To be fair, at some point the regulations agreed with
@EvilEagle (and others). For instance, from the 1944 CAR:
20.762
Logging of pilot flight time.
2. Pilots of private grade or higher. The holder of a pilot certificate, other than a student pilot certificate, may log as solo flight time that portion of any flight during which he is the sole manipulator of the controls
Back then, it was either dual instruction or solo time. Solo just meaning you weren't receiving instruction. There was even this weird clause immediately following that one:
Provided, That he may log as solo flight time only 50 percent of any flight time during which a certificated instructor or a certificated airline transport pilot is in the aircraft serving as an instructor for the purpose of reviewing or increasing such pilot's skill;
I do not have the inclination right now to search and find out when it was changed, but it is STILL a very common misunderstanding that "solo" means "not instruction".