Jakob Hohwy

Is it rational to believe that the mind is identical to the brain? Identity theorists say it is (or looks like it will be, once all the neuroscientific evidence is in), and they base this claim on a general epistemic route to belief in identity. I re-develop this general route and defend it against some objections. Then I discuss how rational belief in mind–brain identity, obtained via this route, can be threatened by an appropriately adjusted version of the anti-physicalist knowledge argument. Responses to this threat usually appeal either to different modes of presentation or to phenomenal concepts. But neither type of response is satisfactory. I provide a novel response, which appeals to an innocuous epistemic peculiarity of phenomenal states, namely their, as I shall call it, evidential insulation.

The notion that the brain is a prediction error minimizer entails, via the notion of Markov blankets and self-evidencing, a form of global scepticism — an inability to rule out evil demon scenarios. This type of scepticism is viewed by some as a sign of a fatally flawed conception of mind and cognition. Here I discuss whether this scepticism is ameliorated by acknowledging the role of action in the most ambitious approach to prediction error minimization, namely under the free energy principle. I argue that the scepticism remains but that the role of action in the free energy principle constrains the demon’s work. This yields new insights about the free energy principle, epistemology, and the place of mind in nature.

In this paper, we consider how certain longstanding philosophical questions about mental representation may be answered on the assumption that cognitive and perceptual systems implement hierarchical generative models, such as those discussed within the prediction error minimization framework. We build on existing treatments of representation via structural resemblance, such as those in Gładziejewski :559–582, 2016) and Gładziejewski and Miłkowski, to argue for a representationalist interpretation of the PEM framework. We further motivate the proposed approach to content by arguing that it is consistent with approaches implicit in theories of unsupervised learning in neural networks. In the course of this discussion, we argue that the structural representation proposal, properly understood, has more in common with functional-role than with causal/informational or teleosemantic theories. In the remainder of the paper, we describe the PEM framework for approximate Bayesian inference in some detail, and discuss how structural representations might arise within the proposed Bayesian hierarchies. After explicating the notion of variational inference, we define a subjectively accessible measure of misrepresentation for hierarchical Bayesian networks by appeal to the Kullbach–Leibler divergence between posterior generative and approximate recognition densities, and discuss a related measure of objective misrepresentation in terms of correspondence with the facts.

Distributive justice decision making tends to require a trade off between different valued outcomes. The present study tracked computer mouse cursor movements in a forced-choice paradigm to examine for tension between different parameters of distributive justice during the decision-making process. Participants chose between set meal distributions, to third parties, that maximised either equality (the evenness of the distribution) or efficiency (the total number of meals distributed). Across different formulations of these dilemmas, responding was consistent with the notion that individuals tend to base decisions in part on the magnitude of these parameters. In addition, dilemmas associated with inconsistent responding across the sample tended to elicit the greatest spatial deviation of the cursor, potentially reflecting dilemma difficulty. One interpretation of these results is that individuals value equality and efficiency in such a way that moral dilemmas are resolved by comparing the perceived value of these qualitatively different parameters, consistent with a value pluralistic framework of decision making. A post-hoc analysis indicated that individuals also incorporated sufficiency concerns during distributive justice decision making. The results are discussed in relation to political philosophy

