Why the Modal Ontological Argument should be preferred to the Reverse Modal Ontological Argument

 Formalised Argument for Preferring the MOA

Premises:

1. Maximally Great Being (MGB): A being possessing omnipotence, omniscience, moral perfection, and necessary existence.

2. S5 Modal Logic: A system of modal logic where, if something is possible in one possible world, and its existence entails necessity, then it exists in all possible worlds (including the actual world).

Core Argument:

1. Premise 1: The MOA asserts: "It is possible that an MGB exists."

2. Premise 2: The RMOA asserts: "It is possible that an MGB does not exist."

Both arguments are symmetrical in structure:

MOA Conclusion: If it is possible that an MGB exists, then an MGB exists in all possible worlds (S5), including the actual world.

RMOA Conclusion: If it is possible that an MGB does not exist, then an MGB does not exist in any possible world, including the actual world.

3. Premise 3: Symmetry in logical structure does not imply equal plausibility. Logical arguments must be assessed on the coherence and plausibility of their premises, not merely their formal structure.

4. Premise 4: The properties of the MGB (omnipotence, omniscience, moral perfection, and necessary existence) are coherent and intelligible.

These properties do not entail contradictions:

Omnipotence is restricted to logical possibilities, avoiding paradoxes (e.g., a rock too heavy for God to lift).

Omniscience is compatible with free will through middle knowledge.

Moral perfection is consistent across all possible worlds.

Necessary existence is a metaphysical property intrinsic to maximal greatness.

5. Premise 5: For the RMOA to succeed, the sceptic must demonstrate that the concept of an MGB is logically incoherent (analogous to a "square circle" or a "married bachelor").

Absent such proof, the premise "It is possible that an MGB does not exist" lacks justification.

6. Premise 6: The MOA is grounded in positive, intelligible, and metaphysically plausible attributes (power, knowledge, goodness). The RMOA lacks such grounding and often relies on parodies or contrived inversions (e.g., a Maximally Evil Being), which fail to demonstrate incoherence in the MGB.

Illustrative Example: Symmetry Does Not Imply Plausibility

Consider the following symmetrical syllogisms:

UNICORNS:

Example 1:

Premise 1: It is possible that unicorns exist.

Conclusion: Therefore, unicorns exist in the actual world (assuming a modal system where possibility entails actuality).

Example 2:

Premise 1: It is possible that unicorns do not exist.

Conclusion: Therefore, unicorns do not exist in the actual world.

While these arguments are symmetrical in structure, they are not equally plausible. The plausibility of the conclusions depends entirely on the justification of the premises:

The first argument requires evidence that unicorns' existence is metaphysically plausible.

The second argument requires evidence that unicorns' existence is metaphysically impossible.

Without such evidence, neither argument is compelling, but the burden of proof lies on the sceptic to demonstrate impossibility before ruling out the first argument.

Application to the MOA and RMOA

1. The MOA asserts the possibility of an MGB based on positive, coherent properties.

These attributes (omnipotence, omniscience, moral perfection, and necessary existence) are intelligible and do not entail contradictions.

As such, the MOA premise "It is possible that an MGB exists" is justified.

2. The RMOA asserts the possibility that an MGB does not exist, but it requires showing that an MGB is logically incoherent.

Without such proof, the premise "It is possible that an MGB does not exist" lacks sufficient justification.

3. As the MOA is grounded in coherent, metaphysically plausible properties, it is to be preferred over the RMOA, which fails to meet its burden of proof.

The Symmetry of Logical Arguments for Universal Morality vs. Moral Nihilism

Argument A: Universal Morality Exists

1. Premise 1: It is possible that universal moral truths exist.

2. Premise 2: If universal moral truths exist in one possible world, they exist in all possible worlds (by their universal nature).

3. Conclusion: Universal moral truths exist in the actual world.

Argument B: Moral Nihilism Holds

1. Premise 1: It is possible that no universal moral truths exist.

2. Premise 2: If no universal moral truths exist in one possible world, they do not exist in any possible world (by their universal negation).

3. Conclusion: No universal moral truths exist in the actual world.

While these arguments are symmetrical in structure, their plausibility hinges on the coherence and justification of their premises:

Argument A is grounded in the positive, intelligible concept of universal moral truths (e.g., "torturing innocents is wrong in all possible worlds"). This concept is coherent and widely defensible based on ethical intuitions and philosophical arguments for moral realism.

Argument B relies on the possibility of universal moral nihilism. However, this requires demonstrating that universal moral truths are logically incoherent or metaphysically impossible a far more difficult task. Without such evidence, its premise remains unjustified.

Thus, despite their formal symmetry, Argument A is far more plausible due to its coherence and justification, whereas Argument B lacks the same grounding.

Parallel to the MOA vs. RMOA

Like universal morality, the MOA's premise ("It is possible that an MGB exists") is grounded in coherent and intelligible properties.

Like moral nihilism, the RMOA's premise ("It is possible that an MGB does not exist") requires demonstrating logical incoherence, which sceptics have failed to do.

This demonstrates why mere symmetry in logical structure does not ensure equal plausibility between competing arguments.

Conclusion

The symmetry in modal logic between the MOA and RMOA is not sufficient to establish equal plausibility. The MOA provides a coherent and positive case for the existence of an MGB. The RMOA, in contrast, requires the sceptic to demonstrate the logical incoherence of an MGB, which has not been achieved. Thus, the MOA is the stronger argument and should be preferred.