Kant, Science, And Human Nature - Guyer

7/27/2019 Kant, Science, And Human Nature - Guyer

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KANT, SCIENCE, AND HUMAN NATURE

PAUL GUYER

University of Pennsylvania

Hannas Goals and Mine

Robert Hannas Kant, Science, and Human Nature1 is an ambitious and challengingwork. Hannas goal is to provide a charitable reinterpretation of Kantsversion of scientific realism and his defense of a libertarian conception offreedom of the will that will avoid the refuge of a strong version of transcen-dental idealism, that is, one that takes spatiality, temporality, causality, and theother categories of the understanding to be imposed on ultimate reality by

ultimate mind, which, whatever properties they both might really have, defi-nitely do not have spatiality, temporality, causality, and so onin other worlds,transcendental idealism on the so-called two-worlds interpretation. The keyto Hannas solution is ascribing to Kant a combination of what he callsmanifest scientific realism and a two-concept or two-property interpreta-tion of transcendental idealism. According to the former, objects really havethe macroscopic spatiotemporal and causal properties that they appear to haveas well as whatever microscopic properties that can be associated with thosemacroscopic properties, but not all of their manifest macroscopic properties areexhausted by the first set of properties, and they also manifestly have freedom

of the will. In particular, Hanna argues that the macroscopically manifestproperties of organic life cannot be reduced to the equally macroscopicallymanifest properties of mechanical causation but are not ontologically incom-patible with them either, that is, not possibly ascribable to one and the samekind of being, and that the properties of organic life can in turn support theascription to human beings of the negatively noumenal property of beingable to act in accordance with reasons even when that seems incompatible withmechanical causation, thus libertarian freedom of the will is not merely com-patible with mechanical causation but is also itself part of what is manifestlyreal, grounded as it is in the manifest properties of organic life in human beings

and not in some mysterious behind-the-scenes noumenon in a positive sense.I agree with certain of Hannas assumptions, but cannot accept his ascrip-

tion of this view to Kant nor the suggestion that it is a viable solution to theproblem of free will. I agree with Hanna that a charitable reconstruction ofKants philosophy should avoid a strong or two-worlds interpretation oftranscendental idealism, because, as I have long argued, this view is not onlyimplausible but is founded on unsound arguments. But strong transcendentalidealism is so pervasive in Kant, above all, in his treatment of the freedom ofthe will, that I do not see how any plausible interpretation of Kant can elimi-nate it. In particular, I think that a strong form of transcendental idealism is

1. R. Hanna, Kant, Science, and Human Nature(Oxford: Clarendon Press, 2006).

Philosophical Books Vol. 50 No. 1 January 2009 pp. 1528


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central to Kants own attempt to reconcile mechanical causation with thepeculiarities of organic life, and that these two ideas cannot be combined ina one-level manifest realism to yield a charitable interpretation rather thanradical reconstruction of Kants own philosophy. That is, mechanical cau-sality and libertarian freedom of the will cannot be combined in a one-levelmanifest realism in anything resembling Kants own philosophy. For me, theonly charitable approach to Kant on freedom of the will is to reconstruct hisnormative moral and political philosophy as a theory of the ultimate andunconditional value of the intrapersonally and interpersonally consistent real-ization of practical rather than transcendental freedom in choice and action;but, then, to reject his assumption that every human being no matter whathis/her prior history is always free to act in accordance with the normativedemands of morality in favor of the implication of his discussions of impu-tation in his lectures on ethics, namely, that responsiveness to reason orreasons is an empirically ascertainable and explicable condition of humanbeings and one that, in particular, can be empirically ascertained to come indifferent degrees, to vary in degree in different human beings, in differentages of human lives, even within particular days and weeks in human lives(depending on how much an agent has drunk and all sorts of other contin-gent factors). In what follows, I will not attempt to defend my own concep-tion of what a charitable response to Kant on freedom of the will is, however,but I will discuss what I take to be several of the key problems in Hannasapproach.

