HUME’S MITIGATED SKEPTICISM WITH REGARD TO THE SYSTEMS OF REALITY* CETICISMO MITIGADO DE HUME EM RELAÇÃO SISTEMAS REALIDADE

In this paper, I argue that Hume’s commitment to mind-independent objects is based on two types of realism or system of realities: (a) a naïve realism based on an unjustified vulgar belief which identifies perceptions and objects, and (b) a representational realism or philosophical system of double-existence. Firstly, I emphasize that the philosophical question “ Whether there be body or not ” cannot be considered a full case of unmitigated skepticism, because Hume accepts a mitigated skepticism compatible with both vulgar and representational realism. Furthermore, I argue that, while the vulgar belief in bodies is based on an unjustified assent, the double-existence theory is based on both an unjustified assent and a rationally justified assent (that corrects the former). Considering all these points, I conclude that Hume’s mitigated skepticism allows and requires a belief in or supposition of continued and distinct existences, and that this must, as a practical matter, take vulgar and philosophical forms at different times.


Introduction 1
In this paper, I examine Hume's distinction between two types of realism -the "popular system" and the "philosophical system," both of which he presents in the section "Scepticism with regard to the senses" (section 1.4.2). These systems represent respectively (a) a naïve realism based on an unjustified vulgar belief which identifies perceptions and objects, and (b) a representational or philosophical system of double-existence. Though Hume's skeptical assessment concludes that there are some difficulties in each system of reality, each one of these has its singular importance: (1) while naïve realism fulfills the purposes of common life (and even has a vital function to the human being), (2) representational realism fulfills the purposes of science and philosophy. I hold that the two types of realism -naïve and representational -are compatible with Hume's mitigated skepticism or academic philosophy. Consequently, it is not necessary to scrutinize whether Hume rejects these systems of reality through his skepticism, given that both are involved in the human cognitive process of beliefs formation. 2 My interpretation proposes a prolific debate with scholars who consider Hume to be a Pyrrhonian who passively assents to only the unjustified vulgar beliefs, without considering Hume's scientific commitment to the doubleexistence theory. For important interpreters such as Popkin (1951), Fogelin (1985;and2009), andBaxter (2006;2018), Hume's rejection of the question "Whether there be body or not" (T 1.4.2.1) means a manifest acceptance of an epistemological unmitigated skepticism. 3 This line of interpretation maintains that though the belief in physical objects can resist skeptical doubt, the skeptical argument concerning the senses is irrefutable. In this way, Hume is skeptical regarding the epistemic justification of the belief in bodies but assumes its practical role. Furthermore, Hume is also committed to endorsing theoretical beliefs, beyond the vulgar ones. In this sense, the objectivity of the material world cannot completely be reduced to these everyday beliefs, since there is a discrepancy between practical beliefs -such as "fire warms" and "water refreshes" -and theoretical beliefs in a causal pattern of nature -such as gravity, impulse, inertia. I affirm that this discrepancy comprises two types of realism or system of reality, vulgar and philosophical, without which the human cognitive process could not be complete, not only to fulfill the purpose of common life, but also of philosophy and science.
However, more recent interpreters, such as Ainslie (2015) and Winkler (2007; reject the realistic account on mind-independent objects. 4 I hold that these interpreters do not properly consider the distinction between mental acts of 'conceiving' and 'supposing,' which is supported by Hume's realistic interpretations. Though realistic interpreters such as Wright (1983;and1986), Strawson (2008;and 2014), Kail (2003;, and Russell (1984) agree that Hume is skeptical about the ability of the human mind to conceive any external existence for something specifically different from perceptions, this does not mean that it is not possible to suppose it through a 'relative idea,' in order to "go towards a conception of external objects, […] without pretending to comprehend the related objects" (T 1.2.6.9). In other words, it is impossible to comprehend mind-independent objects in any way in terms of the theory of ideas once the act of conceiving is nothing more than an act of perceiving a mind-dependent perception. In contrast, the act of supposing refers to mind-independent objects, in which the human mind can at least "attribute to them different relations, connections, and durations" (Idem). In this way, for Hume, both the vulgar and the philosopher is committed to the mind-independent entities (Cf. Strawson, 2014, p. 45).
