## 1. Inner Speech as Actual Speech



The auditory-sensory character of inner speech is usually thought to
be due to its involvement of auditory-verbal imagery (for an
exception, see O'Brien 2013). Mental images (in any modality)
are generally viewed as representations of particular things (or kinds
of thing), not instances of those things. A visual image of a duck,
for example, is a representation of a duck, not an actual duck.
Likewise, it may seem that inner speech, insofar as it involves
auditory imagery, is a representation of speech (and of its sounds, in
particular), not actual speech. "Grass is green", produced
in inner speech, would then represent an utterance of the sentence,
"Grass is green", but it would not actually be an
utterance of that sentence.



Notwithstanding this, many philosophers working on inner speech hold
that inner speech really is a kind of speech. When we produce inner
speech, we are literally speaking, albeit silently. We will call this
view the "actual speech view". Proponents include
Carruthers (1996), Martinez-Manrique & Vicente (2010,
2015), Gauker (2011, 2018), O'Brien (2013), Jorba & Vicente
(2014), Gerrans (2015), Gregory (2016, 2018) (though Gregory has
indicated in more recent work (e.g., Gregory forthcoming) that he no
longer holds the view), Machery (2018), Wilkinson & Fernyhough
(2018), Wilkinson (2020), and Frankfort (2022).
Martinez-Manrique & Vicente argued for the view in their
2010 paper; their 2015 paper, discussed in
 Section 3.3.2,
 sets out an updated version of their theory which incorporates some
further commitments. Historically, the view can be traced at least to
the Soviet psychologist, Lev Vygotsky (1934 [1986]), and it was also
held by Ryle (1949 [2009]). However, Gauker develops a somewhat
different version of the view--one that sharply distinguishes
inner speech from the auditory-verbal imagery typically associated
with it (see
 Section 3.2
 for discussion)--which has its origins in Sellars (1956).



If inner speech is a kind of speech, instances of inner speech could
aptly be called "inner speech utterances", as producing
inner speech would really amount to saying something. However, in
order to be neutral on the issue, we will use the term, "inner
speech episodes", in this section and throughout the entry. An
important issue for a proponent of the actual speech view is to
explain how inner speech can consist of genuine linguistic tokens,
given that it seems to be an imagistic phenomenon--where, as
noted, the images may appear to be representations of speech sounds.
For, even if inner speech consists of images of speech sounds, this
only suggests that it consists of *representations of*
linguistic items, not linguistic items themselves.



One style of answer has been offered by Sam Wilkinson (2020), who
draws a distinction between imagery and imagination. He holds that
sensory imagining is a "personal-level phenomenon", which
has components (2020: 16). One of the components of sensory imagining
(as opposed to propositional or "attitudinal" imagining,
which is typically assumed to be non-imagistic in nature) is mental
imagery. For example, if one sensorily imagines a duck, then one
component of this personal-level mental state may be a mental image
resembling the appearance of a duck. There might also be other
components, such as a stipulation that the image is an image of a duck
and not another bird of similar appearance. But, Wilkinson emphasizes,
mental imagery can be involved in many personal-level mental attitudes
apart from the attitude of imagining, such as remembering, judging,
reasoning, and others. "In a similar way", he claims,



> 
> 
> imagery ... may be involved in an inner assertion. That does not,
> however, make the inner assertion simply nothing more than the imagery
> involved in its production, still less an act of imagination. (2020:
> 16).
> 
> 
> 



Imagery can play many roles, Wilkinson is saying, and there is no
reason that one of those roles should not be as a medium for
linguistic tokens. The inner assertion is "a genuine
assertion"--an instance of language consisting of
imagery.



It might be replied that, although imagery can play a role in many
personal-level mental states apart from imagining, it plays a very
similar role in all of them, viz., representing how a concrete object
(whether actual or possible) appears or sounds. Mental imagery does
not tend to play a role similar to that of a linguistic token. So,
even if mental imagery is involved in a range of personal-level mental
states, it is not obviously well-suited, in the case of inner speech,
to play the specific role of actual linguistic tokens.



This challenge might be met by connecting the actual speech view with
work on the metaphysics of word tokens, as proposed by Wade Munroe
(2022a, 2023). Munroe holds that



> 
> 
> what makes something, *ph*, a token of a word type,
> *w*, is that the process of generating *ph* is
> explained and guided by one's (tacit) knowledge of *w*
> (or the morphological structure of *w*), e.g., one's
> semantic, syntactic, morphophonological/orthographic, knowledge of w
> stored in one's mental lexicon. (2022a: 4)
> 
> 
> 



This allows him to hold that inner speech episodes can involve word
tokens, insofar as their generation is guided by the relevant kind of
tacit knowledge. (Though Munroe himself does not hold the actual
speech view; see
 Section 3.3.1
 for discussion of his view.) Relatedly, J. T. M. Miller (2021)
explicitly denies that word tokens are necessarily substances and
holds, instead,



> 
> 
> that particular or token words are objects, which are bundles of
> various sorts (most notably semantic, phonetic, orthographic, and
> grammatical) properties. [sic] (2021: 5737)
> 
> 
> 



One might hold that inner speech episodes in fact consist in such
bundles.



Although the matter of how inner speech episodes can involve genuine
linguistic tokens is of great importance for the actual speech view,
it is only beginning to receive attention. However, several arguments
have been given in support of the theory generally. These include the
following:


1. Inner speech may be a developmental descendant of a kind of
external speech. Piaget (1923 [1926/1959]) observed that young
children have a practice of speaking to themselves aloud. He described
this kind of speech as "egocentric speech" (ibid, passim)
(egocentric speech can be seen as one kind of private speech; see
Introduction). Vygotsky (1934 [1986]) presented empirical evidence
that inner speech develops in children as they internalize the
practice of producing egocentric speech (though see Gregory
(forthcoming) questioning this evidence). Vygotsky held that
egocentric speech becomes silent, inner speech, but that it does not
change in its fundamental nature, so it remains a kind of actual
speech (see also Wilkinson & Fernyhough (2018), Wilkinson
(2020)).
2. Introspectively, it seems like we can perform speech
acts--e.g., make assertions and ask questions--in inner
speech. But it would only be possible to perform speech acts in inner
speech if inner speech is a kind of speech (Wilkinson 2020; Wilkinson
& Fernyhough 2018). (This issue is addressed further in
 Section 4.1.)
3. On the face of it, we produce inner speech for purposes such as
focusing our attention, motivating ourselves, and evaluating our
actions. These correspond to purposes which instances of external
speech also often serve: focusing the attention of others, motivating
them, and commenting on their actions. There are also parallels in
terms of how inner speech episodes and instances of external speech
are constructed. Both often take the form of short, sub-sentential
items when this is sufficient (e.g., "Here!", upon finding
something which was lost) and more fully elaborated sentences when
this is necessary (e.g., when carefully listing the considerations
relevant to a difficult decision which needs to be made, whether by
oneself or by a group). Marta Jorba, Agustin Vicente, and
Fernando Martinez-Manrique have taken these systematic
parallels as evidence that inner speech and external speech are simply
different types of one phenomenon, namely, speech (Jorba & Vicente
2014; Martinez-Manrique & Vicente 2015).
4. There seems to be a contrast between imagining speaking and
engaging in inner speech, as it is ordinarily understood. This
contrast, Gregory (2016) suggests, parallels the contrast between two
kinds of external actions which we can perform. When an actor says the
lines in their script, what they are producing is a representation of
speech that someone else might produce. The actor is, of course,
speaking, but they are doing so in the context of a pretense. What the
actor is doing contrasts with the speech which they produce in, e.g.,
an ordinary conversation with someone. The contrast between imagining
speaking and producing inner speech seems to map neatly onto the
contrast between what the actor does on the stage and what they do in
an ordinary conversation. If this is so, then a natural analysis is
that the contrast between imagined speech and inner speech is a
contrast between a representation of speech and actual
speech--which implies that inner speech is a kind of actual
speech.



A couple of philosophers who hold the actual speech view but express
it in different terms, or who hold very similar positions, should be
mentioned. First, Philip Gerrans (2015) describes inner speech as
involving "imaginary action" (2015: 296), but he is
explicit that, by this, he means only to say that producing inner
speech is an action performed covertly. He takes inner speech to
involve speaking, but doing so silently.



