External-world scepticism is the thesis that we cannot know that the external world exists or that it is as we perceive it to be. The canonical summary of Reid’s reply to external-world scepticism is that found in chapter 6 of the Inquiry:
However, I believe Reid’s argument is much more subtle and sophisticated than it may first appear. Reid is not simply saying that we cannot offer a rational justification for our belief in the external world. He is making the further point that such a belief is not the kind of thing one should offer a rational justification for. In brief, our belief that our senses provide us with reliable knowledge of the external world is a first principle—that is, a belief that arises out of how we have been constituted by Nature:
Reid can therefore be described as offering a poly-foundationalism. Cartesian foundationalism (or what may just as easily be called traditional foundationalism) is the idea that there is some indubitable first principle upon which all our other beliefs can be built—it is where the epistemic buck stops. However, Reid represents a poly-foundationalism in that he offers not one, but several first principles. But the most distinctive feature of Reid’s foundationalism is that he sees reason as merely one among the many sources of knowledge. Within the Cartesian rationalist system, only beliefs that bore reason’s stamp of approval were deemed acceptable. However, the Reidian system forsakes the monopoly of reason found in Cartesianism and in its place establishes an epistemological oligarchy comprised of various first principles, each equally authoritative in their own right.
The mistake the sceptic makes, then, is seeking for rational justifications in places where she has no business looking. Our belief that our sensory faculty is, all things being equal, trustworthy is a first principle that stands on its own two feet and does not need to be vindicated by reason. This is not to deny that we may sometimes be mistaken about our perceptual beliefs. However, the fallibility of the sensory faculties is shared by all other faculties, including reason:
Relevant Reading:
De Rose, Keith. (1989). ‘Reid's Anti-Sensationalism and His Realism’, Philosophical Review. 98, 313-348.
Greco, J. (2004). ‘Reid’s Reply to the Skeptic’, The Cambridge Companion to Thomas Reid. T. Cuneo and R. Van Wouldenberg (ed.), Cambridge: Cambridge University Press.
Reid, T. (1969). Essays on the Active Powers of the Human Mind, (ed.) Baruch A. Brody (ed.), Cambridge, MA: MIT Press.
Reid, T. (1990). Practical Ethics, (ed.) Knud Haakonssen, Princeton: Princeton University Press.
Reid, T. (1997). An Inquiry into the Human Mind on the Principles of Common Sense, (ed.) Derek R. Brookes, University Park: Pennsylvania State University Press. (Inquiry)
Reid, T. (2002). Essays on the Intellectual Powers of Man, (ed.) Derek Brookes, University Park: Pennsylvania State University Press. (Essays) Yaffe, G. (2004). Manifest Activity: Thomas Reid’s Theory of Action. Oxford: Clarendon Press.
The sceptic asks me, Why do you believe in the existence of the external object which you perceive? This belief, sir, is none of my manufacture; it came from the mint of Nature; it bears her image and superscription; and, if it is not right, the fault is not mine: I even took it upon trust, and without suspicion. Reason, says the sceptic, is the only judge of truth, and you ought to throw off every opinion and every belief that is not grounded on reason. Why, sir, should I believe the faculty of reason more than that of perception?—they came both out of the same shop, and were made by the same artist; and if he puts one piece of false ware into my hands, what should hinder him from putting another?[Inquiry, VI, 20: 168-9]Reid notes that whether we believe that the objects we perceive exist independently of our perceptions is not up to us. To wit, when it comes to the external world, to believe or not to believe is never the question. This belief is something that arises from how we have been constituted by Nature and is therefore something over which we have little or no control. At first glance, Reid seems to be suggesting that we can’t be held responsible for the fact that we believe in the external world since we simply have no choice in the matter. This interpretation is further supported by Reid’s mot: “if it [belief in external objects] is not right, the fault is not mine”. However, to say we can’t help but believe in an external world would be to offer exculpations when what the sceptic demands are justifications. That is, the fact that we cannot help but believe in the external world does not imply that we should believe in the external world.
