Free will and mental disorder: Exploring the relationship


A link between mental disorder and freedom is clearly present in the introduction of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). It mentions “an important loss of freedom” as one of the possible defining features of mental disorder. Meanwhile, it remains unclear how “an important loss of freedom” should be understood. In order to get a clearer view on the relationship between mental disorder and (a loss of) freedom, in this article, I will explore the link between mental disorder and free will. I examine two domains in which a connection between mental disorder and free will is present: the philosophy of free will and forensic psychiatry. As it turns out, philosophers of free will frequently refer to mental disorders as conditions that compromise free will and reduce moral responsibility. In addition, in forensic psychiatry, the rationale for the assessment of criminal responsibility is often explained by referring to the fact that mental disorders can compromise free will. Yet, in both domains, it remains unclear in what way free will is compromised by mental disorders. Based on the philosophical debate, I discuss three senses of free will and explore their relevance to mental disorders. I conclude that in order to further clarify the relationship between free will and mental disorder, the accounts of people who have actually experienced the impact of a mental disorder should be included in future research.


A connection between mental disorder and freedom is clearly present in the introduction of the fourth edition to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). It reads, “In DSM-IV, each of the mental disorders is conceptualized as a clinically significant behavioral or psychological syndrome or pattern that occurs in an individual and that is associated with present distress (e.g., a painful symptom)… or an important loss of freedom” [1, p. xxi]. In this quotation, however, it remains unclear how “an important loss of freedom” should be understood. It could indicate practical impairments (like in physical illnesses) interfering with the freedom to live one’s life as preferred. Alternatively, “loss of freedom” may relate to the freedom of the mind or the concept of free will. In any case, the meaning of freedom within the context of the DSM-IV quotation remains unarticulated. This article seeks to explore the possible link between mental disorder and free will by looking at two domains in which such a link is clearly present: forensic psychiatry and the philosophy of free will.

The article consists of five parts. In the first section, the main themes of the current philosophical free will debate are discussed. Based on an account suggested by Henrik Walter, a distinction will be made between three senses of free will [2]. In the second section, it will turn out that, in fact, mental disorders often feature in the philosophical discussions on free will in the sense that persons are considered to be free and responsible unless they suffer from a mental disorder. In the third section, attention will be shifted to another domain, forensic psychiatry, in particular, to discussions on criminal responsibility. When a person performs a criminal act as a result of a mental disorder we intuit that this person is not responsible for the act. Why is this? In forensic literature, one type of answer to this question points to free will. In the fourth section, I will take stock of the discussions described in the first three sections. I will argue that, in both domains—philosophy of free will and forensic psychiatry—mental disorders are taken to be related to free will in a well-defined manner: they are considered to compromise free will and to reduce responsibility. Based on the previous sections, I explore the relevance of the three senses of free will with respect to mental disorders. In the fifth section, I will argue that in order to further clarify the relationship between free will and mental disorder, the accounts of people who have actually experienced the impact of a mental disorder should be included in future research.

Free will in current philosophical debates

Based on an account suggested by Walter, we can distinguish three main aspects, or components, of free will in the contemporary philosophical debate [2]. The first element is that to act freely, one must be able to act otherwise; one must have alternative possibilities open to one [3].Footnote 1 If people cannot choose between alternatives because they are completely determined to act in a specific way (e.g., because of divine foreknowledge or because of the wiring of people’s brains), they cannot be said to act freely. Second, acting freely can also be understood as acting (or choosing) for a reason. Behavior that is not taking place for an intelligible reason is not considered “freely willed.”Footnote 2 For instance, hitting another person during an epileptic seizure, which does not occur for a reason, is not a free action, nor do we blame the person for such an action. Third, free will requires that one is the originator—(causal) source—of one’s actions. For instance, when an agent is being manipulated (or hypnotized) the agent cannot be said to act freely; although the agent performs the action, she is not the genuine source of it. The free will debate in philosophy is largely concerned with the question of to what extent each of these aspects is, indeed, essential to the concept of free will.Footnote 3 More precisely, at the moment, it is not clear which of these senses is pertinent to a notion of free will that is required for moral responsibility. In addition, we should note that these conceptions are certainly not exhaustive; there are various competing conceptions of free will [4, 7]. Furthermore, each of these elements or senses of free will contains ambiguities, such as “(causal) source,” “person,” “ability to act,” and “acting for a reason.” The exact meaning that people attach to each of these might differ significantly. Sorting out these ambiguities probably hinges on people’s metaphysical and ethical commitments. For instance, being the source of an action can be explained in a libertarian account [3, 6], but also in what can be considered a more naturalist account [8]. This being said, within the context of this article, the distinctions proposed by Walter provide a useful entrance to the complicated and multifaceted philosophical debate on free will.