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 11.1 (2004) 65-70 [Access article in PDF] Top-Down and Bottom-Up in Delusion Formation Jakob Hohwy Keywords delusions, top-down, bottom-up, predictive coding Some delusions may arise as responses to unusual experiences (Davies et al. 2001; Maher 1974;). The implication is that delusion formation in some cases involves some kind of bottom-up mechanism—roughly, from perception to belief. Delusion formation may also involve some kind of top-down mechanism. This could be in the shape of a patient's flawed background beliefs, or biases, which somehow modulate perception or ensure delusional interpretations of experience. There is little agreement about what kind of mechanism is primary in delusion formation, or, indeed, what the particular mechanisms and their neural substrates might be.In the evaluation of top-down and bottom-up mechanisms in delusion formation, a number of conceptual questions should be addressed (Davies and Coltheart 2000). For example, if there is an experiential component, why is a hypothesis with a delusional explanation of the unusual experience seen as relevant? Why do the subjects come to believe it tenaciously? How come some unusual experiences do not develop into delusions?A number of empirical findings also need to be taken into account: for example, the damage to the autonomic system in Capgras delusion (Ellis et al. 1997), the decreased ability for fast error correction in schizophrenia (Frith and Done 1989), modulation of activity in parietal cortex in delusions of alien control and other passivity experiences (Blakemore, Oakley, and Frith 2003), and also in schizophrenia, the increased sensitivity to self-produced stimuli, such as tickling oneself (Blakemore et al. 2000) and the sound of one's own voice (Ford et al. 2001).Theory choice can also be guided by philosophical doctrines about, for example, the nature of belief, the constitutive role of rationality, and intersubjectivity and the nature of judgements about the external world. It is natural, however, to let beliefs about philosophical doctrine be secondary to empirical findings and conceptual issues.The distinction between bottom-up and top-down mechanisms is particularly sharp in John Campbell's (2001) account of delusions and in Tim Bayne and Elisabeth Pacherie's (2004) discussion of Campbell. In this discussion, top-down approaches are associated with the general philosophical doctrine of rationalism, and bottom-up approaches with the philosophical doctrine of empiricism. Campbell's account is top-down because he posits delusional framework beliefs that arise directly as a result of brain damage or malfunction, and that work in some top-down fashion on the interpretation of experience. Bayne [End Page 65] and Pacherie convincingly defend empiricism against Campbell's rationalist account. Among their many other objections, they briefly puzzle about how a delusional framework belief (e.g., that one's spouse is an impostor) in a top-down fashion could cause the damage to the autonomic system seen in the Capgras and Cotard delusions (2004, 1). I think this is a very important objection because skin conductance data are part of the evidence for the bottom-up hypothesis concerning the Capgras delusion. We could add to this, for example, that it is mysterious how belief in a top-down fashion could cause people with schizophrenia to be worse at fast error correction than normal controls, to be better at tickling themselves than normal controls, and to have an increased response to the sound of their own voice.On the other hand, although the skin conductance response (SCR) evidence suggests a bottom-up approach to the Capgras delusion, it does not explain the character of the subjective experience that is hypothesized to give rise to the delusional belief: reduced SCR is not part of the experience itself (thanks to Ian Gold for discussion of this). Something more is required to give a full account of the type of experience that gives rise to the delusion. Further, as they stand, most bottom-up accounts are unable to account for why reality testing fails for beliefs based on these experiences.Neither rationalism nor empiricism on their own seem able to address the conceptual questions while paying...

The last decade has seen impressive and intriguing advances in the exploration of vestiges of consciousness in patients with disorders of consciousness . Consciousness is an extremely complex area of research so it is difficult to provide unequivocal interpretations of these new findings from DOC-studies. This review therefore provides a conceptual analysis of a series of key studies in this area of research. The main upshot is that different studies of preserved consciousness in DOC are best seen as targeting different aspects of consciousness rather than a unitary property of being conscious. These different aspects of consciousness thus seem to dissociate and fractionate in DOC. This provides a deeper understanding of the nature and structure of consciousness in general, and it provides suggestions for future research in DOC and the science of consciousness. Further methodological, conceptual, and ethical issues are discussed

Any position that promises genuine progress on the mind-body problem deserves attention. Recently, Daniel Stoljar has identified a physicalist version of Russells notion of neutral monism; he elegantly argues that with this type of physicalism it is possible to disambiguate on the notion of physicalism in such a way that the problem is resolved. The further issue then arises of whether we have reason to believe that this type of physicalism is in fact true. Ultimately, one needs to argue for this position by inference to the best explanation, and I show that this new type of physicalism does not hold promise of more explanatory prowess than its relevant rivals, and that, whether it is better than its rivals or not, it is doubtful whether it would furnish us with genuine explanations of the phenomenal at all

