The Dorian Mode: How to Actually Use It in Solos
The Dorian mode (see [[guitar-modes-without-seven-boxes:the article on modes without seven boxes]]) is, in practice, the natural minor with one change: the sixth degree raised by a semitone. One note of difference, and it completely changes the character of the sound.
One note versus the natural minor
Both the natural minor and the Dorian mode start with the exact same first, second, third, fourth, fifth, and seventh degrees (see the article on intervals) - only the sixth differs: flattened in the natural minor, natural in Dorian. That single note is the whole secret of the mode.
A raised sixth gives a brighter minor
The natural minor's flattened sixth sounds heavier and darker; Dorian's raised sixth sounds brighter and more 'open', while still being minor in character. That's exactly why Dorian shows up so often in funk, soul, and modal jazz - minor, but not gloomy.
When the accompaniment calls for Dorian
The Dorian mode naturally fits a one-chord minor vamp - a minor seventh chord held for bars with no change (see the article on targeting chord tones). If the accompaniment is just a Dm7 with no clear pull toward another key, Dorian almost always sounds more fitting than the natural minor.
Hearing the difference: the same phrase, two sixths
Play a short phrase on the minor pentatonic (which has no sixth at all - see the article on the pentatonic scale), then add the sixth degree, first flattened, then natural, listening to the difference in character over the same minor chord.
You don't need to run the whole scale to hear the mode
The Dorian sound is already audible from that one note alone, emphasized at the right spot in a phrase - there's no need to mechanically run the scale up and down in full. As soon as the raised sixth lands in a characteristic spot in the phrase, the mode is already recognizable by ear.
Try it in practice
Open chord trainer