The Dispute over Realism

Hannas argument is spread over 450 finely printed pages replete with a widerange of references in both Kant and recent analytic philosophy, and in thespace available to me, I cannot possibly give an adequate exposition of it beforeproceeding to my criticisms. I will give only a quick sketch of it. The work isdivided into two parts, Empirical Realism and Scientific Realism and ThePractical Foundations of the Exact Sciences, each of which is in turn dividedinto four chapters. In part I, the first two chapters present Hannas interpre-tation of Kants direct perceptual realism, chapter 1 presenting an interpre-

tation of Kants Refutation of Idealism, according to which the nerve of theargument is that self-consciousness requires a spatial substratum for experienceand that the representation of space requires orientation in it by means of theaxes originating in ones own body, while chapter 2 interprets Kants notion ofintuition as a form of what is now called non-conceptual content. Chapters3 and 4 then contrast the direct perceptual realism described in the first twochapters to what Hanna takes to be the reigning orthodoxy in contemporaryscientific realism, according to which what is real is not just a microscopicrealm of real essences, such as atomic or molecular structure (where gold isessentially defined by having the atomic weight of 79 or water by having the

molecular structure H2O), but a noumenal realm of empirically inaccessiblemicrophysical structures or essences. Hanna takes this conception of noumenal


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microphysical essential structure to be not only implausible in its own right butalso wedded to an implausible theory of a posteriori or empirically knowablemetaphysical necessities, and instead prefers manifest or direct realism com-bined with the traditional Kantian view that philosophically significant syn-thetic necessities are known only a priori. In part II, Hanna then turns first tothe nature of a priori knowledge, arguing first that the knowledge of truth ingeneral (chapter 5), mathematical truth in particular (chapter 6), and any othernecessary truth (chapter 7) all require practical rationality, or that therecannot be a scientifically knowable world in which human value, humanaction, and human morality are really impossible (p. 252), and then that themechanical worldview expounded in Kants Analogies of Experience is part ofmanifest reality but compatible with organic life capable of supporting humanvalue, human action, and human morality as another part of manifest realitythis is his two-concept or two-property interpretation of transcendentalidealism.

I have no fundamental objections to Hannas claim that Kantian intuitionsare nonconceptual content or to his claim that Kants concept of self-consciousness entails our own embodiment, although I have objections to thedetails of Hannas interpretations of Kant in chapters 1 and 2, in particular, tohis interpretation of the Refutation of Idealism as directly invoking ratherthan indirectly implying the necessity of our own embodiment: On my owninterpretation, the Refutation does not work by directly arguing that therepresentation of space is a condition of the possibility of empirically determi-nate self-consciousness and then invoking Kants earlier view (from the 1768essay on Regions in Space) that our own body is necessary for orientation in

space; it rather works by arguing that supposing that the sequence of our ownrepresentations can only be made determinate by being correlated with alaw-governed sequence of states of objects that must be conceived as indepen-dent of our representations of them, a set of facts about them that we representby representing them as located in space apart from our own bodies but asdetermining the sequence of our mental states by acting on our bodies,although the latter is only hinted at in some of Kants post-1788 reflections onthe Refutation and not in the published text at all. But I do not think that thedetails of Hannas interpretation of the Refutation play any role in hisultimate interpretation of Kants position on the freedom of the will, so I will

not pursue this dispute further here.Hannas attack upon what he takes to be the assumption of noumenal

microphysical essences in contemporary scientific realism is clearly meant todiscredit any attempt to use strong transcendental idealism in contemporaryphilosophy and to prepare the way for his rescue of Kants theory of thefreedom of the will by some version of weak transcendental idealism, so Ihad better say something about that. I have to say that I find Hannasinterpretation of contemporary scientific realism puzzling and unconvincing,because I do not think it would have occurred to any proponent of the recentorthodoxy to describe his position in Kantian terms, that is, to conceive of

the microphysical essences posited by sciencemolecules, atoms, quarks,strings, whateveras in principle inaccessible to the human senses and all


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technological aids thereto. Hanna conceives of contemporary scientificrealism as an amalgamation of the KripkePutnam theory of natural kindsdesignated by rigid designators referring to microphysical real essences, aswater, for example, designates not the phenomenal properties of water inour particular world but rather H2O in all possible worlds, with the view thatthe microphysical real essence is noumenal, and thus necessarily inaccessible toour sensory perception, whether unaided or extended by any devices frommagnifying glasses to electron microscopes. He portrays this view by addinglayers to the conception of realism, beginning with minimal scientificrealism that is committed only to the two theses that knowable things existin objectively real physical space and not merely in consciousness and haveexplanatory primacy in our best theory of the natural world (p. 141), addingto that two further theses to get noumenal scientific realism, namely, thatEach knowable physical spatial thing is ontologically constituted by a setof intrinsic non-relational properties and are transcendent, that is, existwhether human minds do not or cannot exist; whether if they do exist, donot know or cannot know them; and are necessarily . . . not directly andnon-conceptually humanly perceivable or observable but instead only atbest either semantically overdetermined by background theories and concepts orelse indirectly humanly perceivable or determinable (pp. 1412); and thenfinally adding to that yet two more theses to get maximal scientific realism,namely, that There is exactly one true description of the world of knowablephysical spatial things and that The essential properties of all knowablephysical spatial things are microphysical properties (p. 142). The conjunctionof the last thesis with the premise that the essential properties of natural

physical objects are transcendent yields the result that their microphysicalessential properties are necessarily nonperceivable or only indirectly perceiv-able. To this maximal scientific realism, which he takes to be currentdogma, Hanna opposes and prefers what he calls Kants own manifestrealism, according to which,

