As a lover of logic, I was thrilled to discover the following argument mapping and diagramming tools curated by CMU:
http://www.phil.cmu.edu/projects/argument_mapping/
There is also an associated open course on Argument Diagramming located at https://oli.cmu.edu/jcourse/lms/students/syllabus.do?section=df3cb3f10a0001dc0fc0bc307edccf7d – highly recommended.