A special case of the philosophical free will discussion is the compatibility problem. Philosophers have not been able to establish whether or not free will is compatible with determinism [4]. Determinism is the thesis that there is one physically possible future [9]. Whatever happens is inevitable or necessary because of, for example, fate, the will of God, or the laws of nature [5]. According to some people, the everyday “decisions” that we make in this world are basically in obedience to deterministic natural laws. Philosophers have not been able to reach consensus on whether free will can exist in such a deterministic world. The discussion on free will and determinism has not only taken place among philosophers; especially in the last decades, neuroscientists and psychologists have been participating in the debate also [24, 10]. The compatibility debate has been going on for centuries. And in fact, not only determinism but also indeterminism appears to be problematic for free will, for what room would be left for free will, if everything happened by chance? [4]. Yet, the complexity of the concept of free will (and related issues) apparently has not undermined the value and significance attached to it by many. In this article, I will not take a specific position on whether free will is compatible with determinism.

But it is important to note a particular characteristic of free will: its relationship with moral responsibility. It appears that if anything is important to moral responsibility, it is free will [9]. Free will may be defined in many ways, but time after time, the central question is, does this specific concept of free will enable us to explain our moral intuitions? [11] As a result, in philosophy, discussions on moral responsibility (ethics) and free will (metaphysics) are deeply intertwined [4, 11].

Free will and mental disorder in philosophical debates

Interestingly, mental disorders actually feature in philosophical discussions of free will and moral responsibility. Disorders like obsessive–compulsive disorder [2], kleptomania [12], addiction [13], and Tourette’s syndrome [14] are considered relevant to arguments about free will. Mental disorders and references to psychiatric signs and symptoms even feature in crucial papers that have shaped the debates on moral responsibility and free will over the last decades. Examples are Strawson’s Freedom and Resentment [15] and Frankfurt’s “Freedom of the Will and the Concept of a Person” [16]. In the latter paper, in order to explain a hierarchical account of freedom, Frankfurt describes an addict as a person who is not free. More precisely, on Frankfurt’s account, acting of one’s own free will implies that one wills the action and also wants to have the will to perform the action. An addict who has the will (or first order desire) to use heroin but who does not want to have this will is not free when using heroin. And in Watson’s interpretation of Frankfurt’s theory of responsibility, freedom should be perceived as a certain capacity people usually have, which “can be destroyed by addictions or phobias” [10, p. 17].

Another example of the way in which mental disorders or psychopathological symptoms are used in the debate can be found in Galen Strawson:

Compatibilists believe that one can be a free and morally responsible agent even if determinism is true. Roughly, they claim, with many variations of detail, that one may correctly be said to be truly responsible for what one does, when one acts, just so long as one is not caused to act by any of a certain set of constraints (kleptomaniac impulses, obsessional neuroses, desires that are experienced as alien, post-hypnotic commands, threats, instances of force majeure, and so on). [17, p. 222]

Apparently, kleptomanic impulses and obsessional neuroses can undermine free will and responsibility in this compatibilist account. Peter Strawson previously made an almost identical claim with respect to a certain compatibilist position:

What “freedom” means here is nothing but the absence of certain conditions the presence of which would make moral condemnation or punishment inappropriate. They [certain compatibilists] have in mind conditions like compulsion by another, or innate incapacity, or insanity, or other less extreme forms of psychological disorder. [15, p. 73]

