Which one of the two is the stronger base: methoxide ion or hydroxide ion?
We have $\ce{MeO-}$ and $\ce{HO-}$
$\ce{-CH3}$ has a +I effect. Therefore it destabilizes the methoxide ion. $\ce{-H}$ has a comparatively lesser +I
This leads to the conclusion that $\ce{OH-}$ is more acidic than $\ce{CH3O-}$.
This seems like a valid argument, but the order varies in gaseous/aqueous phases, because we consider polarizabilty and solvation effect, rather than inductive effect there