Moral Certainty of Faculty of Reason in Descartes’ Discourse

In this paper, I have made an attempt to understand the concept of moral certainty in Descartes’ philosophy. This concept has not received much attention in the Cartesian scholarship. I argue that Descartes entertains a certainty, called moral certainty, which is a lesser certainty than metaphysical certainty, which we see in his text, Meditations. Only a few Cartesian scholars have talked about this concept in rel ation to other areas in Descartes’ philosophy. In this paper, I draw a relationship between the concept of moral certainty and the faculty of reason in the context of Descartes’ text, Discourse. I argue that Descartes entertains the testimonies of learned men when it comes to practical or moral matters, arguing that their testimonies guarantee moral certainty. I argue that Descartes claims, in the Discourse, that human beings are endowed with the faculty of reason on the basis of moral certainty.


Introduction
Rene Descartes is a rationalist who sought metaphysically certain firm foundations for his sciences, rejecting everything he considered doubtful using the faculty of reason. This is the common narrative of Descartes' philosophy. I argue in this paper that Descartes does not claim metaphysical certainty for accepting the existence of the faculty of reason in his text, Discourse. It is in this text that he designed a method for correctly using the faculty of reason in his inquiries. I argue that in the Discourse, he accepts that there is a faculty of reason equally distributed in all human beings on the basis of moral certainty. In the first section of the paper, I elaborate on Descartes' concept of moral certainty, a certainty less than metaphysical certainty. I argue that testimonies of learned and honest men can guarantee moral certainty. In the second section, I further discuss how moral certainty is ensured in a matter using Descartes' examples. In the third section, I argue that it is due to the nature of the text Discourse, Descartes begins with the claim that reason is a form that distinguishes humans from non-human animals. Here, I also draw a relationship between Descartes' faculty of reason and his method in the Discourse to show the importance the faculty of reason occupies in the method. In the fourth section, I argue how Descartes accepts that we all are endowed with the faculty of reason on the basis of moral certainty in the Discourse.

Moral Certainty and Practical Lives
Moral certainty first appeared in the writings of Jean Gerson, a fifteenth-century French theologian.* For him, in our practical lives, there are times when we must act without having "infallible knowledge" on whether our actions are sinful or not (Gerson, 1883, p. 40). For Gerson, even if we do not have full certainty that our actions are correct, we can be sure of the correctness of the course we take to an extent (ibid.). In such an instance, he says, we can act based on moral certainty that our actions are not sinful. Regarding the nature of moral certainty, he writes: We may obtain a moral certainty, by the advice of prudent men, by good counsel of devout persons, by the Scriptures, by the judgement of our own reason, by our confessor. Such a tempted person ought to conform his opinion to the judgment of these before mentioned. (Gerson, 1883, p. 40) According to Gerson, to ascertain moral certainty that an action is not sinful, we must rely on testimonies of learned men, the scriptures, and our own reason. Descartes also talks about a similar concern when it comes to our actions in our practical lives. He, in the Discourse, writes: For a long time I had observed, as noted above, that in practical life it is sometimes necessary to act upon opinions which one knows to be quite uncertain just as if they were indubitable. But since I now wished to devote myself solely to the search for truth, I thought it necessary to do the very opposite and reject as if absolutely false everything in which I could imagine the least doubt, in order to see if I was left believing anything that was entirely indubitable. (CSM I, p. 126-127; AT VI, p. 31).
