Don't you believe in flying saucers, they ask me? Don't you believe in telepathy? — in ancient astronauts? — in the Bermuda triangle? — in life after death? No, I reply. No, no, no, no, and again no. One person recently, goaded into desperation by the litany of unrelieved negation, burst out "Don't you believe in anything?" Yes", I said. "I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be.

In between he spent three years during World War II working as a civilian at the Philadelphia Navy Yard's Naval Air Experimental Station. During his oral examination shortly thereafter Asimov grew concerned at the scrutiny he received. He especially worries that Israel has been created among hostile neighbours and that Jews have merely created for themselves another "Jewish ghetto".

His only works in the 100s—which covers philosophy and psychology—were forewords for The Humanist Way (1988) and In Pursuit of Truth (1982) a festschrift in honor of philosopher Sir Karl Popper's 80th birthday. He often provides nationalities birth dates and death dates for the scientists he mentions as well as etymologies and pronunciation guides for technical terms. Asimov wrote the Lucky Starr series of juvenile science-fiction novels using the pen name Paul French.