Does Philippe Leon's formulation succeed in renewing the modal cosmological argument while avoiding Graham Oppy's objection concerning the "unique natural initial state" as a legitimate alternative to sufficient reason?

This question lies at the heart of contemporary debate about cosmological arguments, where Philippe Leon's renewal of the modal argument meets Graham Oppy's radical critique of all cosmological arguments. The question requires examining whether Leon has succeeded in formulating a version of the argument that transcends Oppy's fundamental objection, or whether the objection remains standing despite the renewals.

Inadequate responses to be avoided

From some defenders of cosmological arguments:

"Leon solved the problem definitively." Excessive oversimplification. Even Leon himself in his recent works (2019-2023) acknowledges that his formulation faces challenges of the type posed by Oppy's objection, and that the debate has not been settled. The claim of definitive solution ignores contemporary literature.

"Oppy presupposes naturalism in advance." Inaccurate accusation. Oppy does not presuppose naturalism, but rather proposes that the "natural initial state" (natural initial state) is a legitimate explanatory option like the "necessary being." His critique is methodological, not metaphysically presupposed.

"The modal argument does not need the principle of sufficient reason." Conceptual confusion. Even formulations that avoid complete PSR (like Leon's formulation) depend on some explanatory principle (such as "possibles need explanation"). The question is not about the existence of the principle, but about its strength and scope.

From some naturalist critics:

"Oppy destroyed all cosmological arguments." Exaggeration. Oppy himself is more precise: he proposes that cosmological arguments do not provide "compelling reasons" for non-believers, not that they are "destroyed" or logically "invalid."

"Leon merely reformulates old arguments." Unfair reduction. Leon presents genuine innovations: distinguishing between types of possibility, addressing contemporary mathematical formulations, responding to specific objections that were not available to classical formulations.

Why these responses are inadequate

They share a lack of precision in identifying the real point of contention. The debate is not about abstract logical validity, but about the relative persuasive force of competing explanatory options. This requires precise analysis of what each side claims and does not claim.

Leon's updated formulation of the modal argument

Leon in his works (2017-2023) presents a rigorous formulation that attempts to avoid traditional problems:

First premise: Ontological distinction. Leon distinguishes between "limited contingent" (contingent finite) and "possibly infinite contingent" (possibly infinite contingent). This distinction allows him to avoid the problem of "infinite chains" that face traditional formulations.

Second premise: Modified principle of explanation. Instead of complete PSR, Leon adopts the "Principle of Explanation for Finite Contingents" (PEFC): every finite contingent has an explanation, either in another contingent or in a necessary being. This is weaker than PSR but sufficient for the argument.

Third premise: Impossibility of circular explanatory regress. Leon demonstrates that circular explanatory chains are logically impossible, and that infinite chains of limited contingents do not provide adequate explanation for the totality.

Updated conclusion. There must be a "necessary explanatory ground" (necessary explanatory ground) — either one necessary being, or several interconnected necessary beings. Leon leaves the question open about the nature of this ground.

Strength of Leon's formulation

First, it avoids dependence on the controversial strong PSR. PEFC is more intuitively acceptable.

Second, it accommodates the possibility of multiple necessary beings, thus avoiding objections of excessive unification.

Third, it uses tools of contemporary mathematical logic (set theory, infinite analysis) with precision.

Oppy's objection: The natural initial state

Graham Oppy in his later works (2018-2023) develops a sophisticated objection:

Conceptual structure. Oppy proposes that the "Unique Natural Initial State" (UNIS) is a legitimate explanatory alternative to the theistic necessary being. UNIS is an extremely simple natural initial state from which all complexity emerged through natural laws.

Theoretical justification. UNIS fulfills the same explanatory function as the necessary being: stopping regress, explaining contingents, ontological simplicity. But it does so without assuming consciousness, will, or personal attributes.

Superiority by simplicity criterion. Oppy argues that UNIS is simpler than the theistic God: a simple physical state is simpler than an infinitely powerful and knowledgeable mind. By the criterion of ontological simplicity, UNIS is preferable.

Explanatory neutrality. Oppy does not claim that UNIS is correct, but that it is a legitimate option like theism. The result: the cosmological argument does not provide compelling reason to prefer theism over naturalism.

Does Leon's formulation succeed in avoiding Oppy's objection?