However, I believe Reid’s argument is much more subtle and sophisticated than it may first appear. Reid is not simply saying that we cannot offer a rational justification for our belief in the external world. He is making the further point that such a belief is not the kind of thing one should offer a rational justification for. In brief, our belief that our senses provide us with reliable knowledge of the external world is a first principle—that is, a belief that arises out of how we have been constituted by Nature:
All reasoning must be from first principles; and for first principles no other reason can be given but this, that, by the constitution of our nature, we are under a necessity of assenting to them. Such principles are parts of our constitution, no less that the power of thinking: reason can neither make nor destroy them; nor can it do any thing without them. [Inquiry, VI, 7: 71]Among the first principles is included the belief that our faculty of sense is a reliable source of knowledge. Our trust in this faculty is independent of reason, which is itself merely one among the several cognitive faculties we take to be reliable because of how we have been designed by Nature.
Reid can therefore be described as offering a poly-foundationalism. Cartesian foundationalism (or what may just as easily be called traditional foundationalism) is the idea that there is some indubitable first principle upon which all our other beliefs can be built—it is where the epistemic buck stops. However, Reid represents a poly-foundationalism in that he offers not one, but several first principles. But the most distinctive feature of Reid’s foundationalism is that he sees reason as merely one among the many sources of knowledge. Within the Cartesian rationalist system, only beliefs that bore reason’s stamp of approval were deemed acceptable. However, the Reidian system forsakes the monopoly of reason found in Cartesianism and in its place establishes an epistemological oligarchy comprised of various first principles, each equally authoritative in their own right.
The mistake the sceptic makes, then, is seeking for rational justifications in places where she has no business looking. Our belief that our sensory faculty is, all things being equal, trustworthy is a first principle that stands on its own two feet and does not need to be vindicated by reason. This is not to deny that we may sometimes be mistaken about our perceptual beliefs. However, the fallibility of the sensory faculties is shared by all other faculties, including reason:
They are all limited and imperfect…We are liable to error and wrong judgment in the use of them all; but as little in the informations of sense as in the deductions of reasoning. And the errors we fall into with regard to objects of sense are not corrected by reason, but by more accurate attention to the informations we may receive by our senses themselves.[Essays, II. 22: 252]Reid maintains that if we reject the faculty of sense we must reject the faculty of reason as well since they both share the same foibles. In sum, since no cognitive faculty is in anyway privileged above the others, they all stand or fall together:
Thus the faculties of consciousness, of memory, of external sense, and of reason, are all equally gifts of Nature. No good reason can be assigned for receiving the testimony of one of them, which is not of equal force with regard to the others.[Essays, VI. 4: 463]
Relevant Reading:
De Rose, Keith. (1989). ‘Reid's Anti-Sensationalism and His Realism’, Philosophical Review. 98, 313-348.
Greco, J. (2004). ‘Reid’s Reply to the Skeptic’, The Cambridge Companion to Thomas Reid. T. Cuneo and R. Van Wouldenberg (ed.), Cambridge: Cambridge University Press.
Reid, T. (1969). Essays on the Active Powers of the Human Mind, (ed.) Baruch A. Brody (ed.), Cambridge, MA: MIT Press.
Reid, T. (1990). Practical Ethics, (ed.) Knud Haakonssen, Princeton: Princeton University Press.
Reid, T. (1997). An Inquiry into the Human Mind on the Principles of Common Sense, (ed.) Derek R. Brookes, University Park: Pennsylvania State University Press. (Inquiry)
Reid, T. (2002). Essays on the Intellectual Powers of Man, (ed.) Derek Brookes, University Park: Pennsylvania State University Press. (Essays) Yaffe, G. (2004). Manifest Activity: Thomas Reid’s Theory of Action. Oxford: Clarendon Press.
6 comments:
I've not yet read any Reid, but regarding that argument, we do feel more responsible for the quality of our reasoning, than for the quality of our perceptions. And whilst we can imagine the BIV scenarios quite easily, it is harder to believe that PEM might be false. Prima facie, the two are not of the same kind, and so I wonder if his argument is a bit circular, in that they would be of the same kind if we had evolved, as empirical science indicates (?)