In the above remark, Descartes distinguishes between how we accept things in our practical lives and how we go about inquiring in metaphysics. Descartes states that we do not seek metaphysical certainty or indubitable principles in our practical lives; rather, sometimes, we even act on uncertain opinions. Nevertheless, our action must be governed by some sort of certainty, even if that certainty is not a metaphysical one. In order to clarify more on this remark, we need to look into Descartes' comments on moral certainty. Descartes mentions moral certainty in the Discourse in passing, and he dedicates two sections on moral certainty in his Principles. It should also be noted here that Descartes wrote very little on moral certainty. It could be that the use of this concept was common in his time. He did not find it necessary to elaborate on it because his contemporaries were very much aware of the usage of this term. † In the Discourse, Descartes writes: [E]verything else of which they may think themselves more sure -such as their having a body, there being stars and an earth, and the like -is less certain. For although we have a moral certainty about these things, so that it seems we cannot doubt them without being extravagant, nevertheless when it is a question of metaphysical certainty, we cannot reasonably deny that there are adequate grounds for not Tattva-Journal of Philosophy   ISSN 0975-332X   4 being entirely sure about them. We need only observe that in sleep, we may imagine in the same way that we have a different body and see different stars and a different earth, without there being any of these things. For how do we know that the thoughts which come to us in dreams are any more false than others, seeing that they are often no less lively and distinct? (CSM I,p. 130;AT VI,p. 37) In the above passage, Descartes makes a distinction between moral and metaphysical certainty. For Descartes, things that are metaphysically certain cannot be subjected to doubt using extravagant scenarios for doubting -dream argument and malicious demon argument. However, things with moral certainty can be doubted when introducing extravagant doubt. For him, things that we encounter in our everyday lives, such as our bodies, stars, and the earth, can be considered as having moral certainty, but this certainty that they have is not metaphysical certainty. It is a certainty less than metaphysical certainty. Cartesian scholars have debated on whether the distinction between moral certainty and metaphysical certainty is a matter of degree or a matter of kind. ‡ However, what is clear from the above passage is that Descartes entertains a certainty different from metaphysical certainty. These objects for which he claims moral certainty are like the objects in our dreams, lively and distinct and are doubtful if we entertain the argument that we might be dreaming. At this stage, it seems that moral certainty is that certainty that governs our actions in our practical lives. For Descartes, "in practical life it is sometimes necessary to act upon opinions which one knows to be quite uncertain just as if they were indubitable" (CSM I, p. 126-127; AT VI, p. 31). Moral certainty enables us to act according to things we think exist around us without worrying that these everyday things around us are doubtful at the metaphysical level. This understanding that moral certainty is required for us to operate in our practical lives is further reinforced in Descartes' Principles, where he states that moral certainty is sufficient to regulate our behaviour, or which measures up to the certainty we have on matters relating to the conduct of life which we never normally doubt, though we know that it is possible, absolutely speaking, that they may be false. (CSM I, p. 289 Footnote 2; AT 9B, p. 323) But, there is more to moral certainty than the claim that it regulates our behaviour in our day today lives. Moral certainty not only regulates our behaviour, but it also concerns his scientific inquiries. In the next section, I discuss this matter and also elaborate more on Descartes' concept of moral certainty using his examples in the Principles.