According to this view, both “insanity” and “less extreme forms of psychological disorder” undermine freedom to such an extent that moral condemnation is no longer appropriate. In the same vein, Widerker and McKenna state that “not all persons are morally responsible agents (such as small children, the severely mentally retarded, or those who suffer from extreme psychological disorder)…” [6]. According to Kalis et al., in the philosophy of free will, “[a]ddiction and compulsion are… presented as two different manifestations of the same thing—namely, unfree actions or actions caused by irresistible desires” [18, p. 409]. And Watson states that “[a]ddiction… is commonly invoked as a kind of paradigm of unfree will” [10, p. 20]. Meanwhile, with respect to alcoholism or “heavy drinking,” there are also other views. Herbert Fingarette, a philosopher with an interest both in free will/responsibility and mental disorders, for instance, is critical about the idea that heavy drinking or alcoholism (completely) undermines free will [19]. He starts out by writing that “[a]nyone who has ever observed the behavior of a chronic heavy drinker cannot help feeling a sense of momentum at work. In some way the inclination to down another drink seems to escape the full reach of rational judgment and of cool and deliberate free choice” [19, p. 32; emphasis added]. Yet, combining several strands of observations and research, Fingarette aims to prove that this view is, at least in part, falsified by empirical data by emphasizing that there is still (some form of) self-control present in alcoholism (e.g., people appear to be able to moderate their drinking in certain periods). This would imply that there is still a voluntary aspect preserved in heavy drinking, and that it does not involve an all-out loss of control and the ability to choose freely.Footnote 4

Daniel Levy, in a paper on free will and developments in cognitive neuroscience, zooms in on obsessive–compulsive disorder (OCD): “We understand that a person suffering from obsessive–compulsive disorder, spending all day washing his hands and checking dozens of times that he remembered to lock the front door, cannot be thought of as having free will. His actions are mechanically dictated by stereotyped scripts, from which he cannot escape. Thus, obsessive–compulsive disorder is a malady of free will, because it prevents normal strategic planning and meta-control of behavior from overcoming compulsions” [20, p. 214; emphasis added]. And Patricia Churchland apparently has a comparable opinion for she writes in a section on free choice and caused choice, “A patient with obsessive–compulsive disorder (OCD) may have an overwhelming urge to wash his hands…. OCD patients often indicate that they wish to be rid of hand-washing or footstep counting behavior, but cannot stop. Pharmacological interventions, such as Prozac, may enable the subject to have what we would all regard as normal, free choice about whether or not to wash his hands” [21, p. 208; emphasis added]. Finally, within the context of an argument on the requirement of alternative possibilities (one of the elements of free will mentioned earlier), Daniel Dennett even refers to fear of flying as an excusing condition [22, p. 556]. This implies that more common mental traits like phobias have a bearing on responsibility.

As it appears, according to philosophers, mental disorder implies that free will and responsibility are compromised. Addiction and compulsion are kinds of disorders philosophers particularly refer to, but, in fact, all mental disorders, ranging from insanity to less extreme forms of psychological disorder, have some detrimental effect on free will and responsibility.Footnote 5 Meanwhile, what it is exactly that mental disorders do that leads to a suspension of freedom and responsibility remains unclear. Philosophers of free will seem to be primarily interested in describing responsibility and freedom in subjects whose free will and responsibility are not affected. Less attention has been paid to identifying the precise reasons why (certain) mental disorders would diminish free will; a detailed analysis of what it is that mental disorders do that has such an effect on free will is lacking. And while several of the quotations refer to mental disorders within the context of a compatibilist argument or view (which would mean that what mental disorders do to free will is explicable also in a deterministic world), it does not become clear how exactly the effect of mental disorder on free will should be understood in a deterministic world (Strawson and perhaps Wolf may be considered to provide the beginning of such an account [12, 15]).

The topic of the next section is free will in forensic psychiatry, in particular, in theoretical reflections on the conceptual underpinnings of forensic assessment of criminal responsibility. It turns out that there are significant similarities between philosophical debates and forensic psychiatric views on free will and mental disorder.

