PoppaGator posted an answer to this in the other thread last May: Soul of a Man - Chords. He gives (in E):


(E)Well, won't somebody tell me, answer if you (B7)can
(E)Won't somebody tell me, tell me what is the (B7)soul of a (E)man?



As he says, the song on mostly on the tonic. I'd play the basic chords slightly differently in the verse and chorus as:

(E)Well, won't somebody tell me, answer if you (B7)can
(E)Won't somebody tell me, tell me (A7)what is the soul of a (E)man?

(E)I'm going to ask the question, please answer if you can
Is there anybody sure can tell me, tell me (A7)what is the soul of a (E)man?

(Blind Willie Johnson I believe played this using open E tuning (EBEG#BE - see Adventures in Vestapol), though the recording linked is more or less in F, so he may have a capo on the first fret for this).

The A7 chord needs the 7th (G) on top. You could also play an Eb chord there (again with G note on top).

Mick