Moral Certainty, Sciences and Descartes' Examples
In the previous section, I have discussed how the concept of moral certainty was first figured in the domain of theology. But in the seventeenth century, the concept of moral certainty made a move from theology to natural sciences (Wootton, 2015, p. 362). For instance, Robert Boyle argued that the concept of moral certainty must be used in natural sciences, and one should seek moral certainty in scientific experiments (Hankins and Silverman, 1991, p. 230). Descartes also does not limit this concept in discussing how to conduct our lives but also in domains such as physics. As we have seen above, Descartes talks about moral certainty in relation to the dream argument. The dream argument does not apply to the objects around us only but also to the objects of natural philosophy as the objects in natural philosophy are the same objects that are around us. In the "First Meditation," the disciplines such as "physics, astronomy, medicine, and all other disciplines which depend on the study of composite things" become doubtful once the dream argument is introduced and the objects of these disciplines are the objects of our day to day lives such as the stars, our bodies and so on (CSM I, p. 14; AT VII, p. 20). Therefore, we can say that Descartes extends the concept of moral certainty to natural science. § To elaborate more on this, we can discuss Descartes' comment on moral certainty at the end of his Principles. Descartes claims that "his explanations appear to be at least morally certain" (CSM I, p. 289; AT VIIIA, p. 327). The explanations that he is talking about are his findings in natural philosophy, in disciplines such as physics, astronomy and medicine. He devotes an entire section in the Principles to explain how these explanations in the natural sciences can have moral certainty. He writes: Suppose for example that someone wants to read a letter written in Latin but encoded so that the letters of the alphabet do not have their proper value, and he guesses that the letter B should be read whenever A appears, and C when B appears, i.e. that each letter should be replaced by the one immediately following it. If by using this key, he can make up Latin words from the letters, he will be in no doubt that the true meaning of the letter is contained in these words. It is true that his knowledge is based merely on a conjecture, and it is conceivable that the writer did not replace the original letters with their immediate successors in the alphabet, but with others, thus encoding quite a different message; but this possibility is so unlikely that it does not seem credible. (CSM I, p. 290; AT VIIIA, p. 328) Descartes' example of the encoded letter tells us even though we are unsure whether the writer has used the same keys that we are using to read his letter, it seems credible to us given that we can make sense of the letter. If the message we get from the letter, after decoding it, makes sense to us, then it is unlikely that we are wrong in using the keys. However, can we be entirely sure that what we have done to understand the letter is correct? What we know of the letter depends on our conjecture that we should replace one letter with another using the key we have. Nevertheless, we can rely on it even though we might be completely wrong. This is how Descartes understands his concept of moral certainty. He further extends his example to his explanations of the material things. He writes: Now if people look at all the many properties relating to magnetism, fire and the fabric of the entire world, which I have deduced in this book from just a few principles, then, even if they think that my assumption of these principles was arbitrary and groundless, they will still perhaps acknowledge that it would hardly have been possible for so many items to fit into a coherent pattern if the original principles had been false. (CSM I, p. 290; AT VIIIA, p. 328) His understanding of magnetism, fire and the fabric of the entire world, or his explanations in physics, make a coherent whole and is similar to the message that we gained from the encoded letter. He has derived these explanations in natural sciences from very few underlying principles, but he is at the same time uncertain about the principles, just as we were unsure about the code used by the writer of the letter. Earlier, we held that it was quite unlikely for the keys that we used to decipher to be false, given that the message made sense to us. In the same manner, we can say that given that his findings in physics form a coherent pattern, it is quite unlikely that the principles from which they have been derived are false. Hence, these findings have moral certainty.
Descartes gives another example of moral certainty in the French version of the Principles. He says that of a person who has never been to Rome but has no doubt that there is a place called Rome. Descartes writes: "Those who have never been in Rome have no doubt that it is a town in Italy, even though it could be the case that everyone who has told them this has been deceiving them" (CSM I, p. 290; AT VIIIA, p. 328). It could very well be the case that everyone who has told the person that there is a place called Rome in Italy has lied to him, but such a thing is quite unlikely. Even if there is room for doubt, given that everyone might have lied to him, he still has moral certainty that there is a place called Rome. Descartes' contemporary Roderigo Arriaga, in his 1632 book Cursus Philosophicus gives a similar example when he talks about moral certainty. He writes: Moral certainty is what we have when our reasons are indeed fallible physically, though infallible morally speaking, i.e., almost infallible, as, for example, the certainty I have about the existence of Naples, from what has been said by so many knowledgeable and honest men who assert it and make me certain that Naples exists, although, because it is not physically impossible that they should all lie, I am not physically certain of this existence. (Arriaga, 1632, Logica, disp. 16, sec. 4: 226 col. a) [Ariew's (2011, p. 16) translation] Arriaga argues that it is physically possible that all those people who have told him that there is a place called Naples have lied to him. We are not physically certain that there is a place called Naples, given that everyone might have lied to him. But it is quite unlikely that everyone has done so. Therefore, 'Naples exists' is morally certain even though it is not physically certain. We have seen earlier in Gerson's concept of moral certainty that the testimonies of reliable people can provide us moral certainty that our actions are not sinful. Similarly, for moral certainty that there is a place called Rome or Naples, Descartes and Arriaga rely on the testimonies of learned and honest men.