Free will in forensic psychiatry

In legal procedures, forensic psychiatrists may be asked to assess the defendant with regard to criminal responsibility. For the court is not only interested in whether or not the defendant was the person who performed the legally relevant act but also in whether the defendant can be held accountable for that act. The issue at stake in such assessments is often referred to as “criminal responsibility.” Several legal criteria or rules have been established in order to assess criminal responsibility. The most influential is the M’Naghten Rule, which can be formulated as follows: “At the time of committing the act, the party accused was laboring under such a defect of reason, from the disease of the mind, as not to know the nature and quality of the act he was doing; or if he did know it, that he did not know what he was doing was wrong” [23, p. 11]. Although the issue at stake is considered to be criminal responsibility, an area of dispute concerns the question, should forensic psychiatrists indeed express their view on whether the defendant is actually responsible (or not responsible) for the crime? Some hold that psychiatrists should not state whether or not a defendant is actually responsible or not; this judgment should be left to the jury or judge [24].

The legal rules, like the M’Naghten Rule, however, do not immediately answer the question, what basic moral notion makes us intuit that “diseases of the mind” have anything to do with accountability or responsibility? For instance, we intuit that the mother who kills her baby because of a delusional state in a postpartum psychosis is not morally and legally responsible for the act. She should be treated, not punished. Why? One important consideration explicitly refers to free will. A clear example is provided by Reich in Psychiatric Ethics. He states that “the law recognizes that insanity compromises free will, and classifies someone without free will as legally not responsible for his or her actions…” [25, p. 206]. This understanding of the rationale for forensic assessments implies, at least according to Luthe and Rösler, that forensic psychiatrists “will have to concern themselves with the question of whether human actions can be freely chosen or whether the acting person could not avoid acting as he did.” [26]. Because of the perceived role of free will in forensic assessment, some theorists even consider the compatibility question to be relevant to forensic psychiatry [27]. Morse suggests that the idea among forensic practitioners that free will is a specific or foundational criterion for responsibility in morality and law is widespread [28].Footnote 6 Such a view can lead forensic practitioners to refer to free will in their testimony before the court. They might say, for instance, that the defendant “lacked free will” and that, therefore, he or she is not accountable for the act.

In forensic practice, it is relevant that not all mental disorders are usually considered to be “candidates” for an insanity defense. Psychotic disorders, especially, are considered to have potentially decisive influence on human action [23, 29]. However, there are no clear arguments that state that other mental disorders (other than psychosis) could not, in principle, provide grounds for an insanity defense [23].

In sum, the way in which free will is relevant to the forensic debate is in line with the way mental disorders are relevant to the philosophical debates on free will (see previous section). For the overall idea derived from the philosophy of free will is that—if anything—free will is required for moral responsibility and that free will can be compromised by mental disorder. This appears to be the line of thought present in the literature on forensic psychiatry as well. Yet, there also seems to be a difference between both domains. In forensic psychiatry the idea is clearly expressed that while mental disorders can, in certain cases, compromise free will, they do not necessarily undermine responsibility. Forensic assessment, therefore, is necessary not only in order to assess the presence of a mental disorder but also to assess the actual influence of the mental disorder on the agent’s acts. The mere presence of a mental disorder is certainly not sufficient for concluding that the defendant cannot be held accountable for the act. This view is less explicitly present in the philosophical debate.

Three senses of free will

As pointed out, given the current philosophical discussions, we can distinguish at least three senses of free will. Consequently, the sentence “mental disorders are able to compromise free will” can have different meanings. It could mean that mental disorders are able to undermine the agent’s ability to act otherwise, or that they can compromise his acting for intelligible reasons, or finally, it could mean that mental disorders may deprive a person from being the (causal) originator of the action. In what follows, mental disorder will be tentatively linked to each of these three different senses of free will.

