Originally Posted by: JoeNoviceBecause you're not using the right major scale. Play an A minor chord and improvise with C major arrpegios and a C major scale. You can do the same thing with F and G major (kind-of)
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Minus the fact that there's an F# in Gmajor...

Back to the original question, the whoe theory behind blues is playing a minor based scale over a major based backing. That's what makes blues sound like blues. Major scales can work over a minor chord...I don't see why they couldn't.
C major, for instance, if you had a deceptive cadence on the VI (Am) that's a minor chord, and over it you'd be playing a major scale.