The Nature of Argument

The Main Concern of Logic and the Importance of Arguments

In the field of logic, the primary focus is the study and application of arguments. Logic is concerned with learning and establishing the principles used to advance and assess or evaluate arguments. The importance of studying the nature of arguments is multifaceted, particularly within the study of philosophy. All of philosophy can be defined as the attempt to present original arguments and the critical evaluation of the arguments presented by others. Consequently, argument plays a critical role in philosophical discourse.

Beyond philosophy, arguments are fundamental to day-to-day human relations. In our interactions with one another, people consciously or unconsciously present arguments to persuade others or "buy us over to their sides." In academic contexts, argument plays a vital role across nearly every discipline for two reasons: firstly, intellectual activities require providing a solid justification for the views we hold, and secondly, we must evaluate the arguments made by others within our specific academic fields. Peter O. Bodunrin emphasizes this by stating that arguments serve the same purpose for philosophers as proofs serve for mathematicians, experimental demonstrations serve for scientists, or archaeological evidence and archival documents serve for historians.

Defining the Concept of an Argument in Logic

There is a notable difference between how a layman and a philosopher utilize the concept of an argument. To a layman, an argument is typically viewed as a verbal dispute which may result in a quarrel or a disagreement. However, to a philosopher, an argument is a set of declarative sentences composed of two distinct parts: the premise and the conclusion. In this structure, the premise provides support for the acceptance of the conclusion.

Formally, an argument is defined as a set of declarative sentences, also known as propositions, consisting of a conclusion and one or more premises. Several scholars have provided precise definitions for this term. According to A.G.A. Bello, an argument is a type of inference or "a claim to a new piece of information on the basis of something else we already know to be the case." He notes that there are two parts to an argument: a "new" piece of knowledge and the foundation upon which that new knowledge is based. Specifically, Bello defines an argument as any group of propositions where one is claimed (rightly or wrongly) to follow from the others, which are regarded as providing evidence for the truth of that one. The proposition claimed to follow is the conclusion, while those providing evidence are the premises.

C.S. Layman defines an argument as a set of statements where one, the conclusion, is affirmed on the basis of the others, known as the premises. Similarly, Francis Offor defines argument as a group of statements in which the part known as the conclusion is claimed to follow from others called premises.

Propositions and the Constituents of Argument

The basic constituent of an argument is the proposition. A proposition is a declarative sentence that can be classified as either true or false. Because of this, a proposition possesses a truth value. Examples of propositions include: "It is raining," "Nigeria is a black nation," "Omolara is a girl," and "Charles is hardworking." It is important to note that while propositions have truth values (true or false), arguments themselves cannot be said to be true or false. Instead, they are evaluated based on their logical structure and validity.

The Structure and Relationship within Arguments

Every argument has a specific structure defined by the relationship between the conclusion and the premises. An argument must contain at least one premise and one conclusion, and there must be a logical relationship between them. The premise(s) should provide a sufficient ground for the conclusion. If the premises do not provide any ground for the acceptance of the conclusion, then an argument does not exist. This relationship is necessary for intelligibility; without a connection between the propositions, the statement is not an argument.

For example, the sequence "Black is beautiful. Kunle is a fine man. Therefore the car is very fast" is not an argument because there is no relationship between the statements. In contrast, the sequence "All men are mortal. Socrates is a man. Therefore, Socrates is mortal" is a valid argument because a clear relationship exists between the propositions. The conclusion is the claim that one expects people to accept and relies on other propositions for its justification. The premise refers to the body of evidence or the reasons provided for the acceptance of that claim. The support provided by the premise to the conclusion can be categorized as weak, moderate, or strong.

Categories of Arguments: Good vs. Bad and Formal vs. Informal

Arguments are generally divided into two categories: good and bad. Good arguments are those where the premises truly support the conclusion. Bad arguments are those where the premises do not support the conclusion, even if it is claimed that they do. Arguments are further classified by their format and logical properties.

Formal arguments are those that follow a specific logical form. Examples include Modus Ponens and Modus Tollens. Modus Ponens follows the form:

$p \rightarrow q$

$p$

$q$

An example of Modus Ponens is: "If it rains then the ground is wet. It rains. Therefore, the ground is wet." In this case, Premise 1 is "If it rains then the ground is wet," Premise 2 is "It rains," and the conclusion is "The ground is wet."

Modus Tollens follows the form:

$p \rightarrow q$

$\neg q$

$\neg p$

An example of Modus Tollens is: "If it rains then the ground is wet. The ground is not wet. Therefore, it did not rain." Here, Premise 1 is "If it rains then the ground is wet," Premise 2 is "The ground is not wet," and the conclusion is "It did not rain."

Informal arguments are those without a strict form and are the subject of informal logic. These are typically presented in ordinary language during daily discussions, personal exchanges, advertisements, political debates, legal arguments, and social commentary found in newspapers, television, or the internet. A common example of an informal argument found in advertising is: "Buy Omo Detergent, because $99\%$ of Nigerians use this detergent."

Validity, Soundness, and Logical Classification

Arguments are evaluated based on validity and soundness. A valid argument is one in which, if the premises are true, the conclusion cannot be false. An example of a valid argument is:

Premise 1: All men are mortal (True)

Premise 2: Socrates is a man (True)

Conclusion: Socrates is mortal (True)

An invalid argument is one where, even if the premises are true, the conclusion is false. An example of an invalid argument is:

Premise 1: All men are mortal (True)

Premise 2: Socrates is a man (True)

Conclusion: Socrates is NOT mortal (False)

A sound argument is one that is both valid and contains only true propositions (meaning both the premises and the conclusion are actually true). The argument about Socrates being mortal is sound because it is valid and its propositions are true.

Deductive and Inductive Arguments

Arguments are also classified as deductive or inductive based on the level of support the premises provide to the conclusion. A deductive argument is one in which the premise gives full support for the conclusion. If you accept the premises of a deductive argument, you cannot reject the conclusion because the conclusion follows necessarily. For example: "All Nigerians are blacks. All blacks are hardworking. Therefore, Kunle who is a Nigerian is black and hardworking."

In contrast, an inductive argument is one where the premises provide only partial support for the conclusion. In these arguments, you might accept the premises but still reject the conclusion, as the conclusion does not necessarily follow from the premises. An example of an inductive argument is: "Abacha is a military head of state and he is a dictator. Babangida is a military head of state and he is a dictator. Therefore all military heads of state are dictators."