112

1908 Nov 30
Logic
I.i. 15

of special sciences, especially of psychology. I do not admit that
the fact that the moon goes through its changes in 29 or 30 days
was taught us by astronomy or can be attributed to the science of astronomy.
I grant that the science of astronomy has established the fact that the average length
of a lunation is 29 days 12 hours 43 minutes and 27 seconds; but that
the moon goes through its familiar changes in a day or two more than four
weeks, far from being due to astronomy, was one of the facts curiosity
about which first stimulated some men to become astronomers and thus
gave birth to that science. Truths that ordinary observation
teaches every intelligent person or that have been handed down from
generation to generation from prescientific ages as common sense do
not belong to any science nor to science in general, though science may be in part
founded on them. It would not be basing Logic on psychology, or on any science, in