Indeed, Hume does not offer any arguments directly in favor of realism or systems of reality, but only takes it "for granted in all our reasonings" (T 1.4.2.1). Nevertheless, his distinction between mental acts of 'conceiving' and 'supposing' suggests that there is something else than merely mind-dependent perceptions. I do not only agree with one important aspect of the skeptical realistic interpretation: that the notion of 'natural belief' -which Hume calls 'vulgar belief' -must be enough to explain his endorsement to mindindependent objects, since Hume considers that this vulgar belief is false (I will employ the term 'vulgar belief' henceforth). 5 Thus, I propose my interpretive version of Hume's skeptical realistic account based on systems of reality or types of realism, insofar as each one of them -popular and philosophical -supports one specific type of reasoning concerning matters of fact. In the former, beliefs such as "fire warms" and "water refreshes" correspond to naïve realism, because it accepts an identity between perceptions and objects. In the latter, a theoretical belief in a causal pattern of nature -gravitation, inertia, impulse -is a representational realism since it is supported by a double-existence theory.
5 Strawson often uses the term 'natural belief' to hold his interpretation on Hume's endorsement to the mindindependent objects, but there is no reason to differentiate the 'vulgar belief from 'natural belief', since the latter is not a term used by Hume (See Strawson, 2014, p. 3, 4, 5, 17, 21, 22, passim). Maybe Strawson is in accordance with Kemp Smith when he says that both systems of reality are supported by 'natural belief' (See Smith, 1941, p. 455). Instead I state that the philosophy system is only supported by vulgar belief. Therefore, the 'natural belief' and 'vulgar belief' in bodies is the same thing, but perhaps not with the same meaning employed by Strawson or Smith since the vulgar belief is taken as false by Hume.

Mitigated versus unmitigated skepticism
I argue below that Hume cannot follow reason to a total skepticism, not only because nature saves the skeptic from it, but also because the unmitigated skeptical use of reason is incoherent and would destroy or subvert reason itself: "I have already shown that the understanding, when it acts alone, and according to its most general principles, entirely subverts itself, and leaves not the lowest degree of evidence in any proposition, either in philosophy or common life" (T 1.4.7.7 -my emphasis). I maintain that this point has important consequences for Hume's position on the mind-independence of physical objects and shows that the irresolution regarding the philosophical question "Whether there be body or not" is not itself an unmitigated skepticism concerning the independent existence of bodies. Rather, Hume accepts a mitigated skepticism compatible with both vulgar realism and representational realism.
Pyrrhonian interpreters such as Popkin (1951), Fogelin (1985and2009), andBaxter (2008;2018) maintain that Hume's position on the mindindependent existence of physical objects is limited to either an unjustified assent or a rational skepticism based on skeptical arguments. This point is clearly stated by Fogelin: We must take the existence of body for granted, first, because it is incapable proof, second, because we are incapable of doubting it. Now it is important not to let this second point bury the first, for Hume is unequivocal in accepting the force of the standard skeptical arguments against the possibility of proving the existence of external bodies. This becomes evident toward the end of the section where he argues that only causal reasoning could assure us of the existence of bodies, but this, since we never observe bodies conjoined with perceptions, is impossible (Fogelin, 1985, pp. 66 -my emphasis).
Similarly, Baxter (2006) holds that Hume suspends judgment on all active endorsement supported by epistemic reasons, and only accepts a passive acquiescence through the natural carelessness that forces him to believe in the existence of bodies: By following in these Pyrrhonian footsteps, Hume can both assent to the existence of the external world, and not assent to it, without inconsistency. He does passively acquiesce in the natural view thrust upon him by appearance, that there is an external world. However, he does not actively endorse as true the view that there is an external world […] He naturally holds and acts on the belief in the external world because it almost irresistibly appears true, even though careful inquiry into the causes of the belief makes it appear unjustified and even inconsistent. These opposing views of the belief keep him from actively endorsing it or its negation as true. […] In this skeptical way, Hume takes for granted the existence of body. His real interest is in the workings of the human mind. Just as he has the natural belief in the existence of body, so do we all. The fact that we assent in any way to such an ill-grounded view calls for an explanation. He concludes that it is part of our nature passively to assent to it. We believe it instinctively. Were we ideally rational, we would fail to have the belief. So other causes besides justifying reasons must explain the fact that we have it. The bulk of T 1.4.2 is an inquiry into those causes (Baxter, 2006, pp. 409-410).
Baxter's 6 and Fogelin's 7 readings are both influenced by Richard Popkin's original article David Hume: His Pyrrhonism and His Critique of Pyrrhonism (1951), in which he also argues for Hume's epistemological unmitigated skepticism: "these [skeptical] arguments show that there are grounds for doubting the certitude of such [daily] judgments, but the judgments themselves have a pragmatic role in our ordinary endeavors which is unaffected by these doubts" (Popkin, 1951, p. 388). Rather remarkably, Popkin argues that this wavering between belief and skeptical doubt indicates Hume's schizophrenic personality -or at least that of Philo's persona in his Dialogues Concerning Natural Religion: Hume' s full view of himself as the 'consistent' Pyrrhonist comes out in the picture that he painted of what the true sceptic is like, both in the character of Philo in the Dialogues, and in various remarks in all his philosophical writings. The true Pyrrhonist is both a dogmatist and a sceptic. In being entirely the product of nature he welds his schizophrenic personality and philosophy together (Popkin, 1951, p. 406 -my emphasis).
