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ABSTRACT
My goal in this paper is to contribute to the literature on Roger Bacon's epistemology by focusing on the issue of perception of quantity. The reading I aim to substantiate is that Bacon's account is best understood in terms of indirect realism. I call it indirect realism because although we have access to quantities as they exist in nature, the account is mediated by the use of a quasi-syllogism. The quasi-syllogism is constructed based on three inputs, the species of the eye, colour, and light. To defend this reading I follow five steps. First, I analyse the importance of quantity in perception, and then, in steps two and three, I look at Bacon's theory of perception from its two sides, extramission and intromission. In the fourth step I look at the quasi-syllogisms that mediate cognition of quantities, and in the fifth and final step, I draw all the threads together and make the case for Bacon's indirect realism of quantity perception.
Acknowledgements
I would like to thank the two anonymous reviewers, Yael Kedar, Giora Hon, and Sergiu Sava for their suggestions.
Notes
1 “Et primo sic, quia nobis est via nata a sensu ad intellectum, quoniam deficiente sensu deficit scientia quae est secundum illum sensum, ut dicitur primo Posteriourum, quoniam secundum quod proficit sensus, proficit humanus intellectus. Sed quantitas est maxime sensibilis, quia est sensibile commune, et ab aliis sensibus sentitur, et nihil potest sentiri sine quantitate, quapropter maxime potest intellectus proficere circa quantitatem”. [All translations are mine except otherwise mentioned.]
2 I treat quantity as a common sensible. For a treatment of quantity as the subject matter of mathematics see Communia mathematica, Demange, “ … cupiens mathematicam tractare”; Panti, “Natural Continuity”.
3 Bacon speaks of twenty common sensibles: remoteness, place, corporeity, figure, magnitude, continuum, discontinuity or separation, number, movement, rest, roughness, smoothness, transparency, density, shadow, darkness, beauty, and repulsiveness. Apart from these, some categories have subcategories, as is the case with figure which includes concavity, convexity, and other shapes lines can take. This theory is not initially proposed by Bacon, but by Alhazen. For more details about this see Alhacen’s Theory of Visual Perception, ed. and transl. by Smith, and Lindberg, “Alhazen's Theory of Vision”.
4 “Nam sensibilia communia non sic dicuntur quia sentiantur a sensu communi, sed quia communiter ab omnibus sensibus particularibus vel a pluribus discernuntur – et maxime a visu et tactu, quia Ptolomeus dicit secundo Perspective quod tactus et visus communicant in omnibus hiis viginti”. See also DMS, 34–8.
5 There is also the possible reading according to which the ‘communiter’ from the sentence ‘sed quia communiter ab omnibus sensibus particularibus vel a pluribus discernuntur’ in the above-quoted passage could mean co-jointly or concomitant. However, I do not think this is something Bacon would endorse. See, for example, his statement from OM 2: “from the entire quantity and shape [of the thing] come the species of light and colour which are arranged on the surface of the organ of sense, and this suffices (sufficit) [for vision]”. If Bacon had in mind the necessity of multiple sense faculties involved in the recognition of a common sensible, he would not allow for one sense only to have access to common sensibles. Plus, the capacity for recognition by multiple senses does not imply the requirement for simultaneous sensory engagement. Take the following example. Suppose I look at the moon. According to this reading, I would have to see and touch the moon to sense that it has a quantity, a dimension, a size etc. This is, however, both impossible and unnecessary.
6 I use species in the cognitive context to mean the first effect of an agent See DMS 1, 1: “Species autem non sumitur hic pro quinto universali apud Porphirium, sed transumitur hoc nomen ad designandum primum effectum cuiuslibet agentis naturaliter […] Dicitur autem similitudo et ymago respectu generantis eam, cui assimilatur et quod imitatur. Dicitur autem species respectu sensus et intellectus secundum usum Aristotelis et naturalium, quia dicit secundo De anima quod sensus universaliter suscipit species sensibilium, et in tertio dicit quod intellectus est locus specierum. […] Investigandum est igitur quid sit secundum suam essentiam; etquoniam intentio est ostendere quod hec species sit similis agenti et generanti eam in essentia et diffinitione, ideo primum oportet duci in medium quod omnes habent confiteri, scilicet quod species est primus effectus agentis per hanc enim omnes estimant effectus ceteros produci”. For more details about species and species multiplication. See Kedar, “Species and Virtus”.
7 These other considerations are eight in number and are described in the next paragraphs. “Cum igitur obicitur quod hec sunt sensibilia per se, ergo agunt in sensum sicut propria, dicendum est quod non dicuntur per se sensibilia propter actionem in sensum, sed propter hoc quod sensus potest de eis certificare. Et si obiciatur quod tunc visio non certificabitur de eis, postquam non faciunt species suas, dicendum est quod non. Nam non exigitur in omnibus species propria, sed sufficit species visus cum specie lucis et coloris, et cum quibusdam aliis considerationibus”.
8 It is worth noting that accidents of a substance require quantity as quantity provides natural substances with corporeity and three dimensionality.
9 “Dicendum est quod species materie prime non renovatur, sed specifice, et illius proprietates renovantur. Sed hec non sunt corporeitas et figura et huiusmodi communia, quoniam sunt proprietates materie prime. Si igitur ista sensibilia communia non faciant species, […]”.
10 “Unde alia non sunt activa in sensum nec in medium. Et causa quare hec non sunt activa est quia omnia vel sunt quantitates vel proprietates quantitatum, ut patet, et quantitatis non est agere, quia debetur materie, cui non competit actio sed passio, ut Aristoteles dicit primo De generatione. Et Aristoteles in secundo De anima concordat; […]”.