All the essential properties of dynamic individual material substances,natural kinds, events, processes, and forces in objectively real physical spaceand time are nothing but their directly humanly perceivable or observableintrinsic structural macrophysical properties,

Or in other words, for Kant, both cognitively and ontologically speaking,nothing is hidden (p. 142). Hanna claims that Kants physical theory, accordingto which, matter is constituted by distributions of attractive and repulsive forcesin a single all-pervasive ether, is entirely consistent with this manifest realism,because Kants (or the BoscovichianKantian) theory of matter representsa transition from metaphysical substantialism and compositionalism aboutmatter, to metaphysical structuralism about matter, according to which,

Individual material things and material kinds are not ontologically indepen-

dent things-in-themselves, each defined by a set of intrinsic non-relational,mind-independent, non-sensory, unobservable properties, but instead are


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essentially determinate positionsor determinate rolesin a maximally large relationalstructure or system of empirical nature as a whole.

On this theory, matter is essentially relationally constituted by a realspatiotemporally-organized structural complex of attractive and repulsiveforces that are nomologically determined by synthetically necessary causal andinteractive laws and The plurality of particular macrophysical material sub-stances . . . are nothing but positions in that total spatiotemporal structuralcomplex, or otherwise put, are nothing but determinate causal roles, withoutany hidden causal-role players (p. 149).

I find both sides of Hannas contrast between contemporary maximal,noumenal, essentialist scientific realism on the one hand and Kants manifestrealist ether theory on the other difficult to accept. On the one hand, it seemsto me that Hanna attributes to scientific realism a Kantian notion of thenoumenal that no contemporary advocate of the doctrine would accept.Hanna appeals to Lockes conception of essentially unknowable real essence asif that is something that contemporary realists are supposed to have taken onboard, which I am sure many of the latter would be surprised to hear, and inany case, his attribution to Locke of the view that microphysical propertiesand physical microstructures are in fact necessarily hidden from . . . empiricalinquiry and therefore totally empirically inaccessible (p. 160, my emphasis) isdebatable. According to Hanna,

the Lockean doctrine suggests . . . that humans are simply not cognitivelyconstituted so as to have direct or even an indirect, progressive, or regressive

epistemological access to the . . . uncommonsensical entitiesmicrophysicalparticles, energy quanta . . . etcrequired by the scientific image of theworld. . . . For, in order for images to make sense, there must be isomor-phisms, analogies, or some other sort of basic similarity of propertiesbetween the image and imaged object. But, as cognizers with our specificsort of sensibility and our specific sort of sensibility-funded conceptualcapacities, we are not cognitively equipped to bring about any sort of signifi-cant mapping from the microphysical order into the macrophysical order.(pp. 1612)

But that is exactly what Locke thinks we can do, or more precisely, his versionof the primarysecondary quality distinction is based on the assumption thatwe can transfer inferences from the macrophysical to the microphysical order.Locke surely thinks that we do not have microscopic eyes, and do not directlyperceive the microscopic particles of macroscopic objects along with theircausally efficacious primary qualities; but he never claims that we necessarily lackmicroscopic eyes. Moreover, what he does in his chapter on primary andsecondary qualities2 is precisely to infer to the existence and general characterof microscopic particles from the behavior of macroscopic bodies and

2. J. Locke, An Essay Concerning Humane Understanding, ed. P.H. Nidditch (Oxford: ClarendonPress, 1975), Book II, ch. viii.


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processesto realize, in general terms, what the fundamental constituents ofmatter and their qualities must be like, we simply have to think about what canpossibly change in a macroscopic body like a grain of corn if we chop it intofiner and finer pieces. Take a grain of Wheat, divide it into two parts, eachpart has still Solidity, Extension, Figure, and Mobility; divide it again, and it retainsstill the same qualities; and so divide it on, till the parts become insensible, theymust retain still each of them all of those qualities. For division . . . only makestwo, or more distinct separate Masses of matter, of that which was onebefore.3 Thus, for Locke, microphysical properties and microstructures arenot, at least in their general character, necessarily hidden from empiricalinquiry. Of course, modern science has moved on from Lockes conception ofmicrostructure, beginning with attractive and repulsive forces, but proceeds onthe basis of the assumption that there areintelligible analogies or isomorphismsbetween macrophysical and microphysical propertiesthink of the doublehelix. The practicing natural scientist does not assume that microstructure isnecessarily inaccessible to us, and I do not understand why this view should beattributed to contemporary scientific realist philosophers either.

