Lesson · 4 min Stretch
The First Cause
In one line Cosmological arguments reason from the existence of the world to a first cause or necessary being that explains it.
Why is there something rather than nothing? Cosmological arguments start from a plain fact, that the world exists, and reason to a cause beyond it. Thomas Aquinas gave several versions in his Five Ways. Things are moved and caused by other things, he argued, and the chain cannot run back forever, so there must be a first cause.
The Islamic theologian al-Ghazali stressed a version from beginnings: whatever begins to exist has a cause; the universe began; so it has a cause. Leibniz argued from explanation: everything has a reason, and the reason for the whole series of things must lie outside it, in a being that exists necessarily.
Critics ask why the chain cannot be endless, and why a first cause must be God rather than something else.
Go deeper
Hume asked why, if each item in a series is explained, the whole series needs a further explanation. Kant argued that the idea of a necessary being quietly relies on the ontological argument. Modern defenders such as William Lane Craig link the argument from beginnings to the Big Bang, while critics reply that physics does not settle what, if anything, came before it.
The question at bedtime
A child asks where the world came from. Her parent says the Big Bang. “And what made that?” she asks, and keeps asking.
Each answer pushes the question back one step. The cosmological argument says the chain must end somewhere self-explaining. Her parent, a skeptic, says the chain might just stop with a brute fact. Both are taking the child’s question seriously.
Try this today Pick an everyday thing and trace its causes back five steps. Ask whether the chain needs a first link.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “The First Cause.” https://quest2reason.com/learn/lesson/the-first-cause. Accessed 13 November 2026.
Sources
- Stanford Encyclopedia of Philosophy, “Cosmological Argument” — Covers Aquinas, al-Ghazali, Leibniz and the main objections.
- Wikipedia, “Five Ways (Aquinas)” — Summarizes Aquinas’s five arguments for God’s existence.
- Wikipedia, “Kalam cosmological argument” — Explains the argument from beginnings, from al-Ghazali to Craig.
- Thomas Aquinas, Summa Theologiae, First Part, question 2, article 3 — The Five Ways in Aquinas’s own words.