For 10 points, name this Irish philosopher, the author of Three Dialogues Between Hylas and Philonus.
Margaret Atherton wrote about "How [this man] Can Maintain that Snow is White," and in one work he argued against belief in fluxions while another discusses a "visual language."  In addition to writing The Analyst and Alciphron, he notably argued against abstraction of ideas and presented the likeness principle, while his "master argument" claimed that it is impossible to conceive a non-conceived object.  The author of Treatise Concerning the Principles of Human Knowledge, he believed that "to be is to be perceived."  For 10 points, name this Irish philosopher, the author of Three Dialogues Between Hylas and Philonus.
Margaret Atherton wrote about "How [this man] Can Maintain that Snow is White," and in one work he argued against belief in fluxions while another discusses a "visual language."  
George Berkeley