All these Pyrrhonian interpretations are based on an exclusive disjunction between sentiment and reason, in which sentiment is the foundation of nonrational assent, while reason is the source of the negative epistemic evaluation of the judgments or beliefs which are assented to. However, this disjunction between sentiment and reason is incompatible with important points of Hume's epistemological position. There are two well-known passages of the Treatise in which Hume does prescribe that the reason ought to act combined or mixed with natural propensities or sentiments as a means of justifying beliefs: (A) "Where reason is lively, and mixes itself with some propensity, it ought to be assented to. Where it does not, it never can have any title to operate upon us" 8 (T 1.4.7.11 -my emphasis); (B) "Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them" (T, 2.3.3.4 -my emphasis).
In passages A and B, the modal "ought to" plays an important role in rejecting a skeptical negative use of the reason. Even though the term 'sentiment' has a different meaning in each one of these passages, both still play the same role of support to the reason, and it is important for my argument as follows. 9 In both passages, the Pyrrhonian disjunctive pattern is simply abandoned, since Hume is openly stating that reason ought to act in combination or mixed with some sentiment or propensity. Therefore, unlike the disjunctive "or," Hume observes that the relationship between reason and sentiment ought to be based on the conjunctive "and." Passages A and B generate a challenging interpretive problem for all interpreters who see Hume's skepticism only through the opposition between belief and rational doubt. His modal "ought to" has a prescriptive role that operates contrary to reason's purely skeptical use. Hume maintains the disjunctive Pyrrhonian pattern only temporarily. However, this scenario is gradually changed by the influences of sentiments that overlap his radical skepticism, because if the reason were totally conducted in this skeptical negative way, it would totally destroy or subvert itself: 'Tis happy, therefore, that nature breaks the force of all sceptical arguments in time, and keeps them from having any considerable influence on the understanding. Were we to trust entirely to their self-destruction, that can never take place, 'till they have first subverted all conviction, and have totally destroy'd human reason. (T 1.4.1.12, -my emphasis) Moreover, Hume also declares that the unmitigated skeptical negative use of reason is "peculiar to a few extravagant sceptics" (T 1.4.2.50) and affirms that there is indeed another use of reason when it is conjoined with sentiment and natural propensities, according to A and B passages. This point does not mean that the 'passive acquiescence' point of view is totally wrong, but it is only the first phase for a philosophical endorsement and, therefore, these two kinds of assent do not exclude each other; rather, they are only two distinct steps of the same act of philosophical assent on double existence. This point means that, although initially, we accept beliefs employing this "passive acquiescence," this same act of assent will later become an "active endorsement" by the use of the reason conjoined with sentiment and natural propensities.
The use of reason with sentiment provides a foundation for the representational realism, in such a way that Hume's commitment to the mind-independent existence of objects is not only narrowed to the vulgar belief in bodies (sentiment without reason). Therefore, Hume not only recognizes passively the principle that there are external objects, such as Baxter's reading suggests, but also actively prescribes it in all reasonings concerning matters of fact (see T 1.4.2.1), including the philosophical ones. Thus, in the next section, I shall discuss the difference among both systems of reality, the vulgar and philosophical, and the relevance of each of them to Hume's account on mindindependent objects.

The systems of reality in the human cognitive process
In this section, I will argue that the systems of reality do not exclude each other and are compatible with Hume's account of mind-independent objects. Furthermore, Hume also holds that these systems play a relevant role in the human cognitive process of belief formation, though there are important differences among them that I shall examine.
Interpreters such as Fogelin (1985;2009), Ainslie (2015), and Winkler (2007; and 2015) argue that Hume is a phenomenalist or anti-realist regarding mind-independent objects, though they affirm also that Hume is committed to endorsing the vulgar belief in bodies. Instead of this phenomenalism, Hakkarainen (2007) argues that the vulgar belief is compatible with a naïve realism and with Hume's temporary skepticism. For Hakkarainen, although the vulgar belief is not epistemically justified, Hume's epistemological skepticism is not incompatible with a metaphysical commitment concerning the identity between perception and external object (2007, p. 57). I agree that there are no rational arguments to support the legitimacy of belief in the existence of bodies, but it is important to bear in mind that Hume's commitment to mindindependent objects has singular importance not only for common life but also for philosophy.
