the sceptical considerations of his first Meditation have anytitle of novelty or originality.Vis-à-vis ancient Pyr- rhonism, Descartes’ssceptical considerations were original indeed.  Hume’sworks arecited in parentheses according to the followingabbreviations:EHU refers to An EnquiryConcerning Human Understanding,edited by TomL.Beauchamp (Oxfordand New York: Ox- fordUniversityPress, 1999); Trefers to ATreatise of Human Nature,ed. David F. Norton and Mary J. Norton (Oxfordand New York: OxfordUniversity Press, 2000). Citationsfromboth works arefollowed by areferencetoL.A. Sebly-Biggeand P.H. Nidditch’sClarendon editions (1975 and 1978,respective- ly), abbreviated as SBN.  RichardPopkin, “David Hume: His Pyrrhonism and His Critique of Pyrrhonism,” ThePhilosoph- ical Quarterly 1, no. 5(October 1951): 385.  Popkin, 386‒87. Three Varieties of Early Modern Scepticism 191

claims that (many) philosophicalquestions are ultimatelyunanswerable. Second, Popkinholds that Hume does not discuss, let alone accept the traditional Pyrrhonist strategyfor deciding practical questions by appeal to our appearancesand local cus- toms and traditions. UnlikeSextus, who would concede that we can “have opinions about what appears to be the case, withoutgivingupone’ssuspensive attitude as to what really is the case,”²¹ Hume famouslydenied thatweare able to persistently withhold judgmentsabout what appears to be the caseevenifphilosophical enquiry reveals that we lack anyrational grounds for these judgments. Idonot want to discuss Popkin’scharacterisation of Hume’sscepticism here. Let me just note that,unlike Popkin,Iam not fullysure whether there is more than a verbaldisagreement when it comes to Hume’sand Sextus’sdiverging verdicts on the possibilityofshedding our opinions by suspending our judgment.²² However,I very much agree thatmanyofHume’ssceptical considerations are much more dogmatic than thoseprovided by Sextus insofar as they aim not onlyatour suspension of judgment but also at defeating our claims of trueorcertain knowledge altogether.²³ Iwill thus follow Popkin in his first assessment thatHume’sscepticism is less anti-dogmatic than traditionalPyrrhonism. All this leavesthe second corefeature of Pyrrhonian scepticism—its scope—untouched. What about the scope of Hume’s scepticism? Giventhe manysceptical facets of Hume’sphilosophy, this question defies auni- fied and simple answer.There are justtoo manysceptical strandsinHume’sthought to determine the scope of Hume’sscepticism. In the following Iwill focus on onlyone form of scepticism in Hume—his famous scepticism about causation.AsIwillargue, Hume’sscepticism about causation is not onlydecidedlywider in scope than traditional Pyrrhonism, but also venturesbeyond Descartes’smost radical from of scepticism,his evil demon hypothesis.²⁴ Hume’sworries about causation have many facets:One of these concerns our justification in making causal inferences—our practice of inferring from aperceived

 Popkin.  Forsimilar concerns in this direction, see TerenceIrwin, review of Doubt and Dogmatism: Studies in Hellenistic Epistemology,ed. Malcolm Schofield, Myles Burnyeat,and Jonathan Barnes, Noûs 17, no. 1(March 1983): 127; Irwin, TheDevelopment of Ethics: AHistorical and CriticalStudy,Vol. 2: FromSuareztoRousseau (Oxfordand New York: OxfordUniversity Press, 2011), 253‒54;and Julia Annas, “Hume and Ancient Scepticism,” Acta Philosophica Fennica 66 (2000): 271‒85.Ihave profited considerably from discussions with Máté Veresonthis point.  Aparticularlytelling passage with respect to Hume’snegative dogmatism is his famous dictum that all reasoning must,inlight of sceptical reflections, “from knowledge degenerate intoprobabil- ity” (T 1.4.1.3, SBN 181).  Notethat the kind of scepticism that Iaminterested in with respect to Hume also manifests in his considerations about substances (T 1.1.6; 1.4.6). Iconfine myself to Hume’sscepticism about causation because Hume is moreexplicit about the distinctive natureofthis form of scepticism and because it is this kind of scepticism to which Kant explicitlyrefers. 192 Stephan Schmid