Second, Johannes Roessler (2016) holds that there are different kinds
of inner speech, one of which involves imagining speaking (rather than
actually speaking), but in a particular way. He points out that we can
imagine things, or imagine doing things, for different purposes. An
act of imagining will then be successful to the extent that it
achieves the purpose for which it is performed. So, one might, for
example, imagine making an assertion, but do so with the intention of
imagining making an assertion which is true and relevant to context.
Then the act of imagining making the assertion "incurs the same
liabilities" (2016: 548) that the act of actually making the
assertion would incur. If you are puzzling over some question, and you
imagine asserting a possible answer, then the act of imagining will be
successful only if you have imagined asserting the correct answer.
Although you have only imagined performing the speech act of making an
assertion, your imagined assertion will be "in some ways
tantamount to an assertion" (2016: 548).



It would be an open position, though not one Roessler takes, that all
inner speech episodes could be analyzed in this way. On such a view,
inner speech episodes would be something very similar to actual
speech, yet without quite being speech acts, and thus without the
commitment that producing inner speech involves producing actual
linguistic items.


## 2. Inner Speech and Thought



A second question about inner speech is how it relates to thought. It
*seems* that there must be some relationship, but it is an open
question what that relationship is. In general, there are three views
about the nature of the relationship: (1) inner speech episodes
*express* thoughts; (2) inner speech episodes
*facilitate* thoughts; and (3) inner speech episodes (at least
sometimes) *are* thoughts of a certain kind.



The views are not mutually exclusive: one can certainly hold that
inner speech is related to thought in multiple ways.


### 2.1 Inner Speech and Thought Expression



Langland-Hassan & Vicente (2018b: 10) observe that the view that
inner speech (at least often) expresses thoughts that are distinct
from the inner speech episodes themselves coheres with some larger
theories about thought and language. If one is attracted to these
theories, then they may well also be attracted to the view that inner
speech merely expresses thought.



First, there is a natural connection between the language of thought
hypothesis, most closely associated with Jerry Fodor (1975), and the
view that inner speech expresses thought. On the language of thought
hypothesis, our thoughts do take place in a language, but not in a
natural language. Rather, our thoughts take place in a kind of mental
language, often referred to as "Mentalese". If the
language of thought hypothesis is true, then, insofar as inner speech
is keyed to a natural language, it seems that inner speech can at most
serve to express the thoughts which occur in the mental language.



Second, on Willem Levelt's influential theory about language
production, speaking involves conveying a pre-existing
"message" (1989: passim). The structure of this message is
conceptual but not linguistic. Via several stages of processing,
natural language sentences (or sub-sentential items) are formulated
which, once articulated, express the conceptually structured message
with which the process started. If one thinks that inner speech is
actually a kind of speech, then one might incline to think that inner
speech also expresses a pre-existing message.



Thus, Peter Carruthers (2009, 2018) approaches matters from a Fodorian
and Leveltian angle when he proposes that



> 
> 
> the first metacognitive access subjects have to the fact that they
> have a particular belief is via its verbal expression (whether overtly
> or in inner speech). (2009: 125)
> 
> 
> 



For Carruthers, the inner speech episode is not a belief or judgment
itself, but rather the expression thereof (see
 Section 5.2).
 In a similar way, Ray Jackendoff (1996, 2007, 2011, 2012) emphasizes
the distinction between thought itself and the auditory imagery by
which it may be expressed, identifying only the latter with inner
speech (see
 Section 3.1).
 Likewise, Jose Luis Bermudez (2003) and Jesse Prinz
(2011) distinguish between conceptual thought itself and inner speech,
while holding that we often come to know what we are thinking by
attending to inner speech sentences that we might use to express such
thoughts. They stop short of explicitly claiming that such sentences
actually express thoughts, however, specifying instead that the inner
episodes are sentences through which such thoughts "might be
expressed" (Bermudez 2003: 164), or that we "would
use" to express them (Prinz 2011: 186) (see
 Section 5.1).



One can, however, hold that inner speech episodes express thoughts
without committing to the view that a thought must be fully-formed
prior to the production of the relevant inner speech episode.
Jose Luis Bermudez (2018), for example, holds that
producing an inner speech episode can actually play a role in forming
the thought which it expresses. For Bermudez, a thought can be
refined and precisified as an external utterance is being produced
and, equally, a thought can be refined and precisified while an inner
speech episode is being produced. Nonetheless, by the time an inner
speech episode has been produced, it will express an existing
thought.



Finally, it is worth noting the following point of contact between the
actual speech view, discussed in
 Section 1,
 and the question of whether inner speech expresses thought. If it is
an essential feature of speech that it serves to express thought, then
defenders of the actual speech view are likewise committed to the view
that inner speech expresses thought. If, on the other hand, one holds
that there can be (inner) speech that does not express thought, then
the question arises as to what the difference between (inner) speaking
and thinking in a natural language might be--and whether there is
indeed a difference.


### 2.2 Inner Speech and Thought Facilitation



There have been several suggestions as to how inner speech might play
a substantive role in facilitating thought or thought
processes--a role that goes beyond merely expressing thought
processes.



First, inner speech is often thought to play an important role in
working memory. According to Alan Baddeley's influential theory
of working memory (e.g., Baddeley 1992), we can retain a series of
words or numbers in working memory by reciting them in inner speech. A
short series of items will be retained long enough to recite them
again. One can iterate this process via a "phonological
loop" for as long as desired.



Following Vygotsky (1934 [1986]), Clowes (2007) and Jorba &
Vicente (2014) hold that inner speech can serve as a tool for
directing our own attention, just as external speech can serve as a
tool to direct the attention of others. In making this case, both draw
on the Vygotskyan developmental account of inner speech, on which
inner speech is derived from the external phenomenon. See also
Martinez-Manrique & Vicente (2015), who make the same point
but are less directly influenced by Vygotsky's original (1934
[1986]) developmental account.



There is evidence that inner speech facilitates various executive
function tasks, such as planning, task-switching, and inhibiting
impulsive and inappropriate responses, without being essential to
them. The evidence that inner speech can play a role in these tasks is
primarily empirical. For reviews of the relevant literature, see
Alderson-Day & Fernyhough (2015) and Petrolini, Jorba, &
Vicente (2020).



Munroe (2022b; forthcoming) argues that inner speech plays a role in
reasoning which goes beyond merely aiding or improving it. He notes
that reasoning processes often involve preserving representations in
working memory. In doing complex mental arithmetic, for example, one
might recite in inner speech the word for a number which they have
determined will be needed later in the process, e.g., when regrouping
values (i.e., "carrying" and "borrowing"). The
number word will be stored in working memory via the process described
above. But, on Baddeley's model of working memory, which Munroe
is working with, only sensory representations can be stored in working
memory. In the present context, this means that only auditory
representations of the relevant word sounds can be stored, not the
conceptual content which the word would have if spoken aloud (or,
possibly, if it were produced in inner speech in a different context,
depending on one's view on the contents of inner
speech--see
 Section 3).
 When one needs to use the number at a later stage in the process,
they will need to interpret the sensory representation which they are
producing. For example, if they are reciting a sound corresponding to
the word, "six", in inner speech, they will need to
interpret that as the word referring to the number, six, so that six
becomes the number that they now use to continue their calculations.
If this is so, then interpreting the inner speech that one was
producing, and thus the inner speech itself, was essential to the
reasoning process, not merely a dispensable aid. Munroe holds that the
same will apply in many reasoning processes performed that require
making use of an intermediate conclusion.



A number of theorists--especially those working in neo-empiricist
(Barsalou 1999; Prinz 2011, 2012) and embodied cognition traditions
(Borghi et al. 2017; Dove 2014)--have also proposed that inner
speech plays an important role in facilitating abstract thought, i.e.,
thought about objects or properties that are not easily perceived.
Here the idea is that language perception and production
abilities--and their internalization, via inner
speech--provide means for explaining the acquisition and use of
abstract concepts in broadly sensorimotor terms. In particular, Guy
Dove (2014, 2018, 2020, 2022) develops a view where
language--often in the form of inner speech--is used as a
"scaffold" or "tool" for enabling thought
about abstract entities, and where the capacity for abstract concept
use is closely tied to the capacity for language.



Finally, if subsystems and modules in the mind function in isolation
from one another to any significant extent, then inner speech may play
an important role in integrating their output. Carruthers (2002, 2006)
suggests that the process of language production generally, including
the production of inner speech, is especially well suited to integrate
the output of multiple modules, because of the combinatorial nature of
language. In producing an episode of inner speech, one can thus
express complex content, which is then distributed to mental modules
and subsystems for further processing. Other sources relevant to inner
speech and the integration of information produced by different parts
of the mind include Baars (1988) and Dennett (1991).


