simple-minded

adjectives

lacking subtlety and insight
"a simple-minded argument"
simple-minded
is derived from
simplicity
is similar to
marked by or showing unaffected simplicity and lack of guile or worldly experience
"a teenager's naive ignorance of life"; "the naive assumption that things can only get better"; "this naive simple creature with wide friendly eyes so eager to believe appearances"
naif, naive
lacking mental capacity and subtlety
dim-witted, simple, simple-minded
is derived from
simplicity