Irving's book "A History of the Life and Voyages of Christopher Columbus" cannot be considered as an adequate authentic source because he put the book together speedily and impulsively, in the process sacrificing the deliberation needed for creating an accurate, reliable, and original work, as preferred by historians. Irving was even persuaded from time to time, perhaps to recompense for the impracticality of undertaking comprehensive and far-reaching research, to fully let his thoughts wander. As a consequence, perhaps, he reenacts imaginative scenes, not just from what the prevailing account and records evidently indicated had happened, but from what an acquaintance and understanding of the period of discovery directed Irving to believe might have happened (Hedges, 1956). On the other hand, the sources used by Irving for his book project can be deemed adequate. Alexander Everett, the Minister Plenipotentiary of the United States to Spain at the time summoned Irving to Madrid, to translate a collection of documents about Christopher Columbus that had been recently published. Therefore, such sources were adequate.The reason between the difference found between the adequacy of Irving's sources for his book project and his book as a source on Columbus is that Irving was an author seeking to allude to American readers. As a result, his biography on Christopher Columbus was largely made up of theatrical and studied episodes, most of which were founded on myth rather than dependable and reliable sources. Therefore, a key shortcoming of his book as an adequate source encompasses...

In fact, by the time, Aristotle had convinced people that the Earth was spherical (Russell, 1991). However, his sources for his book emanated from primary sources, from documents written by authors who had first-hand experience with navigation and with Columbus. In addition, Columbus' sources for the book encompassed information from navigators that had spent several years in voyage charting routes and perceiving different lands. Therefore, they can be deemed reliable and dependable sources.
Part II

Read Chapter V in Book I of Volume I of Irving's A History of the Life and Voyages of Christopher Columbus. The chapter, titled "Grounds on which Columbus founded...,"begins on page 52 of the book which is freely available as a Google eBook: http://books.google.com/books?id=uIADAAAAQAAJ. Also, look up confirmation bias. Say what it is and say whether Irving has established in that chapter that Columbus committed that mistake in reasoning. Justify your position.

Confirmation bias is the inclination of interpreting new evidence and proof of information as confirmation of one's existing beliefs or philosophies. In particular, confirmation bias can hinder an individual from taking into consideration significant information when making decisions as one would employ such beliefs and not the key facts. Columbus assumed that by undertaking a direct course from east to west, a navigator…