### 2.3 Inner Speech as Thought



A number of philosophers have argued that at least some inner speech
episodes actually are thoughts or, at least, parts of thought
processes. Gauker (2011, 2018) holds that all conceptual thought
occurs in inner speech, where, as elaborated in
 Section 3.2,
 he takes inner speech to involve the tokening of items of a natural
language in neural states that are distinct from the auditory-verbal
representations that many identify with inner speech. In his 2011
book, he responds to arguments that conceptual thought cannot occur in
natural language.



With respect to inner speech understood as a partly sensory
phenomenon, Keith Frankish (2018) describes how inner speech can be
used to break a complicated problem into smaller problems, which can
then be addressed by lower level, automatic thought processes.
Deciding whether to accept an invitation from colleagues to attend a
party, for example, one might produce the inner speech episode,
"What will it be like?". This more circumscribed question
can be addressed by autonomous processes, such as recalling previous
parties with colleagues. Along with other autonomous processes, this
might generate the prediction that an annoying colleague, Henry, will
likely be at the party. If this is significant, it could result in the
inner speech episode, "Henry will probably be there", in
turn prompting a largely autonomous evaluation of the effort involved
in enduring Henry's company. The process could result, depending
on the outcome of this evaluation, in producing the inner speech
episode, "I can't face that; I won't go".
(Quotes from Frankish [2018: 234], though the example is slightly
modified.) The inner speech episodes, Frankish believes, are critical
to making the decision, and are thus rightly considered parts of the
process of thinking itself. See Kompa (forthcoming) for a similar
argument; cf. Munroe (2022b), discussed above, who also holds that an
inner speech episode can be essential to a thought process but does
not infer from this that an inner speech episode can actually be a
*part* of the process, but see also discussion of Munroe (2023)
below.



Frankish (2018) also holds that inner speech episodes can be thoughts
in the form of conscious commitments, where these are "a
distinct kind of mental attitude" (2018: 237), which cannot be
analyzed in terms of other conscious mental states, such as conscious
decisions, beliefs, or desires, or expressions of other mental states.
They are simply commitments made to oneself to "regulat[e] our
future activities, including our intentional reasoning, in line with
the choice or view expressed" (2018: 237). For example, the
inner speech episode, "I will go to the gym today", is a
commitment to go to the gym today, not just the expression of a
decision to do so, because it also generates a kind of obligation to
oneself, as it were, to do so. For Frankish, this follows from
treating inner speech as an internalized version of interpersonal
speech, in which commitments also generate obligations.



On Frankish's account, an inner speech episode can be
*like* a judgment, insofar as it may involve committing oneself
to act and reason in a way which is consistent with the truth of the
proposition expressed by the inner speech episode. Munroe (2023), by
contrast, holds that an inner speech episode can actually function as
a judgment. If an inner speech episode is accompanied by what has been
called a "Feeling of Rightness" (Munroe cites Thomson et
al. 2013 and Unkelbach & Greifender 2013), then it will play roles
typically attributed to judgments such as "terminating inquiry
and causing overt actions" (Munroe 2023: 309). Munroe connects
his claim to a model proposed by Ackerman & Thompson (2015, 2017a,
2017b) on which the roles that mental states play is determined partly
by metacognitive monitoring. The "Feeling of Rightness" is
a cue to a metacognitive monitoring system that a particular mental
state can appropriately play the roles of a judgment. Munroe's
claim is that inner speech episodes can function as judgments if this
is deemed appropriate by the metacognitive monitoring system, on
account of being accompanied by the appropriate "Feeling of
Rightness" (or at least by a feeling of sufficient
certainty).



Nikola Kompa (forthcoming) adds a quite different argument for the
identity of (some) thoughts and (some) inner speech episodes. She
operates with a broad notion of inner speech, on which any
"inner episode that substantially engages the speech production
system" is an instance of inner speech (forthcoming: 4, emphasis
removed). On this understanding of inner speech, any thought with
semantic content and syntactic structure will be an instance of inner
speech, even if it does not become conscious. Kompa rejects the
language of thought hypothesis, on which thoughts can have linguistic
properties because they occur in a non-natural language. Accordingly,
for Kompa, the *only* way that a thought can have semantic
content and syntactic structure is if its formation substantially
involves the speech production system (which she understands in
Leveltian terms, citing Levelt 1989; Levelt et al. 1999; and Indefrey
& Levelt 2004). Insofar as we have any thoughts that have semantic
content and syntactic structure, then, these are, on her definition,
instances of inner speech. If the production of such thoughts does not
proceed further through the speech production process, such that they
are morpho-phonologically encoded in addition to having semantic
content and syntactic structure, they will occur as unconscious inner
speech episodes.



Finally, it has been suggested that there is a close connection
between inner speech and a phenomenon known as "unsymbolized
thought". Using the Descriptive Experience Sampling paradigm,
Russell Hurlburt and Christopher Heavey (e.g., Hurlburt & Heavey
2002; Heavey & Hurlburt 2008) have gathered introspective data
that they interpret as providing evidence that people sometimes have
the experience of



> 
> 
> thinking a particular, definite thought without the awareness of that
> thought's being conveyed in words, images, or any other symbols.
> (Heavey & Hurlburt 2008: 802)
> 
> 
> 



Martinez-Manrique & Vicente (2015), Vicente &
Martinez-Manrique (2016), and Vicente & Jorba (2019)
suggest that these "unsymbolized thoughts" occur when the
production of an inner speech episode is aborted at the earliest stage
of production, when only the content or message to be expressed has
been formulated. Appealing to accounts on which we experience
conscious representations of actions which we begin to perform but
abort, they suggest that an unsymbolized thought is a representation
of the message which one commenced expressing in inner speech, which
becomes conscious because the process was aborted. Insofar as the
process was aborted prior to the message being organized in phonetic
form, the representation is entirely amodal. See also Kompa
(forthcoming).


## 3. Content-Based Theories of Inner Speech



We have seen that there are a variety of views taken on whether inner
speech is indeed a kind of speech, or a kind of thought, or both. A
popular way to gain added leverage on those questions is to advance an
account of the contents of inner speech. Focusing on questions
concerning the contents of inner speech also helps to clarify the
depth of some of the puzzles and controversies already introduced.



Most generally, the content of a representation is what the
representation is *of* or *about*--it is what the
representation represents. The content of the word "cat"
is a certain type of animal (namely, a cat). And, the content of the
sentence "cats are animals" is the proposition that cats
are animals. Two distinct representations can have the same content.
For instance, the French word "chat" has the same content
as the English word "cat"; and the French sentence
"les chats sont des animaux" has the same content as the
English sentence "cats are animals". Thus--to borrow
analogies from Siegel (2005 [2021])--the contents of a mental
state, in the present sense, are akin to the contents of a newspaper
article and not akin to the contents of a bucket. Mental contents are
not things that are contained within mental states themselves (just as
cats are not contained within the word "cat") but are,
instead, what the mental states are of or about.



We will distinguish three broad classes of views about the contents of
inner speech and several sub-views within them, noting their main
motivations and relationships to questions concerning inner
speech's proposed cognitive roles. According to what we will
call the "phonological content view", inner speech
episodes *always and only* have phonological contents. The
competing content-based theories to be discussed hold either that
inner speech only has semantic contents (the "semantic content
view", as we will call it) or that inner speech has phonological
contents *and* semantic and/or other kinds of contents (the
"mixed contents view").



As we will see, the phonological content view is a natural fit with
the view, discussed at the beginning of
 Section 1,
 that inner speech is merely a representation of speech and not
actually a kind of speech. This is because the phonological content
view sees inner speech as consisting in imagistic representations of
speech and as lacking the kinds of contents (or meanings) associated
with word tokens themselves. Likewise, those who hold that inner
speech is actually speech will typically hold either a mixed contents
view or a semantic content view, as these views allow inner speech
episodes to have the kinds of semantic contents that are typically
viewed as essential to being a linguistic token.


### 3.1 The Phonological Content View



To say that inner speech has phonological contents is to say that
inner speech episodes represent phonemes (or *phones*), where
phonemes are the most basic meaningless building-blocks from which any
word of a language can be built. There are 44 phonemes in English,
different combinations of which account for the distinct sound each
word has in relation to all other words from which it can be aurally
distinguished. The notion of a phoneme is somewhat of an abstraction,
however, as slightly different sounds (in terms of pitch, timbre, and
frequency) can fall within the sonic range that constitutes a single
phoneme type. These more specific, concrete sounds that can qualify as
instantiations of a phoneme are known as *phones.* Whether
inner speech episodes represent phonemes or, instead, the
finer-grained property of being a *phone* is a matter of
dispute among those who hold that inner speech episodes have
phonological contents (Patel 2021; Langland-Hassan 2018; Hill
2022).



