The argument against God’s existence using conceivability and metaphysics

An atheist offered the following argument against God’s existence in a chat room. It dealt with conceivability and metaphysics. Basically, it asserts that if you can conceive of something that does not have a logical contradiction, and if you can conceive the idea that God does not exist, therefore God does not exist because it would not be illogical to say so.

Alright, let’s take a look at it.

Premise: 1  Anything that is prima facie conceivable (does not contain a logical contradiction) is metaphysically possible (doesn’t violate any truths about the world).
Premise 2  It is conceivable that God does not exist.
Premis 3  Therefore, God does not exist.

Terms Defined

Prima Facie

Standard Dictionary:  1) “true, valid, or sufficient at first impression,” 2) “self-evident,”  3) “legally sufficient to establish a fact or a case unless disproved” (
Standard Dictionary: “at first sight (= based on what seems to be the truth when first seen or heard)” (
Legal:  “Prima facie may be used as an adjective meaning “sufficient to establish a fact or raise a presumption unless disproved or rebutted.” (
Philosophy: That which does not contain a contradiction (This definition was given to me by the atheist who proposed the argument)


Standard Dictionary:  “a division of philosophy that is concerned with the fundamental nature of reality and being and that includes ontology, cosmology, and often epistemology” (
Standard Dictionary:  “(philosophy) The branch of philosophy that examines the nature of reality, including the relationship between mind and matter, substance and attribute, fact and value.” (


The Ultimate is the thing against which nothing is greater, and nothing precedes. Otherwise, it is not ultimate. Therefore, the ultimate would be non-contingent. It must be singular, not plural; otherwise, there would be multiple ultimates (particulars), which would mean there is no ultimate since it is not possible, by definition, to have multiple ultimates. All facts, actualities, and potentialities must derive (via causal chain) from the ultimate; otherwise, all facts (plurality) are ultimate. Nothing can be grounded without an ultimate, and no facts or explanations can be justified.


“In metaphysics, the term ‘universals’ is applied to things of two sorts: properties (such as redness or roundness), and relations (such as kinship relations like sisterhood, or the causal relation, or spatial and temporal relations). Universals are to be understood by contrast with particulars. Few universals, if any, are truly ‘universal’ in the sense that they are shared by all individuals – a universal is characteristically the sort of thing which some individuals may have in common, and others may lack.” (

Internal Critique

“an internal critique is a critique that assumes the truth of some premise or worldview in order to examine what would be the case if it were true…It attempts to show there is a problem with the consistency of some view.” (

External Critique

“An external critique, on the other hand, does seek to criticize a view on matters of fact. External critiques will, like the internal critiques, not be committed to the truth of the proposition or view involved, but, unlike internal critiques, it will be committed to the falsity of those views. An external critique may or may not grant a consistency aspect to the view involved; this is strictly irrelevant.” (


The argument against God’s existence using conceivability and metaphysics examined


Premise: 1  Anything that is prima facie conceivable is metaphysically possible.

Matt: It makes sense to say that whatever does not contain a logical contradiction is possible to be true.
Matt: Of course, not all conceivable things are metaphysically possible. Conceivability and metaphysics are related, but not all things conceivable are logically correct. If something is said to be prima fascia conceivable then it must be first examined to see if it is logically possible.

Premise 2  It is conceivable that God does not exist.

Matt: How does the atheist establish that the concept that “God does not exist” is logically valid? There is a difference between conceiving of God’s non-existence, and God’s non-existence being logically coherent – per the premise 1 requirement?
Matt: If premise 1 assumes the correspondence between logic and metaphysics, then what is the “ultimate foundation” that provides the necessary precondition for that assumption? Logically, the ultimate will either be personal or impersonal. If an impersonal ultimate foundation cannot be demonstrated to be true, the argument falls apart. The atheist would have to demonstrate that an impersonal foundation can provide the necessary precondition for all intelligibility (all universals, including the Laws of Logic) which would then support the necessary correspondence between the prima fascia conceivability and metaphysical possibility, upon which this argument is based. After all, to ask if it is logically coherent to assert that God does not exist.
Matt: Which of all the theoretical gods does this argument attack? All? One? A few?
Matt: What are the characteristics of this so-called god, that the argument addresses?
Matt: From the Christian Trinitarian perspective, God is a necessary being who, according to His self-revelation, cannot not exist (Psalm 90:2; Malachi 3:6). Therefore, from the Christian perspective, premise 2 proposes a contradiction in itself because it imposes a possibility on the Trinitarian God that cannot be true per the definition of the Christian God. Therefore, to conceive of the Christian God not existing would be an external, not internal critique.

Matt: Conceiving of God not existing does not mean that it is metaphysically possible that God does not exist because the argument does not establish the logical possibility that God does not exist nor does it establish the idea that “prima facie” (does not contain a contradiction), is true when denying God’s existence. It assumes its truth value in the first premise and concludes with the same value in the second.
Matt: If “God does not exist” is a logical possibility, then the atheist must establish it, not assume it. How does the atheist justify universals and particulars (one and the many)? How does the atheist justify our own existence when examining an infinite regression of events which must begin with either a personal or not personal cause?


The argument presupposes the logical validity of the conceivability that God does not exist. Conceivability and metaphysics as they relate to God is worth delving into more. But if we were to assume that position, then we have to ask questions about the nature of facts. All facts exist contingent on a broader context and with other facts. All facts exist in a causal chain back to an ultimate cause. The ultimate cause is either personal or impersonal. If the atheist assumes an impersonal ultimate, then he must justify 1) How does the impersonal lead to the personal? 2) How does the impersonal ultimate provide the foundation for all causally related truths, since truths require minds? 3) How does the impersonal ultimate lead to universal abstractions such as the laws of logic? 4) An impersonal ultimate suggests materialism. How then does the materially based brain produce ultimate truths since that brain is restricted to the laws of chemistry?

In order to justify that it is prima facie conceivable that God does not exist is the question. Assuming its position means the above questions need to be answered. If they cannot, then the prima facie conceivability that God does not exist would appear to be incoherent.

The post The argument against God’s existence using conceivability and metaphysics appeared first on Christian Apologetics & Research Ministry.






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