Selective scepticism over thought: Am I ever justified in doubting that I think that thought but not this one?

In this paper, I subject a number of statements avowing selective doubt about an act of thinking to philosophical analysis (e.g., “A thought occurred just now but I do not believe that I was thinking it”) to ascertain those circumstances under which they constitute a legitimate expression of scepticism. Can a case be made for epistemic discrepancy sufficient to justify the following claim: “I doubt that I think that thought but not this one”? In support of selective scepticism, I discuss the ontological and epistemic properties evident in an indirect form of Moore’s paradox which features beliefs about a thought and a thinker: notably, “I experienced a thought just now but I do not believe that I was thinking it”. I argue that the conjunction above contains conjuncts which are ontologically equivalent but epistemically distinct. This difference explains not only why the statement is indirectly Moore paradoxical but how selective scepticism over thought might be justified. To further support my claim for the legitimacy of selective scepticism, I consider research on how a child acquires beliefs about thinking, and speculate over the cause of a rare pathological condition known as thought insertion.

ABOUT THE AUTHOR Garry Young is a senior lecturer in psychology at Nottingham Trent University. His research interests include delusional beliefs, embodied cognition and the ethics of virtual interactions within video games and cyberspace more generally. His publications include Philosophical Psychopathology: Philosophy without thought experiments (Palgrave Macmillan, 2013), Ethics in the Virtual World: The morality and psychology of gaming (Routledge, 2013), and Transcending Taboos: A moral and psychological examination of cyberspace (Routledge, 2012; co-author Monica Whitty). The current paper is part of an ongoing research programme examining the nature of belief, including delusional beliefs.

PUBLIC INTEREST STATEMENT
Typically, we do not doubt that we think thoughts we experience; it seems self-evident to us that we do think them. Only in pathological cases-e.g. thought insertion-does the relationship between thought and thinker breakdown, such that the subject does not believe that s/he thinks certain thoughts. This paper considers whether I could ever be justified in doubting that a particular thought I experience is one I think. In other words, is it ever legitimate to assert that I doubt thinking that thought but not this one? I am not suggesting that what is doubted could be true (that I really am not the one thinking the thought); rather, I am asking whether such selective doubt is justifiable, insofar as I have a reason to doubt I was thinking that thought. Such justification would of course fly in the face of our everyday experience and beliefs about our thoughts.

PART 1 1. Introduction
Is there not some God, or some other being by whatever name we call it, who puts these reflections into my mind? (Descartes (1641(Descartes ( /1997, §24; emphasis added) The question above forms part of Descartes' Second Meditation. In its original context, and without the added emphasis, Descartes is entertaining the possibility that all of his thoughts (his reflections) are exogenous. By adding the emphasis, however, I wish to create the sense in which Descartes, rather than expressing ubiquitous doubt over the source of his thoughts-that they are thoughts he is thinking (as we traditionally, and rightly, take him to be doing)-is here being more selective. In this amended version of his Second Meditation, let us allow that he is sceptical about the origin of these thoughts, specifically, whatever these thoughts happen to be.
If we accept as necessary the connection between a thought and a thinker, such that the existence of a thought entails a thinker of that thought, is selective scepticism over thought ever justified? To illustrate, consider the following example taken from a patient suffering from thought insertion (a condition we will return to in Section 6): [S]he said that sometimes it seemed to be her own thought … "but I don't get the feeling that it is". She said her "own thoughts might say the same thing … but the feeling isn't the same … the feeling is that it is somebody else's …" (Taken from Allison-Bolger, 1999, #68, cited in Hoerl, 2001 Here, the subject is distinguishing between thought she takes to be her own and thought she does not. Is such a distinction ever legitimate such that I (or anyone) could (legitimately) make the following claim: I doubt that I think that thought but not this one? To be clear, I am not asking whether it is ever legitimate to entertain the possibility that one could doubt that one is thinking certain thoughts; after all, that is precisely what I am doing here and Descartes is doing in my amended version of his Second Meditation. Rather, I am concerned with the legitimacy of the proposition: I doubt that I think that thought but not this one. My query does not stem from a motivation to challenge the entailment between thinker and thought. As noted, for the purposes of this paper, I accept this without defence. Instead, I am interested in whether, epistemically, I could ever be justified in doubting that a particular thought is one that I think, as illustrated by the example of "thought insertion" above.
The aim of this paper is to subject a number of statements avowing selective doubt about an act of thinking to philosophical analysis, in order to ascertain those circumstances under which they constitute a legitimate expression of scepticism. I intend to show that there is an unconventional sense in which one could justify selective scepticism with regard to thought and who is thinking it-namely, adopting the view from nowhere-but that the unconventional nature of this example risks trivialising the scepticism involved (Section 2). That said, the introduction of an "objective stance" does highlight the seemingly important role played by perspectivity in abating scepticism. I say "abating" rather than "eradicating" because I intend to illustrate, through the use of an indirect form of Moore's paradox, how selective scepticism may be granted a degree of legitimacy under certain circumstances, even in the case of thinking thoughts constitutive of one's perspective (Sections 3 and 4). What these circumstances are, and therefore what might constitute a reason for one's scepticism, will be considered in Part 2 when discussing how a child develops an awareness of the act of thinking (Section 5) and the rare pathological condition known as thought insertion (Section 6).

