rationalization n.

1825, "a rendering rational, act of subjection to rational tests or principles," from rationalize + -ation. The specific sense in psychology in reference to subconscious means to justify behavior to make it seem rational or socially acceptable is by 1908.

Of the three works now on our table, the two which we have placed first have these laudable objects in view; an improvement on the former versions of the Psalms as compositions, and the rationalization, if we may so speak, of our Church psalmody. [The British Critic, London, Jan.-June 1825]