1. THE NATURE OF ARGUMENT

2. THE MAIN CONCERN OF LOGIC Basically in logic we deal with ARGUMENTS. Mainly we deal with learning of the principles with which we can advance and assess/evaluate arguments.

3. What is an Argument? Since the concern of logic is mainly arguments, it is important to understand what an argument is. An argument is a set of declarative sentences (propositions) with two parts- 1. conclusion and 2. premise; with the premise giving support for the acceptance of the conclusion

4. EXAMPLES All men are mortal Socrates is a man Therefore, Socrates is mortal  If Afe Babalola founds a university, then Afe Babalola is wealthy Afe Babalola founds a university Therefore, Afe Babalola is wealthy.

5. Basic constituents of arguments One of the basic constituent of an argument is proposition. A proposition is a declarative sentence that can either be true or false. A proposition has a truth value. This means that a proposition may either be be true or false. Note that arguments cannot be said to be true or false.

6. Examples of proposition It is raining Nigeria is a black nation

7. Structure of an argument An argument has a structure. It is such that an argument has a conclusion and a premise/premises. The structure is further defined by the kind of relationship between the conclusion and the premises.

8. Structure of an argument The implication of what is said in the last slide is that 1.There are two parts of a conclusion- the premise and the conclusion 2. There must be a relationship between the two

9. Structure of an argument (Contd) Normally, in an argument the premise(s)should provide sufficient ground for the conclusion. If the premises do not provide any ground for the acceptance of the conclusion then there is no argument

10. There must be a relationship between the propositions making up an argument. The reason for this is not far fetch. It is that whatever one is saying must be intelligible. If there is no connection between the propositions then there is no argument.

11. examples 1. Black is beautiful. Kunle is a fine man. Therefore the car is very fast. 2. All men are mortal. Socrates is a man. Therefore, Socrates is mortal Whereas in the first example above there is no relationship, in the second there is a relationship between the propositions.

12. CONCLUSION This is the claim, in an argument, that one expects people to accept. It may also be conceived as that proposition that relies on other propositions for justification.

13. PREMISE This refers to the body of evidence that one is giving in support of the claim that one wants others to accept. It is the reason that one provides for the acceptance of the conclusion The premise is the part of the argument that provides sufficient ground for the acceptance of the conclusion.

14. Support from the premise to the conclusion The support that he premises give the conclusion may be: Weak Moderate strong

15. Layman’s idea of an argument There is a difference between the way a layman uses the concept argument and the way a philosopher does.

16. To a layman an argument is verbal dispute which may result in a quarrel, or disagreement. However, to a philosopher, an argument is a set of declarative sentences that can be divided into two groups- the premise and the conclusion- with the premise giving support for the acceptance of the conclusion.

17. Some scholars’ definition According to AGA Bello, “An argument is a type of inference, a claim to a new piece of information on the basis of something else we already know to be the case.”

18. There are, to him, therefore, two parts of an argument- a ‘new’ piece of knowledge and that on which the new knowledge is based. More precisely, he defines an argument as “any group of propositions one of which is claimed (rightly or wrongly) to follow from the other(s), which other(s) are regarded as providing evidence for the truth of that one. The proposition which is claimed to follow from the other(s) is called the conclusion, and the proposition(s) which are regarded as providing the evidence for the truth of the conclusion are called the premises.

19. Some scholars’ definition (contd.) 2. C. S. Layman, “an argument is a set of statements, one of which, called the conclusion, is affirmed on the basis of the others which are called the premises.

20. In the words of Francis Offor, “argument refers to a group of statements, in which one part known as the ‘conclusion’ is claimed to follow from the others called the premises.

21. Good arguments and bad arguments Arguments fall into two categories. And they are Good and BAD arguments Good arguments are those arguments in which the premises really do support the conclusion. While bad arguments are those arguments in which the premises do not support the conclusion even though they are claimed to.

22. Types of arguments Formal arguments/informal arguments Valid arguments/invalid arguments Sound arguments Deductive arguments/inductive arguments

23. Formal arguments Formal arguments are arguments with form. E.g modus ponens; modus tollens

24. informal arguments Informal arguments are arguments without form and are studied in informal logic. This form of arguments are presented in ordinary language in our day to day discussion and personal exchange between individuals holding different views, advertising, political debate, legal argument, and the social commentary that characterises newspapers, television, the World Wide Web and other forms of mass media. good example of informal arguments are found under informal fallacies too.

25. All men are mortal Socrates is a man Therefore, Socrates is mortal

26. Valid arguments A valid argument is an argument in which if the premises are true the conclusion cannot be false

27. Invalid arguments an invalid argument is an argument in which if the premises are true the conclusion is false.

28. Sound Arguments argument that are valid and have true propositions (in which the premises and the conclusion are true)

29. Deductive arguments an argument in which the premise gives full support for the acceptance of the conclusion; It is that argument in which if you accept the premise you cannot reject the conclusion In a deductive argument the conclusion necessarily follows from the premise

30. Inductive arguments Premises give partial support for the acceptance of the conclusion. It is that argument in which you may accept the premises and reject the conclusion The conclusion does not necessarily follow from the premises.