object the existenceofits (unperceived) cause.²⁵ Another worry concerns our very notion of acause, which is takentoundergird our practice of causal inferences because it is traditionallyconceivedasanotion of necessaryconnection between objects or events, which licensesthe inferential transition from the perception of one object or event to another.HereIfocus on the latter. Hume’sworry about our notion or our idea of causationgoes back to his empiricist commitment that all our ideas must ultimatelybederived from impressions. Or, as Hume puts it: “all our ideas or more feeble perceptions are copies of our impressions or more lively ones” (EHU 2.5, SBN 19).²⁶ Even though Hume allows for minor exceptions to this principle, he is clear that these are onlysingular cases, and asin- gular case is “scarceworth our observing,and does not merit thatfor it alone we should alter our general maxim” (T 1.1.1.10,SBN 6). He is thus firmlyconvinced that his “general maxim” applies to our idea of causation as well. Accordingly, Hume opens his inquiry into the experiential sources of our idea of causation by noting:

Ibegin with observingthat the terms of efficacy, agency, power, force, energy, necessity, connexion,and productivequality,are all nearlysynonimous; and therefore ’tis an absurdity to employ anyofthem in definingthe rest.Bythis observation we rejectatonce all the vulgar definitions, which philosophers have givenofpower and efficacy; and instead of searchingfor the idea in these definitions, must look for it in the impressions,fromwhich it is originallyderiv’d(T 1.3.14.4,SBN 157).

Giventhat thereisawhole family of conceptuallyinterrelated causal concepts or ideas, it will not help to uncover the empiricist sourceorbasis of our idea of causation by appealing to other ideas of this family(as it is done by what Hume calls “vulgar definitions”). In order to give an empiricisticallyacceptable analysis of causation, we “must look for it in the impressions, from which it is originallyderiv’d”. As Hume famouslyargues, however,there is no single impression that could serveasthe experiential basisorsourcefor the idea of causation thatphilosophers seem to relyonwhen they conceive of causation as anecessary connection between events or objects. While experience makes us acquainted with events or objects(reg- ularly) succeeding each other,itdoes not provide us with anyimpression of aforce or connection between them. As Hume lucidlyputs it:

 As Hume famouslyexplained, “[a]ll reasoningsconcerningmatter of fact seem to be founded on the relation of Cause and Effect. By means of that relation alone we can go beyond the evidenceofour memory and senses” (EHU 4.4, SBN 26).  In his Treatise,Hume articulates his so copy-principle,saying “[t]hat all our simple ideas in their first appearance are deriv’dfrom simple impressions,which arecorrespondent to them, and which they exactly represent” (T.1.1.1.7,SBN 4). Forfurther discussionofthis principle and problems connected with it,see Don Garrett, Cognition and Commitment in Hume’sPhilosophy (Oxfordand New York: Ox- fordUniversity Press,1997), 41‒57. Three Varieties of Early Modern Scepticism 193

[E]ven in the most familiar events, the energy of the cause is as unintelligible as in the most un- usual, and […]weonlylearn by experiencethe frequent Conjunction of objects, without being ever able to comprehend anythinglike Connection between them. (EHU 7. 21,SBN 70)

Consider athrown stone breakingawindow.Wetake it for granted thatthe thrown stone causes the window to shatter.But on what grounds?Humeisclear that this “ground” is no impression or experience of acertain connection holding between the stone and the breakingwindow because all we can actuallyobserveisthe fact that one event—the stone hitting on the window—is followed by another event— the window’sbreaking; an experience,indeed, thatwecan have repeatedly: whenever we have seen astone hitting awindow,wehaveobservedthe window breaking afterwards. But far from being aware of anycausal tie or connection between events or objects, “we onlylearn by experience the frequent Conjunction of objects,” i.e., their regular succession. The lack of asingle impression thatcould figureasasourceofour idea of causation leavesusinanawkwardsituation. GivenHume’s “general maxim” that an idea is nothing but a “feeble copy” of acorrespondingimpression, the lack of an impression that underlies our idea of acausation seems to implythat we do not have an idea of causationinthe first place. Hume is well aware of this difficulty—and sug- gests an ingenious solution to it:

Thus upon the whole we mayinfer,that when we talk of anybeing[…]asendow’dwith apower or force, proportion’dtoany effect; when we speak of anecessary connexion betwixt objects, and suppose, that this connexion depends upon an efficacy or energy,with which anyof these objects areendow’d; in all these expressions,soapply’d,wehavereallynodistinct meaning,and makeuse onlyofcommon words, without anyclear and determinateideas. But as ’tis moreprobable,that these expressions do here lose their true meaningbybeing wrong apply’d, than that they never have anymeaning; ’twill be propertobestowanother consideration on this subject,tosee if possiblywecan discover the natureand origin of those ideas, we annex to them (T 1.3.14.14, SBN 162).

