Visually distinguish supporting and opposing reasons not just by color
The edges between nodes in argument maps should visually distinguish supporting and opposing reasons not just by color, since many people are red-green colorblind.
Adam Elga commented
Crucial to distinguish by a non-color indicator, so that argument maps can be printed on black-and-white printers. Many students hand in hard-copy maps this way.
Mikio Akagi commented
Indeed! For the sake of accessibility, the color scheme should probably not be green and red by default. Blue and red would be as intuitive, and more usable for many people. And another user suggested dotted lines or some other distinctive kind of line for marking objections.