Acting for (intelligible) reasons. Tics in Tourette’s syndrome (a neuropsychiatric disorder) are often considered to be performed without any reasons at all [30]. In such cases, people may flex their arms or utter sounds or words without any particular reason or motive. From the perspective of an “acting for reasons” view of free will, such a movement (which, in theory, can result in a criminal offense) is not performed freely. Also, in catatonia there may be movements for which there are no apparent reasons. For instance, there may be a stereotypical, repetitive behavior that does not seem to be explicable in terms of reasons [31].Footnote 7 Yet, most mental disorders will not result in behavior for which no reason at all can be given. In fact, a characteristic of mental disorders is that, unlike many “somatic” disorders, they affect the intentional aspect of behavior. For example, a person who acts because of a paranoid delusion, acts for reasons influenced by a delusion: he killed his mother because he was convinced that she was continuously intoxicating him, and therefore, he wanted to stop her. So, on this account, except for, e.g., tics in Tourette’s and catatonic states, the criterion of “acting for reasons” per se will not lead to considering psychiatric disorders in general as potentially undermining free will.Footnote 8 (See also the next section on Tourette’s syndrome: not all tics are experienced as completely involuntary.)

The genuine source of the action (origination). Some might prefer to phrase this as “the person is the causal initiator of the action” (this conception is related to the philosophical position of source incompatibilism [6]). According to this view of free will, only actions whose source lies in the agent himself can be considered to be free actions. Now, actions performed because of delusions might not be considered to stem from the person himself. In fact, in forensic psychiatry it is sometimes said that the mental disorder caused the crime [32]. This idea of “mental disorder as the cause of an offense” provides room for the view that it was not the person himself who did it but that it was, instead, a mental disorder that caused the crime. The attribution of blame and responsibility, therefore, should not be directed at the person proper—for he or she is not the genuine source of the action. In one of the quotes from the philosophical debate (by Galen Strawson, see above) this can indeed be found: “just so long as one is not caused to act by… kleptomaniac impulses, obsessional neuroses” [17, p. 222; emphasis added]. On this view, the person apparently is not the genuine source of the act in the sense that it was the mental disorder that caused the offense. For instance, consider an otherwise highly responsible person who is suffering from a bipolar disorder and who is convinced that he is entitled to harm innocent individuals, and via associative thinking, he comes up with a plan which results in a crime. Interpreting what occurred, we might say that during this manic episode, he was not “himself” and hence not responsible; he performed the act, but he was not performing it “freely” but as a result of a bipolar disorder. On such an account, the sense of free will as being the genuine source of the action might lead to considering acts resulting from (certain) mental disorders as “not free.”

Alternative possibilities. Are alternative possibilities for action or choice required for free will? [6]. This has been one of the thorniest issues in the philosophical free will debate, especially during the last decades. Meanwhile, in the forensic literature, alternative possibilities are mentioned as being compromised by mental disorder. For instance, Van Marle, a Dutch forensic psychiatrist, explaining forensic assessments in the Netherlands, states:

Undiminished responsibility means that the person concerned had complete access to his or her free will at the time of the crime with which he or she is charged and could therefore have chosen not to do it. Irresponsibility means that the person concerned had no free will at all with which to choose at the time of the crime with which he or she is charged. Important here is determining the moment when aspects of the disorder become manifest in the situation (“the scene of the crime”) that will eventually lead to the perpetration. The earlier they play a role, the more inevitable will be the (disastrous) sequence of events, and the stronger will be the eventual limitation of free will. [33; emphasis added]

The phrase “could therefore have chosen not to do it” implies, at least within this context, that mental disorders can undermine the possibility to choose between alternatives, and that this is why the person did not act freely. This also appears to be the case in the earlier quotes about OCD by Levy (“he cannot escape”) and Churchland (“OCD patients… cannot stop”)—both point to a lack of alternative possibilities. So, apparently, free will could be negated by mental disorder in that mental disorders may undermine the person’s ability to choose between alternatives. If this is taken to be the meaning of free will within the forensic context, we should note that this perspective also appears to be most directly vulnerable to attacks from (hard) deterministic views on free will, which claim that in our world, there are never any real alternatives. In addition, as mentioned above, compatibilist accounts of free will that do not rely on the element of alternative possibilities also express the idea that mental disorders undermine free will (see quotations from Galen and Peter Strawson above). This would imply that, at least in their (compatibilist) view, the alleged detrimental effect that mental disorders have on moral responsibility is not because they eliminate alternative possibilities.

