Online research in philosophy

Consciousness in experimental subjects is typically inferred from reports and other forms of voluntary behaviour. A wealth of everyday experience confirms that healthy subjects do not ordinarily behave in these ways unless they are conscious. Investigation of consciousness in vegetative state patients has been based on the search for neural evidence that such broad functional capacities are preserved in some vegetative state patients. We call this the standard approach. To date, the results of the standard approach have suggested that some vegetative state patients might indeed be conscious, although they fall short of being demonstrative. The fact that some vegetative state patients show evidence of consciousness according to the standard approach is remarkable, for the standard approach to consciousness is rather conservative, and leaves open the pressing question of how to ascertain whether patients who fail such tests are conscious or not. We argue for a cluster-based ‘natural kind’ methodology that is adequate to that task, both as a replacement for the approach that currently informs research into the presence or absence of consciousness in vegetative state patients and as a methodology for the science of consciousness more generally.

The paper is sympathetic to the idea that speakers have implicit knowledge of the semantics of sub-sentential elements of language, loosely, of words. Implicit knowledge is knowledge which the subject need not be capable of articulating yet which is a genuine propositional attitude and it is to be contrasted with tacit knowledge which refers to an information-bearing state which, however, is not a genuine propositional attitude. I begin by defending the implicit knowledge conception of speakers' knowledge of the meanings of words from a challenge articulated by Evans and then go on the offensive against positions which attempt to replace the notion of implicit knowledge in semantic theory by that of tacit knowledge.

The paper is sympathetic to the idea that speakers have implicit knowledge of the semantics of sub-sentential elements of language, loosely, of words. Implicit knowledge is knowledge which the subject need not be capable of articulating yet which is a genuine propositional attitude and it is to be contrasted with tacit knowledge which refers to an information-bearing state which, however, is not a genuine propositional attitude. I begin by defending the implicit knowledge conception of speakers' knowledge of the meanings of words from a challenge articulated by Evans and then go on the offensive against positions which attempt to replace the notion of implicit knowledge in semantic theory by that of tacit knowledge.

Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without functional communication (i.e., the minimally conscious state). Currently, there remains a high rate of misdiagnosis of the vegetative state (Schnakers et. al. BMC Neurol, 9:35, 8) and the clinical and electrophysiological markers of outcome from the vegetative and minimally conscious states remain unsatisfactory. This should incite clinicians to use multimodal assessment to detect objective signs of consciousness and validate para-clinical prognostic markers in these challenging patients. This review will focus on advanced magnetic resonance imaging (MRI) techniques such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI (fMRI studies in both “activation” and “resting state” conditions) that were recently introduced in the assessment of patients with..

Some patients awaken from their coma but only show reflex motor activity. This condition of wakeful (eyes open) unawareness is called the vegetative state. In 2002, a new clinical entity coined ‘‘minimally conscious state’’ defined patients who show more than reflex responsiveness but remain unable to communicate their thoughts and feelings. Emergence from the minimally conscious state is defined by functional recovery of verbal or nonverbal communication.1 Our empirical medical definitions aim to propose clearcut borders separating disorders of consciousness such as coma, vegetative state and minimally conscious state but clinical reality shows that these boundaries can often be fuzzy (fig 1). Recent clinical, electrophysiological and neuroimaging studies are shedding light on these challenging limits of consciousness encountered following severe acute brain damage. At the patient’s bedside, it is very challenging to differentiate reflex or automatic motor behaviour from movements indicating signs of consciousness, and hence some minimally conscious patients might be misdiagnosed as being vegetative. For some motor responses (eg, blinking to visual threat, brief fixation, normal flexion response to pain, etc) it remains unclear whether they truly are voluntary or willed because we lack convincing scientific evidence. We also lack consensus on how to practically assess some of these behavioural responses. For example, there is no agreement on what stimulus to employ in the assessment of visual pursuit movements— often one of the first clinical signs heralding the transition from the vegetative to the minimally conscious state. Vanhaudenhuyse and colleagues2 recently studied visual pursuit in 51 post-comatose patients comparing eye tracking of a moving object, person or mirror. It was shown that more..

Recent work in neuroimaging suggests that some patients diagnosed as being in the persistent vegetative state are actually conscious. In this paper, we critically examine this new evidence. We argue that though it remains open to alternative interpretations, it strongly suggests the presence of consciousness in some patients. However, we argue that its ethical significance is less than many people seem to think. There are several different kinds of consciousness, and though all kinds of consciousness have some ethical significance, different kinds underwrite different kinds of moral value. Demonstrating that patients have phenomenal consciousness — conscious states with some kind of qualitative feel to them — shows that they are moral patients, whose welfare must be taken into consideration. But only if they are subjects of a sophisticated kind of access consciousness — where access consciousness entails global availability of information to cognitive systems — are they persons, in the technical sense of the word employed by philosophers. In this sense, being a person is having the full moral status of ordinary human beings. We call for further research which might settle whether patients who manifest signs of consciousness possess the sophisticated kind of access consciousness required for personhood.

: This article begins with a discussion of persistent vegetative state (PVS), focusing on concerns related to both diagnosis and prognosis and paying special attention to the 1994 Multi-Society Task Force report on the medical aspects of PVS. The article explores the impact of diagnostic and prognostic uncertainties on prospective thinking regarding the possibility of PVS and considers the closely related question of how prospective thinkers might craft advance directives in order to deal most effectively with this possibility.

Coma, vegetative state, lock-in syndrome and akinetic mutism are defined. Vegetative state is a state with no evidence of awareness of self or environment and showing cycles of sleep and wakefulness. PVS is an operational definition including time as a variable. PVS is a vegetative state that has endured or continued for at least one month. PVS can be diagnosed with a reasonable amount of medical certainty; however, the diagnosis of PVS must be kept separate from the outcome. The patient outcome can be predicted based on etiology and age. Using outcome probabilities and etiology as criteria, patients can be subdivided in 5 groups and reasonable management guidelines can be suggested. Three levels of care can be provided to PVS patients: high technology, supportive and compassionate care. Pragmatic options for the various subgroups of patients are suggested. Management decisions will remain difficult for both the family and the health-care team. The role of the physician in these difficult cases is to share the decision-making with the family.

The concept of tacit knowledge is widely used in social sciences to refer to all those knowledge that cannot be codified and have to be transferred by personal contacts. All this literature has been affected by two kind of biases : (1) the interest has been focused more on the result (tacit knowledge) than on the process (implicit learning); (2) tacit knowledge has been somehow reduced to physical skills or know-how; other possible forms of tacit knowledge have been neglected. These two biases seem interconnected one with each other. A greater consideration of the role and relevance of implicit learning allows us to consider tacit knowledge as something more than pure physical skills or know how. This is the first step in order to develop more detailed categorisation of the different forms that tacit knowledge can assume.