Nevertheless, all these scholars are often more concerned with the unjustified vulgar belief in bodies than the importance of the philosophical opinion of double existence, although Hume has examined this subject in detail between paragraphs §46 and §57 in section 1.4.2. In contrast, I take into account that skeptical realistic interpretations such as those of Wright (1983;and1986), Strawson (2008;and2014), Kail (2003;, and Russell (1984) are compatible with the double-existence theory when they affirm that Hume is committed to the notion of unknown causes in nature. 10 In this sense, though Hume is a skeptic in such a way that the external object is unintelligible, this does not mean that the mind may not form at least a 'relative idea' of external objects to attribute to them different relations, connections, and durations.
As I already noted in the introduction, while practical beliefs such as "fire warms" and "water refreshes" correspond to naïve realism based on a false identity and simplicity between perceptions and objects, theoretical beliefs in a causal pattern of nature -gravitation, inertia, impulse -are compatible with a representational realism. In order to explain that Hume's account is compatible with the systems of reality, I will examine how a belief in ϕ is the case in a system, but cannot be the case in the other one, yet these different evaluations do not contradict his position. In this sense, the systems of reality are compatible, in a such way that both should occur and be accepted or endorsed in the same mind. This means that the popular system is cognitively narrowed to a number of entities that are considered as mind-independent sense-objects (table, chair, tree, stone, boat, house, fire, dog, bird), without any distinction between internal (perceptions) and external (objects) existences: The persons, who entertain this opinion concerning the identity of our resembling perceptions, are in general all the unthinking and unphilosophical part of mankind, (that is, all of us, at one time or other) and consequently such as suppose their perceptions to be their only objects, and never think of a double existence internal and external, representing and represented. (T 1.4.2.36) There are occasions in which the unthinking inference of the vulgar cannot reach a wider scope, since its cognitive restrictions do not allow it, though these occasions may be managed in a philosophical manner. Consequently, the senseobjects have a smaller number of entities than those of the philosophical system, insofar as the latter also supposes a distinction between what is perceived by the mind (perceptions) and what is not (objects). By the way, it should be borne in mind that the double-existence theory in 1.4.2 is not equivalent to the theory of primary and secondary qualities. The theory that emerges from 1.4.2 is that bodies resemble our sensory impressions: "when from a single perception it infers a double existence, and supposes the relations of resemblance and causation betwixt them." (T 1.4.2.4). Nevertheless, the theory criticized in 1.4.4 is the philosophical theory that objects do not resemble sensory impressions. This is the theory of primary and secondary qualities generally associated with Locke's Essay Concerning Human Understanding (1689).
The difference between the popular and philosophical system is more evident when the vulgar reasoning is compared with the philosophical. For Hume, the vulgar reasoning corresponds to probability of chance, while the philosophical reasoning corresponds to probability of causes: WHAT I have said concerning the probability of chances can serve to no other purpose, than to assist us in explaining the probability of causes; since 'tis commonly allow'd by philosophers, that what the vulgar call chance is nothing but a secret and conceal'd cause (T 1.3.12.1).
The vulgar reasonings are those that occur about bodies when they are conceived in accordance with the vulgar view and the philosophical reasonings are those that occur about bodies when they are conceived in accordance with the philosophical view. For example, Hume affirms that when a peasant offers a reason for the stopping of any clock or watch, he simply says that "it commonly does not go right," but obviously this statement is not enough to explain the defect. However, in a reflexive way, the artisan notes that it is "a grain of dust, which puts a stop to the whole movement." From several parallel cases, "the philosophers form a maxim, that the connexion betwixt all causes and effects is equally necessary, and that its seeming uncertainty in some instances proceeds from the secret opposition of contrary causes" (T 1.3.12.5, my emphasis). In other words, the philosophers or scientists share theoretical beliefs not shared by the vulgar, for example, when they state that "each part [of the body] contains this quality [gravity] and contributes to the gravity of the whole" (T 1.3.12.16). Therefore, the vulgar belief and double-existence theory can accommodate this discrepancy between vulgar and philosophical reasonings.