Leon's direct response. Leon argues that UNIS itself needs explanation: why this particular state and not another? Why with these properties? If UNIS is contingent (could be otherwise), it falls under PEFC and needs explanation.

The necessity problem. If Oppy claims that UNIS is necessary, he faces the same problems he raises against divine necessity: how can a specific physical state be metaphysically necessary? Physical necessity does not equal metaphysical necessity.

The laws problem. UNIS presupposes natural laws that transform simplicity into complexity. But the laws themselves need explanation: why these laws? Where does their necessity come from? Theism unifies the explainer and the laws in one source.

Oppy's counter-response

Explanatory symmetry. Everything raised against UNIS can be raised against God: why this God with these attributes? If the answer is "necessity," the same answer is available for UNIS.

Qualitative simplicity. A simple physical state (primordial quantum fields, for instance) is qualitatively simpler than a mind that knows everything and can do everything. The conceptual simplicity of theism does not cancel its ontological complexity.

No need for ultimate explanation. Oppy accepts that there are brute facts — whether UNIS or fundamental laws. Theism also accepts brute facts (God's existence and attributes). The difference is preferential, not logical.

Critical evaluation of the debate

Leon's strengths:
- His formulation avoids many traditional problems
- PEFC is more reasonable than complete PSR
- The ontological distinctions are precise and useful

Leon's weaknesses:
- Does not provide decisive reason to prefer theistic explanation
- Assumes that explanation must end in a necessary being, which is disputed
- Does not settle the issue of relative simplicity

Oppy's strengths:
- Shows that cosmological arguments do not compel non-believers
- UNIS is a logically coherent alternative
- His critique of theism's alleged simplicity is strong

Oppy's weaknesses:
- UNIS appears ad hoc to resist theism
- Does not deeply address the problem of laws and constants
- His position on brute facts appears selective

Current state of the debate (2024)

The debate has reached a kind of equilibrium: both sides have strong arguments, and neither seems to have a knockout blow. This has led to important shifts:

Shift toward cumulative arguments. Many philosophers (Richard Swinburne, Robin Collins) see that the cosmological argument alone is insufficient, but it is part of a stronger cumulative case.

Shift toward Bayesian formulations. Attempts to formulate the debate in Bayesian probabilistic terms, where the question is not about definitive proof but about probabilistic weighting.

Shift toward "inference to the best explanation." Instead of seeking logical necessity, seeking which explanatory framework provides the best coherence for overall data.

Where we stand in this debate today

Between 2020 and 2026, the debate crystallized around three axes. First, Bayesian formulations of the modal argument deepened, where philosophers like Joshua Rasmussen and Andrew Loke tried to shift the question from "Is the argument valid?" to "Is the existence of a necessary explanatory ground more probable than its denial?" — and this shift partially weakened the force of Oppy's objection, because UNIS was no longer an equivalent alternative but an option needing independent weighting. Second, works emerged linking the cosmological argument with the fine-tuning problem, where the UNIS proposed by Oppy faces additional difficulty in explaining why the simple initial state produced laws tuned with such precision — which Collins and Leon exploited together. Third, Oppy and his followers developed more mature responses to the laws problem, suggesting that laws are not independent entities but descriptions of regularities of the initial state itself (renewed Humean tendency). The debate has not been settled, but it has moved from the level of "Is the argument logically valid?" to the level of "Which comprehensive explanatory package is more coherent?" — a shift that favors cumulative approaches.

From the perspective of rational weighting (rajḥān ʿaqlī)

Leon's formulation represents genuine progress in the modal argument: the PEFC principle is more reasonable than complete PSR, and the ontological distinctions close classical gaps. But it does not completely overthrow Oppy's objection, because UNIS remains a logically coherent option even if it appears ad hoc. The rational position within the method of rational weighting:

— The modified modal argument raises the rational probability of the existence of a necessary explanatory ground, but it does not settle alone its nature (personal or impersonal).
— Oppy's objection reveals that the cosmological argument alone does not compel the opponent, but it does not invalidate it — rather it shows its need for cumulative supports (fine-tuning, explanation of consciousness, objective morality).
— When Leon's formulation is added to a cumulative package, weighting in favor of a conscious necessary ground (theism) becomes stronger than weighting in favor of blind UNIS, because theism unifies the explanation of existence, order, and consciousness in one source, while UNIS needs independent explanatory additions for each level.

The modal argument is therefore not a definitive proof, but a weighty probabilistic building block within a broader cumulative construction.