Note also that, while the phonemes of most natural languages are
auditory in nature--and are thus perceived through the sense of
hearing--the notion of a phoneme has also been applied to
gestural languages, such as American Sign Language (Sandler 2012;
Stokoe 2005). So, the concept of a phoneme is not specific to any
modality. It refers to the smallest meaningless units of a language
that can be arranged and recombined to form the smallest meaningful
units of that language, no matter which modality the language occurs
in. In spoken languages, however, the auditory modality takes
precedence over the visual/written modality, insofar as the phonemes
are typically held to be sounds, while the graphemes are held to be
letters or groups of letters that represent phonemes. While most will
not consider the visualization of graphemes and written words to be
cases of inner speech, it bears noting that such visualizations
satisfy the neutral characterization of inner speech provided at the
outset.



There are several reasons one might hold that inner speech episodes
have phonological contents. The first is phenomenological in nature.
What it is like to have an inner speech episode is similar to what it
is like to hear oneself saying the corresponding words aloud. One
might explain this phenomenological similarity by appeal to the fact
that inner speech episodes and the corresponding cases of hearing
represent similar properties--either phonemes or phones of a
certain sort--and, accordingly, have similar contents. A second
reason appeals to the fact that we can use inner speech episodes to
judge whether two visually dissimilar written words--such as
"blood" and "mud"--rhyme. As rhyming is a
relationship between the sounds of words, the usefulness of inner
speech episodes in judging rhymes would be explained if inner speech
episodes represented word sounds and thereby allowed us to compare
those sounds (Langland-Hassan 2014). A third reason that has been
proposed for thinking that inner speech has phonological contents is
that it is the representation of those features that allows one to
discern which language we are exploiting when engaged in inner speech
(Langland-Hassan 2018). (See Patel 2021 for a rebuttal.)



Jackendoff (1996, 2007, 2011) proposes that auditory contents exhaust
the contents of inner speech. Jackendoff's view is motivated in
part by a prior commitment to the thesis that we do not think in a
natural language. Like many in cognitive science, he sees natural
language primarily as a means for communicating thoughts that
themselves occur unconsciously in some other medium (such as a
Fodorian "Mentalese"). According to Jackendoff, thought
itself is never conscious, nor is the use of concepts. By contrast,
inner speech--what he calls the "talking voice in the
head" (1996: 10)--occurs consciously and does not involve
the use of concepts. In having inner speech, he explains, "[w]e
experience organized sounds", whereas,



> 
> 
> the *content* of our experience, our understanding of the
> sounds, is a different organization ... called conceptual
> structure. (emphasis original, 1996: 12-13)
> 
> 
> 



"The organization of this content", he holds, "is
completely unconscious" (1996: 13). Jackendoff identifies the
inner voice with a representation of "phonological
structure", a representation having phonological content, yet no
conceptual or semantic content. Whereas, the mental states
constituting our *understanding* of what the voice is saying,
he notes, are distinct conceptual states that occur unconsciously:



> 
> 
> What we experience as our inner monologue is actually the phonological
> structure linked to the thought,
> 
> 
> 



he explains.



> 
> 
> We are aware of our thinking because we hear the associated sounds in
> our head. (Jackendoff 2011: 613)
> 
> 
> 



(See also Jackendoff [2007: 80-85] where he remarks on the
counterintuitive nature of his view: "How can the contents of
consciousness consist of just a string of sounds?" [2007:
85].)



It should be noted that Jackendoff also suggests that inner speech
episodes "express" thoughts, which would seem to support
the view that such episodes have the semantic contents of our thoughts
(e.g., "the linguistic modality can make reasons as such
available in consciousness" [1996: 19] and "only through
language can such concepts form part of *experience* rather
than just being the source of intuitive urges" [1996: 23]). On
the other hand, he equally emphasizes the overlooked fact that
"linguistic structure has three major departments: phonological,
syntactic, and semantic/conceptual structure", and that
"the forms in awareness--the qualia--most closely
mirror phonological structure" (2007: 81). Most recently, he has
proposed a view where what we intuitively mark as "conscious
thought" has three components: a "pronunciation" of
the thought, a feeling of meaningfulness, and the meaning attached to
the pronunciation. There he holds that only the first two are
conscious and appears to identify inner speech with the
"pronunciation" component. This is in keeping with the
phonological content view, as the (semantic) meaning of the
pronunciation is something separate from the pronunciation and is only
represented "backstage" (i.e., unconsciously) (Jackendoff
2012: 84-5).



Langland-Hassan (2014) provides a qualified defense of a phonological
content view, motivated by worries about how a single mental
state--in particular an episode of inner speech--can be said
to represent both word sounds and word meanings simultaneously. He
notes that a word's meaning and its sound are entirely distinct
properties, related only by convention. If mental states are
individuated by their contents, then it seems that distinct neural or
functional states will be needed to represent these distinct
properties. This has become known as the "binding problem"
for inner speech (see Munroe 2023; Patel 2021; Bermudez 2018
for different approaches to resolving it; see also Prinz 2011 for
related remarks). In light of this problem, Langland-Hassan proposes
that ordinary episodes of inner speech likely consist in two or more
mental states triggered at roughly the same time (this would be a
multiple-state version of the "mixed contents" view,
discussed below). Yet he adds that, when inner speech has been divided
into distinctly occurring states in this way, there are good reasons
to identify inner speech solely with the component that represents
word sounds. Doing so results in a phonological content view.


### 3.2 The Semantic Content View



In contrast to the phonological content view, the semantic content
view holds that inner speech episodes always and only have semantic
contents. By "semantic contents", we mean the kinds of
contents had by ordinary words, phrases, and sentences of a natural
language. Such contents are typically equated with the
*meaning* of a word, phrase, or sentence.



One version of a semantic content view, defended by Christopher Gauker
(2011, 2018), holds that inner speech episodes exclusively have
semantic contents and entirely lack both auditory contents and
auditory phenomenology. Gauker allows that episodes of auditory verbal
imagery often accompany inner speech. However, on his view, this
auditory imagery is not to be identified with inner speech itself.
Rather, according to Gauker, inner speech is a non-sensory linguistic
phenomenon occurring in the brain that is (often) *represented
by* episodes of auditory verbal imagery. Just as we may use
auditory representations to represent someone else's speech that
we are actually hearing, so too, for Gauker, our inner speech is often
represented by verbal imagery--imagery that is in fact distinct
from the (inner) speech itself. (Here Gauker develops related remarks
of Wilfrid Sellars (1956).) Notably, Gauker (2018) grants that, in the
case of inner speech, this auditory-verbal imagery
*misrepresents* our inner speech as having sonic features
(i.e., as instantiating phones or phonemes), given that the neural
events that constitute inner speech episodes are themselves
silent.



Gauker's style of pure semantic content view is not widely
endorsed. This may be because it clashes with the widespread view that
inner speech has a sensory character similar to that of hearing
speech. On the other hand, Gauker's view can be said to have an
advantage in providing a literal sense in which, when we engage in
inner speech, we are thinking *in* words of a natural language
and not merely *about* them. On Gauker's (2011) view, the
neural events that carry semantic content are themselves tokens of
words and phrases of a natural language, and the question of how
auditory-verbal images can also be linguistic tokens does not arise.
His view is also motivated by an opposition to what he calls the
"Lockean" view that sees conceptual thought as something
prior to and separate from the speech that expresses it. One can see
Gauker (2011) as trying to preserve the idea that abstract
(conceptual) thought occurs in a language (and is often
non-conscious), while divorcing it from the thesis that there exists
an innate, Fodorian "language of thought" (and one that
must be exploited in order to learn a natural language).



Bermudez (2018) offers a different style of semantic content
view that allows for inner speech to retain a characteristic auditory
phenomenology. According to Bermudez, the auditory sensory
character of inner speech is a result of inner speech episodes having
*non-representational* auditory properties. For
Bermudez, the only representational contents had by inner
speech episodes are those pertaining to the meanings of words. In
response to the those who argue that inner speech episodes must also
have phonological contents (e.g., to explain why we can use inner
speech to judge whether two words rhyme), he argues that there is no
entailment from the fact that inner speech episodes can be useful in
judging rhyme relations to the conclusion that they represent phonemes
(2018: 216-7).



