Deductive Arguments (The Impossibility of God)

While Christianity might be favorable in the existential aspect of evil, it still has problems regarding the problem of evil. For centuries, atheistic and agnostic philosophers have held that it is impossible for God to coexist with evil, claiming that God and evil are logically incompatible. To argue this case, these philosophers have used deductive arguments.

What is a Deductive Argument?

Deductive arguments are a type of argument, which are watertight. That is, if their premises are true, then their conclusion must follow by necessity. Let’s consider an example of a deductive argument:

P1: Every dog is an animal.

P2: Scruffy is a dog.

CONCLUSION: Therefore, Scruffy is an animal.

If premise 1 and premise 2 are true, then the conclusion is inescapable. This is the strength of a deductive argument. If you have strong premises, then you will have an unavoidable conclusion.

On the other hand, the strength of a deductive argument is also its weakness. These arguments often attempt to prove too much. To demonstrate that a deductive argument is not valid (i.e. the conclusion does not follow from the premises), we simply need to offer one, single counterexample. For instance, in the above argument, if we could offer one example of a dog that was not an animal, then the argument would fall apart.

Most Recent Attack

EvilExists2The most recent atheist to argue the deductive problem of evil was atheistic philosopher J.L. Mackie in his 1982 book The Miracle of Theism. His argument was based on his 1955 essay titled “Evil and Omnipotence.” Mackie writes,

In its simplest form the problem is this: God is omnipotent; God is wholly good; and yet evil exists. There seems to be some contradiction between these three propositions, so that if any two of them were true the third would be false. But at the same time all three are essential parts of most theological positions: the theologian, it seems, at once must adhere and cannot consistently adhere to all three.[1]

Some philosophers have called this the Omni-triad: How can God be all-loving, all-powerful, and exist in the presence of evil? This appears to be impossible. Let’s consider three different formulations of the deductive problem of evil:

Formulation #1

1. God is the author of everything.

2. Evil is something.

3. Therefore God is the author of evil.

Christian philosophers would disagree with premise two. While evil is real, it is not a real thing. Instead, it is the privation or distortion of a thing. As a parasite cannot live without a host, evil cannot exist without a good and perfect standard. For instance, rust can eat away at metal and mold can eat away at bread. However, a totally rusted car is no longer a car; it’s just a brown spot on the pavement. Similarly, evil is parasitic on a good creation. Blindness is only evil, because we have a standard for sight. Rape is only evil, because we have a standard for loving sex. Murder is only evil, because we have a standard for the protection of innocent life. Across the board, evil cannot exist as a thing without distorting a good creation.

Formulation #2

1. God made everything perfect.

2. Imperfection cannot come from perfection.

3. Perfectly created beings cannot be the origin of evil.

4. Therefore, God must be the origin.

Philosophers would disagree with premise three. God created perfect beings with freedom of the will. Part of being a perfect being is to have freedom –a good attribute. In fact, as soon as we say that freewill is not a good attribute, we contradict ourselves. That is, we have to use our freewill to deny freewill. Moreover, we hardly see people marching around with signs that say, “Take away my freedom!” or “Please control me!” Instead, we can generally sense that freedom of the will is a good thing. Philosopher Norman Geisler writes,

[God is not] responsible for evil. He created the fact of freedom; we perform the acts of freedom. He made evil possible; men made evil actual. Imperfection came through the abuse of our moral perfection as free creatures.[2]

Biblically, evil arose when Satan willed a lesser good (himself) over a greater good (God). Therefore, the first sin was pride.

Formulation #3

1. If God is all good, He would destroy evil.

2. If God is all-powerful, He could destroy evil.

3. But, evil is not destroyed.

4. Therefore, there is no such God.

The Christian philosopher would target premise two in this argument, pointing out that it is logically impossible to force a freewilled agent to do something. God might permit evil, because this could affect human freedom. That is, God might not be able to destroy evil without destroying freewilled persons, whom he values. Therefore, instead of currently destroying evil; he is going to ultimately defeat it.

The Christian philosopher would also revise premise three by adding a single word to the statement: “Evil is not yet destroyed.” The atheist might scoff at the return of Christ and the future restoration of God, but how could they know this for certain? This would assume omniscience (or being all-knowing). Therefore, in order for the skeptic to defeat God, they would need to be God.


While atheist and agnostic philosophers still argue the inductive problem of evil (evil makes God improbable), few still argue the deductive problem of evil (evil makes God impossible). This might come as a shock to many atheists and agnostics, but it’s true. The deductive problem of evil was solved in the last few decades by philosopher Alvin Plantinga from the University of Notre Dame. In his conclusion to Part A of his 1977 book God, Freedom, and Evil, Plantinga writes,

The existence of God is neither precluded nor rendered improbable by the existence of evil. Of course, suffering and misfortune may nonetheless constitute a problem for the theist; but the problem is not that his beliefs are logically or probabilistically incompatible.[3]

Likewise, philosophers William Lane Craig and J.P. Moreland write,

It is the atheist who bears the burden of proof to show that there is no possible world in which (Premise 1) and (Premise 2) are true. That is an enormously heavy burden, which has proved to be unbearable. After centuries of discussion, contemporary philosophers, including most atheists and agnostics, have come to recognize this fact. It is now widely admitted that the logical Problem of Evil has been solved.[4]

These are bold claims to make. And yet, after considering the multiple formulations of the problem of evil, it is easy to see how difficult it would be to show that God and evil cannot possibly coexist.


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[1] Mackie, J.L. Evil and Omnipotence, New Series, Vol. 64, No. 254. April, 1955. 200.

[2] Geisler, Norman L., and Ronald M. Brooks. When Skeptics Ask. Wheaton, IL: Victor, 1990. 62-63.

[3] Plantinga, Alvin. God, Freedom, and Evil. Grand Rapids: Eerdmans, 1977. 63.

[4] Emphasis mine. Moreland, James Porter, and William Lane. Craig. Philosophical Foundations for a Christian Worldview. Downers Grove, IL: InterVarsity, 2003. 541.