I have not actually read Michael Ruhlman's Ratio. I know that he describes a basic muffin as 2:2:1:1 of flour, liquid, egg and fat. Prior to discovering Ratio, I only ever thought of a muffin in terms of dry:wet ratios, fat as adding richness, and egg (depending on recipe) as adding richness or structure, so this is new to me.
I am asking because I have not had much success with muffins in the past and am wondering if it is because I have been using recipes without eggs for convenience (because we have usually been out of eggs in this house).
How essential a part do eggs play in a muffin recipe?