Hume cannot simply renounce the naïve or the representational realism since both fulfill different purposes in the human cognitive process of belief formation. When Hume says that "the idea of sinking is so closely connected with that of water, and the idea of suffocating with that of sinking, that the mind makes the transition without the assistance of the memory" (T 1.3.8.13), he considers that the habit operates before any reflection. In this case, the vulgar draw an inference from past experience, without reflecting on it, supported by the unthinking principle, "that instances of which we have no experience, must necessarily resemble those, of which we have" (Idem). In contrast, in reflexive reasonings of the philosophers, Hume says that "the reflection produces the belief without the custom", by means of reflected principle, "that like objects, plac'd in like circumstances, will always produce like effects" (Idem). In this sense, though both the vulgar and the philosophers suppose that external objects have certain properties, but they occasionally differ from each other with respect to the nature of these properties, mainly because the vulgar are narrowed to their senses, while the philosopher is not: In general we may observe, that in all the most establish'd and uniform conjunctions of causes and effects, such as those of gravity, impulse, solidity, &c. the mind never carries its view expressly to consider any past experience: Tho' in other associations of objects, which are more rare and unusual, it may assist the custom and transition of ideas by this reflection. (T 1.3.8.14 -my emphasis) However, even though the systems of reality fulfill distinct cognitive purposes, Hume also develops the thesis that the philosophical opinion of double existence depends on vulgar belief in bodies, since "this philosophical hypothesis has no primary recommendation, either to reason or the imagination" (T 1.4.2.46; T 1.4.2.47), and hence "acquires all its influence on the imagination from the vulgar one" (T 1.4.2.49). As I show below, this point means that the vulgar belief plays a relevant role in representational realism, in a way that the former offers at least a practice justification to the latter, by means of the principles of the imagination.

The falsity of vulgar belief in bodies
Concerning the vulgar belief in bodies, Hume affirms at paragraph § 56 that: I cannot conceive how such trivial qualities of the fancy, conducted by such false suppositions, can ever lead to any solid and rational system. They are the coherence and constancy of our perceptions, which produce the opinion of their continu'd existence; tho' these qualities of perceptions have no perceivable connexion with such an existence. The constancy of our perceptions has the most considerable effect, and yet is attended with the greatest difficulties. 'Tis a gross illusion to suppose, that our resembling perceptions are numerically the same; and 'tis this illusion, which leads us into the opinion, that these perceptions are uninterrupted, and are still existent, even when they are not present to the senses. This is the case with our popular system. (T 1.4.2.56) Although the vulgar belief in bodies plays an important vital function to the human being, there is a natural fault in it, insofar as it is the result of a natural confusion between what is directly felt and seen (perceptions) and what is not directly felt and seen (objects) by the human mind: "the vulgar confound perceptions and objects and attribute a distinct continu'd existence to the very things they feel or see" (T 1.4.2.14 -my emphasis). Though the vulgar belief is deceitful, it is capable of imposing itself on the human imagination: "Tho' this opinion [the vulgar belief] be false, 'tis the most natural of any, and has alone any primary recommendation to the fancy" (T 1.4.2.48). Baxter (2006) argues that only the natural carelessness can rectify this anomaly of the vulgar belief and return Hume to the view that it is natural for him to passively assent to the existence of the bodies (2006, pp. 409-410).
In this sense, the vulgar belief could remain consistent in relation to the principles of imagination because, as Ainslie notes, "the vulgar take themselves to be immersed in the world" (2015, p. 133). However, Hume does not explicitly affirm that natural carelessness can even rectify the vulgar belief (at least not totally), but only that the human mind cannot think about it all the time. As I show below, this point does not mean that Hume prescribes the suspension of belief, since the vulgar belief in bodies can still be pragmatically justified, in order to fulfill at least the purpose of common life and to play a vital role for the human being.
For Hume, the human mind is involuntarily inclined to believe that color, smell, taste, and sound are not inside the mind. So, for example, along moments of unthinking mental states, even if someone has basic learning of Newton's optical theory, they continue to believe involuntarily that visual or gustatory impressions, such as "colors" and "taste," are qualities of the objects themselves. Nevertheless, Hume states that simple empirical experiments can show that this identity between perceptions and objects is uncontroversially false: "the seeming encrease and diminution of objects, according to their distance"; "by the apparent alterations in their figure"; "by the changes in their colour and other qualities from our sickness and distempers"; "and by an infinite number of other experiments of the same kind; from all which we learn, that our sensible perceptions are not possest of any distinct or independent existence" (T 1.4.2.45). Consequently, this confusion between mind-dependent perceptions and mind-independent objects is a natural inconsistency of the vulgar belief.
