Logic, the discipline that explores valid reasoning, does not need
to be limited to a specific form of representation but should
include any form as long as it allows us to draw sound conclusions
from given information. The use of diagrams has a long but unequal
history in logic: The golden age of diagrammatic logic of the 19th
century thanks to Euler and Venn diagrams was followed by the early
20th century's symbolization of modern logic by Frege and Russell.
Recently, we have been witnessing a revival of interest in diagrams
from various disciplines - mathematics, logic, philosophy,
cognitive science, and computer science. This book aims to provide
a space for this newly debated topic - the logical status of
diagrams - in order to advance the goal of universal logic by
exploring common and/or unique features of visual reasoning.