A reason apart from Lockes supposed noumenal realism for the attributionof this view to contemporary scientific realism is Hannas identification ofnoumenal properties with intrinsic non-relational properties, and then theattribution to contemporary scientific realism of the view that the fundamentalproperties of matter are intrinsic nonrelational properties and therefore nou-menal. This seems to me doubly problematic: The identification of noumenalproperties as Kant understands them with intrinsic nonrelational properties, inwhich Hanna follows Rae Langton, is extremely problematic, because in spite

of Kants appeal to such a conception in one argument for transcendentalidealism added to the second edition of the Transcendental Aesthetic (B667; Hanna, p. 233), the two most fundamental roles of things-in-themselvesor the noumenal for Kant are to ground appearances in the theoretical sphereand to ground empirical character in the practical spherein other words,because the relation of ground and consequence is for Kant, so to speak, theparadigmatic relation, noumena are, if anything, essentially relational. And further, Ifail to understand why any contemporary scientific realist is supposed to believethat the most fundamental properties of matter are essentially nonrelational,and therefore noumenal on the supposed Kantian conception of the

noumenalwhether scientific realists are supposed to stop at the molecularlevel (H2O), the atomic level (golds atomic weight of 79), the subatomic level(protons, electrons), the sub-subatomic level (quarks), or some level even finerthan that (strings), it seems to me that they are always positing entities to whichit is essential that they be able to and do stand in various kinds of relations. So,I just do not get Hannas assumption that scientific realism takes the funda-mental properties of matter to be essentially nonrelational nor his ascription ofthe specifically Kantian notion of the noumenal and therefore necessarilyinaccessible to the fundamental properties of matter.

3. Ibid., 9.


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However, I also have problems in understanding Kants physical theory asa form of manifest realism. Kant himself claims in the Opus Postumum4 that theether is necessarily imperceptible and known to exist only by a prioriargumentsthe existence of such a material is not an object of experienceand derived from thence, i.e., empirically provable, but must rather be postu-lated as the object of a possible experience which can also take place condi-tionally indirectly a priori (21: 576)although that does not lead him to thinkof it as noumenalfor it is also essentially spatiotemporal, indeed, thehypostatized space itself in which everything moves (21: 224), and, therefore,in Kants view, necessarily phenomenal. Kant argues that there must be anether in order to explain how forces can be causally efficacious across distancesin which there is obviously no perceptible matter, and to explain in particularthe special case in which objects (constituted by distributions of attractive andrepulsive forces) are causally efficacious on our own sensory organs (themselves,of course, also constituted by such forces) across distances in which we do notperceive an intervening continuum of macroscopic visible or tangible objectsthe agitation of the senses of the subject through some matter is that whichalone makes possible outer perceptions and these moving forces must bethought of a priori as connected in one experience without gaps (21: 582). Inother words, our knowledge of the existence of the ether is strictly inferential,not perceptual. Kant did not argue for the existence of the ether in the Critiqueof Pure Reason, but there, too, allowed that science includes strictly inferentialknowledge to imperceptible objects, as when we infer from visible patterns ofiron filings to imperceptible magnetic fieldswe cognize the existence of amagnetic matter penetrating all bodies from the perception of attracted iron

filings, although an immediate perception of this matter is impossible for us given theconstitution of our organs (A 226/B 273, emphasis added). Of course, Hannarecognizes Kants use of inferential cognition in his actual scientific views, andattempts to draw a distinction between the bad inference to the imperceptiblein maximal and noumenal scientific realism and the good inference to theimperceptible in Kants manifest realism by distinguishing inference to themicrophysical (bad) from inference to the microscopic (good). Contemporary sci-entific realists are supposed to get themselves into a fix because they want toclaim that empirical knowledge of microphysical essences is possible, Butsince by their own . . . metaphysical theory the essences actually are notand never

can be cognized (sense perceived or empirically conceptualized), there is verygood reason to doubt on their account that natural scientists have . . . anyempirical knowledge whatsoever of the noumenal microphysical . . . world (p.168). On Kants manifest realism, however, such things as cloud chambers,Geiger counters, or cyclotrons, . . . telescopes or microscopes . . . all extend thelimits of the directly perceivable, thus, while

they detect previously undetected fine-grained details of the causal-dynamicnatural world . . . they do not go beyond the domain of the manifest. Thus

4. I. Kant, Opus postumum, ed. E. Frster, trans. E. Frster and M. Rosen (Cambridge: CambridgeUniversity Press, 1993). Passages in this and in further Kantian works other than the Critique ofPure Reason will be located by the volume and page number of the Akademie edition.