Reason and Method in the Discourse
In the Meditations, Descartes (CSM II, p. 17; AT VII, p. 25) writes: What then did I formerly think I was? A man. But what is a man? Shall I say 'a rational animal'? No; for then I should have to inquire what an animal is, what rationality is, and in this way one question would lead me down the slope to other harder ones, and I do not now have the time to waste on subtleties of this kind.
In this passage from the "Second Meditation," Descartes maintains that the answers on the nature of human beings, such as animality and rationality, which we have inherited from ancient and medieval philosophy, cannot be justified at this stage without getting bogged down in difficulties. He makes a similar remark in his dialogue, The Search for Truth. Exodus, an interlocutor in the dialogue, tells the other interlocutor Polyander that the answer that I am a man might seem like a simple answer but it is not at all simple. Exodus says, If, in order to explain what an animal is, he were to reply that it is a "living and sentient being," that a living being is an "animate body" and that a body is a "corporeal substance," you see immediately that the questions, like the branches of a family tree, would rapidly increase and multiply. Quite clearly, the result of all these admirable questions would be pure verbiage, which would elucidate nothing and leave us in our original state of ignorance. (CSM II, p. 410; AT X, p. 515-516) These difficulties are there not because Descartes cannot find answers to these questions in the works of philosophers preceding or contemporary to him. Rather, the answers to these questions can be subjected to doubt. The difficulties that he refers to are extravagant suppositions of the sceptics, the dream argument and the malicious deceiver argument. In the Meditations, he clearly avoids answering the question in these terms; instead, he looks for an answer which extravagant suppositions of the sceptics cannot subject to doubt. In the "First Meditation," the dream argument serves to subject the things that we take for granted in our practical lives to doubt. It subjects, according to Descartes, the objects of physics to doubt. On the other hand, the malicious deceiver argument subjects the objects of arithmetic to doubt. Given that we cannot deny that there could be a malicious deceiver that makes us believe that mathematical truths are true while they are not, we cannot, before establishing the existence of God, believe that one plus one equals two. These extravagant suppositions make it difficult to maintain the claim that I am a man or I am a rational being at the beginning of the Meditations. They render these claims doubtful.
When it comes to the Discourse, Descartes does the exact opposite and begins with the claim that human beings are rational. He claims that the faculty of reason which is the power to distinguish truth from falsity, is a form. This form distinguishes humans from non-human animals (CSM, p. 111; AT VI, p. 2). It is also a power that is equally distributed in all human beings, unlike other faculties such as memory or imagination. Two persons can differ in degrees when it comes to having memory or imagination, one can have a better imagination than the other, but they cannot differ when it comes to having a reason. They are both equally endowed with the faculty of reason (ibid.). The reason behind beginning the Discourse with the exposition of the faculty of the reason could be the nature of the text, Discourse itself. The Discourse allows Descartes to begin with this claim that human beings are rational animals because Descartes is not concerned with the metaphysical certainty of his findings. The text does not require Descartes to be as rigorous as he is regarding Meditations. The elaborate title of the text, Discourse is Discourse on the Method of Rightly Conducting One's Reason and Seeking the Truth in the Sciences and the Optics, the Meteorology and the Geometry, which are essays in this method. The part, Discourse on the Method of Rightly Conducting One's Reason and Seeking the Truth in the Science, is the preface of the whole text. Further, the text consists of three essays, the "Optics," the "Meteorology," and the "Geometry," which, Descartes claims, are the results of the method (CSM K, p. 51, AT I, p. 339). Descartes here talks about the findings of his method, which he had to suppress after the persecution of Galileo (CSM I, p. 79). It consists of a summary of his suppressed writings, The World and Treatise on Man. And it also consists of a summary of the arguments which would appear in his Meditations (ibid.). This text is different from Descartes' other texts, such as Meditations or Principles. It was first published in French for a wider audience and not in Latin, which was the language of the learned men of Descartes' time. It is an autobiographical account of how he developed the method. His findings in many areas ranging from metaphysical issues to the human circulatory system are given in the text (Mathien and Wright, 2006, p. 100). He gives four rules of the method, which increase the light of reason. Descartes declares that the method is a path of "rightly conducting one's reason", and it also stops us from fruitlessly expending our mental efforts and wasting them (CSM I, p. 111; AT VI, p. 1). Furthermore, a description of the faculty of reason is required at the very beginning of the Discourse. Without the faculty of the reason he cannot talk about the method as the rules of the method are designed keeping in mind the faculty of reason.
