ABSTRACT
When we examine our beliefs as to matters of fact, we find that they are sometimes based directly on perception or memory, while in other cases they are inferred. To common sense this distinction presents little difficulty: the beliefs that arise immediately from perception appear to it indubitable, and the inferences, though they may sometimes be wrong, are thought, in such cases, to be fairly easily rectified except where peculiarly dubious matters are concerned. I know of the existence of my friend Mr. Jones because I see him frequently: in his presence I know him by perception, and in his absence by memory. I know of the existence of Napoleon because I have heard and read about him, and I have every reason to believe in the veracity of my teachers. I am somewhat less certain about Hengist and Horsa, and much less certain about Zoroaster, but these uncertainties are still on a common-sense level, and do not seem, at first sight, to raise any philosophical issue.