That said, I hold that Hume's commitment to mind-independent objects is compatible with the Academic skepticism, insofar as it is consistent with Hume's aporetic statement regarding the question on "Whether there be body or not." In the same manner, his position is not purely an unmitigated skepticism (such as Pyrrhonian interpreters hold), since Hume avoids the suspension of judgment about the existence of bodies which "we must take for granted in all our reasonings" (T 1.4.2.1). Moreover, in the section 1.4.1, Hume states that a total suspension of judgment (T 1.4.1.8) cannot lead us to "a total extinction of belief and evidence" (T 1.4.1.6). In other words, it should not lose sight of the fact that a "simple act of the thought" -such as the suspension of judgment -cannot have the same force and vivacity as a belief in the human mind: If belief, therefore, were a simple act of the thought, without any peculiar manner of conception, or the addition of a force and vivacity it must infallibly destroy itself, and in every case terminate in a total suspense of judgment. (T 1.4.1.8) This passage suggests that Hume rejects the capacity of a suspensive act of the human mind, because, insofar as judgments depend on the vivacity of ideas, the skeptic "may safely conclude that his reasoning and belief is some sensation or peculiar manner of conception, which 'tis impossible for mere ideas and reflections to destroy" (T 1.4.1.8). Hume relates the skeptical state of mental suspension to these "mere ideas and reflections" derived from abstruse reasonings, which the human mind cannot actively assent to: The attention is on the stretch: The posture of the mind is uneasy; and the spirits being diverted from their natural course, are not govern'd in their movements by the same laws, at least not to the same degree, as when they flow in their usual channel. (T 1.4.1.10) Once the human mind is not able to disregard the vivacity of ideas derived from the impressions of the senses, skeptical suspension of judgment cannot lead Hume to reject this commitment to the existence of mind-independent objects: "Nature has not left this to his choice, and has doubtless esteem'd it an affair of too great importance to be trusted to our uncertain reasonings and speculations" (T 1.4.2.1), and therefore he concludes that this is a point "which we must take for granted in all our reasonings" (Idem). Similarly, in his Academica, Cicero assumes that, though he cannot comprehend the impressions that strike his mind, he often assents involuntarily to them: I guide my thoughts by the bright Septentriones (Helikê in Greek), i.e., by more easily accessible principles, not ones refined almost to the vanishing point. As a result, I err or wander farther afield. But it's not me, as I said, but the wise person we are investigating. When these (less precise) impressions strike my mind or senses sharply, I accept them, and sometimes even assent to them (although I don't apprehend them, since I think that nothing is apprehensible). I'm not wise, so I yield to these impressions and can't resist them. (Cicero,Ac.66) Cicero describes this as being taken "by more easily accessible principles" and concludes: "I'm not wise, so I yield to these impressions and can't resist them." In the same manner, Hume accepts that only natural carelessness can lead him to assent to (the existence of) external objects, and often affirms that the vulgar belief in bodies is uncontroversially false, although he cannot eliminate it (Cf. T 1.4.2.39;T 1.4.2.43;T 1.4.2.48;and T 1.4.2.56). In this sense, the vulgar belief is pragmatically justified since it fulfills the purpose of common life and plays a vital role for the human being.
The practical justification of the vulgar belief is compatible with the general thesis of the Academic skepticism that the impressions cannot be comprehensible, insofar as Hume does not doubt the existence of the mindindependent objects, but only of the human cognitive capacity to have access to them. Consequently, if Hume is only a skeptic in this way, he cannot also be an anti-realist or a phenomenalist regarding the existence of the outer world. 11 Despite the differences among the systems of reality -vulgar and philosophical ones -, Hume's mitigated skepticism is central to eliminate their tensions since both become consistent with his skeptical view. For example, in paragraph § 56 of the section 1.4.2, Hume is struck by an intense skeptical sentiment that leads him to doubt both popular and philosophical opinion concerning external objects. According to Pyrrhonian interpretations, Hume would accept the vulgar belief in bodies "only because it costs us too much pains to think otherwise" (T 1.4.7.11), and consequently, reason has only a skeptical negative role. Nevertheless, Hume often takes it that this intense skeptical sentiment is only temporary, and might not affect enduringly either popular nor philosophical opinion. As I state above, this unmitigated skepticism is not rationally consistent, because it would destroy or subvert itself. Furthermore, Hume affirms that this intense view is caused by his 'heated brain' produced by the "profound and intense reflection" (T 1.4.2.57), but it does not derive directly from an apparent consistency of skeptical arguments. 12 It may be also argued that in paragraph § 57, which concludes section 1.4.2, and where Hume states that only "carelessness" and "in-attention" can cure the philosopher of his skeptical doubt, Hume is not only referring to double-existence theory. However, in this passage, Hume does not exclude a representational realism since carelessness does not merely mean a return to the vulgar belief in which perceptions and objects are identical to each other. 13 On the contrary, this passage clearly states that, after a period of time, the reader will not only return again to a vulgar opinion, but also to the system of double existence: "that an hour hence he will be persuaded there is both an external and internal world" (T 1.4.2.57 -my emphasis).
