An unusual icon hangs on the icon wall in my living room. It pictures some “pre-Christian philosophers” or “pathfinders of the way.” At the very front of the group of thinkers are St. Paul and St. Justin Martyr. St. Paul holds a scroll with words from Acts 17:23-24, when he preached to the Athenians about their altar to an unknown God, “Therefore what you worship in ignorance, this I proclaim to you. The God who made the world and all things in it, since he is Lord of heaven and earth ...” St. Justin’s scroll reads from his writings, “Come, be taught; become as I am, for I, too, was as ye are.” Behind St. Justin and St. Paul are The Sybil of Erythraea, Socrates, Plato, Solon, Aristotle, Pythagoras, Thucydides, Apollonios, and Homer, all of whom were philosophers or writers who discovered important truths that the Church has used in her theology.

St. Justin wrote to Greeks and Romans about how the Christians “teach the same things as the poets and philosophers whom you honor, and on other points are fuller and more divine in our teaching” (The First Apology, Chapter 20). It has been a long custom in Christianity to take what is true in the thought of a philosopher and in the traditions of a culture and to “baptize” it by drawing it into the tradition and truths of the Catholic Church. This adds to the fullness of our faith, especially as we acknowledge that God can choose to reveal truths to and work in the hearts of any of his human creatures. However, when we do this, we must do so cautiously and be careful to only accept what is actually true in these works.

When we hear ideas from philosophers and theologians that we know the Church holds up as teachers, we can usually trust what they say to be true. But we should never believe things that do not fit with the Church’s teachings or the development of doctrine.

One example of this practice is the Church’s embrace of the thought of Aristotle. His understanding of form and matter has been drawn up into our sacramental theology. The language of substance and accidents, which is applied to the Eucharist, comes from his thought. Much of his understanding of virtue was taken by St. Thomas Aquinas. However, as insightful as Aristotle was, he did make some errors. Even Thomas pointed to one of Aristotle’s errors when considering whether the physical universe existed from all eternity. Aristotle argued that the physical universe always existed. St. Thomas rejected this because God has revealed that the universe had a beginning in time.

However, there is one place that St. Thomas was unable to know about one of Aristotle’s inaccuracies, because neither Aristotle nor Thomas had a microscope. Aristotle, based on extensive biological research, goes into great detail explaining differences in the conception of males and females in his text On the Generation of Animals. Based on Aristotle’s views, St. Thomas holds (Summa Theologiae, I, Q. 92, Art 1, Reply Obj. 1) that women are defective:

As regards the individual nature, woman is defective and misbegotten, for the active force in the male seed tends to the production of a perfect likeness in the masculine sex; while the production of woman comes from defect in the active force or from some material indisposition, or even from some external influence; such as that of a south wind, which is moist, as the Philosopher observes (De Gener. Animal. iv, 2).

We know now, through more advanced biology and the use of a microscope, that the conception of a female human is not due to a material indisposition or the influence of the “moist” south wind, but that it has to do with the dividing of the sex genes when sperm are created. The argument from biology that women are defective or misbegotten is false. That false belief led Aristotle to hold that women cannot be equal to men, are unable to have equal friendships with men, and cannot have genuine virtues. While St. Thomas does not hold that women cannot have virtue, his promoting of Aristotle’s biology about conception still affects women poorly. Even in our time, Catholic writers still take things from Aristotle without questioning the validity of their origin and use them to misconstrue Church teaching and reject legitimate developments about the equality of men and women.

A clearer understanding of human biology led Pope John Paul II to hold that men and women are two different “incarnations” of the image of God (see Man and Woman He Created Them: A Theology of the Body, 8:2). While some theologians have held that women were only created so that humanity could reproduce itself, we must bear in mind that the parts that make men different from women also serve the function of reproduction. If women were only created to reproduce, then men in their current physical state were also only created in that way in order to produce more humans. The Church’s understanding of men and women has developed to teach that God created men and women equal to one another, with the abilities to reason, to grow in virtue, and to have equal friendships with each other.

Besides the works of trusted philosophers, we can draw truths from philosophers and thinkers that the Tradition has not learned to trust. In nearly every erroneous philosophical system, there are some truths that we can draw on as Christians and baptize to make our own, for evil cannot draw us in without including some truth. This very thing was done by the missionaries who brought Christianity into the various cultures of the world. They looked at the root truths within each culture and raised them up with the help of grace to show each culture how God was preparing all of humanity for the coming of a Savior. Through this practice, the Church has discovered many great seekers of truth that have helped form our understanding of theology. And as we encounter various thinkers we must always do this with a docility to the movements of the Holy Spirit and the gifts of the Holy Spirit.