Selective scepticism 1: adopting the view from nowhere
Consider the following claim: D 1 I doubt (qua do not believe) that I think that thought but not this one. D 1 discriminates between thoughts that I doubt thinking and thoughts that I do not. Is this discrimination ever justified?
One defence of D 1 requires that we adopt an objective stance, or what Nagel (1986) refers to as the view from nowhere. Assuming the possibility of other minds, there are countless thoughts which I do not think or have any direct awareness of (nor do I hold the belief that I do). Thoughts are being generated every moment of every day which I have no direct involvement in or access to. From an objective stance-when conceiving of the whole of thought-it would appear to be perfectly legitimate (and indeed rational) for me to doubt that I think those thoughts. 1 But if I were to adopt an objective stance, then given the nature of this stance, what would be the basis for my differentiation of those thoughts from, say, these thoughts, or simply that one from this? In other words, how am I to identify and so discriminate thoughts it is legitimate for me to doubt that I think from thoughts it is not? Adopting the view from nowhere means that there are an indeterminate number of thoughts in existence at any given time; thoughts with different content and (let us allow, pace Russell and Nietzsche) 2 different thinkers. But, to reiterate, how is each thought individuated such that I am able to pick out one particular thought from another in a way that justifies doubting that I think that thought, specifically, and therefore for the corresponding proposition regarding my doubt of that thought to be legitimate?
Borrowing from Williams (1978), when adopting an objective stance, the problem of individuation can be illustrated as follows: take the thought (T1) "I believe that this is true" and the thought (T2) "I do not believe that this is true". Where the demonstrative pronoun is referring to the same thing, both of these thoughts cannot be expressing a truth unless (T1) and (T2) constitute the content of different thought-worlds: for in the same thought-world, it cannot be the case that whatever this is referring to is both believed and not believed to be true. 3 If each thought is to be upheld as legitimate, then the contradictory content of (T1) and (T2) requires that they are located in different thought-worlds, otherwise such contradictory content, contained within the same thought-world, would (in fact, should) be judged irrational. 4 Based on an objective stance, contradictory content would seem to be sufficient for thought individuation, but only insofar as such a criterion (i.e. contradiction) individuates thoughts into different thought-worlds based on assumed rationality. Where one cannot assume rationality, the individuation of (T1) and (T2) into different thought worlds is not possible.
Within the same thought-world, the following thoughts-(T3) "I doubt that that is true" and (T4) "I do not doubt that this is true"-can be true without fear of contradiction: for each demonstrative pronoun ("this" and "that") is picking out a different event the truth of which is either doubted or not doubted. Importantly, though, the same can be said of these thoughts irrespective of whether they are from the same or different thought-worlds. Given this, in the case of (T3) and (T4), the problem of individuation remains. From an objective stance, how do we know if (T3) and (T4) belong to the same or different thought-worlds?
With examples (T3) and (T4), it is not even the case that the first person pronoun "I" is able to distinguish between thoughts in terms of individuating thought-worlds. Each thought could be from the same or a different thought-world, with "I" (as an indexical term) referring either to someone different or the same person depending on which thought-world the two thoughts are from. In order to overcome the problem of thought individuation in the absence of contradictory content and assumed rationality, there needs to exist some kind of identity relation in which the "I" refers to (and is understood to refer to) that which constitutes a particular thought-world. Consider, then, (T5) "A thinks 'I believe that this is true'", and (T6) "B thinks 'I do not believe that that is true'". Thought individuation is made apparent if and therefore because (in this case) there exists a different identity relation in each thought's respective use of "I". In (T5), "I" refers to A, and in (T6) it refers to B, although it could simply refer to "not A". Adapting D 1 so that it can be expressed from an objective stance, we get: D 2 I (qua A) doubt that I think that thought (where the demonstrative pronoun "that" refers to the content of a thought-world individuated as "not A") but not this thought (where the demonstrative pronoun "this" refers to the content of the thought-world individuated by A).
What does A represent? It represents a particular thought-world and therefore a particular perspective. The figurative use of A signifies this point of view and the thoughts constitutive of this point of view are these thoughts (the only thoughts of this perspective). The use of the first person pronoun "I", in being indexical, is fixed to a given perspective (this perspective, in this case), figuratively individuated by A. The certainty with which "I" constitutes something more than an indexical that is attached to a particular perspective (figuratively individuated by A or "not A", as the case may be) and instead identifies a substantive subject of thought (in the shape of, say, Descartes' res cogitans), is beyond the scope of this paper to discuss. Suffice it to say that all that is needed for this discussion is for there to exist a belief that "I" refers to the substantial subject of this perspective. When understood in this way, and in accordance with D 2 , the thought "I doubt that I think that thought but not this one" expresses a legitimate doubt.
