Why is there something rather than nothing?
Intuitively, it could have been that nothing existed at all. Yet you and I are here, plus a whole universe of other stuff. We had parents, and our parents had parents, who had parents, and on and on, back to prebiotic chemicals, stars, and the Big Bang. Yet where did that come from? Surely there has to be some sort of ultimate explanation, right?
Cosmological arguments for God’s existence propose that God is the ultimate explanation or cause of everything. Such arguments begin with an empirical observation of the world—that there is motion, or causes, or just ordinary things that exist—and conclude this observation is explained by God’s existence.
This essay surveys three types of cosmological arguments.
1. First-Cause Cosmological Arguments
St. Thomas Aquinas (1225-1274 CE) argued that all the causation and motion we observe can be traced back to God, who is an uncaused cause or unmoved mover. In summary:
- Causes and motion exist.
- All causation or motion requires some prior cause or motion; things can’t happen nor move for no reason.
- But this chain of causation or motion cannot go back infinitely; this seems impossible.
- Therefore, there must be a first, uncaused cause, or first, unmoved mover.
- The most plausible example of an uncaused cause or unmoved mover would be God.
- Therefore, God exists.
To challenge (2), one might argue that things can just happen for no reason.
To challenge (3), one might question why exactly there can’t be an infinite regress of causes or motion: while this is puzzling, so are uncaused causes. Some also argue that there’s a contradiction in the argument: if every cause or motion requires some prior cause, then how would God or anything else be an exception?
To challenge the inference from (4) to (5), the existence of God, one might ask why the first cause or unmoved mover can’t be a mindless event: it wouldn’t have to be God or a god.
2. The Kalām Cosmological Argument
While the First-Cause Argument holds that God is the ultimate originator of all causation or motion, the kalām cosmological argument is more limited: it’s only about God’s being the cause of the universe’s beginning to exist. In summary:
- If something begins to exist, its existence was caused by something.
- The universe, including time and space, cannot go back infinitely far in time.
- Therefore, the universe began to exist.
- Therefore, the universe’s existence was caused by something.
- The most-plausible example of a creator of time and space would be something like God.
- Therefore, God exists.
The standard support for (1) is both intuitive and empirical. If things could begin to exist uncaused, why doesn’t that happen more often? In terms of our experience, that just doesn’t happen.
Following William Lane Craig, the leading contemporary proponent of this argument, we can distinguish both philosophical and scientific evidence for (2).
The main philosophical evidence is that, allegedly, infinities cannot exist in the real physical world: e.g., a hotel with infinitely many rooms could be full, and yet accommodate infinitely many buses each containing infinitely many passengers without having to kick anyone out.
The main scientific evidence comes from cosmology and thermodynamics, both of which suggest that the universe cannot have an infinite past.
Still, philosophers and scientists have challenged both of these alleged lines of evidence: e.g., there is some scientific evidence that the universe did not begin to exist after all.
As for (5), again, why would the creator have to be God? Why couldn’t it have been some mindless force instead? Defenders of the argument sometimes reply as follows:
All causes we know of are either mechanical or personal, where mechanical causes are just events that follow laws of nature, and personal causes are intentional—perhaps freely-willed—choices. Yet laws of nature seem to be a part of time, and the creation of the universe was allegedly the creation of time itself.
Therefore, defenders allege, the creation couldn’t have been a consequence of a simple law of nature.
3. Contingency Arguments
Cosmological arguments from contingency depend on the concepts of contingency and necessity. Contingent beings actually exist, but could have not existed. In contrast, a necessary being exists and could not possibly not have existed. The same terms describe truths or facts: A contingent fact is actually the case but could have not been the case, and a necessary truth is true, must be true and couldn’t have been false.
Gottfried Leibniz (1646-1716 CE) developed the most famous contingency cosmological argument. In summary:
- Every contingent being needs an explanation for its existence, the cause or reason for its existence.
- Contingent beings can’t be the cause or reason for their own existence.
- Therefore, the explanation for the existence of contingent beings must be some non-contingent being; and since it’s non-contingent, that being must exist necessarily.
- The most-plausible necessarily existing explanation for all the contingent beings would be God.
- Therefore, God exists.
The support for (1) is a principle sometimes called the ‘Principle of Sufficient Reason,’ according to which things don’t just happen for no reason at all.
The support for (2) is intuition or experience: it seems strange for a contingent being to somehow explain its own existence, and that certainly doesn’t happen in our experience.
