Arguments for the Existence of God (SACE Stage 2 Philosophy)
“Explain and evaluate the cosmological, teleological and ontological arguments for the existence of God”
There are three classic families of argument for the existence of God. Cosmological arguments, such as Aquinas's first ways and the Kalam argument, reason from the fact that things exist or are caused to a first uncaused cause. Teleological or design arguments, such as Paley's watchmaker, reason from the apparent order and purpose in nature to a designer. Ontological arguments, originating with Anselm, reason from the very concept of God as the greatest conceivable being to the conclusion that God must exist. You need to state each clearly, distinguish a priori from a posteriori reasoning, and weigh the standard objections.
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What this dot point is asking
You need to reconstruct each argument, classify its reasoning, and evaluate it against the major criticisms from Hume, Kant and others.
Cosmological arguments
Cosmological arguments are a posteriori: they start from a general fact about the world. Thomas Aquinas offered several. The argument from motion holds that everything in motion is moved by another, and since this cannot regress infinitely there must be a first unmoved mover. The argument from causation runs parallel for efficient causes, ending in a first uncaused cause. The Kalam cosmological argument, revived by William Lane Craig, states that whatever begins to exist has a cause, the universe began to exist, so the universe has a cause.
The standard objections target the leap to a first cause. David Hume asked why the causal principle should apply to the universe as a whole rather than only to its parts, and questioned whether an infinite regress is really impossible. A further worry is that even if a first cause exists, the argument does not show it is the personal, perfect God of religion rather than some impersonal origin.
Teleological arguments
Teleological or design arguments are also a posteriori but start from order and apparent purpose. William Paley compared finding a watch on a heath, whose intricate parts plainly serve an end, to finding the eye or the natural world: such fine adaptation of means to ends implies a designer. Modern versions appeal to the fine-tuning of physical constants.
Hume, in his Dialogues, raised several objections in advance of Paley. The universe is unlike a machine, so the analogy is weak; order might arise from many designers, or an imperfect one, or chance over vast time; and the argument tells us nothing about the designer's moral character. Darwin's theory of natural selection later supplied a powerful undesigned mechanism for the biological order Paley cited, weakening the inference considerably.
The ontological argument
The ontological argument is unique in being a priori: it tries to prove God's existence from the concept of God alone. Anselm defined God as that than which nothing greater can be conceived. If God existed only in the understanding, we could conceive of a greater being, one that also existed in reality. Therefore, to avoid contradiction, God must exist in reality.
The most famous objection is Kant's: existence is not a predicate, not a property that adds to the concept of a thing. Saying a hundred real coins differ from a hundred imagined coins is true, but the concept is the same; existence does not make the concept greater. Gaunilo, replying to Anselm directly, parodied the argument by deducing a perfect island into existence, suggesting the form proves too much.
Evaluation
None of the arguments commands universal assent, but they fail in different ways and to different degrees. The cosmological arguments raise a genuine question about why anything exists at all, even if they over-reach in identifying the cause with God. The design argument is strongest as an inference to the best explanation but is undercut by evolution and by Hume's analogical worries. The ontological argument is the boldest and the most suspect, since it appears to define a being into existence. A measured answer notes that even a successful argument would establish only a thin conclusion, leaving the gap between a first cause and the God of religious tradition unbridged.
The ontological argument is a priori, reasoning from the concept of God alone, while the cosmological and teleological arguments are a posteriori, reasoning from facts about the world. Classifying each correctly and matching it to the right objection (Kant for ontological, Hume and Darwin for design) is the fastest route to the analytical marks.
The fastest analytical marks come from classifying and objecting precisely. Work it in steps.
Step 1: classify the argument
State whether it is a priori (ontological) or a posteriori (cosmological, teleological).
Step 2: reconstruct it as premises and conclusion
Lay it out clearly, for example whatever begins to exist has a cause, the universe began to exist, so it has a cause.
Step 3: apply the matching objection
Use Kant for the ontological argument, Hume for the causal leap, and Hume and Darwin for design.
Step 4: judge the strength and the gap
Note that even a sound argument yields only a thin conclusion, leaving the gap to the God of religion. Argument matched to objection plus the thin-conclusion point is what the marks reward.
- Merging the cosmological and teleological arguments
- One reasons from causation or contingency, the other from order and purpose. They face different objections.
- Treating existence as a property in the ontological argument
- Kant's whole point is that it is not, which is why defining a being as existing proves nothing.
- Assuming a first cause must be the religious God
- The arguments at best establish a thin conclusion; the further attributes need separate support.
Assessment-style questions
Questions on this dot point, each with a worked answer, written by ExamExplained. Philosophy has no written exam, so use them to check your understanding before your assessment tasks.
Practice15 marks"The existence of God can be established by reason." Critically discuss with reference to at least two arguments for God's existence.Show worked answer →
A 15 mark essay needs a thesis, at least two arguments reconstructed, their objections and a defended conclusion.
Reconstruct two arguments. For example the cosmological argument (Aquinas or Kalam) to a first cause, and the teleological argument (Paley, fine-tuning) to a designer.
Classify the reasoning. Note these are a posteriori, unlike the a priori ontological argument.
Apply objections. Press Hume on the causal leap and the design analogy, and Darwin on biological order.
Conclude. Defend a position, noting even a successful argument yields only a thin conclusion, not the God of religion. Markers reward arguments matched to the right objections and a defended thesis.
Practice12 marksEvaluate the ontological argument for the existence of God.Show worked answer →
A 12 mark essay needs the argument explained, its a priori nature and the objections judged.
Explain it. Anselm defines God as that than which nothing greater can be conceived; a God existing in reality is greater than one in the understanding alone, so God must exist.
Note the form. Stress it is a priori, reasoning from the concept of God alone.
Object. Press Kant that existence is not a predicate and Gaunilo's perfect-island parody.
Judge. Conclude whether defining a being into existence can succeed. Markers reward Kant's objection engaged directly and a defended verdict.
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Sources & how we know this
- Stage 2 Philosophy subject outline (2025 onwards) — SACE Board
- Stage 2 Philosophy: external assessment — SACE Board