three

There are three major types of syllogism:

• Conditional Syllogism: If A is true then B is true (If A then B).
• Categorical Syllogism: If A is in C then B is in C.
• Disjunctive Syllogism: If A is true, then B is false (A or B).

To be in standard form a categorical syllogism meets the following strict qualifications:

1. · It is an argument with two premises and one conclusion.
2. ·
3. · Major term (P) = Predicate of conclusion.
4. · Minor term (S) = Subject of conclusion.
5. · Middle term (M) = Term that occurs in both premises.

A false premise is an incorrect proposition that forms the basis of an argument or syllogism. Since the premise (proposition, or assumption) is not correct, the conclusion drawn may be in error. For example, consider this syllogism, which involves a false premise: If the streets are wet, it has rained recently.

The Premise in which the Major Term appears will be called the Major Premise. But that’s not all. A syllogism is actually made up of 3 terms. The third term, or the Middle Term, can be thought of as a term used to link the two premises together in forming the conclusion.

Some A can never be B means Some A are not B (definite)….Case 7 : “Can Be ” and “Can never be”

All humans are mortal. Socrates is human. Hence, Socrates is mortal. The subject of the conclusion (Socrates) is called the minor term; the predicate of the conclusion (mortal) is called the major term.

Terms in this set (4)

• A’s. AAA-1. AAI-1. AII-1. AEE-2. AEO-2. AOO-2. AAI-3. AII-3. AAI-4. AEE-4. AEO-4.
• E’s. EAE-1. EAO-1. EIO-1. EAE-2. EAO-2. EIO-2. EAO-3. EIO-3. EAO-4. EIO-4.
• I’s. IAI-3. IAI-4.
• O’s. OAO-3.

A fallacy is reasoning that is logically incorrect, undermines the logical validity of an argument, or is recognized as unsound. All forms of human communication can contain fallacies. Because of their variety, fallacies are challenging to classify.

Rules of Syllogism

• Rule One: There must be three terms: the major premise, the minor premise, and the conclusion – no more, no less.
• Rule Two: The minor premise must be distributed in at least one other premise.
• Rule Three: Any terms distributed in the conclusion must be distributed in the relevant premise.

In this and the previous (mathematical) case, a logically valid argument is fallacious. So invalidity is not a necesssary condition for fallaciousness. In other words, not all fallacious arguments are invalid.

As “argument” is defined in the text, every argument has exactly one conclusion. As “argument” is defined in the text, some arguments may have no premises at all. An enthymeme is an argument that is missing a premise or a conclusion or both.

To say an argument is cogent is to say it is good, believable; there is good evidence that the conclusion is true. A weak argument cannot be cogent, nor can a strong one with a false premise(s).

No, a valid argument cannot have all false premises and derive from them a true conclusion.

In the case of an argument which actually has false premises, it takes a short story or fictional work to do this. Such an argument is UNSOUND because the argument does NOT have true premises. For either example, the logic is valid but the premises are false. For the premises to be true, all of them need to be true.

All valid arguments have all true premises and true conclusions. If an argument is valid, then it must have at least one true premise. Every valid argument is a sound argument. The following is a valid deductive argument: If it snows, then we will go sledding, just like when we were kids.

Valid: an argument is valid if and only if it is necessary that if all of the premises are true, then the conclusion is true; if all the premises are true, then the conclusion must be true; it is impossible that all the premises are true and the conclusion is false. Invalid: an argument that is not valid.