:: Designers intent:  To produce a lightweight, portable, bass stringed instrument.  Design outcome - in two separate cases - an electric bass guitar with all features taken from their own treble guitars.Succession of models: Fender - Esquire/broadcaster/telecaster guitar -> Precision bass; Tutmarc - Cello sized upright bass -> no descendents - various models of steel and 'spanish' guitars -> model #736.Electric violins.  Why don't we call them electric guitars?  Probably because they have more features in common with violins that with guitars.  Specifically narrow waist and low radius fingerboard.  There's really no mistaking an electric violin for an electric guitar.  Which of these is a violin and which is a guitar  ?  Now that wasn't hard, was it?  I feel almost sure nobody reading this (if anyone ever does) is confused by the dissonance of the shapes of the bodies of either of those instruments.Yes.  We are talking of refining - refining of the telecaster guitar and tutmarcs steel guitars.  I'm glad we agree.My clear intent in listing the direct comparisons between Fenders treble and bass guitars was entirely to demonstrate that the process was one of scaling up an electric guitar - I'm fairly sure I can answer definitively to my own intent.The counter to 'It looks like a guitar so it must be a guitar' is clearly "It doesn't look at all like an upright bass, why are they related?" - your only answer to this is 'they intended to replace the upright bass' - that is a non-seqitur.  It has been clearly demonstrated that it doesn't just 'look' like a guitar - it 'is' a guitar, everything, every feature.  Perhaps not surprisingly it doesn't look at all like an upright bass. The BG argument, as you so quaintly describe it, doesn't ignore convegent design, it lists quite clearly how each design element comes directly from the guitar.  If, as you suggest, this is some form of parallel or convergent evolution, you really need to show the steps.  As yet your personal bass viol argument has not come up with a single explanation for why every single physical feature of the upright bass viol has been changed to a guitar form.Yes, as you say Paul Tutmarc, and indeed Leo Fender, had a quest for an alternative to the double bass.  That's what they produced.  An alternative.  Honestly, why is this so hard to accept?