Of course, under D 2 , I do not experience the thought I doubt thinking as if from nowhere; instead, I only conceive of it as belonging to a different thought-world, and therefore a different perspective, even if this perspective is simply understood as "other than mine". 5 As Williams (1978) notes when referring to the particular perspective constitutive of that which I (qua A) experience, which he calls Cartesian reflection: "There is nothing in the pure Cartesian reflection to give us that perspective [the view from nowhere]. The Cartesian reflection merely presents, or rather invites us into, the perspective of consciousness" (p. 100; emphasis added). Cartesian reflection, by inviting us into consciousness, is perspectival; and in being perspectival, there is something-it-is-like to have thoughts (thoughts constitutive of a particular point of view; see Nagel, 1974). As Williams informs us, from this perspective-which I will call my perspective-experiential events either happen for me or they do not. I cannot experience events as happening outside of this perspective. Indeed, the quotation from Descartes' Second Meditation presented at the start of this paper reflects this perspectival requirement: for Descartes scepticism concerns thoughts "located" within his mind and therefore constitutive of his perspective.
If the demonstrative pronoun "that" is referring to a thought-event in a different thought-world, identified figuratively as "not A", then, given my restricted (and unique) perspective, within the phrase "I doubt that I think that thought", the term "that", for it to be legitimate, must be referring to a thought-event outside my experience. If it is a thought I cannot experience, then I do not stand in any first person epistemic relation to it. At best, it refers to something which I either conceive as a possibility or come to believe occurs in virtue of some mediated third person epistemic relationsome inference-based on my folk psychology interpretation of the actions of another (e.g. if I see S put up his umbrella then I infer the existence of the belief "it is raining"). In contrast, the demonstrative pronoun "this", in referring to a thought I do not doubt, must be referring to something which I experience (in virtue of constituting a thought-event from within my perspective) and therefore something which I stand in a first person epistemic relation to. Let us reconsider D 2 , this time taking into account the fact that my unique perspective necessarily provides a means of differentiating thought-events which I experience from those which I do not. D 2 therefore becomes: D 3 I doubt that I think that thought (where "that" refers to some indeterminate thought-from within thought-world "not A"-whose existence I can only conceive of and infer rather than experience directly, and so cannot stand in a first person epistemic relation to), but not this thought (where "this" refers to a thought-event constitutive of my perspective which I experience directly and therefore stand in a first person epistemic relation to).
According to D 3 , what justifies my doubt that I am thinking that thought but not this one is my lack of direct experience of the former thought. That which I experience, I refer to using the demonstrative "this" and (according to D 3 ) consider the fact that I experience it (and therefore stand in a first person epistemic relation to it) sufficient to make illegitimate any claim about doubting that I think it. A thought I do not experience I refer to using the demonstrative "that", and the fact that I can only conceive of it occurring (and stand in a mediated third person epistemic relation to it) justifies my doubt that I think it. 6 What this means in terms of the use of demonstratives, of course, is that, in the context in which they are employed, "that" refers to an experiential event of which I can only conceive (namely, the occurrence of any indeterminate thought from outside of my perspective) whereas "this" refers to a particular experiential event that only I can experience. 7 It is worth noting that underlying D 3 is a more refined version of the ontological position stated earlier-"a thought necessitates a thinker"-in which the assumption is now that a thought I experience (a thought within my thought-world) necessitates that I am its thinker (henceforth "author"). I do not wish to dispute this ontological position. Instead, I seek to challenge the epistemic relationship described within D 3 which complements it (namely, that I do not doubt thinking this thought: the one I experience). It is my contention that the assertion that I do not doubt thinking the thought I experience (in virtue of experiencing it), if interpreted as necessitating that I cannot legitimately doubt thinking it (which is a reasonable interpretation of D 3 ) is erroneous. To understand why, consider the following statement: (1) A thought occurred just now but I do not believe that I was thinking it.
Statement (1) is entirely consistent with D 3 . There are lots of thoughts occurring right now that I am not thinking; it is therefore quite legitimate for me to doubt that I am thinking any of these. In light of this, consider statement (2): (2) I experienced a thought just now but I do not believe I was thinking it Statement (2) is not consistent with D 3 . At first glance, this may not appear to be a problem. After all, statement (2) seems a rather odd, perhaps even contradictory, thing to say; so why be concerned if a proposition that is likely to be illegitimate is inconsistent with D 3 ?
To understand why statement (2) is potentially problematic for D 3 , we first need to understand that statement (2) expresses what I am claiming is an indirect form of Moore's paradox. It is indirectly Moore paradoxical because it lacks the formal structure of Moore's paradox (as I will demonstrate below) whilst retaining a seeming contradictory set of conjuncts (indicative of Moore's paradox). On closer inspection, however, the first conjunct (concerned with experiencing a thought) does not contradict the second conjunct (not believing that I was thinking the thought) unless one enforces the entailment between experiencing a thought and thinking it. But even if one accepts that "I am experiencing p" entails "I am thinking p" (an ontological claim), this does not negate the possibility that one's epistemic relationship to the thought is such that there are nevertheless grounds-based on the nature of this epistemic relationship-for doubting that one is the author of the thought, and, importantly, that these grounds are justified.
A closer examination of the indirect form of the paradox is therefore informative, as it reveals an epistemic disparity in the relationship between oneself (qua author) and the thought as expressed within the two conjuncts in (2), even where one tacitly accepts the assumption I have been making about the entailment between a thought and its thinker. It is my contention that this epistemic discrepancy, in the face of ontological equivalence (see 4.1), is what legitimises statement (2)'s challenge to D 3 , thereby making erroneous the claim "I do not doubt this thought because it is a thought I experience" (where "do not" is taken to mean "cannot"). This, in turn, opens up the possibility of justified doubt regarding one's authorship of a thought one experiences, even when, owing to the ontological equivalence already noted, one is necessarily the author of the thought one has just experienced.
