What is the connection between thought and inner speech (the processes of speaking to oneself mentally)? Can we experience thoughts without associating them with inner speech? Is the thought itself conscious or just its inner speech expression? Well, let’s get right to it.
1. Inner Speech as the Conscious Byproduct of Thought
A traditional way to view inner speech is as the conscious presentation of thoughts. This is to say that to have a “conscious” thought there must be some conscious unit of inner speech, which has as its content the ideas that are constitutive of the “mentalese” thought that generated it (mentalese thoughts are pure thoughts, not structured by language, images, ect). For example, under this view of thought and inner speech, if one had the experience of the inner speech thought “the cat is on the mat” then we could assume that there was also a mentalese thought with the same content as that sentence. I won’t go into any more detail about this conception of thought, however, since it suffers from several major problems. First there is the possibility that the inner speech generated by a thought might misrepresent the underlying thought, since we do make mistakes in normal speech from time to time. Such a possibility implies that either the underlying thought or the conscious thought is effectively epiphenomenal, since if the mentalese thought really mattered for the development of conscious experience over time then cases of mis-“speaking” would lead to incoherent conscious experience (i.e. “that is a nice boat” followed by “I wish I had a car like that”). On the other hand if it is really the inner speech that matters for the progression of consciousness then it is hard to see why we should suppose there are underlying mentalese thoughts at all. A second problem is the neurological basis for our powers of inner speech, specifically that the mechanisms for generating speech and understanding it are separate, making it a mystery how a statement such as “that car is nice” could have a definite meaning, since the understanding mechanisms, certainly part of the path that incorporates inner speech into conscious experience, wouldn’t know how to resolve the indexical, unless the mentalese thought has a much larger role than simply generating the inner speech.
2. Inner Speech as Partly Constitutive of Thought
An alternative description of the connection between inner speech and thought, proposed by Peter Carruthers (not me) in his paper “Conscious Experience versus Conscious Thought”, is that the inner speech is paired with the “mentalese” thought. This pairing has several advantages over the traditional model. First it explains why some thoughts are conscious and some are not; only those with an attached inner speech expression are conscious. It also explains how an indefinite indexical can have a definite meaning in thought; the attached mentalese component provides the definite meaning. Although definitely an improvement over the traditional approach, this model of thought still has a few problems. One problem is that it doesn’t explain why exactly the association of an inner speech sentence with a thought should make it conscious, a problem that is more serious when we consider that some conscious thoughts have inner imagery associated with them instead of inner speech. Why should two very different mechanisms be both able to make a thought conscious, why not just one of them? This problem is made even more pressing by the fact that some conscious thoughts seem to have neither imagery nor words associated with them. For example, when reflecting upon my conscious experience of performing chores, my conscious thoughts at that time, concerning what I should be doing and the best way to accomplish it, did not seem to be formalized by inner speech or imagery, although admittedly while reflecting on them I tend to associate words with them in order to make them easier to study. Finally, the possibility of mismatches between mentalese and inner speech pose a problem for this theory. It would seem that this model would require that they either be impossible or unconscious, but there seems little motivations to propose either of these options, other than that the model requires it.
3. Inner Speech as an Addition to Conscious Thought
Let me then propose a third model in order to resolve some of the problems encountered by other models of thought. The model described leans somewhat on the description of consciousness proposed here. Of importance for our investigation of conscious thought here is the idea that a thought is conscious in virtue of being part of a conscious experience, which, more precisely, means that a conscious thought is incorporated into the conscious mind such that it has a certain causal role in the formation of the thought component of future experiences (a dominant role) and the possibility to influence the information that the mind associated with itself. The unconscious has a different role in the system, preventing it from being experienced as conscious; instead of being part of experience it plays an indirect role, only occasionally influencing the development of conscious experience. However, as detailed elsewhere, I find that the idea of an unconscious thought to be somewhat contradictory, and would argue that such “thoughts” should really be classified as unconscious beliefs or desires. In any case, this model of thought makes inner speech and mental imagery superfluous, in the sense that we can have conscious thoughts without them (a fact I feel is supported by experience, as mentioned above). I would not deny, though, that we do have the conscious experience inner speech, and that experiences of a thought with and without inner speech are different and that the difference is conscious and has causal powers. I would explain this inner speech as being generated by some conscious thoughts (possibly before they are fully formed or incorporated into conscious experience, the details are largely irrelevant). The produced speech (or images) are then passed the appropriate understanding mechanisms, and through them are incorporated into conscious experience, along with the thought that generated them. Thus, as in Carruthers’ model, the “mentalese” component plays a role in providing a definite meaning for the sometime vague sentences of inner speech. In many ways then these models are similar, but there is an important difference concerning how mismatches between mentalese thought and inner speech are handled. In this model it is entirely possible that mismatches may occur, and if they are the conscious subject will be aware of them as mismatches. In fact I have personally experienced this effect. Much like the phenomena of misspeaking, one hears oneself say onething but you know that you really meant something else (in my case the word “train” kept substituting itself for “thought”), and even though you know you really mean something else it takes a few tries before the speech production mechanisms “reset” and you can say what you mean. Accounting for this specific experience motivates many of the features of this account, specifically that one can have a thought with one meaning, an associated sentence of inner speech with another, and at the same time be conscious of both, and that there is a difference between them. Finally, let me conclude the description of this model by mentioning that even though the mentalese component of thought is independently part consciousness this does not prevent inner speech from being an important part of conscious experience as well. Inner speech seems to clarify thoughts and to make it easier to think about complex ideas and their connections; it is not epiphenomenal just because thoughts unaccompanied by inner speech may be conscious.
5. The Evolution of Conscious Thought
This account of thought does pose some problems for some theories concerning the evolution of conscious thought. A common account of the origins of thought, presented by Daniel Dennett in Consciousness Explained, is that the ability of people to ask questions of other people eventually led to the ability to ask questions of oneself, and that for reasons of privacy this process was eventually internalized, becoming the “chain of thought” we are all so familiar with. I think that this may very well be a good account of the origins of inner speech, but, obviously, I don’t see thought as originating in this way. If the model proposed here is correct then thoughts are more fundamental, such that the possibility of intelligible inner speech requires the pre-existence of thoughts (to lend inner speech a definite interpretation, ect), and possibly to even generate speech in the first place (although this conclusion isn’t motivated by the description of thought presented here). However, there are other possible explanations for the development of conscious thoughts (if there weren’t our model would be in big trouble). I suspect that it is advantageous for organisms with the power to learn to be able monitor their own mental activity, so that they can make more accurate adjustments to their behavior. This would be the origin then of information that was part of consciousness but not about the external world. This information would already then have the power to guide the organism’s behavior and mental activity, and from there it is a sort jump to mentalese thoughts (specifically, that the information becomes more detailed, ties into systems concerning representation of the external world more closely (so that it can be “about” non mental events), and begins to be based somewhat on its previous output, giving rise to a chain of thought). I will leave the exact details to biologists, but, given this sketch, I don’t think that an evolutionary explanation of thought requires inner speech as an essential component.