11 See also DMS 1, 334–45. In stating that prime matter, that is matter that has not received any form, has properties such as quantity or properties of quantities, Bacon’s theory of prime matter as something that has an actuality is quite far away from, say, Aquinas’ theory of prime matter as pure potency. For the issue of prime matter see Polloni, “Bacon on the Conceivability of Matter”, and Rodolfi, “Roger Bacon on the Ontological Status of Matter”.
12 “Et Aristoteles in secundo De anima concordat; nam medium vel instrumentum susceptivum soni est absonum, et susceptivum coloris non coloratum, ut dicit. Et ideo sententia sua est quod medium et sensus non debent habere naturas sensibilium quarum species debent suscipere ut iudicent de sensibilibus per eas. Unde humor glacialis non habet naturam aliquam lucis vel coloris sub illo gradu quem habent res visibiles extra. […] Sed bene habet figuram et quantitatem et corporeitatem et alia sensibilia communia que ei competunt; et ideo nec est natum recipere species horum; nec ipsa sunt activa”.
13 It is worth mentioning that not only do common sensibles lack proper species, but some proper sensibles as well, such as sounds (DMS 1, 213–5) and partly even odours (OM 2, 57). I thank one of the reviewers for making me aware of this passage in Bacon. It is because of this lack of species that we have access to common sensibles indirectly and through the cooperation of many senses, as it will become clear below.
14 “Secundum quod exigitur ad visum est distantia. Nam universaliter sensibile positum super sensum non sentitur, ut Aristoteles dicit secundo De anima. Cuius causa est quod omnis sensus fit extramittendo, id est, faciendo virtutem suam a se in medium, ut species sensibilis reddatur magis proportionalis sensui; et recipiat esse nobilius a specie sensus, quatenus sit magis conformis sensui”.
15 “Ex hoc autem capitulo patet bene consideranti quod oportet visum fieri per suam speciem factam ad visibile. Nam si perspicuum unum continuatum in superflua distantia terminat visum, et non terminat propter densitatem perfectam, que secundum se sit sensibilis in omni distantia, sed propter debilitatem speciei visus, que deficit ad nimiam distantiam, oportet quod visus fiat extramittendo speciem, id est, faciendo speciem a se propter actum videndi”.
16 “Et primum quod hic consideratur est quod visus indiget specie rei visibilis; nam sine illa non videbit, secundum quod dicit Aristoteles secundo De anima quod universaliter sensus suscipit species sensibilium ad hoc ut fiat operatio sentiendi. Item oportet patiens assimilari per agens; sed visus est virtus passiva, ut ostendit Aristoteles secundo De anima, et ideo oportet quod assimiletur agenti quod est visibile. Sed similitudo agentis non est nisi species, ut omnes sciunt. Item res continue facit speciem undique secundum omnes diametros. Sed cum obstaculum est inter speciem rei et visum, non fit visus, quando vero omne impedimentum amovetur, ut species ad oculum veniat, tunc videtur res. Quapropter oportet quod visio fiat per speciem, sed precipue per speciem lucis et coloris”.
17 Assimilation in this case means that the species, that is, the first effect of the agent, triggers a change in the patient such that, from the matter of the patient, something similar to the agent is made. See DMS 1, 1, 80–5.
18 “Quapropter videretur quod quantitas et figura et huiusmodi faciant impressionem et speciem in organo, et ideo prius in aere. Ad hoc dicendum est quod illud intelligendum est sicut loquitur de magnitudine rei vise quando dicit quod ordinatur et describitur in superficie membri sentientis; hoc enim non est quia magnitudo faciat suam speciem, sed quia a tota rei magnitudine venit species coloris et lucis et a tota superficie; et tunc species coloris venientes a singulis partibus rei vise non confunduntur in una parte pupille, sed distiguuntur et ordinantur in superficie pupille in quantitate sensibili, secundum numerum partium in re visa, ut visus distincte comprehendat totum colorem vel lucem rei vise. Sie igitur describitur in pupilla magnitudo rei vise, id est, color totius magnitudinis vel lux, ita quod solum sit ibi species coloris et lucis ordinata in pupilla, et non ipsius magnitudinis.” (Trans. D. Lindberg, starkly modified). See also Bacon, OM 2, 78: “a tota quantitate et figura veniunt species lucis et coloris, que ordinantur in superficie membri sentientis, et hoc sufficit”.
19 Bacon, Communia mathematica, 23: “Quantitas vero est secundum quam aliquid dicitur equale vel inequale”.
20 See Bacon, OM 2, 79–82. On cognition per syllogismum see Mantovani, “Visio per sillogysmum”.
21 “Cognitio vero tertia adhuc est que non potest fieri solo sensu; et non est per comparationem ad prius visum, sed absolute considerat presentem rem. Ad cuius cognitionem plura requiruntur, et est quasi quoddam genus arguendi, sicut cum aliquis tenet in manu lapidem perspicuum et non percipit eius perspicuitatem; sed si exponat eum aeri, et sit aliquod densum retro illud in debita distantia et lux sufficiens, videbit lucem et densum ultra lapidem; et tunc cum non potest mediante lapide videre que est retro nisi sit dyaphanus, arguit quod sit transparens et perspicuus. Sed in rebus consuetis nos utimur hac cognitione subito, et non percipimus nos arguere, cum tamen arguamus”.
22 Another reason why this process only resembles that of reasoning is that it takes place in non-rational animals as well, and they lack intellect by definition.
23 For authors who discuss the role of the extramissive species in Bacon’s theory of perception see also Lindberg, Theories of Vision, 107–16, especially 115; Smith, “Picturing the Mind”; Smith, From Sight to Light, 256–75, especially 262, 264–6; and Smith, “Getting the Big Picture”, especially n. 44, 258; Lička, “The Visual Process”, 87–95.