In the field of forensic science, the philosophy or philosophical approach means a desire to understand the reasons for striking or perplexing problems or phenomenon by the use of reasons and argument in seeking truth and knowledge of reality, principles that govern existence, and perception of physical materials and evidence. A. S. Osborn, one of the greatest forensic document experts of the 20th century, wrote "Questioned Documents" (1929, second edition), which still elicits the highest esteem of document examiners throughout the world. Osborn has contributed to the field of questioned document examination by providing precise comments, precautions, citations, and exhaustive explanations on various topics related to questioned document examination. He interweaves scientific principles with a philosophical approach that contributes to the identification of what needs to be proven and the means of doing so. Osborn's message to those involved in the profession of questioned document examination is to believe what you know; believe only what you see; and believe what you understand and conclude after correct observation, skillful comparison, rational interpretation, and logical reasoning regarding data obtained objectively. 5 references