17 Hence to neglect, or to reject,or to devalue so many and such great resources which have been conceived, expressed and perfected so often by the age-old work of men endowed with no common talent and holiness, working under the vigilant supervision of the holy magisterium and with the light and leadership of the Holy Ghost in order to state the truths of the faith ever more accurately, to do this so that these things may be replaced by conjectural notions and by some formless and unstable tenets of a new philosophy, tenets which, like the flowers of the field, are in existence today and die tomorrow; this is supreme imprudence and something that would make dogma itself a reed shaken by the wind. The contempt for terms and notions habitually used by scholastic theologians leads of itself to the weakening of what they call speculative theology, a discipline which these men consider devoid of true certitude because it is based on theological reasoning.
Source: Humani Generis (Vatican.va)