constructive (adj.)

1670s, "derived by interpretation, not directly expressed but inferred," from Middle French constructif or directly from Medieval Latin constructivus, from Latin construct-, past-participle stem of construere "to heap up," from assimilated form of com "with, together" (see con-) + struere "to pile up" (from PIE root *stere- "to spread").

Meaning "pertaining to construction" is from 1817; sense of "having the quality of constructing" is from 1841, especially "contributing helpfully." Related: Constructively; constructiveness. Constructive criticism is attested by 1841, originally in theology and philosophy.

Constructive criticism has frequently secured, in various departments of scientific inquiry, positive results, the value of which cannot be over-estimated; but there are not wanting instances in which a destructively critical method has performed services equally as valuable. Groundless hypotheses, unwarrantable theories, and baseless prejudices, required to be swept away, so that a constructive criticism might operate freely and successfully. [The Christian Ambassador, vol. ix, 1871]

It later was extended to education and became personal:

Constructive criticism points out a specific deficiency, and suggests a specific remedy. It is destructive in tearing down the wrong, but constructive in replacing value. Such criticism will afford the teacher the satisfaction of having a definite basis on which to work. [George M. Baker, "Constructive Supervision," in The American School Board Journal, February 1918]