Abstract

Understanding the biological basis of consciousness is one of the central challenges for modern science. Is a mature scientific explanation really possible, and if so, how should consciousness science be organized so as to achieve this? This thesis is a collection of four papers which approach these questions via an account of the natural categories or ‘kinds’, drawn from philosophy of science, to which paradigmatic mental phenomena like consciousness belong. The central claims defended in the thesis are twofold. Firstly, that to facilitate a mature science of consciousness it is crucial to explicitly introduce a new organizing concept of consciousness modelled on the kinds of concepts which underpin previous successful explanations of other natural phenomena – that of a natural kind concept of consciousness. This draws on the general observation that some concepts are better suited to scientific theorizing about the world than others, and thus that progress in scientific and philosophical domains can be (and indeed, has often been) made by working to refine our existing conceptual schemes to reflect this. Secondly, that a mature science of consciousness will be one which recognizes the reality and explanatory importance of a particular category of mental phenomena called ‘global states of consciousness’ which includes dreaming and wakefulness. Examination of this latter claim leads to a third idea explored and motivated in the thesis which brings consciousness science into closer connection with psychiatry. This is the hypothesis that Major Depressive Disorder involves a change to a subject’s global state of consciousness, marking a change from a state of ordinary wakeful consciousness to an altered ‘depressive state’ of consciousness akin to a dream or psychedelic state.