Cognitive neuropsychiatry attempts to understand psychiatric disorders as disturbances to the normal function of human cognitive organisation, and it attempts to link this functional framework to relevant brain structures and their pathology. This recent scientific discipline is the natural extension of cognitive neuroscience into the domain of psychiatry. We present two examples of recent research in cognitive neuropsychiatry: delusions of control in schizophrenia, and affective disorders. The examples demonstrate how the cognitive approach is a fruitful and necessary supplement to the otherwise successful biological psychiatry paradigm, which tend to bypass the cognitive level. Philosophy concerns some of the core concepts involved in psychiatric illness, particularly concerning rationality, thought and action, reality testing, and the self. We present concrete examples that illustrate how philosophical conceptual tools can be particularly important for the construction and interpretation of the cognitive models relevant to the understanding of psychiatric illness. We conclude that cognitive neuropsychiatry is a fruitful and necessary supplement to biological psychiatry. Furthermore, cognitive neuropsychiatry itself may benefit significantly from employing philosophical conceptual tools in the interpretation and construction of its cognitive models. The cognitive and philosophical approaches may thus be further steps towards a scientific psychopathology.

The phenomenology of agency and perception is probably underpinned by a common cognitive system based on generative models and predictive coding. I defend the hypothesis that this cognitive system explains core aspects of the sense of having a self in agency and perception. In particular, this cognitive model explains the phenomenological notion of a minimal self as well as a notion of the narrative self. The proposal is related to some influential studies of overall brain function, and to psychopathology. These elusive notions of the self are shown to be the natural upshots of general cognitive mechanisms whose fundamental purpose is to enable agents to represent the world and act in it

After being sorely neglected for some time, consciousness is well and truly back on the philosophical and scientific agenda. This entry provides a whistle-stop tour of some recent debates surrounding consciousness, with a particular focus on issues relevant to the scientific study of consciousness. The first half of this entry (the first to fourth sections) focuses on clarifying the explanandum of a science of consciousness and identifying constraints on an adequate account of consciousness; the second half of this entry (the fifth to seventh sections) examines a number of the methodological challenges facing the science of consciousness.

There is surprising evidence that introspection of our phenomenal states varies greatly between individuals and within the same individual over time. This puts pressure on the notion that introspection gives reliable access to our own phenomenology: introspective unreliability would explain the variability, while assuming that the underlying phenomenology is stable. I appeal to a body of neurocomputational, Bayesian theory and neuroimaging findings to provide an alternative explanation of the evidence: though some limited testing conditions can cause introspection to be unreliable, mostly it is our phenomenology itself that is variable. With this account of phenomenal variability, the occurrence of the surprising evidence can be explained while generally retaining introspective reliability

A new theory is taking hold in neuroscience. It is the theory that the brain is essentially a hypothesis-testing mechanism, one that attempts to minimise the error of its predictions about the sensory input it receives from the world. It is an attractive theory because powerful theoretical arguments support it, and yet it is at heart stunningly simple. Jakob Hohwy explains and explores this theory from the perspective of cognitive science and philosophy. The key argument throughout The Predictive Mind is that the mechanism explains the rich, deep, and multifaceted character of our conscious perception. It also gives a unified account of how perception is sculpted by attention, and how it depends on action. The mind is revealed as having a fragile and indirect relation to the world. Though we are deeply in tune with the world we are also strangely distanced from it.

Recent research has begun to investigate sensory processing in relation to nonclinical variation in traits associated with the autism spectrum disorders (ASD). We propose that existing accounts of autistic perception can be augmented by considering a role for individual differences in top-down expectations for the precision of sensory input, related to the processing of state-dependent levels of uncertainty. We therefore examined ASD-like traits in relation to the rubber-hand illusion: an experimental paradigm that typically elicits crossmodal integration of visual, tactile, and proprioceptive information in an unusual illusory context. Individuals with higher ASD-like traits showed reduced effects of the rubber-hand illusion on perceived arm position and reach-to-grasp movements, compared to individuals with lower ASD-like traits. These differences occurred despite both groups reporting the typical subjective experience of the illusion concerning visuotactile integration and ownership for the rubber hand. Together these results suggest that the integration of proprioceptive information with cues for arm position derived from the illusory context differs between individuals partly in relation to traits associated with ASD. We suggest that the observed differences in sensory integration can be best explained in terms of differing expectations regarding the precision of sensory estimates in contexts that suggest uncertainty.

