Thinking in threes about software testing

In the episode "Thinking magically with Ramsey Dukes" of the "What magic is this?"-podcast, Ramsey Dukes (pen name of Lionel Snell) says some interesting things about thinking in twos as opposed to thinking in threes. (The quotes are from a section starting at 01:03:47 and ending at 01:08:02. Transcription mine.) Thinking in twos and threes from the perspective of Magic Thinking in twos, dualistic…