A third type of theory on which inner speech exclusively has semantic
content proceeds by arguing that inner speech is a genuine form of
speech. This argument is typically made on either phenomenological or
functional grounds. From there it is inferred that inner speech must
have the same kind of contents as external speech. If episodes of
external speech--i.e., the words we hear when someone
speaks--have semantic content but no phonological content
(because they do not *represent* phonemes), so too must
episodes of inner speech. This approach to theorizing about inner
speech is discussed in more detail in
 Section 1.
 Assuming that (unlike Gauker) proponents of such a view wish to
maintain that inner speech episodes constitutively have auditory
sensory character, they may concur with Bermudez in his claim
that the auditory phenomenology of inner speech does not entail the
representation of auditory properties; or, alternatively, they may
provide some other account of why, in many instances, inner speech
seems to represent phonemes even if it does not really do so.


### 3.3 Mixed Contents Views



Mixed contents views hold that inner speech episodes typically have at
least two kinds of content--phonological and
semantic--simultaneously. On a mixed contents view, the inner
speech episode "Dogs are mammals" represents both the
sound of the sentence "Dogs are mammals", as uttered
aloud, and the proposition that dogs are mammals. We can distinguish
two species of mixed contents view: single-state and multiple-state.
Single-state views hold that what we intuitively mark as a single
inner speech episode consists in a single mental state that has both
auditory and semantic contents. Multiple-state views hold that the
apparent unity of a single inner speech episode is in some sense
illusory, as such episodes typically consist in the contemporaneous
occurrence of two or more mental states, where one of the states
represents phones or phonemes and another has semantic contents. (Some
multiple-state views hold that inner speech episodes involve
additional distinct states with articulatory and syntactic contents as
well.) As earlier noted, some phonological content views hold that
mental states with corresponding semantic contents occur
contemporaneously with the representations of phonemes that are
identified with inner speech. These phonological content views differ
from multiple-state mixed contents views in that the former identify
inner speech solely with the state that has phonological content,
perhaps on the grounds that it is the only sort of state of which one
is consciously aware (this appears to be Jackendoff's
motivation).


#### 3.3.1 Single-State Mixed Contents Views



Carruthers (2011, 2018) defends a single-state mixed contents view,
proposing that inner speech involves the generation of a
representation of word sounds (i.e., phonemes) which--in a
process akin to what occurs in outer speech perception--is then
interpreted by one's speech comprehension mechanisms so that a
semantic content can then be assigned to the represented utterance.
(He notes that a representation of the semantic content of the
represented phrase--referred to as the "message" on
Levelt's [1989] speech-production framework--sometimes
precedes the representation of the word sounds, albeit
non-consciously.) Once the represented word sounds are interpreted,
Carruthers suggests, the information that the represented utterance
has a certain semantic content is "bound into" a single
"event-file" that contains information both about the
sound and the meaning of the represented utterance (2018:
41-42). (See Frankish [2004: 57; 2018] for a similar view.)
Carruthers analogizes such binding to the way in which the color,
shape, and category properties of a visually perceived object are said
to be "bound into" a single object-file that accumulates
multiple forms of information about a single object, despite those
properties being represented in temporally distinct stages and in
distinct neural regions. These event-files, when activated and
globally-broadcast, are said to constitute a single conscious inner
speech episode that has both auditory and semantic contents.



Munroe (2023) develops a similar style of single-state mixed contents
view, arguing that, in addition to representing phonemic and semantic
features, inner speech episodes also represent the likelihood that the
content of the represented utterance is true. The latter is necessary,
he holds, for inner speech episodes to qualify as judgments (see
 Section 2.3).
 These three distinct features are, for Munroe, bound into a single
mental state in the sense that a single mental state predicates these
three distinct properties of a single represented utterance (Munroe
2023: 304).


#### 3.3.2 Multiple-State Mixed Contents Views



Other mixed contents views of inner speech--inspired by
Levelt's (1989) multi-stage model of speech
production--attribute the different representational contents
entertained during an inner speech episode to multiple distinct states
that tend to co-occur. Martinez-Manrique & Vicente (2015)
defend a multiple-state view under the moniker of the "activity
view" of inner speech, highlighting the multi-component
processes of both inner and outer speech. "It is quite
natural", they explain,



> 
> 
> to try to understand inner speech in terms of all the representations
> that are mobilized in speech, i.e., semantic, syntactic, maybe
> articulatory .... The representations involved--from
> conceptual to phonological--form an integrated system. (2015:
> 8)
> 
> 
> 



The view which Martinez-Manrique & Vicente set out in their
2015 paper bears clear similarities to the actual speech view, insofar
as they hold that inner speech is functionally similar to external
speech. What separates it from the actual speech view, however, is
that they do not hold that inner speech consists of actual words and
sentences which express semantic content, but of distinct
representations of phonological and semantic (and other) content. (For
complementary multiple-state mixed contents views in cognitive
neuroscience, see Grandchamp et al. 2019 and Loevenbruck et al.
2018.) While these representations are unified in the sense of
occurring within a single system for language production, they remain
distinct mental states--distinguished, in part, by their distinct
contents, and their ability to occur in isolation of each other.
(Note, however, that this way of categorizing the view assumes that
each mental state is composed of exactly one mental representation. It
may be possible to articulate a view where one mental state is
composed of multiple mental representations. The question then
becomes: in virtue of what do the multiple representations qualify as
a single mental state, as opposed to components or stages of a single
cognitive system?)



Christopher Hill (2022: 136-139) develops a similar
multiple-state mixed content view, emphasizing that the
representations of semantic content lack any associated phenomenology.
The phenomenology of inner speech is, for Hill, entirely a function of
its auditory-phonological contents. He further specifies that these
phonological contents are (the more abstract) phonemes, and not
phones, to account for the relatively impoverished sensory character
of inner speech in comparison with speech perception. Patel (2021)
also defends a multiple-state mixed contents view, on which, in
addition to having some combination of semantic, syntactic, auditory,
and articulatory contents, inner speech episodes have vocal contents.
To have vocal contents is to represent some particular person's
voice as communicating some combination of semantic, syntactic,
auditory, or articulatory information. According to Patel, whether we
are representing the semantic, auditory, or articulatory contents,
these mental events involve one's representing a certain
person's voice as attempting to convey such information. This
common representation of a voice, he argues, provides a kind of unity
to the class of mental events that can be considered inner speech.



Because multiple-state views allow that the distinct components of
inner speech can potentially occur in isolation, they face a question
of which components need to occur for the episode to be properly
counted as an instance of inner speech. Vicente & Jorba (2019),
Martinez-Manrique & Vicente (2015), and Vicente &
Martinez-Manrique (2016) see this as an advantage, insofar as
it allows them to place different phenomena related to inner speech on
a single continuum (see also Kompa & Mueller forthcoming and
McCarthy-Jones & Fernyhough 2011). For instance, when the semantic
and syntactic contents of ordinary inner speech are represented in the
absence of any auditory-phonological contents, they propose, this can
be understood as a case of so-called "unsymbolized
thought" (Heavey & Hurlburt 2008; Heavey, Moynihan, et al.
2019). See
 Section 2.3
 for further detail.



A notable feature of the surveyed mixed contents views (as well as the
phonological content view) is that they need not (and often do not)
hold that inner speech episodes occur in a natural language. Rather,
on these views, inner speech episodes *represent* natural
language utterances (in virtue of their phonological contents),
without necessarily being instances of such utterances themselves.
This is because, on mixed contents views, the semantic content of an
inner speech episode may not be represented by tokens of a natural
language. For instance, for Carruthers, the semantic contents of an
inner speech episode are represented via symbols of an amodal language
of thought (e.g., a Fodorian [1975] *Mentalese*), which are
coupled with sensory representations of the sound of the corresponding
sentence as spoken aloud. One language (Mentalese) is used to
represent the meaning of an expression in another (e.g., English). In
this way, Carruthers (2010, 2018) deviates from Carruthers (1996),
with the latter defending the idea that inner speech episodes
literally occur in--and are expressions of--a natural
language. Carruthers now emphasizes the point, raised also by Machery
(2005), that introspection does not provide grounds for claims about
the representational format of our inner speech episodes.


## 4. Inner Speech and Pragmatics



In general, the philosophy of language has focused primarily on
language used interpersonally. It is natural to wonder to what extent
this material is applicable to inner speech. This question can be
asked whether or not one thinks that inner speech is actually a kind
of speech, as no one denies that there is some interesting
relationship between inner speech and interpersonal speech.