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entities accessible to human perception only via detection technology are stillessentially manifest, unhidden entities. They are natural phenomena. . . insharp contrast with microphysical noumenal entities, which as Verstandeswe-sen are consistently thinkable but never apparent.

For the Kantian manifest realist, Microscopes are not noumenoscopes (p. 239).Hannas claim is that contemporary scientific realism posits an unintelligibleinference from the empirical level of macrophysical objects to a noumenallevel of microphysical structure, while Kantian manifest realism supposesonly a harmless extension of natural, unaided human perception by devicesthat of course can themselves be explained in intelligible natural terms. Butthis stretches my sense of direct perception or realism beyond recognitionand goes in the face of Kants own explicit assertion that such a theoreticalentity as the ether is not known by empirical observation but is knownentirely a priori, while saddling other scientific realists with Kants own dis-tinction between phenomena and noumena in a way that I cannot imagineany would accept. To be sure, for Kant, genuine scientific inference is alwaysfrom something spatiotemporal (e.g., patterns of iron filings) to somethingelse spatiotemporal (e.g., magnetic fields) and, therefore, by reason of hisarguments for transcendental idealism, which have nothing at all to do withthe nature of such inference, necessarily phenomenal, while other realists,who surely do not affirm Kants own arguments for transcendental idealisms,are nevertheless supposed to conceive of the ultimate objects of science asnoumenal. I cannot buy either the account of contemporary scientific realismas noumenal or of Kants own version of inferential science as direct or

manifest realism.

Transcendental Idealism and Freedom of the Will

Because I have just mentioned transcendental idealism, I will have to say aword about that perennially vexed topic, although Hannas reconstruction ofKants defense of freedom of the will, which is what I am ultimately interestedin, does not, as far as I can see, actually make direct use of the first part of hisreconstruction of transcendental idealism. There are two stages to Hannas

treatment of transcendental idealism. The first stage is the rejection of what hecalls a strong interpretation of Kants transcendental idealism in favor of aweak one. Strong transcendental idealism is the doctrine that things inthemselves are mind-independent, non-sensory, unobservable Really Realentities while space and time are nothing but subjective forms of humanintuition, and [since] every objective appearance or empirical object is intrin-sically structured by space and time, then necessarily every empirical object isnothing but a subjective, humanly mind-dependent entity on which spa-tiotemporal form is imposed by the human mind, while weak transcendentalidealism . . . says that the existence of space and time requires only the necessary

possibility [emphasis added] of minds capable of adequately representing spaceand time by means of pure or formal intuition, and does notsay that space and


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time are nothing but necessary a priori subjective forms of human sensoryintuition (pp. 424). Here, I just want to mention that, on the one hand,although there can be no question that Kants arguments for strong transcen-dental idealism are flawed, there can also be no doubt that Kant held that view(Space is nothing other than merely the form of all appearances of outersense; A 26/B 42), while, on the other hand, I really do not understand theconcept of the necessary possibility of the human perception of space andtime which defines Hannas notion of weak transcendental idealism. Accord-ing to Hanna,

Weak transcendental idealism says that by their very nature actual space andactual time properly satisfy, or are correctly represented by, our pure orformal intuitions of them. Therefore the actual or possible existence ofmaterial things . . . in actual objectively real spacetime directly entails thenecessary possibility of rational human minds. . . . actual space and time canexist in a possible world (including of course the actual world) even if norational human minds actually exist in that world . . . provided that if therewererational human minds in that world, then they couldcorrectly representspace and time. (p. 169)

This seems to me, first, to fly in the face of Kants own assertion that Wecan . . . speak of space, extended beings, and so on, only from the humanstandpoint (A 26/B 42), in other words, that we cannot speak of the verynature of actual space and time independently of the constant form ofhuman receptivity (A 27/B 43). And I fail to see how the actual or possible

existence of material things in objectively real sense is supposed to entail thenecessary possibility of human minds. Hanna suggests that Kant accepts C.I.Lewiss modal logic S4 or else some conservative extension of S4, so thatwhatever is actual is thereby also possible and whatever is possible isthereby also necessarily possible (p. 304), but even if we were to concede this,it would not seem to explain why the actual existence of space should imply thenecessary possibility of human perceivers of space; it would rather imply thatthe actual existence of human perceiversof space implies their necessary possibility,which nobody would deny, because it really does not mean anything more thanthat the actual existence of somethingentails(i.e., necessitates) its possibility. In

