Defining life

Scientists are in a lot of tension these days on issues of bioethics. If it isn’t stem cell research, it’s end-of-life issues and defining death. With that famous report last week of doctors finding new signs of life in a brain-injured woman in England, questions about the parameters of the ‘persistent vegetative state’ surfaced again. This NYTimes column, aptly called “The Basics,” reports that the presence of consciousness in such a patient is causing a stir. 

Why the concern? The tension reflects a wide, and perhaps unbridgeable, chasm between the lay and scientific understanding of consciousness.

The public is inclined to liken awareness to a lamp, either on or off. Brain-injured patients are either there or not there.

For researchers, however, unconsciousness is less like a lamp than a bundle of old Christmas lights: some dark, others with lights blinking here and there, still others flickering. It is a diverse, changeable condition — a continuum from little to partial to full awareness, with several unknown stops along the way.

The key word there is “unknown,” and scientists ought to respect that limitation in their efforts to define when life ends.

While brain imaging can show signs of awareness, as it did in the case of the brain-damaged woman in England, it does not predict who will emerge and who will not.

That’s what rattles the scientists. It remains beyond their control, and defies definition.