Theology as a science draws material from various sources. There are those having their basis on the authority (the Bible and sacred tradition), ‘signs of the times’, humanities and natural sciences. Among them it is the natural science that is a flashpoint of different disputes arising between theology and natural sciences. Nevertheless, one is not allowed to reject natural sciences since they mould a human perception of the world. The aim of the article is to present the use of the levels of complexity having their roots in natural sciences in the Fourth Way of Saint Aquinas. Hierarchical levels of reality are a common element of these two concepts. There will also be made an attempt to update the argument.