other words, S4 does not imply that the existence of space entails the necessarypossibility of perceivers, but only that the existence of perceivers implies theirnecessary possibility. Moreover, it seems to me, any foundation of an interpre-tation of transcendental idealism in a supposedly purely logical principle ofinference, even if were valid, would make the truth of the doctrine analytic apriori rather than synthetic a priori, which, I take it, would be an unKantianand therefore uncharitable result. And at a more intuitive level, I just do notunderstand what is being claimed with this necessary possibilitythat in aspatiotemporal world of cosmic dust and rays, it could not have been impos-sible for perceivers sufficiently like us to be capable of perceiving and repre-

senting that world to have evolved? If this just means that there is no logicalcontradiction between the concept of such a world and the concept of human-


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like representers of it, then we just have a trivial logical possibility; but I am notclear what a stronger sense of, as Kant would call it, realnecessary possibilityis supposed to be.

But in any case, Hannas reconstruction of Kants solution to the age-oldconundrum of the freedom of the will, so far as I understand it, does not turnon the ascription to Kant of this notion of weak transcendental idealism but onsomething else, namely, Hannas ascription to him of a two-concept or two-property interpretation of transcendental idealism. Hanna rejects each ofwhat many have regarded as the two alternative models for the interpretationof transcendental idealism, namely, the Two-World or Two-Object Theory,the traditional metaphysical approach on which appearances and things inthemselves are ontologically distinct kinds of things, and the Two-Aspect orTwo-Standpoint Theory, the epistemological approach of Gerold Praussand Henry Allison according to which these terms just refer to two differentways in which we can represent what is ontologically a single kind of thing.The problem with the two-world approach, according to Hanna, is thatit assumes causal relations between kinds of things that cannot be causallyrelated, namely, spatiotemporal phenomena and nonspatiotemporalnoumena, and, as if that were not bad enough, also indulges in causal over-determination, on which one phenomenal event (an action) has two differentkinds of causes, one phenomenal and one noumenal. The problem with thetwo-aspect approach is that it neither explains why we perversely persist inascribing contradictory intrinsic propertiesfor example, being subject tophenomenal causation in accordance with laws of nature and being subject tonoumenal causation in accordance with laws of pure practical reasonto the

same objects, nor does it justify our beliefs in the objective correctness of thoseascriptions (pp. 4223). He further rejects approaches to the problem of thefreedom of the will in particular that would sally forth under the aegis of thesetwo approaches to the phenomenalnoumenal distinction in general, namely,the Timeless Agency Theory, an application of the Two-World Theory,and the Regulative Idea Theory, which would exploit the Two-AspectTheory to say that not only can we, but we should, think of phenomenalactions as if they could implement the moral law as well as seeking always toextend the scope of natural causal laws (pp. 4245). Instead, Hanna proposeswhat he calls the Two-Concept or Two-Property Theory, the core of which

is that while we should certainly assert the existence and causal efficacy ofmacroscopical empirical phenomenal things on the one hand, on the otherhand, we should remain consistently agnostic about and methodologically elimi-nate positive concepts of noumenal things-in-themselves while howeverattributing to phenomena negative noumenal properties, because bothnegative noumenal properties and phenomenal properties are not only instan-tiable but also actually instantiated, and directly known or felt by us to beinstantiated (pp. 4256). By negative noumenal properties, Hanna meansnon-sensible properties which are also spontaneously causally efficacious or nomologicallysufficient (for example, the property of trying to do the right thing even when it

is counter-prudential, or against the animals best interests or strongest desire,to do the right thing) (p. 427). The idea seems to be that doing the right


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thing or trying to do the right thing is not a sensible property like yellowor smooth, so it is not a phenomenal property, but it is not in any wayobviously incompatible with phenomenal properties such as yellow or smooth,so it can be attributed to a phenomenal object without contradiction of itsphenomenal properties.

So far, so good, and perhaps one might argue (although Hanna does not)that there is precedent for a conception of merely negative noumenal prop-erties in the concept of intelligible or noumenal possession that Kantdevelops in his analysis of property rights in the Doctrine of Right of theMetaphysics of Morals, where intelligible possession consists not in a sensiblerelation between a person and an object, a persons visible act of grasping orsitting upon an object, but in a nonperceptible relation among the wills ofpersons regarding an object, namely, their agreement as to who may use theobject without hindrance from others. Of course, that notion of intelligiblepossession by itself does not require any particular interpretation of what it isto have a will, certainly not a positively noumenal conception of free will asnot determined by any laws of nature, so we can accept Kants use of the ideaof intelligible possession in his theory of property without worrying aboutapproaches to transcendental idealism. Matters are not so simple in the presentcase, however, for Hanna does not content himself with the simple claim thatbeing able to act in accordance with moral law is just not the kind of thing thatis sensibly perceivable and therefore cannot contradict any of the properties ofan agent that are sensibly perceivable. Instead, he goes on to ascribe absolutespontaneous causal efficacy or nomological sufficiency to the negativelynoumenal self-legislating will (p. 427), an ability to bring about a natural causal