As Hume reminds us, concluding that we do not have anycausal notions or ideas— such that all of our causal vocabulary is meaningless—is onlyone of two possibili- ties. Another possibleconclusion—and this is the conclusion that Hume is going to embrace—is that our causal vocabulary has adifferent meaning than philosophers usually assume: it does not express an idea of anecessary connection between distinct events or objects (which—due to alack of acorresponding impression—we do not have in the first place). AccordingtoHume, our idea of acause is rather the idea of “an object, followed by another,and where all the objects, similar to the first, are followed by objects similar to the second” (EHU 7. 29,SBN 76), as our experience reveals us no more than such regular sequences. Hume’ssolution to the awkwardsituation mentioned aboveconsists in providing arevisionist theory of causation accordingtowhich causation simplyamounts to a regular succession or “conjunction”—as Hume puts it—as opposed to amodallyro- bust relation or a “connexion.” In addition to this,Hume offers an explanation for 194 Stephan Schmid

the fact that manyphilosopherstake their idea of causation to be about anecessary connection between distinct objects or events, even though we simplycannot have such an idea. In Hume’sdiagnosis,philosophers are usuallymistakenabout their idea of causation because they misinterpret the impressions that accompanyour ideas of regular successions. If we observearegular succession between objectsor events frequently, we grow accustomed to this succession. Andhaving grown accustomed to this sequence, we tend to expect and thereby mentally anticipatethe suc- ceedingevent or object upon the observation or imagination of its typicalantece- dent.Inthe course of acquiringanidea of aregular succession of events, then, we also acquirethe habit to mentally transit from the appearance of the formertothe idea of the latter.Thishabit manifests itself in atypical feeling:upon the experience of an event of aregular succession we feelurgedtoexpect its usual attendant.Itis “[t]his connexion,” Hume explains, “which we feel in the mind, this customary transition of the imagination from one object to its usual attendant,[that] is the senti- ment or impression, from which we form the idea of power or necessary connexion” (EHU 7. 28,SBN 75). Philosophers,then, tend to conceive of A causing B as aform of A necessitating B,because they themselvesfeelpsychologicallyforced or necessitated to think of Bsupon the appearance of As. And since they acquired this psychological determination in the course of having observed Bsregularlyfollowing As, they mis- takenlytake to perceive this psychological “necessitation” as ametaphysical necessitation in the regularlysucceeding objectsorevents themselves. Let me clarify the precise nature of Hume’sscepticism about causation. As re- vealedbymybrief sketch, this scepticism is primarilydirected towards our idea or notion of causation. Not onlydoes Hume call into question the possibility to know whether events or objects are genuinely causally connected (in the sense of being re- lated by anecessary connection), he even disputes thatwecan have the very idea or notion of such arelation. In Hume’swords:

[W]e cannot […]point out that circumstanceinthe cause, which givesitaconnexion with its effect.Wehavenoidea of this connexion; nor even anydistinct notion what it is we desire to know,whenweendeavour at aconception of it (EHU 7. 29,SBN 77).

Closelyinspecting our idea of acause and cognate notions, Hume argues, we find that they onlyrefertoaregular succession of objectsorevents and that every assumption about this regular succession having adistinct modal character is due to amisunderstanding of our felt psychological tendencytotransit from the appearance of one object to its usual attendant.Lacking adistinctiveimpression of a cause necessitatingits effect,wecannot even have an idea or notionofwhat the distinctive mode of necessitation thatwetend to attribute to what we describeascausal relations would actually be like. Three Varieties of Early Modern Scepticism 195

4Three Varieties of Scepticism

How is Hume’sscepticism about causationtobedistinguished from the othervari- eties of scepticism considered in this chapter?Being first and foremost concerned with our ideas or notion of causation, it goes significantlybeyond the forms of scepticism that Descartesinvokes by his dream and evil demon hypothesis. Forasradical as Descartes’s “hyperbolic” doubtmight be, it never questions the very meaning of our ideas. This is particularlyevident from the strategyDescartes uses to rebut the hyperbolic doubtheintroduced, namely provingGod’sexistence, who—as abenev- olent and omnipotent being—would never allow us to be systematicallydeceived along the lines suggested by Descartes’sdream and evil demon hypotheses. This argument for God’sexistenceproceeds from asurvey of our ideas in our minds, about which Descartes explains, in the third Meditation:

[A]s far as ideas areconcerned, provided they areconsidered solelyinthemselvesand Idonot referthem to anythingelse, they cannot strictlyspeakingbefalse; for whether it is agoat or a chimera that Iamimagining, it is just as true that Iimagine the former as the latter (AT7:37; CSM 2:26).

