Limits of natural science: brain research and computers.

The criterion that pure natural science can only investigate objective phenomena which can be observed by independent observers sets certain limits to our scientific understanding of brain functions. The methods and the present state of brain research and of computer development are described. The limitations of brain research are discussed by comparing the properties of brains and computers. At least for the time being we do not know of any natural scientific--i.e. physical or chemical--method which allows the objective measurement of consciousness, sensations, and emotions.