3.3.1 - Incoherence challenges to God

The Coherence Problem

An existence argument asks whether there is evidence or proof that God exists. An incoherence challenge asks a prior question: is the concept of God logically consistent enough to be instantiated at all?

For this lesson, God is the classical theistic being described as:

An incoherence argument is normally conceptual and deductive. It tries to show that if the divine attributes are defined in the usual way, they imply a contradiction. If a contradiction follows, then the problem is not that God is unlikely; it is that the described being is impossible.

This is why precision matters. A weak answer says, "God cannot do that, so God is not omnipotent." A stronger answer first asks what counts as a real possible action. A weak answer says, "God knows the future, so we are not free." A stronger answer asks whether knowledge causes, fixes, or merely tracks what we freely do.

The three official challenges each target a different attribute:

1. The paradox of the stone targets omnipotence.
2. The Euthyphro dilemma targets omnibenevolence and God's relation to morality.
3. The omniscience/free will problem targets omniscience and human freedom.

The exam skill is not to list these puzzles. It is to identify exactly which premise, definition, implication, or hidden assumption a reply must repair.

Logical Possibility And Divine Power

Before the stone paradox, separate three senses of "possible":

Omnipotence is not usually taken to mean power over only physical or practical possibilities. If it did, God would be merely very strong. The important question is whether omnipotence includes power over logical impossibilities.

Aquinas' clarification in Summa Theologica I.25.3 is that divine omnipotence extends to what is absolutely possible. A contradiction does not describe a hard task; it fails to describe a genuine possible task at all. Making a square circle, making a human who is not a human in the same respect, or making something both done and not done in the same respect are not feats awaiting more power.

This reply does not simply assert that God has limits. It changes the target definition:

Unrestricted definition:
God is omnipotent iff God can do absolutely anything describable in words.

Aquinas-style definition:
God is omnipotent iff God can do everything that is logically possible and compatible with divine perfection.

The second definition blocks easy contradictions, but it also creates a residual issue. A critic can ask whether the defender has saved omnipotence by weakening it. The defender replies that power is the ability to actualise possibilities, not the ability to make contradictions true.

Paradox Of The Stone

The paradox of the stone asks whether God can create a stone so heavy that God cannot lift it. The question is designed as a trap: either answer seems to produce something God cannot do.

Reconstruction:

1. P1: If God is omnipotent, God can perform any possible task.
2. P2: Creating a stone so heavy that God cannot lift it is a possible task.
3. P3: If God cannot create such a stone, then there is a possible task God cannot perform.
4. P4: If God can create such a stone, then there is a possible task God cannot perform: lifting it.
5. Therefore, C: Either way, God is not omnipotent.

Hidden assumption: "A stone too heavy for an omnipotent being to lift" is a coherent possible object.
Inference type: deductive dilemma.
Main pressure point: P2 and the hidden assumption.

The argument is initially plausible because it uses an ordinary idea of power. A stronger person can lift heavier objects than a weaker person. If God's power is unlimited, it seems there should be no object beyond God's power to create. But if there is no object beyond God's power to lift, the requested stone seems impossible.

Targeted analysis:

The strongest reply is the Aquinas-style logical-possibility reply. The phrase "a stone too heavy for an omnipotent being to lift" is not like "a stone too heavy for a human to lift." The human case is coherent because human power is finite. The divine case defines the stone by reference to exceeding unlimited power. If omnipotence means power over all logically possible states of affairs, then an unliftable-by-omnipotence stone is not a possible object.

Residual issue: this reply works best against the simple stone paradox, but the critic may reformulate the challenge as a self-limitation problem. Could God choose to stop being omnipotent? If not, is there something God cannot do? The defender can reply that losing essential divine perfection is not a power. Still, the debate has moved from a quick puzzle to the deeper question of whether omnipotence should be defined by actions, results, or perfect power.

Euthyphro Dilemma

Plato's Euthyphro is originally about piety or holiness in a polytheistic Greek setting. Socrates presses Euthyphro on whether the gods love pious things because they are pious, or whether things are pious because the gods love them. AQA uses this text as the boundary for a later monotheistic challenge about God and moral goodness.

Adapted to classical theism, the dilemma becomes:

1. P1: Either morally good actions are good because God commands or loves them, or God commands or loves them because they are morally good.
2. P2: If actions are good because God commands them, then morality seems arbitrary: any command would become good.
3. P3: If God commands actions because they are already good, then goodness seems independent of God.
4. P4: If morality is arbitrary, God is not perfectly good in a meaningful way.
5. P5: If goodness is independent of God, God is not the ultimate source of moral value.
6. Therefore, C: The concept of an omnibenevolent God faces a dilemma.

Hidden assumption: the two horns exhaust the possible relation between God and goodness.
Inference type: deductive dilemma.
Main pressure point: P2, P3, and the hidden assumption that there is no third option.

The dilemma is powerful because either horn threatens a divine attribute:

There are two common replies.

First, a defender can reject arbitrariness by saying God's commands flow from God's necessarily good nature. God could not command cruelty for its own sake because such a command would conflict with divine goodness. This targets P2: commands are not arbitrary expressions of power.

Second, a defender can reject the external-standard horn by saying goodness is neither independent of God nor created by a bare command. Goodness is grounded in God's nature. This targets P3: the moral standard is not outside God, but neither is it a random decree.

Residual issue: the reply may sound like a third option, but it needs explanation. If "God's nature is good" means God's nature is measured against goodness, the external-standard problem returns. If it means goodness is whatever God's nature is, the arbitrariness worry may return in a new form. A strong evaluation asks whether grounding morality in God's nature explains goodness or merely relocates the dilemma.