AccordingtoDescartes,therecan be no question about the “falsity” of our ideas: they have adistinctive representational content,which is—at least primarily—fully transparent to us and about which we cannot be deceived; an idea about agoat is about agoat,and an idea about achimeraisabout achimera.²⁷ The question invoked by Descartes’sscepticism onlyappears when we ask ourselvesabout the relation between our ideas and the external reality:doour ideas, with their distinctive content,correspond to an extra-mental reality?Inthis vein, Descartes’sscepticism takes the intentionality of our ideas for granted. He does not question that they have adistinctive intentional content or representational purport.Hesimply questions theirtruth: is the world reallythe waythat our ideas represent it to be? This is different from Hume’sscepticism about causation.UnlikeDescartes’s form of scepticism, Hume’sscepticism about causation not onlycalls into question whether thingsare in fact causallyrelated, but undermines our very idea of causation as anecessary connection. In Hume’sview,when we think about causation as anecessary connection, we are deceivedabout our own ideas. Being misled by our psychological habit to associate ideas of causes with ideas of their effects, we

 Notethat in the third Meditation,Descartes concedes that while ideas by themselvescannot strict- ly speakingbefalse, still some of them qualify as materiallyfalse, “when they represent non-things as things” (AT7:43, CSM2:30). (His paradigm example is the idea of coldness that represents some- thingasrealand positive even though it is just an absenceofheat.) Nonetheless,Descartes is clear that materiallyfalse ideas exist and have adistinctive representational content, it is just that this content is so confused that “Iamunable to judge whether or not what it represents to me is something positive which exists outside of my sensation” (AT7:234,CSM 2:146). 196 Stephan Schmid

take causes to stand in anecessary connection to their effects, even though “we have no idea of this connexion; nor even anydistinct notion what it is we desire to know, when we endeavour at aconception of it” (EHU 7. 29,SBN 77). As opposed to the truth of our thoughts, which are questioned by Descartes’sscepticism, Hume’sscepticism about causation concerns the very meaning or intentional content of our idea of causation: are our causal notions in fact about anecessary connection or about something else? The particularthreat of Hume’sscepticism consists in his caseofthe possibility that we can be and in fact are deceivedabout the content of our own thinking,something which had been exempt from Descartes’shyperbolic doubt. This all makes plain thatfar from just rehashing forms of Pyrrhonian scepticism, Descartes’shyperbolic scepticism and Hume’sscepticism about causation introduce varieties of scepticism that are markedlydifferent from the kind of scepticism described by Sextus Empiricus. Not onlyare Descartes’sand Hume’sforms of scepticism both “negatively dogmatic” in the sense that they justify the claim that we do not have anygenuineknowledge about their specific domains, they are alsosig- nificantlymore comprehensive,calling into question what Pyrrhonism stilltakes for granted. In fact,Hume’sscepticism about causation defines avariety of scepticism that is even strongerthan Descartes’shyperbolic scepticism insofar as it calls into question the very intentionality or meaningofour ideas, which Descartes takes to be unquestionablytransparent (though not necessarilyadequate).²⁸ We should thus distinguish between at least three forms of scepticism, each characterised by adistinctive form of doubt:

Pyrrhonian Scepticism asks whether x is really F,oronlyappears to be F,and pertains to the adequacyofour thoughts as to the nature of things,leaving the existenceofthe thingsrevealed in our thoughts untouched.

Cartesian Scepticism—as manifested in Descartes’shyperbolic doubt—asks whether there is in fact an x that is F,asitappears to be and pertainstothe truth of our thoughts (of the form x is F), leaving their meaning or intentionality untouched.

HumeanScepticism—as manifested in Hume’sscepticism about causation—asks whether the thought of x being F is athoughtabout x being F at all and concerns the very meaning or intentionality of thoughts.