In conclusion, there are different senses of free will, and, in principle, each of them could be relevant to the question of why mental disorders threaten responsibility. Each of the senses might also result in different answers to the question of whether free will is indeed undermined by certain mental disorders. Based on our preliminary considerations, one could understand the sentence “mental disorders are able to compromise free will” in terms of mental disorders undermining the person being the actual source of the action. This could make sense both from a forensic and philosophical perspective. Mental disorder, then, would affect the element of origination.

Apart from these senses of free will, there is the issue of degrees of freedom. It might be that various mental disorders result in different degrees of “compromised” free will. For instance, psychotic disorders appear to be the paradigm cases of compromised free will in forensic psychiatry [23, 29], which suggests that their effects on free will are more pronounced than those of, e.g., obsessive–compulsive disorder (OCD). But is it indeed justified to look at these disorders in this way? Is the severity of the disorder proportionally related to the (alleged) influence on free action and free choice? Are mental disorders capable of undermining free will and responsibility irrespective of their severity? The philosophy of free will seems to suggest the latter, because “less extreme forms of psychological disorder” are also considered to be relevant to free will.

Theory and real people

So far, the exploration of the link between mental disorder and free will in this paper has been a theoretical endeavor. However, elucidating the relationship between mental disorder and free will and/or responsibility should not be a merely conceptual topic. It would be particularly interesting to qualitatively and quantitatively study the extent to which people who actually suffer(ed) from mental disorders experience(d) an effect on their free will and/or responsibility. Their accounts are remarkably absent from the philosophical and forensic discussions on free will and mental disorder; in general, philosophers, as well as forensic theorists, appear just to assume the (partial) absence of freedom in these conditions. However, outside the theoretical literature, we occasionally find brief accounts of people with mental disorders linking their condition to free will, like in the case of John in Best Possible Odds: Contemporary Treatment Strategies for Gambling Disorders: “John, a 38-year-old salesman, was being treated on an outpatient basis for a $1,000-a-week video poker gambling habit. As part of his sales job, he commuted by or near a number of video poker establishments. ‘Often,’ he noted, ‘I find them almost irresistible. It’s like I lose my free will when I am around them’” [34, p. 138; emphasis added].

There are several reasons for the importance of a “first person” perspective on this matter. The first reason is that it is about psychopathological mental states. Such mental states are not easily accessible to everybody. Therefore, those who have had experiential access to these states or conditions should not be excluded from, but welcomed into, discussions on the relation between mental disorder, free will (in whatever sense), and responsibility. Notably, there are a huge variety of mental disorders, so being familiar with one of them is certainly not enough.

Second, an interesting study by Lang on movement disorders showed some surprising results with respect to “voluntariness” and certain psychopathological features [35]. It was long taken for granted that the tics in the neuropsychiatric Tourette’s syndrome were produced involuntarily. However, Lang aimed to determine the subjective perception patients have of abnormal movements by interviewing these patients on the “voluntary” versus “involuntary” aspects of their symptoms [35]. The majority of tic-disorder patients reported that their tics were voluntary; their motor and phonic tics were intentionally produced (this, of course, does not imply that these people want to have tics or Tourette’s syndrome, but it is, rather, about the specific nature or phenomenology of some of the tics and how their execution comes about [30]). Apart from the significance of this observation as such, there was an interesting practical implication of this finding. Because of the apparent intentional nature of some of the tics, it was hypothesized that cognitive behavioral therapy, especially the element of exposure and response prevention, might be beneficial. And, indeed, this kind of therapy has been used with at least some success to treat Tourette’s syndrome [30]. This indicates, first, that one can be surprised by the experience of “(in)voluntariness” reported by persons with a (neuro)psychiatric disorder and, second, that these reports can eventually result in the development of successful therapeutic interventions as well. So, we might be surprised by what people with OCD, addiction, and impulse-control disorders have to say about the “freedom” of their actions.

The third, though related reason concerns the fact that the discussion, as we have seen, apparently takes for granted that mental disorder is linked to reduced freedom. Now it might be that this basic view is not in line with actual experience, at least in some conditions. In fact, it might be that the kind of mental disturbance that intuitively appears to compromise “freedom” the most (e.g., manic or psychotic disorder) is not experienced as such by the person himself or herself during a psychotic episode. It would be interesting to ask people, not only during but also after the psychotic (delusional) episode, how they feel about their “free will” during the psychotic episode.