That said, I maintain that the system of double existence is only gradually different from popular opinion. Consequently, Hume's natural carelessness does not lead him to reject the philosophical opinion, but respectively to accept both the vulgar belief and the double-existence theory. In effect, the doubleexistence theory is partly based on an unjustified assent in mind-independent 11 Fogelin (1985), Ainslie (2015), andWinkler (2007; hold that Hume doubts the existence of mindindependent objects. 12 See Fogelin (1985), Baxter (2008;and 2018), and Popkin (1951), Winkler (2007. 13 Many scholars that sustain an unmitigated skepticism affirm that Hume considers only the vulgar belief in bodies in the final paragraph. However, even if it is true, recovering the vulgar belief entails recovering the philosophical theory with one stroke, since the last is associated with first, through the principles of continuance and independence from the imagination.
objects and a rationally justified assent on mind-dependent perceptions: it is the result of both types of assents. Thus, as I will show in the section below, the system of double existence is an intermediate position between the principles of continuance and independence derived from the imagination and the principles of interruption and dependence derived from reason. In other words, the imposition of the vulgar belief in bodies upon the human mind and empirical scrutiny on the mind-dependent perceptions result in this philosophical opinion of double existence. Consequently, this explains because the system of double existence can properly accommodate the human reasonings in an epistemic way, in a way that the popular system could not do.

The philosophical opinion of double existence
About this philosophical system, Hume affirms in paragraph § 56 that: Philosophers deny our resembling perceptions to be identically the same, and uninterrupted; and yet have so great a propensity to believe them such, that they arbitrarily invent a new set of perceptions, to which they attribute these qualities. I say, a new set of perceptions: For we may well suppose in general, but 'tis impossible for us distinctly to conceive, objects to be in their nature any thing but exactly the same with perceptions. What then can we look for from this confusion of groundless and extraordinary opinions but error and falshood? And how can we justify to ourselves any belief we repose in them? (T 1.4.2.56) Ainslie (2015) and Winkler (2007; affirm that, in this paragraph, Hume is conclusively rejecting the philosophical system, in such a way as to affirm that the human mind cannot distinctly conceive external objects, and "arbitrarily invent a new set of perceptions." However, as I have already noted, Hume is only affirming that the human mind cannot conceive a specific reality different from perception, and evidently when the philosophers make it, they only produce a "new set of perceptions". However, for Hume, though the philosophers cannot conceive external objects, they can still form a relative idea of such objects to attribute to them different relations, connections, and durations. 14 In contrast, the vulgar confound the constant conjunction among perceptions as if they were the external existences, and this supposition is uncontroversially false. In this way, Hume considers that, for the philosophical opinion, there is an alignment between [1] doxastic principles of continuance and independence derived from the imagination and [2] epistemic principles of interruption and dependence derived from the reason. By these means, philosophers remove the natural confusion of vulgar opinion between what is felt and seen (perceptions) and what is neither felt nor seen (objects): This philosophical system, therefore, is the monstrous offspring of two principles, which are contrary to each other, which are both at once embrac'd by the mind, and which are unable mutually to destroy each other. The imagination tells us, that our resembling perceptions have a continu'd and uninterrupted existence, and are not annihilated by their absence. Reflection tells us, that even our resembling perceptions are interrupted in their existence, and different from each other. The contradiction betwixt these opinions we elude by a new fiction, which is conformable to the hypotheses both of reflection and fancy, by ascribing these contrary qualities to different existences; the interruption to perceptions, and the continuance to objects. Nature is obstinate, and will not quit the field, however strongly attack'd by reason; and at the same time reason is so clear in the point, that there is no possibility of disguising her. (T 1.4.2.52) I have already noted that the vulgar provide a practical justification to the double existence opinion, since the vulgar belief in bodies is pragmatically justified, so that it fulfills the purpose of common life and plays a vital role for the human being. Nevertheless, insofar as it is uncontroversially false, the vulgar belief should be replaced by the double-existence theory in order to fulfill the purpose of science and philosophy. In the case of the philosophical opinion of double existence, the principles of imagination and reason must act in a conjoined manner. Consequently, it is not wrong to affirm that there is a compatibility between double-existence theory and Hume's title principle (in which reason and sentiment are conjoined to each other).
In this way, Hume states that the philosophical opinion "pleases our reason, in allowing, that our dependent perceptions are interrupted and different; and at the same time is agreeable to the imagination, in attributing a continu'd existence to something else, which we call objects." (T 1.4.2.52). The principle of interruption and dependence is confirmed by a few simple experiments (see T 1.4.2.45). Rather than revealing any connexion between resembling perceptions in the human mind, the philosophical investigation reveals that there is a numerical difference among perceptions (p₁; p₂; p₃; p₄; ...; pₓ). This point means that reason finds a "philosophical relation" of "proportions in quantity or number" among perceptions in the human mind, in such a way that the principles of interruption and dependence can be seen as epistemic ones, because they are "objects of knowledge and certainty" (T 1.3.1.2) like all other relations of quantity or number. This point makes it clear that the philosophical opinion is nothing more than an "intermediate situation of the mind" (T 1.4.2.52) between these epistemic principles derived from reason (dependence and interruption) and those doxastic ones derived from the imagination (continuance and independence). Thus, when Hume holds that this philosophical hypothesis "has no primary recommendation either to reason or the imagination", he is indeed only affirming that the double-existence theory results from both assents of imagination (doxastic) and reason (epistemic), in order to form a kind of "intermediate situation of the mind" among these principles that were originally opposed to each other. Otherwise, as previously mentioned, there would be no commitment to science and philosophy.