In order to defend the claim that statement (2) is an indirect form of Moore's paradox, and in order to gain further insight into what this reveals about the nature of the epistemic discrepancy said to exist in the presence of ontological equivalence, and how this makes legitimate the proposition "I doubt that I think that thought"-where "that" (contra D 3 ) refers to a thought I experience-let us briefly consider the structure of a traditional Moore paradoxical utterance.

Moore's paradox
The following is an example of Moore's paradox: (3) I went to the cinema today but I do not believe that I did. 8 More formally, this can be written p & ~ IBp, where p equates to going to the cinema today, and ~ IBp represents not believing that I did. 9 To those unfamiliar with Moore's paradox, at first glance, the proposition may appear to be a simple case of contradiction and therefore a somewhat peculiar or even absurd thing to say. Certainly, any alleged paradox may not be immediately apparent to the reader. So what is paradoxical about statement (3)?
The first conjunct (p) concerns some event in the world-a fact-which is either true or false: either I went to the cinema today or I did not (either p or ~ p must hold). The second conjunct (~ IBp) refers to some "inner" mental state of mine which, independent of the first conjunct, can also be true or false depending on whether I hold the belief or not. As a consequence, the first conjunct has nothing to say about my mental states, and the second tells me nothing about my actual cinema behaviour (Lawlor & Perry, 2008): for irrespective of whether I went to the cinema today, I can believe that I did or not. The truth or falsity of p is not therefore dependent on the truth or falsity of my belief about p, in much the same way as the truth or falsity of whether I hold a belief about p is not dependent on p. 10 Given the independence of each conjunct, it is possible that I went to the cinema today and equally possible that I do not believe that I did; just as (3) describes. Yet as Moore observed, even though each conjunct could be true-thus making the statement non-contradictory-the assertion of the conjunction (I went to the cinema today but I do not believe that I did) remains an absurd thing to say because it implies a contradiction. What is paradoxical about p & ~ IBp, then, is that despite the fact that the conjunction as a whole can be true and therefore non-contradictory, it cannot be coherently asserted (Vahid, 2005).

Selective scepticism 2: Evidence from an indirect form of Moore's paradox
Statement (2) has the appearance of a Moore paradoxical utterance although it does not conform to the formal structure found in (3). Instead, it takes the following form-q & ~ IBp(q)-where q equates to "experiencing a thought just now" and ~ IBp(q) equates to "not believing that I was thinking that thought". Given this structure, the truth or falsity of q is independent of the truth or falsity of ~ IBp(q). For (2) to be Moore paradoxical, one would have to endorse the entailment between q and p(q), such that q (experiencing a thought just now) entails p(q) (thinking that thought). Only by endorsing such an entailment would statement (2) contain all the hallmarks of a Moore paradoxical utterance. To illustrate, consider statement (4): (4) I experienced a thought just now (which entails I was thinking it) but I do not believe that I was thinking it.
Put differently, but reflecting the entailment in (4), the traditional Moorean structure (p & ~ IBp) becomes more evident when expressed as follows: (5) I was thinking a thought just now but I do not believe that I was thinking it

Ontological equivalence; epistemic discrepancy
The ontological implication of "q entails p(q)" is that experiencing the thought and thinking it amount to the same event. This means that statements (2) and (5) are ontologically equivalent insofar as the mental event <experiencing a thought> is equivalent to the mental event <thinking that thought> even though they are differently described, at least within the first conjunct of conjunctions (2) and (5). Of course, where it is accepted that q is ontologically equivalent to p(q)-more formally, q = p(q)then it is somewhat unremarkable to add that q entails p(q). But if statements (2) and (5) are ontologically equivalent, insofar as they pick out the same mental event, then what is revealed by any further comparison between (2) and (5) is that the epistemic relationship between the first and second conjuncts described in (5) does not match the epistemic relationship the subject has with what we now understand to be the same mental event described in (2). This is evidenced by the fact that statement (5) expresses an epistemic relationship between the first and second conjuncts that is prima facie contradictory in a way that the relationship between the first and second conjuncts in statement (2) is not.
To illustrate, the seeming contradiction within traditional Moore paradoxical utterances (p & ~ IBp) is often explained as follows: when uttered intelligently, "that p" is understood to be equivalent to one's belief that p (Evans, 1982;Williams, 2004). What is implied within statement (3) (I went to the cinema today but I do not believe that I did) is made explicit in statement (3*) "I believe I went to the cinema today but I do not believe that I did". Transferring this to (2) (I experienced a thought just now but I do not believe that I was thinking it), we get (2*) "I believe I experienced a thought just now but I do not believe that I was thinking it". What the subject believes within the first conjunct of (2*) is therefore not equivalent to what they believe within the first conjunct of (5), as is made even more apparent when expressed as follows: (5*) "I believe I was thinking a thought just now but I do not believe that I was thinking it". The epistemic positions differ insofar as the subject believes, according to the first conjunct in (2*), that they have just experienced a thought, compared to believing they were thinking a thought (as claimed within the first conjunct of (5*)). Now, whilst the mental event that each belief is about may be ontologically equivalent, owing to the entailment between q and p(q) (as discussed), the manner in which each mental event is described within the context of the belief expressed, which differs in the respective first conjuncts of statements (2*) and (5*), means that the epistemic relationship the subject has with the mental event is not equivalent. As a result of this difference (and to reiterate my earlier claim), the epistemic relationship between the first and second conjuncts of statement (2*) is not prima facie contradictory, unlike that found in statement (5*).
