Basics of Logic for Rhetoric Flashcards
What is an argument
A set of premises that work together and are supposed to convince a person that another premise (the conclusion) is true.
What is a syllogism
A type of argument in which a conclusion is drawn from two propositions (premises), each of which shares a term with the conclusion, and shares a common or middle term not present in the conclusion (e.g., all dogs are animals; all animals have four legs; therefore all dogs have four legs ).
All syllogisms have a:
1 MAJOR PREMISE
2 MINOR PREMISE
3 CONCLUSION
What are the three types of syllogisms?
Categorical (universal statements, like “all men are mortal”)
Hypothetical (if then statements, like “If it rains the ground will be wet”)
Disjunctive (either-or statements, like “Either you are human or you are not”)
What is a premise (or proposition)?
A premise (or proposition) is ANY single sentence, statement, or claim in an argument. (e.g. Cats are mammals. Climate change is a problem. God exists. Football is fun).
What is deductive reasoning?
Reasoning (or argument) that begins with a general statement or law, and then draws certain specific conclusions from it. Just think of syllogisms; they are all deductive.
What is inductive reasoning?
Reasoning (or argument) that begins with multiple specific examples and infers/derives a general statement from all of the preceding examples.
Example: Every president of the United States has been rich. To become the president of the United States you probably have to be rich.
What is an enthymeme?
(a) A shortened form of argument that is used in speeches and papers, where one of the premises or the conclusion of a syllogism is left unstated.
Example: Joe Biden is the president of the United States. So, you know he must be rich.
The premise left out is “Every president of the United States is usually rich.”
Why are enthymemes used in papers/speeches instead of syllogisms?
- Because we assume everyone already knows (or believes) the statement we leave out.
- It is the natural way we speak and write. In other words, it sounds strange to write out the entire syllogism instead of an enthymeme.
Which of the three rhetorical appeals does the enthymeme fall under?
It is usually part of LOGOS. Logos is one of the three rhetorical appeals besides pathos and ethos. Logos involves convincing your audience using good reasons, argument, and logic.
What is a formal fallacy?
A formal fallacy is a mistake in deductive reasoning where the mistake is caused by using the wrong FORM/STRUCTURE for your argument.
Example:
All criminals are mean.
All bullies are mean.
Therefore all criminals are bullies.
What is a fallacy?
A fallacy is a mistake in reasoning or argument.
What are the two major types of fallacies?
Formal fallacies
Informal Fallacies.
What does it mean to say that an argument is VALID?
In a properly formed deductive argument, if each of the premises is true, the conclusion MUST be true.
An INVALID argument is one where the all the premises are true, but the conclusion still turns out false.
Valid:
P1 - All cats meow.
P2 - Tom is a cat.
Con. - Tom meows.
Invalid
P1. - All cats meow.
P2 - All cats are animals with fur.
Con - All animals with fur also meow.
What is an INFORMAL fallacy?
An error in reasoning that involves problems with the CONTENT of the argument, not the FORM. Usually it involves arguments that are convincing (even though they are wrong) because the premises mislead us somehow, or perhaps the person doesn’t actually respond to your evidence but responds to something else. They mislead us because the words are use in an unclear way, or we are distracted by irrelevant information, or they offer what looks like evidence but that really is not.
(Other cards have examples of informal fallacies)
What is the informal fallacy known as Appeal to Authority?
Insisting that a claim (or premise) is true simply because an important, famous, or intelligent person said it was true.
Important: this is a fallacy especially when other evidence is not given.
