Catholicism & Evolution Part 1: We must carefully distinguish between the different meanings of the words theory of evolution in order to give a clear and correct answer to this question. We must distinguish (1) between the theory of evolution as a scientific hypothesis and as a philosophicalspeculation; (2) between the theory of evolution as based on theistic principles and as based on a materialistic and atheistic foundation; (3) between the theory of evolution and Darwinism; (4) between the theory of evolution as applied to the vegetable and animal kingdoms and as applied to man.
Scientific hypothesis vs. philosophical speculation
As a scientific hypothesis, the theory of evolution seeks to determine the historical succession of the various species of plants and of animals on our earth, and, with the aid of palæontology and other sciences, such as comparative morphology, embryology, and bionomy, to show how in the course of the different geological epochs they gradually evolve from their beginnings by purely natural causes of specific development. The theory of evolution, then, as a scientific hypothesis, does not consider the present species of plants and of animals as forms directly created by God, but as the final result of an evolution from other species existing in former geological periods. Hence it is called "the theory of evolution", or "the theory of descent", since it implies the descent of the present from extinct species. This theory is opposed to the theory of constancy, which assumes the immutability of organic species. The scientific theory of evolution, therefore, does not concern itself with the origin of life. It merely inquires into the genetic relations of systematic species, genera, and families, and endeavours to arrange them according to natural series of descent (genetic trees). How far is the theory of evolution based on observed facts? It is understood to be still only an hypothesis. The formation of new species is directly observed in but a few cases, and only with reference to such forms as are closely related to each other; for instance, the systematic species of the plant-genus Œnothera, and of the beetle-genus Dimarda. - 56 minutes ago