Let us now briefly discuss some of the rules of the method Descartes talks about in the Discourse and the place the faculty of reason occupies in these rules.** In the Discourse, Descartes mentions as the first rule of the method: [N]ever to accept anything as true if I did not have evident knowledge of its truth: that is, carefully avoid precipitate conclusions and preconceptions, and to include nothing more in my judgements that presented itself to my mind so clearly and so distinctly that I had no occasion to doubt it. (CSM I, p. 120; AT VI, p. 18) The first rule ensures that we use the faculty of reason which is the power to distinguish truth from falsity. It states we must only accept things that are true and reject doubtful things as false. For Descartes, those things which we conceive clearly and very distinctly are all true, and truths cannot be doubted. Given the first rule of the method begins with the mental operation of intuition, which is an operation of the faculty of reason, the rule avoids other faculties such as imagination or sense perception. For Descartes, intuition does not involve "fluctuating testimony of the sense or the deceptive judgement of the imagination as it botches things together" (CSM I, p. 14; AT X, p. 369). The first rule ensures that mental operation and intuition function easily. The method also "reduce[s] complicated and obscure propositions step by step to simpler ones" and "starting with the intuition of the simplest ones of all, try to ascend through the same steps to a knowledge of all the rest," as stated in the second rule (CSM I, p. 120; AT VI, p. 18). The third rule mentions the breaking down of difficulties into manageable parts, and the third one talks about the arrangement of parts (CSM I, p. 120; AT VI, p. 18). The third rule has to do with the arrangements of our findings. The third rule requires the faculty of reason for it is this faculty which is going to perform what this rule entails. Such is the importance of the faculty of reason in Descartes' method, but he does not claim metaphysical certainty for the existence of the faculty of reason in the Discourse.

Given that Descartes' Discourse is an autobiographical account
where he talks about his method, unlike Meditations, where he sets out to find indubitable principles using the method, he does not mind starting with doubtful claims when subjected to extravagant suppositions of the sceptics. But, what sort of certainty does he appeal to for accepting that human beings are rational animals when he himself knows that extravagant suppositions of the sceptics can subject this claim to doubt? The next section argues that Descartes begins his Discourse with the moral certainty of the faculty of reason.

Moral Certainty of Reason in Discourse
Descartes (CSM I, p. 111; AT VI, pp. 1-2) begins his Discourse by saying Good sense is the best distributed thing in the world: for everyone thinks himself so well endowed with it that even those who are the hardest to please in everything else do not usually desire more of it than they possess. In this it is unlikely that everyone is mistaken.
