The letter by Calvin Kalman in the August 2013 issue of Physics Today (page 10) attributes to the Jewish philosopher Moses Maimonides the idea that, as Kalman says, “it is important to be a scientist and to find scientific reasons for everything in the world.”

The word “everything” is somewhat ambiguous. Is Kalman claiming, by quoting Maimonides, that all that exists is the subject matter of science? That if we have no scientific reason or evidence for something, then that something cannot exist?

Surely, not only the question of the origin of life, which Keith Schofield raised in his letter (Physics Today, August 2012, page 12), but questions of consciousness and of free will may be beyond the bounds of science. For instance, what measuring devices, other than human beings themselves, can we use to detect human consciousness? Clearly, purely physical data cannot penetrate the mystery that is the human mind.