"The symmetry argument also simplifies brain death criteria by overlooking the most appropriate definition of brain death, either loss of function of the whole brain (destruction of the cerebral hemispheres plus brain stem, or brain stem alone since this is a precursor of whole brain death), or irreversible loss of higher brain functions (total loss of consciousness and awareness, loss of cognitive faculties, representing widespread destruction of the cerebral hemispheres). This is a distinction between a vitalist interpretation, with its emphasis on biological integration, and a personalist interpretation, stemming from the significance of sentience or consciousness for the existence of persons. The contrast is between "mere human biological life" and "being alive as a person"."