He says everyone believes that they all have sufficient reason or good sense endowed in them and "...it is unlikely that everyone is mistaken" (CSM I, p. 111; AT VI, p. 2). Hence, the reason is "best distributed thing" (ibid.). But, he, himself, does not accept this sort of argument as proper in Meditations claiming that such kinds of arguments are argumentum ad populum. In the "Sixth Objections and Replies" of his Meditations, one of his critics objected to his claim that animals lack sensation and intellect, saying that "there are plenty of people who will say that man himself lacks sensation and intellect" (CSM II, p. 288 AT VII, p. 427). Descartes responds that "this is surely not an argument that proves anything, except perhaps that some people have a confused conception of everything and cling so tenaciously to their preconceived opinions" (ibid.). He does not count the testimonies of the learned people as reliable in his metaphysical studies. But, in the Discourse, he accepts the testimonies of reliable people to argue that there is a faculty of reason equally endowed in all human beings. He writes: It is the only thing that makes us men and distinguishes us from the beasts; I am inclined to believe that it exists whole and complete in each of us. Here I follow the common opinion of the philosophers, who say there are differences of degree only between the accidents, and not between the forms (or natures) of individuals of the same species. (CSM I, p. 111; AT VI, p. 2) While discussing the faculty of reason, Descartes makes an honest announcement that he is following the "common opinion of the philosophers" (ibid.). He is someone who has put to the test all the propositions that he encounters to doubt, even by invoking extravagant scenarios. But, he is taking the common opinions of philosophers as it is when it comes to the faculty of reason in his Discourse. Since these common opinions of philosophers are testimonies and testimonies guarantee moral certainty, the claim that reason is unique to humans has moral certainty. So, Descartes accepts the claim that reason is equally endowed and is uniquely human on the basis of moral certainty.
To elaborate the matter further, we can take the passage in the Discourse where Descartes distinguishes humans from non-human animals, arguing that they lack the faculty of reason. Descartes (CSM I,p. 139,AT VI, writes: I made special efforts to show that any such machines had the organs and outward shape of a monkey or of some other animal that lacks reason, we should have no means of knowing that they did not possess entirely the same nature as these animals; whereas if any such machines bore a resemblance to our bodies and imitated our actions as closely as possible for all practical purposes, we should still have two very certain means of recognizing that they were not real men. † † Michael Wheeler (2008) and Roger Ariew (2011) argue that the phrase, for all practical purposes, can be read as "morally." John Cottingham translates the French phrase, moralement impossible, as "for all practical purposes" (CSM I, 139; AT VI, 56). But, Cottingham (1992, p. 249) translates the same passage in his book, The Cambridge Companion to Descartes, as "morally impossible." Therefore, we can say that Descartes claims that it is morally impossible for us to distinguish a monkey and a machine when the machine has the same outward appearance as a monkey and the same organs as a monkey. However, it is different in the case of humans. It is morally possible for us to distinguish between a human and a machine even if the machine has the outward appearance of a human because the machine would lack reason and language. Again, the faculty of reason, for Descartes, is responsible for the language that human beings have. For Descartes, it is morally impossible for a machine to pass off as a human in front of us because it lacks the faculty of reason and speech. Furthermore, Descartes (CSM I,p. 140,AT VI,p. 57) in his Discourse writes: For whereas reason is a universal instrument which can be used in all kinds of situations, these organs need some particular disposition for particular action; hence it is for all practical purposes impossible for a machine to have enough different organs to make it act in all the contingencies of life in the way in which our reason makes us act. ‡ ‡ For Descartes, the faculty of reason can be used for varied actions, unlike other organs which are disposed towards only a particular action. It is practically impossible for a self-moving machine or an automaton to have enough organs to act in the way humans do in all the contingencies that we encounter in our life because they lack reason which is a universal instrument. In terms of moral possibility and impossibility, Descartes articulates the distinction between humans and non-human animals. As we have seen above, the distinction between humans and animals is that humans are endowed with reason. And, this distinction is not expressed in the Discourse in terms of metaphysical certainty but rather in terms of practical or moral certainty, i.e. it is unlikely that humans lack reason or it is practically impossible for humans not to have the reason given things that we see humans do. The distinction between humans and animals is a moral or practical matter rather than metaphysics, at least in the Discourse.

