Category Archives: Commentaries

An Argument for the Impossibility of Omniscience

In his work God and Evidence: Problems for Theistic Philosophers, Rob Lovering presents an argument for the impossibility of omniscience.

This particular argument rests on the distinction between propositional knowledge (knowledge that p) and experiential knowledge (knowledge of what it is like to x), a seemingly uncontroversial distinction.

Assuming that the distinction is justified, the argument proceeds as follows. One can differentiate between omniscience (complete, unfettered knowledge) with regard to either type of knowledge: a ‘propositionally omniscient’ entity knows all propositional knowledge, while an ‘experientially omniscient entity’ knows all experiential knowledge. A reasonable thought is that an entity isn’t fully omniscient unless it is both propositionally and experientially omniscient. Yet, no entity can be as such because necessarily, an entity that is propositionally omniscient is not experientially omniscient. This is because an experientially omniscient entity will know what it is like not to know that (‘p’ being a variable for any proposition we like), while a propositionally omniscient entity will know that and thus not know what it is like not to know that p.

Formally construed, the argument might look something like this:

1. (x) [Rx–>(Px & Ex)]
2. (x) [Ex–>~Px]
3. Rg –> (Eg & Pg)   [1, UI]
4. Eg –> ~Pg   [2, UI]
5. ~Eg V ~Pg   [4, material implication]
6. ~(Eg & Pg)   [5, DeM]
7. ~Rg   [6,3, MT]

8. (x) ~Rx [7, UG]

Where R=robustly omniscient (or, ‘fully’ omniscient), P=propositionally omniscient, E=experientially omniscient, and where g=god (though we could plug in any letter we like; the point is to instantiate the variable, use the rules of propositional logic to deduce some things, then generalize back into quantified form, which is what we do to reach premise (8))

Here are a few ways to address the argument:

A. Deny premise (1). Denying premise (1) amounts to denying the posited definition of full omniscience. “That isn’t what it is to be fully omniscient,” we might say. This is engaging in semantics — not necessarily a bad thing — since we will presumably supplant the definition of omniscience in (1) with a different one more to our liking, i.e., we will define the expression such that at least one entity can be fully omniscient.

B. Deny premise (2). This entails insisting that an entity can be both experientially and propositionally omniscient, which in this context amounts to denying that an entity that knows that p can’t also know what it is like not to know that p This may be done in a variety of ways. One way is to indicate that an entity can acquire omniscience by acquiring the knowledge of what it is like not to know that for any proposition, then acquiring the knowledge that p, thereby achieving omniscience (since the knowledge of what it is like not to know will presume remain even once one learns that p).

This particular solution won’t be to most theist’s liking, since their god is typically posited as having been timelessly omniscient, or, as having never not been omniscient. But there are strategies available — one imagines that an entity capable of creating the universe might somehow be able to decipher the knowledge of what it is like not to know that without thereby ever not knowing that p.

C. Accept the argument’s soundness; shrug shoulders. It’s not clear what the import of the argument is in a theological context, other than to deny the possibility of a maximally omniscient (in the sense defined above) god. A fair question to ask at this point is, so what if a god is propositionally omniscient but not quite experientially omniscient? What is the significance of this for theologically minded persons?


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Commentary: The Politics of Personhood

Mississippi voters recently voted down Amendment 26, a constitutional amendment which would have defined fertilized eggs as persons. [1] Completely independent of its intended purpose – to outlaw abortion – the failure of this measure is a positive outcome for Mississippi and the American people. Amendment 26, which was advanced by the ‘Personhood Mississippi’ movement, was logically unsound, flew in the face of scientific evidence, and would have had several unpalatable side effects if passed. Its passage would have set a negative precedent for state politics. This commentary will focus on the logical aspects of Personhood Mississippi’s goal, ignoring all other aspects, substantial as they are.

