Figure 1. The Battelle thought-group. The group is defined by the reasoning principles commonly accepted by its members, and by the scientific facts that are recognized as such on the basis of the shared principles. The principles include but are not limited to the principles of physics. Some possible statements are neither shared principles nor facts acceptable on the basis of those principles. These statements, therefore, have no epistemological status among the members of the Battelle thought-group. The statements may, however, be accepted as scientific facts by other thought-groups who hold different principles. There may also exist thought-groups for which the statements are scientific principles.