### 4.1 Inner Speech and Speech Acts



As mentioned in
 Section 1,
 the intuition that we can perform speech acts in inner speech is the
basis of an argument that inner speech is a kind of speech. There are
different ways, however, that we might understand the claim, depending
on how one thinks of speech acts.



On the traditional analysis of Austin (1962) and Searle (1969),
performing a speech act is inherently something one does in accordance
with conventions tacitly understood by both speaker and listener. For
example, for Searle, asserting *p* involves (approximately)
undertaking to someone that *p* is true, where the speaker does
not know that the listener already knows that *p* is true. The
reason that an assertion can be effective is precisely that both
speaker and hearer understand that this is the nature of the
transaction. It is hard to see how this kind of analysis could apply
to inner speech. One would need to explain how one individual can have
two distinct roles, as speaker and listener, such that the conventions
that make interpersonal language-use possible can have any relevance
(see Gregory 2017, 2020a for related discussion).



Not every version of speech act theory, however, emphasizes
conventions. Drawing on some ideas from Strawson (1964) and Bach &
Harnish (1970), though not adopting their theories in whole, Wilkinson
(2020) holds that what is essential to speech acts is that they
express particular mental states. An assertion, for example, is simply
an utterance which expresses a belief; a question is an utterance
which expresses a desire to acquire certain information; etc. On this
view, understanding someone else's utterance is simply a matter
of grasping its content and knowing what kind of mental state the
relevant type of utterance expresses. Setting aside the question of
whether one needs to interpret their own inner speech, it may be that
inner speech episodes can be speech acts if one thinks of speech acts
merely as expressions of particular mental states, rather than as
actions which depend on conventions in the way that Austin and Searle
suggest. For another analysis of inner speech in terms of speech act
theory, see Geurts (2018), who emphasizes that inner speech episodes
can operate to generate commitments in a way characteristic of speech
acts; see also Frankish (2018) and Fernandez Castro (2019).



An issue which sits just behind the question of whether inner speech
episodes are speech acts is whether they are actions at all. Gregory
(2020b) argues that, in the vast majority of cases, inner speech
episodes are not actions, because we cannot give reasons for them
(which is the criterion for actionhood on Davidson's (1963)
causal theory); they are not subject to our control (the criterion on
Harry Frankfurt's [1978] guidance theory); and we do not try to
produce them (the criterion on O'Shaughnessy's [1973]
theory and Hornsby's [1980] theory). If inner speech episodes
are not actions, then they cannot be speech acts.



Tom Frankfort (2022) takes the opposite view. He observes that a great
deal of inner speech is involved in deliberation, where this is an
expansive category including "reflecting, reasoning,
considering, evaluating" (2022: 52). He then applies
Mele's (2009) distinction between actions which involve
"trying to bring it about that one *x*-s" (Mele
2009: 18) and actions which are done in order to bring it about that
one *x*'s. Frankfort suggests that deliberating is an
action in the first sense, insofar as it involves (for example) trying
to make a decision, and inner speech episodes are actions in the
second sense, insofar as they are produced in order to bring it about
that one deliberates successfully and (for example) comes to a
decision.



Jorba (forthcoming) also holds that inner speech episodes are
typically actions, applying affordance theory. Affordances are
opportunities for actions suggested by things in one's
environment. For example, an apple has the affordance of being edible;
a cup has the affordance of being graspable. Some hold that
affordances can also be things which suggest *mental* actions
(Jorba cites McClelland 2020 and Jorba 2020). Jorba's suggestion
is that some mental states afford the production of inner speech
episodes. For example, an inchoate thought affords being articulated
clearly in inner speech, and an emotion can afford being labeled.
Insofar as inner speech episodes are produced in response to
affordances, they are actions and, specifically, speech acts. See
Bar-On & Ochs (2018) for another account on which inner speech
episodes can be "acts of innerly speaking our mind" (2018:
19, emphasis removed).


### 4.2 Inner Speech and Conversation



Closely related to the question of whether there can be speech acts in
inner speech is the question of whether inner speech can involve a
kind of dialogue or conversation. A theory which characterizes inner
speech this way has been developed at length in psychology, primarily
by Charles Fernyhough (e.g., 1996, 2008, 2009). However, the
suggestion has been made in a variety of ways by philosophers as well,
including by Machery (2018), Frankish (2018), Gauker (2018), and
Wilkinson, in collaboration with Fernyhough (Wilkinson &
Fernyhough 2018).



The idea that inner speech involves an internal dialogue or
conversation clearly has intuitive appeal for some. One often finds
inner speech described outside the philosophical context as the
"inner dialogue". But, if inner speech involves a kind of
internal dialogue or conversation on more than a metaphorical level,
then it is natural to wonder who the interlocutors are (Gregory
2020a). Machery (2018) and Frankish (2018) suggest that different
parts of the brain communicate with one another via inner speech.
Gauker (2018) suggests that inner speech involves conversing with
oneself (see also the discussion of inner speech as a means for
interaction between subsystems or modules in the mind in
 Section 2.2).
 One difficulty with both of these suggestions, however, is that
philosophers of language generally (though not universally) think of
conversation as fundamentally involving distinct human agents.



Gregory (2017) appeals to Grice's (1975 [2013]) account of
conversation to make this point. Grice argued that conversations are
"characteristically ... cooperative efforts" (p.
314). But cooperation requires multiple agents and there is only one
agent in inner speech. That said, Gauker (2011, 2018) is working with
an explicitly non-Gricean picture of conversation, motivated by an
opposition to the doctrine that speech acts serve to express thoughts
that are distinct from and precede the expressive utterance. He holds
that speaking is,



> 
> 
> in the first instance, something we do whenever there is no reason not
> to, because of the good it tends to do. (2018: 71)
> 
> 
> 



In certain circumstances, where multiple individuals are present,



> 
> 
> [a] conversation can be the occasion for each interlocutor to reflect
> on what he or she has experienced, ... and on that basis to
> elicit a statement that is useful from the other. (2018: 72)
> 
> 
> 



Insofar as we can generate inner speech episodes which cause us to
reflect on some matter and then produce further inner speech episodes
which are useful for us in the context, inner speech will be
conversational. Gauker's analysis here obviously reflects the
expression-oriented approach to the question of whether there can be
speech acts in inner speech.



In contrast to Gauker, Deamer (2021) argues that inner speech can be
seen as being communicative in a Gricean sense. She holds that, to at
least some extent, humans are "self-blind": mental states
such as our intentions are not always transparent to us. When we
produce inner speech, we reveal our communicative intentions to
ourselves, just as we reveal our communicative intentions to others
when we converse with them.



While there is disagreement as to whether a series of inner speech
episodes can be a dialogue in a literal sense, most agree that inner
speech often closely resembles dialogue. As Gauker notes, one episode
of inner speech will often prompt another, as happens in interpersonal
dialogue. We can produce episodes of inner speech corresponding to
different points of view, e.g., when thinking about the considerations
for and against some course of action, in a way similar to two people
with different opinions. Some participants in studies report that some
of their inner speech episodes take place in the voices of others
(McCarthy-Jones & Fernyhough 2011; Alderson-Day, Mitrenga, et al.
2018). This last consideration raises an important issue. We can
certainly imagine conversing with others and we can certainly imagine
others conversing. Such cases are usually taken to be distinct from
inner speech (see
 Section 1).
 However, if inner speech can involve the voices of others, possibly
expressing viewpoints other than our own, it becomes difficult to say
how instances of inner speech with these characteristics differ from
cases of imagining others speaking. How to delineate the extension of
"inner speech" in a way that distinguishes inner speech
acts from cases of (merely) imagining speech remains an underexplored
issue.


## 5. Self-Knowledge and Metacognition



Inner speech plays an important role in a number of philosophical
accounts of self-knowledge and metacognition. By
"self-knowledge" we will mean knowledge of one's own
mental states, including both dispositional states--like beliefs,
desires, and intentions--and occurrent states, such as thoughts,
imaginings, decisions, and judgments. The notion of metacognition is
somewhat broader, also encompassing judgments and non-cognitive
assessments (e.g., "feelings of knowing") concerning the
validity of one's own reasoning, the quality of one's
evidence, one's degree of certainty, and so on (Proust 2013).
While some theorists implicate inner speech in their accounts of both
self-knowledge and metacognition (Jackendoff 1996; Clark 1998;
Bermudez 2003, 2018), others focus more narrowly on the
question of how inner speech might facilitate self-knowledge (Byrne
2018; Carruthers 2011; Roessler 2016). A common thread among theorists
who invoke inner speech in their accounts of metacognition or
self-knowledge is the idea that certain others of our mental
states--namely, those that our inner speech helps us to know
about--are either less readily available to introspection or less
well suited to serve a metacognitive role. Thus, these views all
appear against a backdrop of broader commitments about the nature of
mental states and our introspective access to them.