Logical Considerations Regarding Personhood

Amendment 26 aimed to define a fertilized egg as a person. What is a person? Despite over twenty-five hundred years of debate, no one is exactly sure. But what is sure is that a person is a thing which has hopes, dreams, and fears, and which experiences all other such mental states. It is in virtue of our unique ability to experience such states that we are widely supposed to be persons, and if there are ever silicon-based or martian organisms, they too shall be persons in virtue of the fact that they experience the full range of mental states, if indeed they do.

The problem with defining a fertilized egg as a person is that a fertilized egg has no mental life whatever. It does not even have the barest prerequisites for mental life, which includes a functioning nervous system and a sufficiently developed brain. Indeed, the brain and spinal cord do not even begin to form until the embryonic stage of pregnancy, which itself begins five weeks after conception. [2] Personhood Mississippi is thus wrongheaded to even suggest that a fertilized egg is equivalent to a human with a full-blown mental life.

Logically, there are other ways to formulate an anti-abortion proposal. One highly unintuitive method is to insist that what we are is the human organism – the thing which begins to form after the egg is fertilized, continues to grow until it has a mental life, lives a life outside the womb, and which can subsequently enter into a vegetative state, losing its mental life once again. This would mean that we are not persons after all, but the underlying organism which makes a person with a mental life possible. (Cognitive science suggests that the thing experiencing the rich mental life is a sort of software on the hardware of the brain. The human organism can persist even without that software: see the case of humans in a vegetative state with their core cognitive functions rendered impossible due to brain damage. The organism can persist without the person). To kill oneself would just be to kill a human organism – that a person would die as well would just be an incidental fact of the matter.

Any anti-abortion campaign based upon such logic would be right to insist that abortion is wrong, since abortion does kill human organisms. It kills what we are, if the above logic is sound. That the egg would be designated a person would simply be a pragmatic consideration: the law would require it (the law assumes that we are persons). But such a campaign would be a hard roe to hoe: the intuitive idea that we are all people and that mental life is indispensable for our existence runs deep in all of us. The ‘organism’ approach to banning abortion is for all intents and purposes unviable.

Another approach, probably more in line with Personhood Mississippi’s worldview, is to say that a person is a soul of sorts. The Personhood Mississippi website includes a page of testimonials of how God is working through the movement to save lives. [3] A virtually ubiquitous ancillary belief for religious persons is that we are souls – immaterial things which exist for a time inside the human body, but will continue to exist after the body ceases to be.

Unfortunately, this view fails the test of logic: if we are souls that will survive the death of the body, then by definition the person inside a fertilized egg (mysteries of how God deposits the soul into the egg and how the soul and egg interact aside) will not be killed by an abortion. The person will continue on into the next phase of existence, whatever that might be. In fact, if this view is correct, no one has ever been killed: what we thought were deaths throughout history were merely merely the destruction of the temporary habitation of the soul. Talk of souls and religiosity cannot justify the position that it is wrong to kill fertilized eggs.


The proposal to define a fertilized egg as a person does not make sense, whether one is an evangelical Christian, a diehard Atheist, or somewhere inbetween – if a person is a thing with a mental life, then the egg is definitively not a person; but if one accedes to the religious worldview of Personhood Mississippi then the egg is still not a person. It is merely the temporary shell which houses the person in this world. And if the person is such a soul, then it will persist through the death of the body, thus rendering abortion not at all akin to killing persons. But if that is the case, then the sole reason underwriting Personhood Mississippi’s mission – to save lives – is removed from the picture.

The only logically sensible justification for supposing that destroying fertilized eggs is wrong is to suggest that we are the human organism, and not the person with the rich mental life. But this approach is complex and highly unintuitive: it cuts against the grain of common sense (despite its being logical validity) and is unlikely to garner much support in a generally religious society such as the United States.

Those who would define a fertilized egg as a person do not have reason on their side. Their only recourse, then, is to rely upon rhetoric and emotional appeals. Opponents should point out as often as they are able — since there are likely more ‘Personhood’ movements in the wings — that the position makes no sense scientifically, philosophically, religiously, or logically.

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