Introspection, as the term is used in contemporary philosophy of mind, is a means of learning about one’s own currently ongoing, or perhaps very recently past, mental states or processes. You can, of course, learn about your own mind in the same way you learn about others’ minds—by reading psychology texts, by observing facial expressions (in a mirror), by examining readouts of brain activity, by noting patterns of past behavior—but it’s generally thought that you can also learn about your mind introspectively , in a way that no one else can. But what exactly is introspection? No simple characterization is widely accepted. Although introspection must be a process that yields knowledge only of one’s own current mental states, more than one type of process fits this characterization.
Introspection is a key concept in epistemology, since introspective knowledge is often thought to be particularly secure, maybe even immune to skeptical doubt. Introspective knowledge is also often held to be more immediate or direct than sensory knowledge. Both of these putative features of introspection have been cited in support of the idea that introspective knowledge can serve as a ground or foundation for other sorts of knowledge.
Introspection is also central to philosophy of mind, both as a process worth study in its own right and as a court of appeal for other claims about the mind. Philosophers of mind offer a variety of theories of the nature of introspection; and philosophical claims about consciousness, emotion, free will, personal identity, thought, belief, imagery, perception, and other mental phenomena are often thought to have introspective consequences or to be susceptible to introspective verification. For similar reasons, empirical psychologists too have discussed the accuracy of introspective judgments and the role of introspection in the science of the mind.
1.1 Necessary Features of an Introspective Process
Introspection is generally regarded as a process by means of which we learn about our own currently ongoing, or very recently past, mental states or processes. Not all such processes are introspective, however: Few would say that you have introspected if you learn that you’re angry by seeing your facial expression in the mirror. However, it’s unclear and contentious exactly what more is required for a process to qualify as introspective. A relatively restrictive account of introspection might require the process to be of a type that can only yield knowledge of one’s own currently ongoing mental states via attention to and direct detection of those states; but many philosophers think attention to or direct detection of mental states is impossible or at least not present in many paradigmatic instances of introspection.
For a process to qualify as “introspective” as the term is ordinarily used in contemporary philosophy of mind, it must minimally meet the following three conditions:
- The mentality condition: Introspection is a process that generates, or is aimed at generating, knowledge, judgments, or beliefs about mental events, states, or processes, and not about affairs outside one’s mind. In this respect, it is different from sensory processes that normally deliver information about outward events or about the non-mental aspects of the individual’s body. Of course, knowledge of one’s mental life might enable or subserve conclusions about matters beyond the mind. Knowledge that you are visually experiencing redness at the center of your visual field might ground the conclusion that there is a red object directly in front of you (whether a philosopher regards this sort of inference as a strange case or as the way perception normally works depends on her take on indirect realism about perception; see the discussion of indirect realism and phenomenalism in the entry on the problem of perception.) The border between introspective and non-introspective knowledge can begin to seem blurry with respect to bodily self-knowledge such as proprioceptive knowledge about the position of one’s limbs or nociceptive knowledge about one’s pains. But perhaps in principle the introspective part of such processes, pertaining to judgments about one’s mind—e.g., that one has the feeling as though one’s arms were crossed or of toe-ishly located pain—can be distinguished from the non-introspective judgment that one’s arms are in fact crossed or one’s toe is being pinched.
- The first-person condition: Introspection is a process that generates, or is aimed at generating, knowledge, judgments, or beliefs about one’s own mind only and no one else’s, at least not directly. Any process that generates knowledge equally of one’s own and others’ minds is by that token not an introspective process. Of course, introspective self-knowledge may sometimes serve as a basis of knowledge of other minds. For example, if I learn introspectively that I am angry, I might on that basis conclude that others are angry too. If a certain version of simulation theory (see the entry on folk psychology as mental simulation) is right, much of our knowledge of others’ minds depends on first determining what our own reactions, attitudes, or other mental states are or would be, then drawing an implicit or explicit parallel between them and ourselves (Goldman 1989; though see Gordon 1995 for a different perspective on simulation theory). However, when I arrive at conclusions about others in this way, the introspective contribution to those conclusions is at most in the discovery of my own anger; the extension to others is probably best regarded as non-introspective. Some philosophers have contemplated peculiar or science fiction cases in which we might introspect the contents of others’ minds directly—for example in telepathy or when two individuals’ brains are directly wired together—but the proper interpretation of such cases is disputable (see, e.g., Gertler 2000).
- The temporal proximity condition: Introspection is a process that generates knowledge, beliefs, or judgments about one’s currently ongoing mental life only; or, alternatively (or perhaps in addition) immediately past (or even future) mental life, within a certain narrow temporal window (sometimes called the specious present (see the entry on the experience and perception of time). You may know that you were thinking about Montaigne yesterday during your morning walk, but you cannot know that fact by current introspection alone—though perhaps you can know introspectively that you currently have a vivid memory of having thought about Montaigne. Likewise, you cannot know by introspection alone that you will feel depressed if your favored candidate loses the election in November—though perhaps you can know introspectively what your current attitude is toward the election or what emotion starts to rise in you when you consider the possible outcomes. Whether the target of introspection is best thought of as one’s current mental life or one’s immediately past mental life may depend on one’s model of introspection: On self-detection models of introspection, according to which introspection is a causal process involving the detection of a mental state (see Section 2.2 below), it’s natural to suppose that a brief lapse of time will transpire between the occurrence of the mental state that is the introspective target and the final introspective judgment about that state, which invites (but does not strictly imply) the idea that introspective judgments generally pertain to immediately past states. On self-shaping and self-fulfillment models of introspection, according to which introspective judgments create or embed the very state introspected (see Sections 2.3.1 and 2.3.2 below), it seems more natural to think that the target of introspection is one’s current mental life or perhaps even (though few philosophers explicitly go so far) the immediate future.