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 11.1 (2004) 65-70 [Access article in PDF] Top-Down and Bottom-Up in Delusion Formation Jakob Hohwy Keywords delusions, top-down, bottom-up, predictive coding Some delusions may arise as responses to unusual experiences (Davies et al. 2001; Maher 1974;). The implication is that delusion formation in some cases involves some kind of bottom-up mechanism—roughly, from perception to belief. Delusion formation may also involve some kind of top-down mechanism. This could be in the shape of a patient's flawed background beliefs, or biases, which somehow modulate perception or ensure delusional interpretations of experience. There is little agreement about what kind of mechanism is primary in delusion formation, or, indeed, what the particular mechanisms and their neural substrates might be.In the evaluation of top-down and bottom-up mechanisms in delusion formation, a number of conceptual questions should be addressed (Davies and Coltheart 2000). For example, if there is an experiential component, why is a hypothesis with a delusional explanation of the unusual experience seen as relevant? Why do the subjects come to believe it tenaciously? How come some unusual experiences do not develop into delusions?A number of empirical findings also need to be taken into account: for example, the damage to the autonomic system in Capgras delusion (Ellis et al. 1997), the decreased ability for fast error correction in schizophrenia (Frith and Done 1989), modulation of activity in parietal cortex in delusions of alien control and other passivity experiences (Blakemore, Oakley, and Frith 2003), and also in schizophrenia, the increased sensitivity to self-produced stimuli, such as tickling oneself (Blakemore et al. 2000) and the sound of one's own voice (Ford et al. 2001).Theory choice can also be guided by philosophical doctrines about, for example, the nature of belief, the constitutive role of rationality, and intersubjectivity and the nature of judgements about the external world. It is natural, however, to let beliefs about philosophical doctrine be secondary to empirical findings and conceptual issues.The distinction between bottom-up and top-down mechanisms is particularly sharp in John Campbell's (2001) account of delusions and in Tim Bayne and Elisabeth Pacherie's (2004) discussion of Campbell. In this discussion, top-down approaches are associated with the general philosophical doctrine of rationalism, and bottom-up approaches with the philosophical doctrine of empiricism. Campbell's account is top-down because he posits delusional framework beliefs that arise directly as a result of brain damage or malfunction, and that work in some top-down fashion on the interpretation of experience. Bayne [End Page 65] and Pacherie convincingly defend empiricism against Campbell's rationalist account. Among their many other objections, they briefly puzzle about how a delusional framework belief (e.g., that one's spouse is an impostor) in a top-down fashion could cause the damage to the autonomic system seen in the Capgras and Cotard delusions (2004, 1). I think this is a very important objection because skin conductance data are part of the evidence for the bottom-up hypothesis concerning the Capgras delusion. We could add to this, for example, that it is mysterious how belief in a top-down fashion could cause people with schizophrenia to be worse at fast error correction than normal controls, to be better at tickling themselves than normal controls, and to have an increased response to the sound of their own voice.On the other hand, although the skin conductance response (SCR) evidence suggests a bottom-up approach to the Capgras delusion, it does not explain the character of the subjective experience that is hypothesized to give rise to the delusional belief: reduced SCR is not part of the experience itself (thanks to Ian Gold for discussion of this). Something more is required to give a full account of the type of experience that gives rise to the delusion. Further, as they stand, most bottom-up accounts are unable to account for why reality testing fails for beliefs based on these experiences.Neither rationalism nor empiricism on their own seem able to address the conceptual questions while paying...