singularity in contrast to mechanistic causality, and further claims that theexistence of such a non-mechanistic and new or one-off causally-dynamic law of nature (p. 429) is epistemologically manifest, part of Kants supposed manifestrealism, in a persons non-conceptual, non-propositional consciousness of her ownlife, in the human conscious experience of embodiment (p. 435), and in herteleological inner sense intuitions of [her] own biological life, a real biologicalfact that she cannot scientifically know but can still truly feel (p. 436). On thisview, both mechanistic laws of nature and the laws of one-off causality aresupposed to be able to hold, at one and the same level of reality, the level ofspatiotemporal reality that is the only level of reality there is, and moreover, the

existence of the latter kind of causality is supposed to be manifest in our feelingof our own life. Hanna takes the existence of such a felt biological fact as apersons own spontaneity and its sufficiency for the demonstration of freedomof the will as the capacity to create causal singularities and, thus, to groundfreedom from the universal constraint of mechanistic laws of nature, to be thelesson of the Critique of the Power of Judgment.5

I cannot accept this interpretation of the third Critique. Although Kant didannounce in the introduction to this work that its aim is to demonstrate thatthe concept of freedom . . . should have an influence on the domain of the

5. I. Kant, Critique of the Power of Judgment, ed. P. Guyer, trans. P. Guyer and E. Matthews(Cambridge: Cambridge University Press, 2000).


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concept of nature, he makes it clear, as Hannas own quotation of this passagereveals, that it is the concept of nature, as the supersensible, that is, to havethis influence.6 That is, he does not claim that freedom is the concept of anonsensible property that can nevertheless be realized without problem insideofspace and time, as Hanna puts it (p. 427), and is thus entirely compatiblewith the other, deterministically causal, sensible properties of objects in nature,as Hannas two-concept interpretation of transcendental idealism wouldhave it; rather, Kant argues that the phenomenon of organic life itself can onlybe understood by means of a firm division between sensible and supersensibleor positively noumenal properties, and that this fact about the comprehensionof organic life gives us further evidence for the correctness and necessity of thetwo-level or two-world solution to the problem of the freedom of the will. I takethis to be the lesson of Kants antinomy of the power of judgment in theCritique of the Teleological Power of Judgment. Kants resolution of thisantinomy does not support Hannas two-concept approach.

The antinomy is supposed to obtain between the thesis All generation ofmaterial things and their forms must be judged as possible in accordance withmerely mechanical laws and the antithesis Some products of material naturecannot be judged as possible according to merely mechanical laws.7 Kantstarts his discussion of this antinomy by saying that there would really be acontradiction between thesis and antithesis if both were taken as objectiveprinciples for the determining power of judgment, that is, constitutive prin-ciples about objects of experience, but that if they are both taken as maximsof a reflecting power of judgment, that is, as regulative principles about whatsorts of explanations we should seek, then there is no contradiction between

them. However, Kant begins his Preparation for the resolution of the aboveantinomy only after having stated this point, thus implying that the appeal toregulative principles is at best provisional and that the possibility of using twosuch different regulative principles itself needs to be supported by furtherargumentation. His further argument then comes in the form of a review ofvarious systems concerning the purposiveness of nature,8 in which he arguesthat idealism about purposiveness in nature, that is, insistence uponmechanical causation only, cannot be demonstrated, but that realism aboutpurposiveness in nature, that is, assertion of an alternative to mechanicalcausation and thus allowance for causal singularity, also cannot be main-

tained in the form of a one-level doctrine about nature, or hylozoism, theview that (at least some) matter is also alive, but can only be maintained in theform of or in a form analogous to theism, that is, by means of the hypothesisthat free and purposiveness agency is exercised at the supersensible level, wherea free cause can be hypothesized outside of, but as the ground, of nature. This isbecause the possibility of a living matter . . . contains a contradiction, becauselifelessness, inertia, constitutes its essential characteristic9a proposition ofwhich Kant was much enamored, and repeated at least 14 times in his lectures