More precisely, examining “first person” reports may shed light on questions like the following: Are there perhaps specific symptoms that lead to the experience of a reduction in or loss of “free will”? Should free will as it relates to mental disorders be considered primarily as a matter of degree? In principle, research aimed at systematically collecting and analyzing such first person accounts should cover the entire range of mental disorders, from phobias to psychotic disorders.

Given the fact that there is a significant lack of clarity about the nature of forensic assessment, getting a clearer view on the elements of the concept of free will that are potentially relevant to forensic assessments could help to clarify this psychiatric practice. This is especially important since this practice may have a profound impact on legal procedures and, therefore, on people’s lives. Still, we should consider the possibility that it is easier to (intuitively) know when free will is or is not present than it is to give an account of free will itself, and that, in a way, the former might be accomplished more effectively if we do not insist on linking it to the latter. Yet, as it is, forensic theorists and practitioners are actually already troubled by the topic of free will as it relates to the insanity defense [28, 36]. More precisely, (at least some) forensic theorists and practitioners are concerned about the role of free will in forensic assessment in view of allegedly deterministic (e.g., neuroscientific) theories [28]. Given their concern, it might, for instance, be important to know whether mental disorder affects free will in a meaningful way in a deterministic world.

Although I have pointed to the relevance of empirical research on the experience of freedom in several mental disorders, conceptual issues also deserve further attention. As mentioned earlier, the framework of the three elements leaves ample room for questions and alternative interpretations. For instance, with respect to the person being the “genuine source of the action,” I mentioned that the mental disorder—rather than the “person proper”—could be considered the cause of a crime. Yet, this raises the question, what is the person proper and how can one distinguish the person proper from a mental disorder? This line of questioning will, sooner or later, bring up the question, what exactly is a mental disorder?—a central topic in the philosophy of psychiatry [37]. And if we focus on the “cause” of an event, then we must decide how to assess, among the manifold phenomena that contribute to the occurrence of a particular event (e.g., actions), which of these contributory phenomena count as an authentic “cause.” For instance, did an addict’s original decision to use heroin cause the heroin addiction and thus also cause the actions that subsequently resulted from the heroin addiction? In brief, a central issue will be, how do the person proper and the disorder relate and how can they be distinguished when it comes to the initiation of actions?

Within the medical domain, exploring the link between mental disorder and free will might not only be relevant with respect to forensic practice but also to questions about informed consent. Roberts clearly points to the role of “freedom” as a component of voluntarism in issues of informed consent: “Voluntarism involves the capacity to make this choice freely and in the absence of coercion” [38, p. 707]. She also states, “Our understanding of voluntarism in this country is more intuitive and involves philosophical ideals of freedom, independence, personhood, and separateness” [38, p. 705]. Moreover, she identifies mental illnesses and other psychological conditions as factors that may hamper voluntarism thus understood. Elucidating the relationship between mental disorder and matters of free will might therefore not only be beneficial to forensic discussions and to the philosophy of free will but, moreover, to other responsibility-related topics in which mental disorders play a role, like discussions on what it takes to obtain valid informed consent [39].

Finally, as mentioned before, while to some it might appear self-evident that mental disorders may compromise free will, we should not take that for granted. It is important, at least, to clarify whether mental disorder would invariably lead to some effect on free will or whether it is possible that a specific mental disorder does not affect free will at all. Notably, not considering people suffering from a mental disorder to be responsible agents (with respect to certain acts or decisions) might lead to a form of exclusion—which is always a risk with mental disorders [40]. On the other hand, holding persons responsible for behaviors that were, in fact, the result of a mental disorder, like postpartum psychosis, might also lead to forms of exclusion. Indeed, acknowledging that a certain behavior was the result of a temporary mental disorder and not due to the person’s own choice, so to speak, might even prevent that person from being excluded from the community.


