# A Class-Room Introduction to Logic

## May 4, 2009

### Unit-XII: Arguments of Ordinary language

Filed under: Argument in Ordinary Language,Uncategorized — Dr. Desh Raj Sirswal @ 7:52 am

Argument:

An argument is a connected series of statements or propositions, some of which are intended to provide support, justification or evidence for the truth of another statement or proposition. Arguments consist of one or more premises and a conclusion. The premises are those statements that are taken to provide the support or evidence; the conclusion is that which the premises allegedly support.

Argument Form: In logic, the argument form or test form of an arguement results from replacing the different words, or sentences, that make up the argument with letters, along the lines of algebra; the letters represent logical variables. The sentence forms which classify argument forms of common important arguments are studied in logic.

Here is an example of an argument:

All humans are mortal. Socrates is human. Therefore, Socrates is mortal.

We can rewrite argument  by putting each sentence on its own line:

All humans are mortal.

Socrates is human.

Therefore, Socrates is mortal.

To demonstrate the important notion of the form of an argument, substitute letters for similar items :

All S are P.

a is S.

Therefore, a is P.

Thus arguments are structural pieces of articulated critical reasoning. Every argument must have a conclusion and a premise or some premises.

Deductive and Inductive Arguments

There are two types of arguments:

Deductive Argument: A deductive argument is an argument in which it is thought that the premises provide a guarantee of the truth of the conclusion. Here the premises are intended to provide support for the conclusion that is so strong that, if the premises are true, it would be impossible for the conclusion to be false.

Inductive Arguments: An inductive argument is an argument in which it is thought that the premises provide reasons supporting the probable truth of the conclusion. Here the premises are intended only to be so strong that, if they are true, then it is unlikely that the conclusion is false.

Difference between Deductive and Inductive Argument:

The difference between the two comes from the sort of relation the author or expositor of the argument takes there to be between the premises and the conclusion. If the author of the argument believes that the truth of the premises definitely establishes the truth of the conclusion due to definition, logical entailment or mathematical necessity, then the argument is deductive. If the author of the argument does not think that the truth of the premises definitely establishes the truth of the conclusion, but nonetheless believes that their truth provides good reason to believe the conclusion true, then the argument is inductive.

Arguments have certain special characteristics:

1. Arguments are not claims.
2. Every set of claims is not an argument.
3. There is no fixed number of premises in the argument.
4. Format of an argument may not always be simple.
5. There may be unstated premises.
6. There can be missing premises.
7. Arguments have a standard format:

Premises

Therefore, Conclusion

To put arguments in the standard format, one has to do the followings:

1. Separate the premises from the conclusion.
2. State, the premises first in a sequential order and, if necessary, number them.
3. Then state the conclusion with a conclusion marker, such as the symbol “/” or any of the conclusion-indicator words.

Recognizing and Argument:

Premise- indicator words: Since-For-Because-Given that.

Conclusion- indicator words: Therefore- Hence- It follows that-So-Consequently-Thus.