Very few contemporary philosophers of mind would call a process “introspective” if it does not meet some version of the three conditions above, though in ordinary language the temporal proximity condition may sometimes be violated. (For example, in ordinary speech we might describe as “introspective” a process of thinking about why you abandoned a relationship last month or whether you’re really as kind to your children as you think you are.) However, many philosophers of mind will resist calling a process that meets these three conditions “introspective” unless it also meets some or all of the following three conditions:
- The directness condition: Introspection yields judgments or knowledge about one’s own current mental processes relatively directly or immediately. It’s difficult to articulate exactly what directness or immediacy involves in the present context, but some examples should make the import of this condition relatively clear. Gathering sensory information about the world and then drawing theoretical conclusions based on that information should not, according to this condition, count as introspective, even if the process meets the three conditions above. Seeing that a car is twenty feet in front of you and then inferring from that fact about the external world that you are having a visual experience of a certain sort does not, by this condition, count as introspective. However, as we will see in Section 2.3.4 below, those who embrace transparency theories of introspection may reject at least strong formulations of this condition.
- The detection condition: Introspection involves some sort of attunement to or detection of a pre-existing mental state or event, where the introspective judgment or knowledge is (when all goes well) causally but not ontologically dependent on the target mental state. For example, a process that involved creating the state of mind that one attributes to oneself would not be introspective, according to this condition. Suppose I say to myself in silent inner speech, “I am saying to myself in silent inner speech, ‘haecceities of applesauce’”, without any idea ahead of time how I plan to complete the embedded quotation. Now, what I say may be true, and I may know it to be true, and I may know its truth (in some sense) directly, by a means by which I could not know the truth of anyone else’s mind. That is, it may meet all the four conditions above and yet we may resist calling such a self-attribution introspective. Self-shaping (Section 2.3.2 below), expressivist (Section 2.3.3 below), and transparency (Section 2.3.4 below) accounts of self-knowledge emphasize the extent to which our self-knowledge often does not involve the detection of pre-existing mental states; and because something like the detection condition is implicitly or explicitly accepted by many philosophers, some philosophers (including some but not all of those who endorse self-shaping, expressivist, and/or transparency views) would regard it as inappropriate to regard such accounts of self-knowledge as accounts of introspection proper.
- The effort condition: Introspection is not constant, effortless, and automatic. We are not every minute of the day introspecting. Introspection involves some sort of special reflection on one’s own mental life that differs from the ordinary un-self-reflective flow of thought and action. The mind may monitor itself regularly and constantly without requiring any special act of reflection by the thinker—for example, at a non-conscious level certain parts of the brain or certain functional systems may monitor the goings-on of other parts of the brain and other functional systems, and this monitoring may meet all five conditions above—but this sort of thing is not what philosophers generally have in mind when they talk of introspection. However, this condition, like the directness and detection conditions, is not universally accepted. For example, philosophers who think that conscious experience requires some sort of introspective monitoring of the mind and who think of conscious experience as a more or less constant feature of our lives may reject the effort condition (Armstrong 1968; Armstrong 1999; Lycan 1996).
Though not all philosophical accounts that are put forward by their authors as accounts of “introspection” meet all of conditions 4–6, most meet at least two of those. Because of differences in the importance accorded to conditions 4–6, it is not unusual for authors with otherwise similar accounts of self-knowledge to differ in their willingness to describe their accounts as accounts of “introspection”.
1.2 The Targets of Introspection
Accounts of introspection differ in what they treat as the proper targets of the introspective process. No major contemporary philosopher believes that all of mentality is available to be discovered by introspection. For example, the cognitive processes involved in early visual processing and in the detection of phonemes are generally held to be introspectively impenetrable and nonetheless (in some important sense) mental (Marr 1983; Fodor 1983). Many philosophers also accept the existence of unconscious beliefs or desires, in roughly the Freudian sense, that are not introspectively available (e.g., Gardner 1993; Velleman 2000; Moran 2001; Wollheim 2003; though see Lear 1998). Although in ordinary English usage we sometimes say we are “introspecting” when we reflect on our character traits, contemporary philosophers of mind generally do not believe that we can directly introspect character traits in the same sense in which we can introspect some of our other mental states (especially in light of research suggesting that we sometimes have poor knowledge of our traits, reviewed in Taylor and Brown 1988; Paulhus and John 1998; Vazire 2010).
The two most commonly cited classes of introspectible mental states are attitudes, such as beliefs, desires, evaluations, and intentions, and conscious experiences, such as emotions, images, and sensory experiences. (These two groups may not be wholly, or even partially, disjoint: Depending on other aspects of her view, a philosopher may regard some or all conscious experiences as involving attitudes, and/or she may regard attitudes as things that are or can be consciously experienced.) It of course does not follow from the fact (if it is a fact) that some attitudes are introspectible that all attitudes are, or from the fact that some conscious experiences are introspectible that all conscious experiences are. Some accounts of introspection focus on attitudes (e.g., Nichols and Stich 2003), while others focus on conscious experiences (e.g., Hill 1991; Goldman 2006); and it is sometimes unclear to what extent philosophers intend their remarks about the introspection of one type of target to apply to the other type. There is no guarantee that the same mechanism or process is involved in introspecting all the different potential targets.
Generically, this article will describe the targets of introspection as mental states, though in some cases it may be more apt to think of the targets as processes rather than states. Also, in speaking of the targets of introspection as targets, no presupposition is intended of a self-detection view of introspection as opposed to a self-shaping or containment or expressivist view (see Section 2 below). The targets are simply the states self-ascribed as a consequence of the introspective process if the process works correctly, or if the introspective process fails, the states that would have been self-ascribed.