Conclusion
The concept of moral certainty in Descartes' philosophy has not received much attention in the contemporary Cartesian scholarship compared with other themes such as metaphysical certainty or the human-animal divide. Few Cartesian scholars have used the concept of moral certainty in relation to other areas in Descartes' philosophy. For instance, Lynn E Rose (1965) used the distinction between moral certainty and metaphysical certainty to address the problem of the Cartesian circle. Michael W Hickson (2011), employing this distinction, argues that Descartes entertains three senses of the immortality of the soul. Similarly, this paper has examined the concept of moral certainty in relation to another area in Descartes' philosophy, the faculty of reason, a concept much more popular than moral certainty. I have examined the concept of moral certainty to show that testimonies of learned men guarantee moral certainty on a matter, a certainty less than metaphysical certainty. Further, moral certainty is not just applicable to our actions in practical lives but also, for Descartes, provides a basis for accepting the findings of natural philosophy. The relationship between moral certainty and the faculty of reason, I have drawn in this paper, provides an insight into Descartes' concept of reason as I have argued that Descartes has moral certainty for accepting that there is a faculty of reason endowed in all human beings equally in the Discourse. This understanding of reason has implications in another contentious area in Descartes' philosophy, the humananimal divide. Many scholars have criticised Descartes for the distinction he maintains between humans and non-human animals, arguing that his claim that animals are not endowed with the faculty of reason encourages the cruel treatment of animals. § § I have touched upon Descartes' understanding of the human-animal divide in the paper to highlight that he articulated the distinction between humans and non-human animals not in terms of metaphysical certainty but in terms of moral certainty. It means, in the Discourse, Descartes is sure only to the extent that it is only humans who have the faculty of reason and he is not claiming to have infallible knowledge on the matter.

End Notes
* See Schüssler (2008) for detailed discussion on Gerson's understanding of moral certainty. † William Chillingworth defends the textual authority of the Bible saying that the Book has a lesser kind of certainty (Pasnau, 2017, p. 36). Eusyachus a Sancto Paulo and Francisco Suarez did not use the phrase moral certainty (Ariew, 2011). However, they maintain a distinction between metaphysical certainty and a certainty less than metaphysical certainty (Ariew , 2011). ‡ Peter Markie (1981Markie ( ) (1986, Curley (1993), Araujo (2003 and Schachter (2005) argue that the distinction between moral certainty and metaphysical certainty as a matter of degree. On the other hand, Gueroult (1984, p. 311), Bonnen and Flage (2002), Ariew (2011), argue that the moral and metaphysical certainty differ in kind. § Flage and Bonnen (2002, p. 32) write, "Descartes maintains that the physics of the Principles possesses at least moral certainty, though wanting to make a stronger claim for it." ** For discussion on rules of Descartes' method see Bonnen and Flage (2002), Williams (2005) and Broughton (2009). † † French equivalent of the passage: Et je m'étais ici particulièrement arrêté à faire voir que, s'il y avait de telles machines qui eussent les organes et la figure extérieurs d'un singe ou de quelque autre animal sans raison, nous n'aurions aucun moyen pour reconnaître qu'elles ne seraient pas en tout de même nature que ces animaux ; au lieu que, s'il y en avait qui eussent la ressemblance de nos corps et imitassent autant nos actions que moralement il serait possible, nous aurions toujours deux moyens très certains pour reconnaître qu'elles ne seraient point pour cela des vrais homes. (AT VI, p. 57) ‡ ‡ French equivalent of the passage: Car, au lieu que la raison est un instrument universel qui peut servir en toutes sortes de rencontres, ces organes ont besoin de quelque particulière disposition pour chaque action particulière ; d'où vient qu'il est moralement impossible qu'il y en ait assez de divers en une machine pour la faire agir en toutes les occurrences de la vie de même façon que notre raison nous fait agir. (AT VI, p. 57)