I do not believe that Reid's argument works either, since I don't think that the faculty of reason and the faculty of sense are on a par. However, this claim is in need of some defence. Moreover, while your reservations are suggestive, I am not sure they’re adequate for refuting Reid. Firstly, I don’t think that the unreliability of the rational faculties is any less conceivable than that of the sensory faculties. For example, consider certain types of mental illness and dementia. In fact, I have had moments when I was in bed with the flu when my rational faculties proved to be completely unreliable (though I was only able to appreciate this fact in retrospect, when I was no longer ill). Admittedly, cases in which a subject’s sensory faculties may be unreliable may prove to be more prevalent than ones in which our sensory faculties are unreliable. But frequency and conceivability are two different things; and only the latter seems salient vis-à-vis the efficacy of Reid’s argument.
Yes, and we may be fooled by a demon into believing falsely what 2 + 2 is, or that our hands are real, but still it does seem inconceivable to me, that I could now be irrational (although I might well seem irrational to others, or to myself later), whereas it seems conceivable that this might be a dream (although obviously not what I now mean by 'dream')...
Enigman,
You seem to be conflating two separate issues here: (1) the claim that both faculties give rise to beliefs that are equally certain, and (2) the claim that both faculties are capable of malfunctioning. Reid only endorses the latter, not the former. Let me explain. Reid may concede that the truths that reason deliver (when functioning properly) engender a greater degree of certainty (in the subject) than the truths that perception deliver (when functioning properly). Thus, I may attach greater certainty to the claim that 1+1=2 than I do to the empirical claim that there is a computer in front of me (even assuming that both claims are true and that both my rational and sensory faculties are functioning properly). This seems perfectly consistent with the claim that my rational faculties may malfunction (i.e., due to brain damage, disease or degeneration) in a manner on par with the malfunction of the sensory faculties.
For example, once when sick with the flu, I believed that my roommate (who I asked to pick up some meds for me) was both home and not home at the same time, without even realising that these two propositions were in conflict (please don’t tell me I’m the only one this kind of thing has ever happened to!). In brief, Reid is not asking us to imagine that something we know to be logically true, ~(p&~p), is false. Rather, he is asking us to imagine a case, where due to some type of malfunction, one believes something of the form p&~p (while fully recognising that it takes this form). Once one concedes that this is possible (as you seem to do with your reference to the demon), then Reid seems to have all he needs to get his argument going.
Did you believe p (= your roommate was home) sometimes and ~p at other times, and maybe a&b (where a is a consequence of p and b a consequence of ~p), or did you actually believe that your roommate was both home and not home?
The actual experience was quite incoherent and blurry and so what follows is more or less an attempted reconstruction after the fact. What I remember is that there was a period of time (let’s say t1 to t9) and at different points during that time (let’s say t2, t5, t8) I believed that my roommate was home (and I would imagine him moving about downstairs etc). However, there were also various points during the same time period (let’s say t3, t4, t6) when I believed that he was at the drug store. However (and this is the crucial bit), in my delirious state I took both sets of beliefs to be perfectly consistent (keeping in mind that I did not believe that my roommate was coming and going at these different times). Since I did not believe that my roommate was moving in and out of the house between t1 and t9, I take this to represent a case of my entertaining contradictory beliefs.
However, I don’t want the force of my argument to rest on my anecdotal retelling of what was admittedly a confused experience. I was simply trying to suggest that this kind of scenario is not as far-fetched as it may sound. But whether or not my own case represents a bona fide case of a subject’s rational faculty malfunctioning, such cases are indeed conceivable. Presumably, the words ‘mad’ and ‘crazy’ are sometimes used to pick out just such cases, and are not limited to cases of perceptual illusion or hallucination.
But all of this is really beside the present point. Since you already concede that a demon could deceive someone into believing 2+2=5 then we’re already in agreement on the conceivability question. This shared assumption, combined with my aforementioned distinction between (1) the claim that the beliefs each faculty gives rise to are equally certain (to which Reid is not committed) and (2) the claim that both faculties are capable of malfunctioning (to which Reid is committed), is enough to get Reid’s argument up and running.
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