1. BASIC CONCEPTS OF ARGUMENTS

2. What is an Argument?
To justify or defend a claim is to give reasons or arguments to support it.
Reasoning (or inference) is a psychological process.
When we express this process into words, we have arguments.
An argument is set of STATEMENTS (or propositions) composed of PREMISES and CONCLUSION such that the former supports the latter.

3. What is an Argument? A STATEMENT is a sentence that is either T or F.
So questions, commands, requests are not statements.

4. What is an Argument? The structure of an argument: Premise 1 Premise 2
Premise n
Conclusion

5. What is an Argument? He was not speaking the truth.
Example of argument:
Either CY Leung was speaking the truth or he was lying.
He was not speaking the truth.
Therefore, he was lying.

6. What is an Argument? Example of argument: Most new students took DSE.
He is a new student.
He took DSE.

7. What is an Argument?
Conclusion indicators: therefore, hence, thus, so, as a result, wherefore . .
Premise indicators: since, for , because, as, given that, owing to . . .

8. What is an Argument? SUB-CONCLUSION
Sometimes, one or more of the premises of an argument support a conclusion as a statement that in itself serves as a premise in the argument for the final conclusion. Such a statement is a sub-conclusion of the argument.

9. What is an Argument? E.g.: 1. Leon is a genius. (premise)
2. Geniuses are weird. (premise)
3. Therefore, Leon is weird. (sub-conclusion)
4. All weird people have problems in social relation. (premise)
5. Therefore, Leon has problems in social relation. (conclusion)

10. What is an Argument? IMPLICIT (OR UNSTATED) PREMISE
An implicit premise of an argument is a statement that is assumed but needs to be added to the premises if they are to support the conclusion.

11. What is an Argument?
E.g.: What is the implicit premise in the following argument?
All murder is immoral.
Therefore, mercy killing is immoral.

12. E.g.: What is the implicit premise in the following argument?
Using pirate software violates the inventors’ property rights.
Therefore, it is wrong to use pirate software.

13. Passages Similar to Arguments
EXPLANATIONS
They have the same structure of arguments but the reasons given in an explanation are not used to prove a claim. Instead, they are used to make sense of a claim that has already been well accepted.
E.g., “I am late because there is a traffic congestion."

14. Passages Similar to Arguments
Conditional propositions
They state that something will happen if certain conditions are fulfilled.
E.g., "if you work hard, you will pass the test."

15. Passages Similar to Arguments
Statements of belief
They simply express someone's beliefs without providing any evidence to support those beliefs.
E.g., "I believe that he is guilty and should be put to jail."

16. The Logical Strength of an Argument
The logical strength of an argument is the measure of how its premises, assumed to be true, support its conclusion.
We divide arguments into two types according to their logical strength:
Deductive arguments
Inductive arguments

17. The Logical Strength of an Argument
Deductive argument
If all its premises are true, its conclusion is logically impossible to be false.
I.e.: The truth of its premises guarantees the truth of its conclusion.
E.g.: Either Albert or Bill is late. Albert is not late. Therefore, Bill is late.

18. The Logical Strength of an Argument
Inductive argument
If all its premises are true, its conclusion is likely to be true but still possible to be false.
I.e.: The truth of its premises makes it reasonable to hold that the conclusion is true.
E.g.: Most people who are infected with HIV will develop AIDS, and he is infected with HIV. Therefore, he will develop AIDS.