Is Natural Theology Possible?

Natural theology is the use of human reason to draw conclusions about God. It is typically contrasted with revelation which appeals to Scripture. Thomas Aquinas (d. 1274) noted the distinction in the following words:

Some things… are beyond all the competence of human reason, as that God is Three and One. [There are] other things… which even human reason can attain, as the existence and unity of God. (Summa Contra Gentiles, Bk. 1, Chap. 3)

Aquinas illustrated his point by providing a natural theology which included five ways of proving the existence of God. In 1923, Pope Pius XI reiterated the Church’s commitment to Aquinas’ position, when he said:

The arguments adduced by St. Thomas to prove the existence of God… are still to-day… the most cogent of all arguments. (Studiorum Ducem 16)

These considerations seem to suggest that a natural theology has occurred, and so it must in fact be possible. But that conclusion rests upon an assumption, which we can see if we ask how genuinely “natural” is the natural reasoning of natural theology?

1. What Is Natural Reason?

There are two different ways of thinking about (natural) reason. They are reason-as-a-process and reason-as-a-content.

Reason-as-a-process is the use of logic, which is often described as “reasoning.” This typically includes classic forms of argument with explicit steps, such as syllogisms. (For example: Socrates is a human. Humans are mortal. Therefore, Socrates is mortal.) But it might also include more casual (enthymeme) forms of reasoning, with implicit steps. (For example: The egg smells bad, therefore the egg has gone off.)

Reason-as-a-content refers to the principles (or premises) which are the starting points for arguments. It can include ethical statements (such as “murder is wrong”) or it might even include statements about the nature of reality. (See “Space Angels: Arguing a Point.”)

Christians have traditionally recognized that problems can arise in the use of both types of reason.

If people neglect to argue properly with reason-as-a-process, then they can become illogical, and illogical theology typically falls into fideism. (See: “Modernism: Did Vatican II Save the Church From Disaster?”)

If people neglect to argue properly with reason-as-a-content, then they can fall into a rationalism which prefers opinions to the content of revelation. (See “Faith and Safety: Balancing Faith and Reason?”) This form of rationalism is generally referred to as liberalism. (See “Did Vatican II Accept Liberalism?”)

When it comes to using natural theology, reason is used in both of the above senses. It provides both a process of argument and it also provides a content of principles which provide premises for the arguments.

2. Reasoning to the Existence of God

There are a number of different arguments for the existence of God. On a somewhat simplistic analysis, the arguments typically share a broadly similar kind of approach, which we can understand as follows.

Arguments generally cite a principle and an observation. Then they conclude that God exists. Thus, a very crude version of a possible argument might look something like this:

1. Principle: All changes must be caused.
2. Observation: There is change in the world.
3. Conclusion: There must be an (unchanging) cause of the change (i.e., God).

When critics query theistic arguments, there are broadly three kinds of criticisms which they make. Some criticisms focus on whether the conclusion really follows from the premises. Some criticisms focus on whether what has been proven in the conclusion is really God. And some (perhaps even the majority) of criticisms focus upon the truth of the principle which drives the argument.

The kinds of criticisms levelled at the principle may query how we can be so sure that a principle which applies in the world can apply to the unique case of a universe. Some criticisms may query whether the principle applies in contexts involving infinities. And other criticisms may query other aspects, such as whether humans can know the truth of any principles.

This analysis of theistic arguments is an extremely crude and simplistic overview of the kinds of issues which typically arise in a natural theology which proposes arguments for the existence of God. In reality, theistic arguments often involve considerable additional subtly and sophisticated nuances. Nevertheless, the crude analysis above illustrates a pertinent point. Principles are a key issue in natural theology, and arguments about the existence of God often hinge on issues involving principles.

3. Disagreements About Principles

Principles play a key role in natural theology arguments about the existence of God. They also play an important role in many of the natural reason arguments which can be seen in social and political contexts.

We can see this particularly clearly in the context of arguments about human rights. When people argue about matters such as torture, freedom of speech or reproductive rights (etc.), they are typically appealing to a principle (such as “torture is wrong”). Arguments will then typically identify an observation of the occurrence of a behavior (such as an instance of torture), and then they will conclude that such behavior is wrong.

When there are disputes about human rights issues, there may be arguments about the accuracy of observation (i.e., is torture really taking place?), or there may be arguments about the applicability of the principle (i.e., is it true that torture really is always wrong?).

When an argument becomes a dispute over a principle, it can all too easily become an unresolvable difference of viewpoint. One side says “yes” and the other says “no.” And further argument collapses into simply shouting louder and louder at each other.

These considerations show that the role of principles in natural reason is not a uniquely theological issue. Principles can be an issue whenever humans use natural reason about any matter.

4. Pius XII on Principles

The Church has been aware of the problem of principles for centuries. In 1879 Pope Leo XIII decided to promote Thomism, and part of his reason for doing so was that it addressed a contemporary problem of wrong philosophical and political principles. (See “Did Vatican II End Thomism?”)

The same issue of principles was identified as a problem by Pope Pius XII in his 1950 encyclical Humani Generis (HG). He stated:

It is well known how highly the Church regards human reason, for it falls to reason to demonstrate with certainty the existence of God…  But reason can perform these functions safely and well only when properly trained, that is, when imbued with… sound philosophy… [which includes] the unshakable metaphysical principles of sufficient reason, causality, and finality. (HG 29)

In the last sentence, Pius XII gives examples of the principles which he considered to be part of a “sound philosophy.” Those principles are typically points of dispute in arguments about the existence of God. We can see the presence of those kinds of principles in the language which the Jesuit Frederick Copleston used when he debated Bertrand Russel, in the BBC 1948 Copleston–Russell debate. (See YouTube audio recording of the debate.)