6. Hanna, p. 343; Kant, CPJ, 5: 176.7. Kant, CPJ, 70, 5: 387.8. Ibid., 72, 5: 389.9. Ibid., 73, 5: 394.


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on metaphysics (at least because that is just the number of occurrences listedin the index of Ameriks and Naragons selection). In other words, in Kantsview, in the Critique of the Power of Judgmentjust as much as in the other critiques,there is a contradiction between mechanical causation and the spontaneouscausation characteristic of living beings, and room can be made for the latteronly by ontologically distinguishing a supersensible level of existence from thephenomenal level. Kants position is that our experience of organic life doesforce an idea of spontaneous purposiveness on us, that teleology does have afoundation in phenomenology, as Hanna would put it, but that this sort of spontaneity can only be comprehended, only be conceived as even possible, by appeal to thedistinction between the sensible and the supersensible: for us there remains no otherway of judging the generation of its products as natural ends than through asupreme understanding as the cause of the world.10 In other words, Kanthardly assumes that our experience of life, whether in our own case (as Hannasupposes) or that of any organism (which is what Kant is actually discussingand the very fact that using the phenomenon of life to support the existence offreedom of the will would make all living beings free, or even, all living beingscapable of having a feeling of their life, ought itself to make one suspicious ofthis argumentative strategy), suffices to confirm the existence of negatively nou-menal spontaneity as part of manifest realism; he rather supposes that ourexperience of organic processes merely poses a problem for us that can only be solvedby transcendental idealism as he understands it, namely, as an ontological distinctionbetween the sensible and supersensible levels of existence, where the latter canbe the ground, though, of course, not the temporal cause of the former. Thepoint of the third Critique is not to revise Kants obvious use of such an

interpretation of transcendental idealism in the second Critique, where freedomof the will can be understood and salvaged only if the whole sequence of[ones] existence as a sensible being is regarded in the consciousness of hisintelligible existence as nothing but the consequence and never as the deter-mining ground of his causality as a noumenon,11 but rather to show that thephenomenon of organic life in general, something more general than humanlife, also requires transcendental idealism so understood and to that extentconfirms the use of transcendental idealism in the previous Critique. By addingthat the invocation of a supersensible ground of phenomenal reality in thesolution to the problem of organic life is only a ground for the reflecting, not

for the determining power of judgment, and absolutely cannot justify anyobjective assertion,12 Kant may also mean to remind us that the appeal totranscendental idealism on practical grounds in order to solve the problem offree will should not have been taken to be the objective assertion of a theoreti-cal proposition on theoretically sufficient grounds, but that restriction on theepistemic status of the assertion of transcendental idealism does not change thecontent of what is asserted, namely, transcendental idealism on the two-worldinterpretation.

10. Ibid., 73, 5: 395.11. I. Kant, Critique of Practical Reason in Practical Philosophy, ed. and trans. M.J. Gregor (Cambridge:

Cambridge University Press, 1996), 5: 978.12. Kant, CPJ, 74, 5: 395.


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By all of this, I do not mean, of course, to suggest an endorsement oftwo-world transcendental idealism; my own position that Kant intended thetwo-world interpretation of transcendental idealism but asserted it on inad-equate grounds has long been clear. What I do mean to suggest is that the thirdCritique does not give us better evidence for an alternative interpretation oftranscendental idealism than the previous two do, and that the third Critique

therefore cannot be appealed to in support of Hannas two-concept inter-pretation and thus in support of his strategy for rescuing freedom of the will.My own position on this matter thus remains unchanged, namely, that when itcomes to the traditional assumption that freedom of the will is a condition ofmoral responsibility, we do better to follow the lead of Kants precriticalwritings, namely, his argument in his first philosophical work, the Nova Deluci-datio of 1755, that a libertarian conception of the freedom of the will wouldreduce responsible action to random behavior, and the position of his discus-sion of the imputation of responsibility in his lectures on ethics, namely, thatresponsiveness to reasons is a natural phenomenon, naturally subject to modi-fication by entirely natural factors such as stupefaction by alcohol, immaturity,injury, and so on, and compatible with our practices of blame and punishmentas long as we understand the latter as a matter of deterrence rather thanretribution. To be sure, Kant may have rejected such an approach to freedomof the will in his mature period, as he signals in his review of J.H. SchulzsSittenlehrein 1783, shortly before the publication of his own Groundwork, in whichhe rejects Schulzs determinism precisely because it cannot support a retribu-tive theory of punishment and instead insists that the ought or imperativethat distinguishes the practical law from the law of nature also puts us in idea

altogether beyond the chain of nature (8: 1213). But to prefer a view thatKant held but later rejected seems to me a more charitable use of his workthan to attribute to him a theory of free will that he clearly never could haveheld at all.


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Kant, Science, And Human Nature - Guyer