Given the prima facie contradiction inherent in statement (5*) but absent from (2*), consider the following remark by Shoemaker (1995): "what can be coherently believed constrains what can be coherently asserted" (p. 227). In the case of (5*), Shoemaker's constraint clearly applies because what is believed is prima facie contradictory (as noted) and therefore cannot be coherently asserted. But what about (2*)? Here, what is believed is not prima facie contradictory, even though what is believed cannot be true given the entailment between q and p(q) and the ontological implication of this. Given that there is no prima facie contradiction in (2*), might there be grounds to justify those beliefs underlying the assertion found in (2*), thus making the proposition "I doubt that I think that thought but not this one" legitimate?
As a means of considering this question, in Part 2 I present findings from the field of developmental psychology indicating that children learn-qua acquire the belief-that the thoughts they experience are their thoughts that they think. The association between a thought and its thinker, then, irrespective of whether one endorses the ontological position presented here, is not an epistemic given. In other words, it does not constitute innate knowledge that we possess but, rather, is something we come to believe over time. If we acquire this belief then one might conjecture that such a belief is open to change, such that under certain circumstances one might come to doubt the association between thought and thinker. When speculating about what these circumstances might be, I draw on contemporary explanations of thought insertion to inform my discussion.

Developing an awareness of thinking
According to Flavell, Green, and Flavell (1995; see also Flavell, 1999), preschool children (aged between 3 and 5) understand that thinking is a private activity which occurs "in the head". Around this time, they also acquire an understanding of themselves as "knowers": that their thoughts amount to a source of knowledge for them (Kuhn, 2000). Preschoolers are, however, poor at identifying when someone is thinking, even in the case of their own thoughts. They do not assume, for example, that they must have been thinking when engaged in a task (Flavell, Green, & Flavell, 1993); neither do they always show an understanding of what they might have been thinking about or even what others might be presently thinking about in a given context (Flavell et al., 1995). In fact, Flavell and Wong (2009) conclude that, to a large extent, preschoolers severely underestimate the amount of mental activity taking place within a person (including themselves) at any given time. 11 They fail to realise (it seems) that individuals, including themselves, experience a continual flow of mental content; an unstoppable stream of consciousness (James, 1890)-what Harris (1995) calls an "involuntary pulsation" (p. 51)-even in someone who may not be trying to think of anything in particular (see Flavell, Green, & Flavell, 1998). This has led Flavell, Green, Flavell, and Lin (1999) speculatively to claim that "children are less aware than adults of the experiential, what-it-is-like-to-have-them, aspects of conscious mental states such as thoughts and percepts, and instead focus almost exclusively on their cognitive content" (p. 411). In short, an accurate description of the preschoolers' ability is that these children are introspectively aware of thought content before they begin to understand what thinking is (that it involves a thinker, for example), let alone that they themselves continually engage in thinking.
Alongside this general lack of awareness of the fact that they are thinking, preschoolers show little understanding of cognitive cueing (Gordon & Flavell, 1977). They do not appear to understand that mental events trigger other mental events, usually in a coherent manner related to one's experiences. Thus, Flavell et al. (1995) describe young children's concept of thought as being quite different to adults.
First, the concept of a thought (thinking, mental activity etc.) is doubtless less salient for them than it is for most adults; they do not think about thoughts very often spontaneously. When they are brought to think about them, however, they are more likely than adults to regard them as isolated and largely inexplicable mental happenings, not linked to preceding cues or subsequent effects. Although they may occasionally become aware that something instigated a thought (e.g. an instruction to think, an emotionally arousing situation) or that a thought instigated something (e.g. an action based on that thought), the question of possible causes and effects usually does not even arise for them when thinking about thinking. (pp. 84-85) It would seem that even if preschoolers do demonstrate awareness of the act of thinking, because they lack an understanding of cognitive cueing, it is not equivalent to the older child/adult's awareness of their stream of consciousness. Instead, this awareness, such as it is, is of isolated islands of thought. Moreover, because preschoolers lack sustained awareness of their own mental activityowing to their sporadic ability to perform meta-cognition (or reflexive thinking)-they are less likely to be aware of their own "mental history" (Flavell et al., 1995;Flavell, Green, & Flavell, 2000). So, when performing a task which requires them to express their thoughts, the process by which they arrive at a given solution or judgement will be less accessible to them compared to older children and adults. As such, by the time children enter kindergarten, the child's ability to perform metacognitions is only rudimentary and effortful (Dimmitt & McCormick, 2012). Therefore, if distracted, such that their thoughts "stray", they may be less likely to notice that this distraction has impacted their own thinking, resulting in the production of less relevant thoughts. In fact, on those limited occasions when a preschooler is aware of the fact that she is thinking x, she remains largely ignorant of the fact that this process forms part of her continuous stream of consciousness, and to whether it was a thought she initiated (through the process of cognitive cueing) or was unbidden (Flavell et al., 1998).