When we recognize that natural reason arguments hinge upon principles which can be disputed, it raises a question. If all humans are meant to possess the same natural reason, then why do people differ over which principles they accept?

Pius XII’s answer to that question is that people have false principles because of “evil passions,” and because of the “influence of original sin” (HG 2). He also noted that people bring “prejudice” and “bad faith” to their thinking processes (HG 4).

What this means is that although every human being has access to natural reason, not everyone has access to a properly functioning natural reasoning.

5. Vatican II on the Use of Natural Reason

When Vatican II reflected in 1965 on the Church’s engagement with the modern world, it essentially repeated the teaching of Pius XII about natural reason. Although the Council expressed some optimism about human achievements in Gaudium et Spes (GS), on several occasions it also drew attention to the fact that there are problems in the use of natural reason.

The Council noted that some people are “blinded” by false philosophies. It stated:

No doubt many whose lives are infected with a practical materialism are blinded against any sharp insight… (GS 10)

The Council also noted that moral “taint” and “sin” can undermine the use of reasoning. It said:

Values… are often wrenched from their rightful function by the taint in man’s heart. (GS 11)

[Humans]… can with genuine certitude attain to reality itself as knowable, though in consequence of sin that certitude is partly obscured and weakened. (GS 15)

In one of its stronger comments, the Council even noted that reasoning from wrong principles leads to “poisonous doctrines,” when it proclaimed:

The Church… cannot cease repudiating… those poisonous doctrines and actions which contradict reason. (GS 21)

6. John Paul II on Principles

Pius XII and Vatican II’s views about natural reason have continued to feature in post-conciliar theology. We can see that fact particularly clearly in Pope John Paul II’s 1998 encyclical Fides et Ratio (FR).

In that document John Paul II accepts that natural reason can conclude to the existence of God. He stated:

[There is a]… “book of nature”, which, when read with the proper tools of human reason, can lead to knowledge of the Creator. (FR 19)

But the reference to “proper tools of human reason” flags up the fact that there is an improper use of reason. To reason properly, humans need to start from the correct principles, which Pope John Paul II clarified as follows:

It is possible to discern a core of philosophical insight, … for example, the principles of non-contradiction, finality and causality, as well as the concept of the person as a free and intelligent subject… [This] body of knowledge… [is a] spiritual heritage of humanity. It is… an implicit philosophy,… [in which] all feel that they possess… [the correct] principles. (FR 4)

Following Pius XII and Vatican II, Pope John Paul II also recognized that some people start their thinking from wrong principles. He noted that this may be due to moral failings, such as the sin of pride (FR 4). But it may also be due to the effects of “original disobedience” (original sin) which “wounded” (FR 22) and “weakened reason” (FR 51), and which leads some people to “poor philosophy” and to “assertions… [which are] poorly grounded in reason” (FR 55).

7. Solving Failures of Reasoning

When the Church has reflected on how to deal with the problem of people reasoning inadequately from wrong principles, it has sometimes noted that faith can provide a solution.

Thus, in 1879, Pope Leo XIII said:

The Catholic philosopher will know that he violates… the laws of reason if he accepts any conclusion which… [is] opposed to revealed doctrine. (Aeterni Patris 8)

In 1998 Pope John Paul II addressed the issue more explicitly when he said:

Illumined by faith, reason is set free from the fragility and limitations deriving from the disobedience of sin. (Fides et Ratio 43)

These views have serious theological implications. If the misuse of rational principles is due to sin, then the correct acquisition and use of principles must involve resisting sin, and overcoming its effects. In the Anti-Pelagianism of traditional Church doctrine, that outcome is only possible when God’s grace supports human activity.

The Catechism noted the need for God’s assistance, when it made the following comment mentioning that there was a need for enlightenment:

Man stands in need of being enlightened by God’s revelation, … “about those religious and moral truths which of themselves are not beyond the grasp of human reason.” (CCC 38)

Vatican II made it clear that the need for divine assistance was not just a requirement for baptized Christians:

All this holds true not only for Christians, but for all men of good will in whose hearts grace works in an unseen way. (Gaudium et Spes 22)

These remarks suggest that humanity’s ability to properly use its natural reason depends upon God’s assistance. That means that it is a fundamental misunderstanding of the idea of “natural theology” to view it as something which can happen “apart from” or “independently of” God’s active assistance. As Vatican II put it,

Without the Creator the creature would disappear. (Gaudium et Spes 36)

8. Conclusion

Whether natural theology is possible, depends upon how we understand “natural reason(ing).” If it just refers to a different domain of knowledge, contrasting information from Scripture with information obtained from other (natural reason) principles, then yes, natural theology is clearly possible.

But if the “natural reasoning” of natural theology is supposed to describe an activity which humans can do independently of, or apart from God, then natural theology is not possible. This is because the Church believes that sin, and its effects, are at work in the selection of the principles of natural reasoning, and humans cannot manage sin and its effects independently of the assistance provided by divine grace.

What this all means is that when it comes to arguing about the existence of God, people need to be mindful that although they may think that they are arguing about God, sometimes they may actually be contesting a rather different set of issues about the principles which constitute human reasoning.

And to the extent that arguments about God do indeed involve disagreements about the nature and content of the principles of human reasoning, then perhaps sometimes the most appropriate way of moving those kinds of disagreements forward, would be to redouble prayer, rather than to refine logic?