### 5.1 Metacognitive Approaches



One approach sees inner speech as especially well suited to aid in
metacognition due to its linguistic structure, or its link to public
language more generally. According to Andy Clark (1998), the fact that
inner speech occurs in a language--where such language is seen as
abstracting away from the particularities of perception--allows
it to play a special role in "second-order cognitive
dynamics" (see also Prinz 2011, 2012). This, he holds, is
because the natural language sentences featured in inner speech are
"context resistant" and "modality
transcending" in ways that facilitate a more objective and
reliable assessment of the soundness of one's own thought
processes (Clark 1998: 178). Bermudez (2003, 2018) builds on
Clark's proposal, specifying that awareness of inner speech is
essential for enabling humans to become conscious of their own
propositional thought processes, which are otherwise amodal and
inaccessible to introspection. According to Bermudez,



> 
> 
> all the *propositional* thoughts that we consciously introspect
> ... take the form of sentences in a public language. (emphasis
> original, 2003: 159-160)
> 
> 
> 



While he does not identify these public language sentences with our
core thought processes themselves--these, he holds, occur in a
subconscious language of thought--Bermudez argues that the
linguistic structure of inner speech is needed to adequately represent
the relationships of entailment and rational support that may (or may
not) exist among the subconscious thoughts the inner speech episodes
serve to express. As he puts it,



> 
> 
> we think about thoughts through thinking about the sentences through
> which those thoughts might be expressed. (2003: 164)
> 
> 
> 



Jackendoff (1996, 2007, 2011, 2012) and Prinz (2011, 2012) likewise
hold that there is a level of conceptual thought that is not directly
available to introspection and that inner speech is well suited for
making us aware of such thoughts. Yet, for Jackendoff and Prinz, inner
speech is able to play this role primarily because, like other
imagistic mental states, inner speech occurs at an
"intermediate" level of representation, which, on their
theories, is the only level of representation at which mental states
are consciously available to the subject. Thus Jackendoff's
comment that "we are aware of our thinking because we hear the
associated sounds in our heads" (2011: 613). Echoing
Bermudez and Clark, Prinz finds it



> 
> 
> likely that we often come to know what we are thinking by hearing
> inner statements of the sentences that we would use to express our
> thoughts (2011:. 186)
> 
> 
> 



and judges inner speech to be "a way of registering complex
thoughts in consciousness" (2011: 186). (See also Machery 2005,
2018.)


### 5.2 Inferentialist Approaches



Several theorists, who we will term "inferentialists",
follow Ryle (1949 [2009]) in his claim that we often come to know what
we are thinking by "overhear[ing]", or
"eavesdrop[ping] on ... our own silent monologues"
(1949 [2009: 165]). On these views, we come to know what we are
thinking, or what we believe or desire, by drawing a kind of inference
(the nature of which differs, depending on the theorist) from the fact
that we "hear" ourselves say something in inner speech.
The views of Clark, Bermudez, Jackendoff, and Prinz, already
reviewed, are inferentialist in nature. Yet there are other approaches
that incorporate inner speech into a process that is even more
explicitly inferential.



Carruthers (2009, 2010, 2011, 2018) is an inferentialist of this
latter sort. While, in earlier work, he argued that thought itself
occurs in inner speech (Carruthers 2002), Carruthers later abandoned
that idea to hold that thoughts (including one's beliefs) are
always unconscious. On this view, inner speech episodes remain more or
less directly available to introspection, yet only provide a kind of
indirect evidence for what we are in fact judging or deciding (or
believing, desiring, or intending) unconsciously. He emphasizes the
fallible nature of such inferences, arguing on the basis of various
empirical studies that many of the inferences people arrive at about
their own beliefs and desires are in fact incorrect. Similarly to
Jackendoff and Prinz, Carruthers holds that only sensory states are
able to serve as inputs to the mental mechanism responsible for self-
(and other-) directed mindreading. These inputs include visual and
other forms of sensory imagery in addition to inner speech. However,
in cases where we are having thoughts about abstract matters that are
difficult to unambiguously represent with other forms of
imagery--such as the thought that philosophy is a challenging
subject--episodes of inner speech are held to provide an
especially important source of information that one is having such
thoughts. Carruthers emphasizes that the process becomes especially
inferential in nature where other contextual information--such as
that one sees oneself lingering over a choice of cereal
box--combines with one's inner speech to generate an
all-things-considered appraisal of what one is currently judging or
deciding. Cassam (2011, 2014) likewise implicates inner speech in a
multi-faceted inferentialist account of self-knowledge, though not
pitched in terms of "mindreading" mechanisms or other
constructs from cognitive science.



Alex Byrne (2011, 2018) puts inner speech to somewhat different ends
in his inferentialist account of how we know what we are thinking. For
Byrne, there is no such thing as inner speech, strictly speaking,
because there are no sounds (or voices) in the head. However, there
are such things as auditory-phonological representations of voices.
These give rise to an apparent perception of what we come to think of
as the "inner voice". By trying to attend to what the
inner voice says, Byrne proposes, we can reliably form judgments about
what we are thinking. The epistemic rule he proposes for doing so
is:



> 
> 
> THINK: If the inner voice speaks about *x*, believe that you
> are thinking about *x*.
> 
> 
> 



As with Carruthers, a key motivation for Byrne's account of how
we know what we are thinking is a background view--motivated by
the work of Shoemaker (1994), Dretske (2003), and others--that we
have no other, more direct introspective method for knowing our own
thoughts (i.e., we lack something like an "inner sense").
Note that Byrne's approach is inferentialist in that he takes
inner speech to be implicated in inferences that lead to knowledge of
one's own occurrent thoughts. Yet the sort of inference involved
is quite different from that envisioned by Carruthers and Cassam, who
both hold that inner speech episodes are just one kind of information
among many that may be brought to bear in inferences about one's
standing and occurrent mental states. Importantly, the form of
inference envisioned by Carruthers and Cassam is essentially the same
in its first and third person applications, whereas Byrne's
THINK rule is of an inferential procedure that can only be used to
reliably generate true beliefs about one's own mental states. In
Byrne's view, this helps to explain the "peculiar"
nature of introspection, where this peculiarity lies in the fact that
our methods for knowing our own mental states are (intuitively)
different from those we use to know others' (Byrne 2011, 2018).
Further, on Byrne's version of inferentialism, the inferences we
form by trying to follow THINK are extremely likely to amount to
knowledge--thereby cohering with the intuition that knowledge of
one's own current thoughts is epistemically privileged. Whereas,
the kinds of metacognitive inferences that Carruthers and Cassam
envision to rely on inner speech are (by their own telling)
epistemically on a par with our inferences about the mental states of
others and far more susceptible to error.


### 5.3 Inferentialism's Critics



Several philosophers object that inferentialist proposals leave us at
too great an epistemic distance from our own thoughts (Bar-On &
Ochs 2018; Roessler 2016) or have other unworkable features
(Langland-Hassan 2014; Martinez-Manrique & Vicente 2010;
Roessler 2016). Roessler (2016) pursues a non-observational account of
the role of inner speech in generating self-knowledge. Rejecting the
idea that we need to "eavesdrop on ourselves" by attending
to our inner speech, Roessler suggests we follow remarks of Ryle (1949
[2009]) and Anscombe (1957) in understanding the knowledge gained
through inner speech as a kind of "practical knowledge",
(or, for Ryle, "serial knowledge"), where knowing what one
is thinking is understood as a special case of knowing what one is
doing.



Bar-On & Ochs (2018) likewise take aim at what they term
"Neo-Rylean" invocations of inner speech, arguing that
Byrne's THINK rule fails to identify a special role for inner
speech in facilitating self-knowledge. Drawing on Bar-On's
(2004) broader expressivist approach to self-knowledge, Bar-On and
Ochs hold that a proper account of inner speech's role in
self-knowledge should show how such knowledge is "distinctive
and uniquely first-personal" in that it is



> 
> 
> knowledge that one can be said to have in virtue of being in a
> privileged position to give direct voice to one's thoughts.
> (2018: 20)
> 
> 
> 



They do not, however, develop a positive account in detail.