 In fact,Ithink that Cartesian scepticism and the Humean scepticism induced by Hume’sreflec- tions on causation correspond to the twokinds of sceptical problematics that JimConant has distin- guished in terms of “Cartesian” and “Kantian scepticism.” See Conant, “Two Varieties of Skepticism,” in Rethinking Epistemology,Volume 2,ed. Günter Abel and James Conant (Berlin and Boston: de Gruyt- er,2012), 1‒72.MyunderstandingofCartesian and Humean scepticism developed hereisvery much indebted to Conant’srevealingdiscussion of these twovarieties of scepticism. Three Varieties of Early Modern Scepticism 197

GiventhatPyrrhonian, Cartesian, and Humean scepticism articulate distinctive forms of doubt, each of which undermines adifferent claim or pretenceofour thought(is it adequate?isittrue? and is it genuine thought or about anything at all?), it is certain- ly of systematic importance to avoid subsumingthem under the uniformlabel of “Pyrrhonism,” as Richard Popkin had done.But distinguishing between these varieties of scepticism is also important from the point of view of the history of philosophy. This is because these three varieties of scepticism raise different philosophical questions or problematics that have influenced prominent discussions in different periods of the history of philosophy. While Pyrrhonian scepticism raises questions about the adequacyorveracityofour thought,Cartesian scepticism calls into doubt the very existenceofthingsoutside our thought.Humean scepticism, in turn, raises aquestion about the content of our thought and our capacity to decide whether our thoughtisabout certain objectsinthe first place. The Pyrrhonian type of question is representative of the ancient discussion about acriterion of truth: is thereafeature of our thought that we can appeal to in order to justify its truth or adequacy—acriterion by which we can decidewhether thingsare reallythe waythat we take them to be? While the Epicureans and Stoics have fa- mouslydefended such acriterion, Pyrrhonists have denied its existence.²⁹ The Cartesian problematic invitesthe exploration of radicallyrevisionist metaphysical options that we can famouslyobserveamong prominent earlymodern philosophers such as Berkeley and Leibniz. Is there amaterial reality which our thoughts correspond to or should we rather embrace aversion of idealism according to which reality is ultimatelyconstituted by mind-like entities with particular thoughts?³⁰ Humean scepticism, finally, is akey for understanding Kant’sphilosophicalproj- ect.While Kant concedes in afamous letter to Herz that in previous work he just passed over the “question of how arepresentation that refers to an object without being in anyway affected by it can be possible,”³¹ it is this question thatlies at the heart of his transcendental philosophy, which he develops in his Critique of Pure Reason.Inthis work Kant prominentlyasks how there can be meaningful metaphysical thoughts, which are about something thatwecannot experience. It should not come as much of asurprise that this is the problem raised by Humean scepticism about causation: how can we be sure that our metaphysical idea of causation as a necessary connection between two events or objectsisreallyabout something rather than an empty phrase that we take to expressanidea, even though it does not.

 Foradiscussion of this debate, see Gisela Striker, “The Problem of the Criterion,” in Essayson Hellenistic Epistemology and Ethics (Cambridge and New York: Cambridge University Press,1996), 150‒65.  Burnyeat, “Idealism and Greek Philosophy,” makes apowerful case to the effect that idealism is a peculiar earlymodern idea, which is virtuallyabsent from ancient thought.  Kant,Letter Nr.65, to Marcus Herz, February 21,1772, in Kant’sgesammelte Schriften,ed. Köni- glich Preußischen Akademie der Wissenschaften (Berlin 1900‒), 10:125. 198 Stephan Schmid

Against this backdrop, Kant’sfamous Copernican revolution—according to which we should conceive objects as conforming to our mode of cognitionrather than taking our cognition to be determined by its objects—can be seen as ameans to ensure the representational purport of our metaphysical thoughts thathas been forcefullyundermined by Hume’sscepticism about causation. Giventhat our objects of cognition are constituted by our cognitive faculties,wecan be sure that thereare objects that our cognition is about.³² In fact,Kant himself points out that it was David Hume who “interrupted his dogmatic slumber and broughthim to adopt a fullynew direction in his investigations in the area of speculative philosophy.”³³ In light of the fact that it was David Hume’sscepticism rather than Descartes’s that awakened Kant from his dogmatic slumber and broughthim to develop his transcendental philosophy, it is important not to conflate these different varieties of early modernscepticism, each of which is concerned with adifferent problematic of our thought.

