The Basic Terms and Rules of Logic

If the terms, such as statement, premise, conclusion, or logical argument are new to you, you may have to read through the bullet points below several times to understand them.

  • Logic = a limited but powerful tool to try to determine what is true. A premise statement (there can be more than one) is used to demonstrate the truth of a single conclusion statement. (problems)

Read through these bullet points and give each one some thought until you can say that it makes sense:

  • Premise = the reason, proof, or rationalization which makes someone believe something to be true.
  • Conclusion = whatever is claimed to be true because of the premise.
  • Logical Argument = a conclusion plus at least one premise, or reason that you think that the conclusion is true. (read)
  • There are 3 obvious classical laws: Things are what they are; two mutually exclusives can’t both be true at the same time and in the same way; and there is no middle ground between two mutually exclusives.
    • Example: God is God. He can’t both exist and not exist, and there is no middle ground between claims of His existence as opposed to claims of His non-existence. (read)
  • Statements can be either true or false. (not valid or invalid) (read)
    • A premise is a statement and it can be true or false.
    • A conclusion is a statement and it can be true or false.
  • A premise plus a conclusion constitutes a logical argument,
  • but that argument is not necessarily either valid or sound.
  • Arguments can be either valid or invalid. (not true or false)
  • Arguments can be either sound or unsound. (not true or false)
  • Validity has to do with the form of the argument.
  • Valid Argument = an argument where IF all the premises are true, the conclusion must be true–it would be impossible for the conclusion to befalseIF all the premises are true.
  • Sound Argument = an argument where the argument is valid and all its statements (premises & conclusion) are true.
  • Inductive reasoning is reasoning that if a certain premise is true it indicates that a certain conclusion might be true.  (read)
  • Deductive reasoning is reasoning where if the premise is true and the argument is valid, the conclusion is necessarily true.
    • Deductive reasoning can be evaluated for the validity of the form. (read)
    • Deductive reasoning can be evaluated for the truth of the premises.

Sound/Unsound argument: An argument is called sound if and only if it is valid and all its statements (premises & conclusion) are true. Otherwise, theargument is called unsound. (examples of unsound reasoning) Every unsound argument is a lie whether it is told by an Atheist or a Christian theologian.

Is every premise testable and true? See the diagrams above to see why many premises that are taught, especially in secular schools, are not true.

Examples of the testability of premises:

  • It is impossible to test to see whether molecules-to-man evolution actually happened.
  • Bible verses are often quoted as a premise, but when you look them up, the conclusion doesn’t follow from what is written in Scripture.
  • It is possible to test whether every person who seeks God in sincerity, humility, reverence, and submission, will find Him. (read)

Is the premise true?

Does the conclusion follow from the premise?

  • Examples:
    • The conclusion that evolution actually happened does not follow from the fact that most scientists say that they believe in it.
    • If assumptions are required to make a case against the Bible for claimed errors or inconsistencies (as it is in every case), then those claims don’t follow from the evidence.
    • Someone may claim that the Bible says a certain thing, but when you go to look up the verse, it doesn’t really say what was claimed, so the claim doesn’t follow from the premise/evidence.
    • “We can scientifically observe that there are changes from generation to generation; therefore, molecules-to-man evolution is a scientific fact!!!” That conclusion doesn’t follow from the evidence.
    • “Complex protein molecules are formed in nature; therefore, it is just a matter of time before a self-sustaining life-form will pop into existence and begin to reproduce and evolve!!!” The conclusion doesn’t follow from the evidence.
    • “Natural selection, the survivors survive, is fact, therefore, molecules-to-man evolution is fact!!!” The conclusion doesn’t follow from the evidence.
    • “The human mind is easily tricked and can’t be trusted, therefore we should not trust God to reveal but should only trust the human mind!!!” The conclusion doesn’t follow from the evidence. (read)

Fallacy = any error in an argument that makes the reasoning not sound. There are many fallacies and they are often hard to detect. Fallacy means to deceive, to trip, to lead into error, or to trick. We can trick ourselves or be tricked by others. As with the word, logic, the word, fallacy, can have more than one meaning. We define it broadly because that is most useful to you. (read)


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