In rubber hand illusions and full body illusions, touch sensations are projected to non-body objects such as rubber hands, dolls or virtual bodies. The robustness, limits and further perceptual consequences of such illusions are not yet fully explored or understood. A number of experiments are reported that test the limits of a variant of the rubber hand illusion. Methodology/Principal Findings A variant of the rubber hand illusion is explored, in which the real and foreign hands are aligned in personal space. The presence of the illusion is ascertained with participants' scores and temperature changes of the real arm. This generates a basic illusion of touch projected to a foreign arm. Participants are presented with further, unusual visuotactile stimuli subsequent to onset of the basic illusion. Such further visuotactile stimulation is found to generate very unusual experiences of supernatural touch and touch on a non-hand object. The finding of touch on a non-hand object conflicts with prior findings, and to resolve this conflict a further hypothesis is successfully tested: that without prior onset of the basic illusion this unusual experience does not occur. Conclusions/Significance A rubber hand illusion is found that can arise when the real and the foreign arm are aligned in personal space. This illusion persists through periods of no tactile stimulation and is strong enough to allow very unusual experiences of touch felt on a cardboard box and experiences of touch produced at a distance, as if by supernatural causation. These findings suggest that one's visual body image is explained away during experience of the illusion and they may be of further importance to understanding the role of experience in delusion formation. The findings of touch on non-hand objects may help reconcile conflicting results in this area of research. In addition, new evidence is provided that relates to the recently discovered psychologically induced temperature changes that occur during the illusion.

Cognitive neuroscience aspires to explain how the brain produces conscious states. Many people think this aspiration is threatened by the subjective nature of introspective reports, as well as by certain philosophical arguments. We propose that good neuroscientific explanations of conscious states can consolidate an interpretation of introspective reports, in spite of their subjective nature. This is because the relative quality of explanations can be evaluated on independent, methodological grounds. To illustrate, we review studies that suggest that aspects of the feeling of being in control of one's bodily movement can be explained in terms of the complex and surprising way the brain predicts movement. This is a modest type of functional, contrastive explanation. Though we do not refute the threatening philosophical arguments, we show that they do not apply to this type of explanation.

Some monothematic types of delusions may arise because subjects have unusual experiences. The role of this experiential component in the pathogenesis of delusion is still not understood. Focussing on delusions of alien control, we outline a model for reality testing competence on unusual experiences. We propose that nascent delusions arise when there are local failures of reality testing performance, and that monothematic delusions arise as normal responses to these. In the course of this we address questions concerning the tenacity with which delusions are maintained, their often bizarre content, the patients' inability to dismiss them, and their often circumscribed character

The theory of rationality has traditionally been concerned with the investigation of the norms of rational thought and behaviour, and with the reasoning pro‐cedures that satisfy them. As a consequence, the investigation of irrationality has largely been restricted to the behaviour or thought that violates these norms. There are, how‐ever, other forms of irrationality. Here we propose that the delusions that occur in schizophrenia constitute a paradigm of irrationality. We examine a leading theory of schizophrenic delusion and propose that some delusions can be traced to a violation of a condition on thought we call egocentricity. We argue that the violation of egocen‐tricity leads to irrational states that cannot be explained by the traditional categories of irrationality and conclude, therefore, that these states belong in a new branch of the theory of irrationality, that of experiential irrationality.

It appears that consciousness science is progressing soundly, in particular in its search for the neural correlates of consciousness. There are two main approaches to this search, one is content-based (focusing on the contrast between conscious perception of, e.g., faces vs. houses), the other is state-based (focusing on overall conscious states, e.g., the contrast between dreamless sleep vs. the awake state). Methodological and conceptual considerations of a number of concrete studies show that both approaches are problematic: the content-based approach seems to set aside crucial aspects of consciousness; and the state-based approach seems over-inclusive in a way that is hard to rectify without losing sight of the crucial conscious-unconscious contrast. Consequently, the search for the neural correlates of consciousness is in need of new experimental paradigms.

Crispin Wright has sought to establish the possibility of ‘significant metaphysics’ in the shape of a common metric with which to measure the realism or robustness of various discourses. One means by which to place discourses in the metric is via the ‘cognitive command constraint’. Importantly, this constraint must be a priori. Richard Rorty has argued against this, that, given content is a function of standards of representationality, the a priori requirement cannot be satisfied. I show that this attack is inconsistent: to run his own argument Rorty must take recourse to a idealized view of identification of discourses which conflicts with his own basic premise about the determination of content. Hence Rorty’s argument should not lead us to conclude that significant metaphysics is impossible