In this paper the link between mental disorder and free will was explored as it is present in two domains: philosophy of free will and forensic psychiatry. As it turns out, philosophers working on free will often view mental disorders as compromising free will and, hence, as threatening or reducing responsibility. In forensic psychiatry, mental disorders are also viewed as compromising the agent’s free will and legal responsibility. Meanwhile, in philosophy, free will turns out to be hard to define. However, three central elements or senses of free will are present in the philosophical debate. Consequently, the sentence “mental disorders are able to compromise free will” can have at least three different meanings. In order to explore the link between mental disorder and free will, we tentatively related each of these three senses to mental disorder. Based on our preliminary considerations, understanding the sentence in terms of the mental disorder preventing the person from being the actual source of the action could make sense both from a forensic and a philosophical perspective. Mental disorder, then, would affect the element of origination.

Returning to the “important loss of freedom” phrase in the introduction of the DSM-IV, which motivated this article, I conclude that freedom in the sense of free will could indeed be a meaningful understanding of this phrase. Both the philosophical debate on free will and forensic psychiatry suggest that mental disorders may affect free will. Yet, the sense of free will that may be affected by mental disorder in general and by specific disorders in particular remains to be elucidated. It is, therefore, important to further study this link, especially because of the value attached to free action and free decision-making in the lives of individual people and because of the impact of (not) ascribing praise and blame to an agent. It is noteworthy that the mental states associated with mental disorders are not immediately accessible to everybody. Therefore, further research should not only be conceptual in nature but also involve first person and firsthand accounts of people who actually suffered or suffer from mental disorder. Their experiences should inform the discussion on free will and mental disorder.


  1. 1.

    Walter describes these three “features,” or “components,” of the philosophical debate on free will while acknowledging that not all philosophical theories agree on these three elements: “Those various theories differ solely in the fact,” Walter claims, “that they either deal only with part of the components, or they declare one of them to be particularly significant, or they support variously strong interpretations” [2, p. 6]. Within the framework of this article, I consider these three elements of the philosophical debate as three senses of free will. See also the “Three sense of free will” section for further discussion on these senses.

  2. 2.

    Walter provides the following definition of the component of intelligible action (acting for reasons): “A person acts (wants, decides, chooses) intelligibly, if she at least partially mentally represents alternatives and their possible consequences, apprehends their meanings, and using this knowledge actively realizes one of the alternatives for reasons which are—in principle—inducible to insight” [2, p. 31]. This implies that the expression “acting for a reason” is not to be understood merely as asserting that there is an explanation of some kind for the agent’s conduct.

  3. 3.

    We have to note that in philosophical debates, “free will,” “freedom of the will,” and “personal freedom” are often used interchangeably (see, e.g., Kane [4, 5] and Widerker and McKenna [6]).

  4. 4.

    Meanwhile, it is important to note that Fingarette doesn’t consider alcoholism to be a psychopathological condition [19].

  5. 5.

    Although, based on Fingarette’s account, one could challenge this view with respect to alcohol addiction.

  6. 6.

    It should be noted that not everyone is convinced that free will is essential to forensic assessment (see, e.g., [28]). Meanwhile, given the focus of this article, I will concentrate on the perspective on forensic assessment in which free will is relevant.

  7. 7.

    We have to note that both Tourette’s syndrome and catatonia may also be relevant to both of the other senses of free will (being the genuine source of the action and having alternative possibilities).

  8. 8.

    In my account of “acting for understandable reasons,” I emphasize the fact that actions are performed for reasons as such. Walter mentions “acting for understandable reasons” in order to grasp the notion of intelligibility [2, p. 31]. If one would emphasize, however, the understandability of the reasons with respect to actions stemming from mental disorder (for instance in case of delusional behavior), this might well lead to a different conclusion in the sense that the reasons behind actions stemming from mental disorders may not always be (easily or fully) understandable.


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This work is supported by the Netherlands Organisation for Scientific Research, Grant 275-20-016. I thank Prof. David Widerker for his helpful suggestions.

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Meynen, G. Free will and mental disorder: Exploring the relationship. Theor Med Bioeth 31, 429–443 (2010).

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  • Free will
  • Responsibility
  • Mental disorder
  • Psychiatry
  • Philosophy
  • Forensic psychiatry