5Conclusion

Richard Popkin famouslyargued thatthe earlymodernperiod wasshaken by an “an insoluble crise pyrrhonienne,asthe various gambits of Sextus Empiricusare explored and worked out”.³⁴ In this chapter,Iargued that Popkin’sdescription of the varieties of scepticism developedinthe earlymodern period as aspecies of Pyrrhonism is highlymisleading and blurs important differences. As Ihaveshown, both,René Descartes and David Hume,invoked and employed certain forms or varieties of scepticism which differ from Pyrrhonian scepticism. Even setting aside worries about the problematic assumption thatancient and earlymodern forms of “scepticism” are indeed forms of asingle overarching genus of intellectual endeavour,the forms of doubt launched by Descartesand Hume are cruciallydifferent from the doubts that would have been raised by Pyrrho- nians if they had raised anydoubts at all. In fact,the earlymodern varieties of scepticism,which Ihaveanalysed here, not onlydiffer from traditional Pyrrhonian scepticism with respect to the kinds of doubtthey incite, but also with respect to the epistemologicalverdict they justify. Concerningthe latter,wehaveseen that Sextus Empiricus puts great emphasis on the fact that Pyrrhonian sceptics recommend suspension of judgment about ev-

 Kant articulates his thoughtofaCopernicanrevolution in philosophyinthe preface of the second edition of his Critique of Pure Reason,Bxvi‒xvii (Schriften 3:11‒12).For an excellent commentary of Kant’scritical project and its relation to his Copernican revolution see Sebastian Gardner, Routledge Philosophy GuidebooktoKant and the Critique of Pure Reason (London: Routledge,1999), 18‒33.  Kant, Prolegomena zu einer jeden künftigen Metaphysik die als Wissenschaft wirdauftreten können (Schriften 4: 260).  Popkin, HistoryofScepticism,5. Three Varieties of Early Modern Scepticism 199

erything and even withhold their judgment as to the question about our possibility of knowledge.Pyrrhonism is anti-dogmatic, as it were. The varieties of scepticism ar- ticulated by Descartes and Hume, by contrast,are not anti-dogmatic in this sense. Moreover,the forms of scepticism put forward by Descartesand Hume and dis- cussed in this chapter,which Ilabelled as Cartesian scepticism and Humean scepticism, raise different and moreall-encompassingkinds of doubts than those raised by Pyrrhonism. While the Pyrrhonian sceptics mainlycall into question whether we can know the nature of things, they do not doubt that there are thingsthat appeartous in acertain way. They leave the question about their existenceuntouched and merely question our ability to discern the adequacy or veracity of our thoughts with respect to the metaphysical structure of the world. Cartesian scepticism, by contrast,isdi- rected preciselyagainst the realist presumption of Pyrrhonism by calling into question the very existenceofthe external world. It therebyquestions our ability to discern the truth of our thoughts in general. Still, it leavesunquestioned whether—and thereby presupposes that—we have thoughts with adeterminatecontent in the first place. This presupposition is undermined by Hume’sscepticism about causation. In Hume’sview, we have no genuine idea of causation proper—viz.anecessary connection between twoevents or objects. Unlike Cartesian scepticism, then,Humean scepticism is concerned not onlywith the truth of our thoughts but with their intentional content or representational purport.Itputs into question whether what we take to be thoughts about certain thingsare proper thoughts about these thingsatall. Being clear about these three varieties of scepticism is important for bothsys- tematic or philosophical and historical reasons.The distinction is philosophicallyim- portant because the three varieties of scepticism differ in scope and strength: They call into question what is taken for granted by other varieties of scepticism. Distinguishing these three varieties of scepticism is alsopivotal for doing history of philosophyasitprovides us with abetterunderstanding of the problems that historical authors weregrappling with. In particular, distinguishing Cartesian from Hu- mean scepticism is crucial to understand the objectiveofKant’scritical project, which was first and foremost aresponse to David Hume’sscepticism about causation, and not to the varieties of scepticism suggested by René DescartesorSextus Empiricus.³⁵

 This is not to saythat Kant’sphilosophywas not also influencedbyother forms of scepticism. Michael N. Forster, Kant and Skepticism (Princeton: Princeton University Press, 2008), argues quite convincinglythat Kant’sdiscussion of the antinomies is cruciallyinfluenced by Pyrrhonian scepticism. 200 Stephan Schmid

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