Vicente & Martinez-Manrique (2005, 2008;
Martinez-Manrique & Vicente 2010) have criticized
Bermudez's and related inferentialist views on the
grounds that the semantics of natural language sentences--and
inner speech episodes, in particular--are underdetermined in ways
incompatible with providing knowledge of one's thoughts. For
instance, the sentence "Jane's cup is full", is
ambiguous in several ways, including the sense in which it is
Jane's cup (does she own it? is she just using it? is it the one
she merely wants?) and the sense in which it is full (is it full of
air? of liquid? of coins?). If the explicit meaning of a sentence is
only extracted (and disambiguated) at the level of thought itself,
they argue, it is unclear how awareness of semantically indeterminate
inner speech utterances could suffice for awareness of one's
own--presumably explicit and unambiguous--propositional
thoughts. Bermudez replies in his 2018 paper.



Jorba & Vicente (2014) and Martinez-Manrique & Vicente
(2015) criticize what they call the "format view" of inner
speech (which they attribute to Jackendoff and others) which holds
that we are conscious of our inner speech episodes only because of
their sensory format (see also Fernandez Castro 2016). If these
criticisms succeed, they cast doubt on views, such as those of
Carruthers (2010), Jackendoff (1996), and Prinz (2012), which link the
metacognitive or introspective value of inner speech to its occurrence
in a sensory format.



Langland-Hassan (2014) raises a different sort of challenge for
inferentialist views. Recall that it is a common assumption of those
views that propositional thought itself is amodal (i.e., non-sensory)
and non-conscious. For theorists such as Carruthers, Prinz,
Jackendoff, and Bermudez, inner speech is a conscious mental
process just because it has sensory features that render it the sort
of state that is apt to be conscious. Langland-Hassan argues that
there is a conflict in holding that an episode of inner speech is a
single mental state with both sensory features (relating to the
representation of phonemes) and semantic features (relating to the
meanings of the corresponding words). If this criticism is correct, it
creates problems for the proposal that inner speech is especially well
suited (due to its sensory character) to serve as input to inferences
about one's non-conscious mental states. Bermudez (2018),
Carruthers (2018), and Munroe (2023) have articulated different ways
of responding to this challenge (see also Prinz 2011 for relevant
remarks).


## 6. Auditory Verbal Hallucinations and Inserted Thoughts



Inner speech features prominently in philosophical and cognitive
scientific discussions of auditory verbal hallucinations (AVHs) and
thought insertion. Both are common symptoms of schizophrenia but can
occur in other contexts (e.g., brain injury, drug use) as well. AVHs
are hallucinatory experiences of another's speech, while thought
insertion is understood either as a non-veridical experience of having
someone else's thoughts in one's mind (Wing et al. 1990),
or simply as the delusional belief that someone else's thoughts
are in one's mind (Andreasen 1984). Two central questions
explored by theorists are, first, whether (abnormal) inner speech is
indeed the basis of AVHs or thought insertion, and, second, what might
lead an episode of inner speech to be experienced as an AVH or
inserted thought.



On the first question, an initially plausible approach to AVHs is to
hold that they are more a matter of hallucinatory speech
*perception* than of (unwitting) speech production, and thus
not well conceived as episodes of inner speech. Wu (2012) and Cho
& Wu (2013, 2014) advance a theory of this kind, holding that AVHs
result from the spontaneous activation of speech perception areas in
the brain. On their account, inner speech--and, in particular,
the neural regions implicated in speech production--are not
implicated in AVHs. Despite the attractive simplicity of this account,
most researchers have pursued options that explicitly involve inner
speech, for several reasons. First, in formal surveys, patients often
report that the phenomenological characteristics of their AVHs are
different from those of hearing speech, insofar as their AVHs are not
as subjectively "loud" as cases of hearing speech, are not
equally rich in sensory features, and do not always seem to emanate
from outside the head (Stephens & Graham 2000; Hoffman et al.
2008; Laroi et al. 2012; Nayani & David 1996; Stephane 2019). It
appears that an explanation of the seemingly "alien"
nature of these episodes, as well as of thought insertion, will
require some other apparatus than an appeal to perception-like
phenomenology. Given the need for such an alternative, one may hope to
extend it also to cases of AVHs that are reported as having rich,
perception-like phenomenological features (Langland-Hassan 2008;
Moseley & Wilkinson 2014).



Second, neuroimaging has shown activation in both language perception
*and* language production areas when patients are experiencing
AVHs (Allen, Aleman, & Mcguire 2007; Allen, Modinos, et al. 2012;
Bohlken, Hugdahl, & Sommer 2017). Here as in other areas of the
study of inner speech, it is important to recognize that the neural
regions underlying speech production (such as Broca's area, in
the left inferior frontal gyrus) are distinct from those governing
speech perception (such as Wernicke's area, in the superior
temporal gyrus). This is why damage to one area but not the other (as
in some cases of stroke) can result in markedly different language
impairments. The fact that the mechanisms governing speech production
and perception are dissociable in these ways provides an important
means for assessing whether AVHs are best viewed as productive or
perceptual (or both) in nature.



Nevertheless, those who see abnormal inner speech episodes as the
basis for AVHs or thought insertion face a difficult task in
explaining what would lead a person to not identify their own inner
speech as their own, or to not feel in control of their own inner
speech. Some have offered content-based explanations, where it is some
feature of the semantic content of the inner speech that leads a
person to disown it. For instance, Stephens and Graham (2000) argue
that a patient may disown inner speech episodes with contents that are
"intentionally inexplicable", in the sense that they are
not easily accommodated within a coherent self-narrative (see also
Roessler (2013), Sollberger (2014), Bortolotti & Broome (2009),
and Fernandez (2010) on the idea that AVHs or inserted thoughts
are episodes with contents the patient is unwilling to endorse).
Challenges for this approach are patient reports of voices that are
helpful or encouraging. As the Swiss psychiatrist Eugen Bleuler notes
in early work on people with schizophrenia, "besides their
persecutors, the patients often hear the voice of some
protector", and, occasionally, the hallucinatory voices
"represent sound criticism of the [the patient's]
delusional thoughts and pathological drives" (1911 [1950:
98]).



A popular alternative approach--sometimes known as the
"comparator" or "sensory feedback"
approach--builds on work in cognitive neuroscience concerning the
mechanisms by which bodily movements are determined to be one's
own (Feinberg 1978; Frith 1992; Miall et al. 1993; Wolpert, Miall
& Kawato 1998). The basic idea behind these approaches is that,
below the level of consciousness, the brain is continually generating
predictions about the likely sensory consequences of planned actions,
which are then compared with actual sensory feedback. When there is a
mismatch between the prediction and sensory feedback, one may have the
phenomenological sense of not being in control of one's actions
(Frith 2012). A number of authors have proposed that the generation of
both inner and outer speech may be attended by the same kind of
prediction and comparison mechanisms, and that the malfunctioning of
these mechanisms could lead to one's own inner speech seeming
not to be in one's control (Blakemore, Smith, et al. 2000;
Campbell 1999; Langland-Hassan 2016; Proust 2006). These proposals
derive some support from the fact that people with schizophrenia have
been shown to have broader deficits in automatically anticipating and
adjusting for the sensory consequences of their own actions
(Blakemore, Smith et al. 2000; Blakemore, Wolpert, & Frith
1998).



Nevertheless, the comparator approach to AVHs and thought insertion
has come in for criticism on several grounds (Synofzik, Vosgerau &
Newen 2008; Vicente 2014; Vosgerau & Newen 2007). One complaint
has been that the lack of sensory features associated with inserted
thoughts, in particular, makes sensory-feedback approaches ill-suited
to their explanation (Vosgerau & Newen 2007). In response, some
defenders have shifted to pitching the thesis in terms of predictive
processing models of perception and action (Gerrans 2015; Swiney 2018;
Swiney & Sousa 2014; Wilkinson 2014; Wilkinson & Fernyhough
2017), while others have developed other alternatives (Langland-Hassan
forthcoming). The matter of how best to characterize the phenomenology
and underlying etiology of AVHs and thought insertion--and the
relation of each to inner speech--together with the precise
relationship between predictive processing models and the comparator
approach, remain active areas of research. See Wilkinson &
Alderson-Day (2016) for an introduction to an edited special-issue on
the topic oriented at philosophers; see Lopez-Silva &
McClelland (forthcoming) for a philosophically-oriented anthology on
thought insertion. (Note: Parts of this section draw on a more
in-depth overview in Langland-Hassan 2021).