Page 13 - Masters Sample Courses

These laws are also called “rules of inference.” They reflect the way God thinks and the way we must
think if we are to think God’s thoughts. These laws of logic are universal, invariant, and abstract rules of
thought that govern all correct reasoning, because they parrot the mind of God. They are universal in
that they apply everywhere in the universe to every situation. They are invariant in that they, like God,
do not change over time. They are abstract in that they exist in our minds and have no physical
substance.

In the Christian worldview, laws of logic are justified which means we have good reason or reasons to
believe in them. And in the Christian worldview, we have an absolute, objective standard for correct
reasoning: God. These laws reflect the way God thinks and are rooted in His nature. We can use these
ways because we are made in the image of God (Genesis 1:27). Our minds have a finite capacity to
reflect God’s thoughts, as these laws describe.

Not only does the Christian worldview account for the laws of logic and their properties, but we can see
how each of the three fundamental laws of thought is rooted in the nature of God. Consider the law of
non-contradiction. Why is it that a proposition and its negation cannot both be true at the same
time? It is because all truth is in God (Colossians 2:3, John 14:6), and God cannot deny Himself (2
Timothy 2:13). Hence, truth will never contradict truth. It would be dishonest to say both “yes” and
“no” at the same time about the same thing because this would be unfaithful to the nature of God and
would therefore be false (2 Corinthians 1:18).

Likewise, the law of identity is rooted in the character of God. God says, “I am who I am” (Exodus
3:14). God is Himself, and He is truth. Consequently, truth is itself. Thus, for all truth statements p,
if p is true then p is true.

The law of the excluded middle is also rooted in the nature of God. God is truth, and that which is not of
God is not true (John 14:6). Any given proposition will therefore either be in line with God’s thinking
and thus true, or not aligned with God’s thinking and therefore false. Specific instances of the law of the
excluded middle are found throughout Scripture. In Exodus 16:4 The Lord promises to send bread from
heaven, and to test whether the people (1) will obey God, or (2) will not obey God. The Lord’s test
indicates that no middle position is possible. Either a person will obey, or it is not the case that the
person will obey.

In Matthew 5:37 Jesus said, “But let your statement be, ‘Yes, yes’ or ‘No, no’; anything beyond these is
of evil.” The context here concerns oaths: Jesus instructs his followers not to make oaths that they do
not intend to follow. It would be better to make no oath at all. If you say you are going to do
something, just do it, otherwise don’t say you are going to do it. The basis for this it that you are either
going to do the thing, or you are not – that’s the law of the excluded middle. Christ instructs us to be
truthful about our intentions – “yes” we will do something or “no” we will not, since (by the law of the
excluded middle) these are the only two possibilities. Anything else is evil because it is not true and
therefore contrary to the nature of God.

All people know something about the laws of logic. Even those who have never formally studied these
laws and cannot recite them nonetheless use these laws in their thinking. The Christian worldview can
make sense of the existence and properties of laws of logic, as well as our ability to know and use
them. But no other worldview can justify them. A person might assert that laws of logic just “are” and
have the properties that they have (universal, invariant, abstract). But apart from the Bible, one can