Preschoolers understand that thoughts are private inner entities, but this does not necessitate that they further equate inner and private with personal ownership (either with these thoughts being my thoughts, or with them being thoughts I think); nor are they aware of the subjective-whatit-is-like-to-have-them-quality of thoughts. The discrepancy between an awareness of the content of thought and the act of thinking that thought indicates that preschoolers do not yet understand that these private inner entities are necessarily generated, let alone self-generated. As such, "[f]or a child for whom the world of thought is largely causeless, any thought might occur at any time" (Flavell et al., 1995, p. 86). Given this, even if we endorse the premise that experiencing a thought necessitates thinking it, it does not follow that experiencing thoughts necessitates experiencing thinking: if by "experiencing thinking" one means experiencing it as thinking: for, as we have seen, this is not the case in preschoolers.
Where S has cognitive abilities equivalent to the preschooler, S would not have formed the belief that they are thinking and are therefore the author of the content of the thoughts experienced. But how does this help us assess the legitimacy of selective scepticism regarding thought? Given S's cognitive abilities, a lack of belief about the authorship of a thought is the case for any thought content experienced, not just for some: that one, say, but not this one. What the developmental literature reveals is that one's belief about being the author of thought is not a given; it is something we acquire. Once acquired, the mechanism underlying this belief acquisition must function consistently. For selective doubt to occur, one could conjecture that this mechanism is functioning intermittently. This possibility will be explored in the next section with reference to the pathological condition known as thought insertion.

Thought insertion
Thought insertion is characterised by the subject's attribution of their thoughts to someone else, such that "it is as if another's thoughts have been engendered or inserted in them" (Cahill & Frith, 1996, p. 278). As Gerrans (2001) further explains: [T]he subject has thoughts that she thinks are the thoughts of other people, somehow occurring in her own mind. It is not that the subject thinks that other people are making her think certain thoughts as if by hypnosis or psychokinesis, but that other people think the thoughts using the subject's mind as a psychological medium. (p. 231) The subject claims that certain thoughts are being put into their mind, like "Kill God" (Frith, 1992, p. 66). There is something about the occurrence of these thoughts specifically that leads the subject to believe that they have been inserted. What, then, is the means or mechanism by which the subject is discriminating between thoughts they doubt thinking and thoughts they do not? 12 A number of explanations of thought insertion have been proposed over the years. My intention, here, is not to critique these or provide any kind of review. Instead, by presenting suitable candidates from among these explanations, I aim to support the legitimacy of the proposition "I doubt that I think that thought but not this one" and so provide a way to justify, epistemically, selective scepticism. As a means to that end, I present explanations proffered by Fernández (2010) and Billon (2013).
When considering the phenomenon of inserted thoughts, Fernández asks: What does the subject experience? In response, he states: she experiences a lack of commitment to a particular belief; a belief which, in virtue of this lack of commitment, is experienced as "inserted". To understand how this might come about, Fernández presents an account of how we typically become committed to our beliefs (concerning our thoughts and perceptions); something he refers to as the "bypass" procedure or model of self-knowledge. As he explains: The bypass model of self-knowledge … is a view about what constitutes our epistemic grounds for believing that we have a certain belief. The view is that the mental states that constitute our evidence or grounds for a given belief (states such as our perceptual experiences or our memory experiences) perform a sort of double duty. They entitle us to have that belief, and they also constitute our evidence or grounds for the meta-belief that we have it. (2010, p. 81) By his own admission, Fernández employs an "undemanding notion of epistemic justification" (ibid.) in which a belief is justified if it is a belief that regularly co-occurs with a particular mental state (e.g. the belief that there is a chair in front me is justified if it regularly co-occurs with the perception I have of a chair in front of me). Certainly, the epistemic relationship described here is not of the kind demanded by Descartes' method of doubt (for example); Fernández does not require certainty, just reliability. The epistemic relationship employed within the "bypass model" therefore seems compatible with selective scepticism.
To explain: the "bypass" process concerns the manner in which we acquire evidence to justify a particular belief we hold. Let us say that I perceive a chair in front of me. In doing so, I acquire the first-order belief with content "there is a chair in front of me". Given this is the case, consider the extent to which the following two questions differ: (i) Do you believe that there is a chair in front of you? (ii) Is there a chair in front of you? Based on the level of epistemic justification we are operating at, it would make little sense to answer "yes" to one and "no" to the other. One's response to the question "Is there a chair in front of you?" reveals one's belief on the matter. Thus, when asked "Do you believe that there is a chair in front of you?", I do not need to introspect and search out my belief; rather, I turn my gaze outward to see if there is indeed a chair there. What justifies my belief (my meta-belief: believing that I have the first-order belief) such that I feel justified in believing that there is a chair in front of me is the same evidence that justifies my first-order belief with content "there is a chair in front of me". When answering (i), I bypass the need to introspect in order to justify my meta-belief, and in fact answer the question using the same process I would use when responding to (ii).