It should be taken into consideration that the vulgar belief in bodies may not serve satisfactorily as a reference to all reasoning concerning matters of fact. Thus, while the vulgar remain unreflectively narrowed to describe phenomenological relationships between sensorial objects, the philosophers or scientists also consider a secret causal pattern in nature. Though both philosopher and the vulgar assume that an object A has the property to cause B, only the philosopher acknowledges that this power or force -gravity, impulse, inertia -is totally unknown. Therefore, I reinforce that the double-existence theory is not only relevant to mind-independent objects, but also to Hume's notion of secret causation, in order to move away him from mistakes and errors, when power or force are taken as known qualities: "But when, instead of meaning these unknown qualities, we make the terms of power and efficacy signify something, of which we have a clear idea […] obscurity and error begin then to take place, and we are led astray by a false philosophy" (T 1.3.14.27).
Thus, in the section "Of the antient philosophy" (1.4.3), Hume returns to the discussion about the double-existence theory, but without mentioning it explicitly. Hume proposes that the vulgar belief is not totally opposed to those of the philosophers, particularly when they acquire "new degrees of reason and knowledge" (T 1.4.3.9). The vulgar opinion is directly associated to "the common and careless way of thinking" (T 1.4.3.9; and 1.4.2.57), characterized by the predominance of habit. Thus, habit makes it difficult to separate the ideas that are commonly presented in conjunction, so the vulgar consider it absurd to separate them. Philosophical opinion, on the other hand, allows us to "abstract from the effects of custom," separate and compare ideas with each other (T 1.4.3.9), in order to correct vulgar opinions through reflection. Similarly, when the human mind confounds mind-dependent perceptions with identical objects outside the mind, the philosopher must also correct this mistake derived from vulgar belief.
All these points reinforce that the double-existence theory plays also a relevant role in the causal reasoning: "[...] As long as we take our perceptions and objects to be the same, we can never infer the existence of the one from that of the other, nor form any argument from the relation of cause and effect; which is the only one that can assure us of matter of fact" (T 1.4.2.14 -my emphasis). This point does not completely remove the skepticism, since "our reason neither does, nor is it possible it ever shou'd, upon any supposition, give us an assurance of the continu'd and distinct existence of body (Idem -my emphasis). But the most important point is another one: unlike the vulgar, the philosopher cannot simply confuse the perception of the sun that appears in his mind (representation) with the sun out of his mind (represented). Therefore, if a philosopher insists in the identity and simplicity between perceptions and objects, he would never be able to reason properly on matters of fact, because in this case, he would be unable to distinguish what is what: he would not only confuse 'object' with 'perception', since in general, he would not know how to say what is exactly 'cause' and 'effect' and vice versa, because he could not "form any argument from the relation of cause and effect" (Idem). Consequently, the correction of the popular opinion by means of the double existence allows Hume to accept representational realism, but not because in this way it is possible to prove rationally the existence of mind-independent objects. But rather it is because it allows at minimum a proper prediction in our causal reasoning in order to fulfill the purpose of science and philosophy, in a way that the Academic skeptic can finally assess what is and what is not the case.
It is important to bear in mind that Hume does not propose the gradation of vulgar and philosophical opinions as static postures, but rather as functions or roles that human beings adopt at different times during the course of their lives (see T 1.4.2). In this way, Hume's mitigated skepticism becomes central to eliminate the conflict among the systems of reality, so that one cannot exclude the other, since each one of them plays a relevant role in the human cognitive process of beliefs formation.

Conclusion
In this paper, I argued that Hume's commitment to mind-independent objects is based on two types of realism or system of realities: (a) a naïve realism based on an unjustified vulgar belief which identifies perceptions and objects, and (b) a representational realism or philosophical system of double existence. Firstly, I emphasized that the philosophical question "Whether there be body or not" cannot be considered a full case of unmitigated skepticism, because Hume accepts a mitigated skepticism compatible with both vulgar and representational realism. Furthermore, I argued that, while the vulgar belief in bodies is based on an unjustified assent, the double-existence theory is based on both an unjustified assent and a rationally justified assent (that corrects the former). Considering all these points, I concluded that Hume's mitigated skepticism allows and requires a belief in or supposition of continued and distinct existences, and that this must, as a practical matter, take vulgar and philosophical forms at different times.