Some critics challenge the Principle of Sufficient Reason. A few others argue that a being could potentially explain itself.
One might also question (4). Perhaps this necessary being could be some sort of mindless entity or law of nature.
Cosmological arguments enlist both scientific and philosophical evidence to make their cases. The only general objection to all of them challenges the last step: to conclude that the ultimate explanation is God, and not something else.
To claim that the universe began to exist is counter-intuitive, but so is claiming that it never began to exist. It’s mysterious to think that God caused it and mysterious to imagine that there’s no first cause. Cosmological arguments attempt to make progress against these mysteries.
 Cosmological arguments are a posteriori arguments, meaning that the justification for at least one premise of the argument is empirical or sensory-based, in contrast to a priori arguments, which depend on thought and reflections alone for the justification for their premises. An example of an a priori argument for God’s existence is the ontological arguments; further examples of a posteriori arguments for God’s existence include design arguments. See The Ontological Argument for the Existence of God by Andrew Chapman, Design Arguments for the Existence of God by Tom Metcalf and Epistemology, or Theory of Knowledge by Tom Metcalf for further discussion of the a priori and a posteriori distinction. Note that philosophers generally regard cosmological arguments to be the most-persuasive arguments for the existence of God (PhilPapers n.d.).
 Aquinas (2017 , I, q.2, a3).
 See Cameron (2021) on infinite regress arguments and see below at n. 9 for some discussion of whether actual infinities are possible.
 A version of this objection is sometimes stated in the form of a question: “What caused God?” Defenders of cosmological arguments typically argue that God, unlike the events in the universe, does not need a cause after all, perhaps because he is a necessary being, or did not begin to exist. See the following two types of cosmological arguments in this entry.
 See e.g. O’Connor (2004) and Rasmussen (2009) for attempts to bridge this gap.
 Craig (1979: 65); see Reichenbach (2021: Section 7) for more-detailed discussion of these steps.
 See Oppy et al. (2021, Section 5.1). Here’s the example in more detail: If infinitely many people arrive and want rooms at the hotel, the hotel management can move all the existing guests into the room that’s double their current room number, thereby freeing up infinitely many new rooms without having to kick anyone out. As for infinitely many infinitely-large buses, imagine that each room at the hotel is numbered by a positive integer: 1, 2, 3, 4, and so on. Imagine that each of these infinitely large buses is numbered by a prime number greater than 2 as in 3, 5, 7, 11, and so on. And each passenger in each of the buses is numbered by a positive integer, as in 1, 2, 3, 4, and so on. Now when the infinitely many buses arrive, move the hotel guest in room 1 into room 21 = 2; the hotel guest in room 2 into room 22 = 4; the hotel guest in room 3 into room 23 = 8, and so on. Move the first passenger in bus #3 into room 31 = 3; the second passenger into room 32 = 9; the third passenger into room 33 = 27; and so on. Move the first passenger in bus #5 into room 51 = 5; the second passenger into room 52 = 25; the third passenger into room 53 = 125; and so on. Move the first passenger in bus #7 into room 71 = 7; the second passenger into room 72 = 49; and so on. The infinitely many infinitely-large buses’ passengers can all get rooms at the hotel without kicking anyone out. See Pires (2016) for more discussion.
 It may go back infinitely in time after all, or it may be wrong to consider it an event (Grünbaum 1991).
 See e.g. Craig (1994: 117) and compare Morriston (2000).
 See Possibility and Necessity: An Introduction to Modality by Andre Leo Rusavuk for more explanation of these concepts.
 Aquinas (2017 , I, q.2, a3) offered a sort of contingency-based argument too. See also Gale and Pruss (1999).
The Concept of God: Divine Attributes by Bailie Peterson
Leibniz’s Principle of Sufficient Reason by Mark Bobro
The Ontological Argument for the Existence of God by Andrew Chapman
Design Arguments for the Existence of God by Tom Metcalf
Epistemology, or Theory of Knowledge by Tom Metcalf
Al-Ghazālī’s Dream Argument for Skepticism by John Ramsey
Possibility and Necessity: An Introduction to Modality by Andre Leo Rusavuk
Time Travel by Taylor W. Cyr
About the Author
Tom Metcalf is an associate professor at Spring Hill College in Mobile, AL. He received his PhD in philosophy from the University of Colorado, Boulder. He specializes in ethics, metaethics, epistemology, and the philosophy of religion. Tom has two cats whose names are Hesperus and Phosphorus. http://shc.academia.edu/ThomasMetcalf