Under normal circumstances, when answering "yes" to the question "Is there a chair in front of you?", I am committed to the belief-my meta-belief-that there is a chair in front of me (I metabelieve that there is a chair in front of me; recall the explanation of Moore's paradox in Section 3; see also Evans, 1982;Williams, 2004). Similarly, if I am thinking about chairs and their relative location to me, typically, I am committed to the following: "I meta-believe I am thinking about chairs … (etc.)". Through "bypass" the epistemic justification for one's first-order belief and one's meta-belief is the same (again, based on the relatively undemanding epistemic justification we are operating at, which is compatible with D 3 ); but, more than this, one's meta-belief acts to endorse the content of one's first-order belief: one is committed to its content as something one believes. What Fernández suggests in the case of thought insertion, however, is that the subject cannot always commit to a first-order belief based on the process of "bypass".
Where there is disruption in the process of "bypass", the same evidence used to justify the firstorder belief corresponding to the presence of a chair in front of me no longer provides sufficient justification for the meta-belief "I believe that there is a chair in front of me". In the absence of such a meta-belief, the thought I am experiencing with content "there is a chair in front of me" does not correspond to any meta-belief I possess-in contrast to what would be the case if the process of "bypass" were working normally-and so is not recognised by me as a thought I have initiated. By not committing to the first-order belief, I do not endorse it. Consequently, I doubt that I am its author.
What remains unclear, however, is how the disruption in "bypass"-which results in a lack of commitment and endorsement-manifests itself to the subject, such that it should be experienced as "inserted", and whether this change is the means by which discrimination in authorship occurs. Is there, for example, a change in the subjective quality of the experience of the first-order belief, and is it this qualitative shift that justifies (at least to the subject) selective scepticism? It is not clear from Fernández's account what the evidence is (again, from the subject's perspective) that justifies the lack of commitment to the first-order belief and so justifies that that thought does not correspond to a (meta-) belief I possess, which then allows me to doubt it is a thought I was thinking. There is, of course, the possibility that the failure to commit occurs at the subpersonal level (although, given the absence of research, such a possibility remains unsubstantiated). In short, what remains unresolved is what it is like (if it is like anything) for a failure in "bypass" to occur and whether this change acts as a means of discriminating between thoughts, and so as a means of justifying the kind of selective scepticism we are discussing here.
Interestingly, Billon (2013) proffers just such a qualitative shift as a mean of identifying and therefore distinguishing "inserted" from "non-inserted" thoughts. Billon acknowledges that subjects are reflexively aware of putatively inserted thoughts-insofar as they have adequate introspective access to them-and also that they accept that these thoughts occur within the boundary of their experience (constitutive of their perspective; again, as required by D 3 ). However, for Billon, what inserted thoughts are not is phenomenally conscious. Typically, thoughts, in virtue of occurring within the bounds of my perspective, are accompanied by a certain something-it-is-like-for-me to have them (as touched on previously), thereby making the thought phenomenally conscious. This quality, one might conjecture, increases my commitment to the thought (the first-order belief), in keeping with Fernández's account, and so contributes to the formation of the corresponding meta-belief with the same content (again, as described by Fernández). What is missing, in the case of thought insertion, Billon conjectures, is this phenomenal quality, such that (as subject) there is nothing-it-islike-for-me to have these thoughts. What I experience, then, is a thought I have normal introspective access to, occurring within my perspective, but for which there is nothing-it-is-like-for-me to have the thought (recall the extract presented in Section 1, taken from the patient suffering from thought insertion, in which she described something feeling different in the case of the putatively inserted thought). The lack of phenomenal quality corresponds to a qualitative shift, I contend, which one might surmise, in virtue of the absence of phenomenal consciousness (or even a salient sense of its loss with regard to that thought) means that there is insufficient evidence to justify any commitment to the thought (the first-order belief).
Something to consider, of course, is whether the lack of phenomenal consciousness is the result of a failure to commit to the first-order belief (which is compatible with a higher-order thought theorist's approach to phenomenal consciousness in which a higher-order thought (meta-belief) is necessary for phenomenal consciousness) or whether, as the result of some form of disruption, there occurs a lack of phenomenal consciousness which would normally accompany the first-order belief (as posited by first-order thought theorists), the absence of which prevents one's commitment, or perhaps further reinforces one's lack of commitment, to the thought. Billon's position would seem to be more compatible with the latter view.
As a final point, it is worth emphasising that, throughout this paper, the epistemic justification I have sought is merely that which justifies one's selective doubt; in other words, that which provides a reason to be sceptical over one's authorship of certain thoughts. I am not trying to defend a stronger position in which the subject is justified in believing "not p" (as opposed to doubting-qua not believing-p). After all, one could have a reason to be sceptical about p without having a sufficient and therefore justified reason to believe "not p". In the case of thought insertion, the subject typically makes the stronger claim: "I believe 'not p'" (namely, I believe that this thought is not something I think). My selective use of explanations of thought insertion is therefore purely instrumental, insofar as drawing on these explanatory accounts allows me to conjecture over the mechanism(s) that may impact one's belief system. Such impact, I contend, is enough to justify doubt over the authorship of some thoughts-at least from the point of view of the subject-as it provides the subject with sufficient evidence (and therefore reason) to doubt the authorship of those thoughts; but I would not go so far as to say that what has been presented here justifies the belief that one is not the author of certain thoughts.

