Tag Archives: Bible

Symbolizing Scripture

Intermediate Logic,

Translating Bible verses into symbolic form is sometimes fun and insightful.
Consider Exodus 21:18-19,

bible_with_books_med[1]“If men contend with each other, and one strikes the other with a stone or with his fist, and he does not die but is confined to his bed, if he rises again and walks about outside with his staff, then he who struck him shall be acquitted. He shall only pay for the loss of his time, and shall provide for him to be thoroughly healed.”

Recognizing this as a single logical proposition, it symbolizes as follows: Continue reading Symbolizing Scripture →

Yet More Logic in Scripture

Introductory Logic, Why learn logic?,

bible_with_books_med[1]Logic students regularly struggle with immediate inferences, and (as is often the case when students have more than usual difficulty) they can begin to wax philosophical about the value of learning this particular concept. As an initial response to such students, I want to give a couple of examples of immediate inferences used in the Bible. Two equivalent immediate inferences for categorical statements are obverse and contrapositive.

Obverse changes the quality of the statement, and takes the complement of the predicate. It gives equivalent statements for all four forms of categorical statement:

All S is P  ≡  No S is non-P
No S is P  ≡  All S is non-P
Some S is P  ≡  Some S is not non-P
Some S is not P  ≡  Some S is non-P

Jesus uses the obverse in Mark 2:22, where He says,

“No one pours new wine into old wineskins. Otherwise, the wine will burst the skins, and both the wine and the wineskins will be ruined. No, they pour new wine into new wineskins.”

Contrapositive switches the subject and predicate of the statement, and changes both to their complements. It gives equivalent statements for universal affirmative and particular negatives:

All S is P  ≡  All non-P is non-S
Some S is not P  ≡  Some non-P is not non-S

Paul uses something like the contrapositive in Romans 11:6 when he argues,

“And if by grace, then it is no longer of works; otherwise grace is no longer grace. But if it is of works, then it is no longer grace; otherwise work is no longer work.”

This is more obviously the contrapositive when the conditional statements are translated into categorical form.

Incarnation Deduction

Intermediate Logic, Why learn logic?,

The Westminster Confession of Faith declares the value of logic for understanding truth, saying, “The whole counsel of God concerning all things necessary for His own glory, man’s salvation, faith and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture.” The truth that Jesus is God is set down in John 1:1, 8:58, Titus 2:13, and Hebrews 1:8, as is the truth that Jesus is Man, in John 8:40, Acts 2:22, and Hebrews 2:14.

But the truth that Jesus is both God and Man is deduced “by good and necessary consequence” from those statements set down expressly, by a rule of inference called conjunction (we know P, we know Q, therefore we know P and Q). This may sound obvious enough, but the nature of that conjunction (eg. was Jesus one Person in two natures, divine and human, or only of or from two natures?) took several centuries for the church to apprehend and set down in creeds, such as the Definition of Chalcedon.

More Logic in Scripture

Logic, Why learn logic?,

Last week we considered examples of enthymemes in the Bible, and noted that we can use the rules of validity to determined their unspoken assumptions. In this post we will consider another form of logical argument.

If we look closely into the arguments in the Bible, we can see several examples of hypothetical syllogisms, arguments using “if/then” propositions.

The most basic valid hypothetical syllogism is modus ponens, which follows this pattern:  If P then Q. P, therefore Q. This is the form of reasoning shown in Matthew 8:2-3,

And behold, a leper came and worshiped Him, saying, ‘Lord, if You are willing, You can make me clean.’ Then Jesus put out His hand and touched him, saying, ‘I am willing; be cleansed.’ 

The modus ponens can be also seen in Proverbs 23:13-14,

Do not withhold correction from a child, for if you beat him with a rod, he will not die. You shall beat him with a rod, and deliver his soul from hell.

Another valid hypothetical syllogism form is the modus tollens, which follows this pattern: If P then Q. Not Q, therefore not P. We see this form used in 1 John 2:19,

If they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us.

Here is another modus tollens, in slightly different form, from 1 Corinthians 15:13,20:

If there is no resurrection of the dead, then Christ is not risen… But now Christ is risen from the dead, and has become the firstfruits of those who have fallen asleep.

 We learn about hypothetical syllogisms in Introductory Logic, Lesson 31, and Intermediate Logic, Lesson 13.

Logic in Scripture

Introductory Logic, Why learn logic?,

Many syllogisms in the Bible leave a premise unstated. Arguments like this are called enthymemes. Using the rules of validity, we can determine what the assumed premise must be. We locate enthymemes by recognizing premise identifiers (for, because, since) or conclusion identifiers (therefore, thus, so, consequently).

For example, in Hosea 10:3, the people complain, “We have no king, because we did not fear the Lord.” Put these statements in categorical form, leaving the assumed premise blank:

(___________________)
No we are God fearers
∴ No we are king havers.

Continue reading Logic in Scripture →

Biblical Defining

Introductory Logic, Why learn logic?,

Some people believe that Jesus’ command to love your enemies is an absurd requirement because they are defining love to mean ‘believe the other to be a nice person,’ when in fact they know their enemies to be quite wicked and depraved. But biblically, love means ‘to treat the other person lawfully from the heart,’ which is to be our behavior toward all men. If this definition is made clear, the people may still think that the command is impossible, but at least they no longer should see it as absurd.

Every Speech in the Bible

Rhetoric,

I have worked through the Old and New Testament, trying to identify every speech in the Bible by reference, speaker, audience, and brief description. By my criteria, I found 235 speeches in the Old Testament and 278 in the New Testament, for a total of 513 speeches. This will be a useful tool as I work on writing a Rhetoric text. Some interesting notes:

  1. The gospel of Luke had the most speeches of any book (81)
  2. Moses delivers the longest single speech (Deuteronomy 5:1 through 26:19)
  3. The longest New Testament speech is, of course, the Sermon on the Mount.
  4. Jesus delivers the most speeches (214), followed by Moses (24), then David (13)
  5. Job, Peter and Paul all deliver the same number of speeches (11)

I am now working on the best way to make it available for others to use.

There are a lot!

Rhetoric,

I am currently working on identifying every speech in the Bible.

“And how do you define a speech, exactly?” Good question. Here is my criteria:

  • It must be spoken before an audience (or written with that intention); e.g. not a song without an identified audience
  • Spoken from man to man; not a prayer, nor from God, nor a prophet saying “Thus says the Lord”
  • Formal, self-contained, structured (not merely a conversation)
  • Not an epistle
  • Three or more sentences in length.

I will let you know when I am done.

The Philosopher and the Apostle

Classical Education, Old Western Culture, Rhetoric, ,

Aristotle presents the general line of argument “That if it is possible for one of a pair of contraries to be or happen, then it is possible for the other: e.g. if a man can be cured, he can also fall ill; for any two contraries are equally possible, in so far as they are contraries” (Rhetoric II.19).

I was wondering if anyone would really argued this way, when I recalled an argument from Paul about the resurrection: “For since death came through a man, the resurrection of the dead comes also through a man. For as in Adam all die, so in Christ all will be made alive” (1 Cor. 15:21-22).

Paul either knows his Aristotle, or Aristotle knows how people think.

Paul Preaching to the Ephesians
Paul Preaching at Athens