The scientist is by virtue of his method an empiricist. For him knowledge grows out of the experience of particular objects. Statements of laws, of course, being universal, go beyond particular experiences, but these experiences suggest them and ultimately test and verify them. Although certain objects, such as electrons, cannot be directly experienced, these objects are nevertheless conceived in terms of what is directly experienced. Thus science demands concrete referents for its terms.
Terms are merely symbols.
Their meaning lies in their referents. No matter how logically rigorous and convincing an argument may be, if the terms used have no referents, experiencable either directly or indirectly, the statements composing the argument cannot be said to have any definite meaning. In the light of this brief analysis of scientific method let us see what sort of criticisms based on it can be raised against theosophical ideas. The usual criticism is stated in terms of referents. The inability to indicate a concrete referent has led psychology to become more and more a biological science.