Conclusion
In conclusion, what I hope to have shown in this paper is that there are epistemic grounds to justify selective scepticism over the authorship of one's thoughts, thereby making the proposition-"I doubt that I think that thought but not this one"-legitimate. Even where one accepts the entailment between a thought and its thinker (culminating in a particular ontological position), there is nevertheless a case to be made for epistemic discrepancy sufficient to invite and even justify the kind of selective scepticism discussed here. Whilst the argument presented has drawn on respected empirical work in the field of child development, strongly suggesting the acquisition of certain beliefs regarding thought and oneself as thinker (as opposed to this being a given), I nevertheless acknowledge that the same argument has selectively drawn on more speculative work, specifically regarding explanations of thought insertion (pace these authors). My aim in presenting some of these tentative claims has been merely to proffer conjecture: to speculate over what form the mechanisms underlying selective scepticism might take and, subsequently, what might constitute the epistemic basis for this scepticism.

Funding
The author received no direct funding for this research.

Citation information
Cite this article as: Selective scepticism over thought: Am I ever justified in doubting that I think that thought but not this one?, Garry Young, Cogent Arts & Humanities (2016), 3: 1145567.
Notes 1. One could also argue, in this case, that in addition to doubting that I think those thoughts, one is justified in believing that those thoughts are not thoughts that I think. The focus of this paper, however, is on what constitutes evidence to justify selective scepticism. I do not intend to discuss what might constitute sufficient grounds for a belief (even a belief that something is not the case). 2. Although I say pace Russell and Nietzsche (see Nietzsche, 1886Nietzsche, /2003Russell, 1927Russell, /1970Russell, , p. 171, 1946Russell, /1961, in a sense this is unnecessary because these authors question the certainty with which Descartes, using his method of doubt, could legitimately claim to know that there is an "I" which thinks and not necessarily that an "I" which thinks, or is the subject of thought, exists. This epistemological objection was, of course, first raised by Lichtenberg (1806Lichtenberg ( /1990). 3. The normative position alluded to here is based on the law of non-contradiction, whereby believing ɸ and not believing ɸ is contradictory. Following the law of non-contradiction, if one were to believe ɸ, and equally not believe ɸ, then one would be considered irrational. Priest (2006), however, challenges this position. He accepts that, prima facie, a contradiction presents itself but adds that, on occasion, one could nevertheless rationally believe and not believe the truth of ɸ. By adopting dialetheism, Priest proposes the truth of some contradictions: for example, that the proposition "I always lie" is both true and false when uttered by a liar, thereby making it something that can be believed and not believed to be true. Given dialetheism, the law of non-contradiction is not universally accepted (I thank the anonymous reviewer for bringing this fact to my attention). Nevertheless, the possibility of the truth of contradictions, and therefore the possibility of contradictory beliefs, does not threaten the point I am making. If anything, it adds to the problem of individuating thought under the circumstances described. 4. Again, such a normative claim is based on the law of non-contradiction (see Note 3). 5. For the sake of argument, I assume the existence of other minds (therefore other thought-worlds). I therefore assume that there is sufficient evidence to justify the belief in the existence of other minds, even if this evidence is not direct experiential evidence. What I doubt, based on a lack of direct experiential evidence, is that I think those thoughts. 6. It is the case, of course, that I do not experience thoughts occurring at the subpersonal level (that is, below the level of conscious awareness). The extent to which one is justified in doubting these thoughts would make for an interesting discussion that, unfortunately, is beyond the scope of this paper. 7. For simplicity's sake, I am using the term "thought" in the context of an experiential state to mean something linguistic rather than, say, pictorial (an image). Thus, the thought I experience is, for example, the phrase "Marry, Mary, quite contrary", rather than the image of a young lady tending her garden. 8. Adapted from a version used by Moore (1942, p. 543). http://dx.doi.org/10.1080/23311983.2016.1145567 9. This is an example of the omissive form of the paradox.
The paradox can also be presented in the commissive form: p & IB~ p (I went to the cinema today and I believe that I did not). Only the omissive form is discussed in this paper. This fact should not detract from the argument presented, however. 10. The same cannot be said for the truth or falsity of the content of the belief, of course-that is, what the belief is about-which is dependent on p (in this case, on whether I went to the cinema today or not). 11. Interestingly, preschoolers are likely to overestimate the "strength" of their memory; claiming prior to a memory test that they will remember far more of the items to be recalled (sometimes all of them) than they actually do (Lipko, Dunlosky, & Merriman, 2009;Van Overschelde, 2008). 12. In this paper, I am concerned with the act of doubting (qua not believing) "that p" and not with believing "not p". Those suffering from thought insertion often believe "not p"-believe, that is, that they did not think these thoughts-rather than simply doubting (qua not believe) p: that they were the one thinking these thoughts. A prerequisite of believing "not p", however, is doubting "that p". For this reason, I consider the phenomenon of thought insertion to be pertinent to the issue of selective doubt.