Understanding arguments — and the difference between truth and validity
and no, this is not about who is right in a shouting match
In our daily lives, knowingly or unknowingly, we put forward and hear various arguments. These arguments include reasons we think justify our beliefs.
A logician is concerned only with the form of the argument, its quality and in determining if it is likely to yield a warranted conclusion.
We will be discussing the meaning of ‘argument’, its structure, and the different types of arguments — deductive and inductive. Then we will go over the concepts of ‘truth’ and ‘validity’ in detail. Then we will try to understand why logicians are chiefly concerned with deductive arguments only.
Meaning of Argument
Arguments are said to be a chief, technical term in Logic. Contrary to popular belief — arguments need not involve disagreement or controversy.
In Logic, an argument merely refers to any structured group of propositions, of which one is claimed to follow from the others, which provide support for the truth of that one.
Every argument varies in its degree of complexity. Some are simple, and others are quite complicated. This can be attributed to their structure. The simplest argument consists of 1 premise and a conclusion that is inferred from it. For example-
Premise — There is rain.
Conclusion — Therefore, we shall not go for a picnic.
An example of a more complex argument is-
Premise 1 — If A then B.
Premise 2 — If B then C.
Conclusion — Therefore, if A then C.
Parts of Argument
Arguments are built with propositions. Proposition refers to what is typically asserted using a declarative sentence, and hence always either true or false — although its truth or falsity may be unknown. But an argument is not just a random collection of propositions. It is a collection of propositions with a definite structure of premise(s) and a conclusion. Inference is referred to a cluster of propositions that lead to a conclusion.
Difference between Argument and Explanation
It is not uncommon to mistake an explanation for an argument or vice versa. Even indicators like ‘because, for, since, and therefore’ are common between the two. The only way to distinguish between the two is to understand the purpose served by them.
An argument is a rationale in which the reason functions as evidence in support of the conclusion. Its purpose is to provide a rational basis for believing the conclusion to be true. An example of an argument is-
Premise 1 — All men are mortal.
Premise 2 — Harry is a man.
Conclusion — Therefore, Harry is mortal.
An explanation is a rationale in which the conclusion represents an accepted fact and the reason represents the cause of that fact. Its purpose is to help us understand how or why that fact occurs. An example of an explanation is-
The sky appears blue from the earth’s surface because light rays from the sun are scattered by particles in the atmosphere.
Summing up, arguments answer the question — ‘How do you know?’ ,whereas explanations answer the question — ‘Why is that so?’
Types of Argument
All arguments have one thing in common. They make a claim that their premises provide grounds for the truth of their conclusion. That claim is the mark of an argument. There are, however, two distinct ways of doing so. And so, there are two great classes of arguments — deductive and inductive.
A deductive argument makes the claim that its conclusion is supported by its premises conclusively.
Given below is an example of a deductive argument.
Premise 1 — All noble gases are stable.
Premise 2 — Helium is a noble gas.
Conclusion — Helium is stable.
In easier words, deduction involves going from the general to the particular.
An inductive argument, in contrast, does not make such a claim. Given below is an example of a deductive argument.
Premise 1 — Most people like chocolate.
Premise 2 — Harry is a person.
Conclusion — Therefore, Harry probably likes chocolate.
In easier words, induction involves going from the particular to the general.
Because every argument either makes this claim of conclusiveness (explicitly) or it doesn’t, it is either deductive or inductive. Thus, our basis for characterizing the two different types of arguments is as follows: In a deductive argument, the conclusion is claimed to follow from its premise with absolute necessity — not being a matter of degree and not depending on whatever else may be the case. Whereas in an inductive argument, the conclusion is claimed to follow from its premises only with probability, this probability being a matter of degree and dependent on other probable causes.
In other words, the distinction rests on the nature of the claims made by the two types of arguments about the relations between their premises and conclusion.
Validity and Truth
Validity can be defined as a characteristic of any deductive argument, whose premises, if they were all true, would provide conclusive grounds for the truth of its conclusion. Then the argument can be called ‘valid’.
The concept of validity and invalidity does not apply to inductive arguments.
There is a profound difference between validity and truth. Validity is a formal characteristic; it applies only to (deductive) arguments, as opposed to truth, which applies to propositions. So, a deductive argument is valid when it successfully connects, with logical necessity, the conclusion to its premises.
It should be noted that validity can never apply to any single proposition because the needed relation cannot be established until the other propositions are present. An example of a valid argument is-
Premise 1 — All wines are beverages.
Premise 2 — Chardonnay is a wine.
Conclusion — Therefore, chardonnay is a beverage.
An example of an invalid argument is-
Premise 1 — All wines are beverages.
Premise 2 — Ginger ale is a beverage.
Conclusion — Therefore, ginger ale is a wine.
Whereas, truth and falsehood are attributes of individual propositions. Also, there can be many possible combinations of true and false premises and conclusions in both valid and invalid arguments. A single statement that acts as a premise in an argument may be true, and its conclusion may be false. An argument may be valid even when its conclusion and one or more of its premises are false. Thus, the validity of an argument depends only on the relationship between its premise and its conclusion.
This difference between validity and truth needs to be highlighted — truth and falsity are attributes of single propositions whereas validity and invalidity are attributes of arguments.
Why Logicians Are Chiefly Concerned With Deductive Arguments
Logicians mainly concern themselves with deductive arguments because the chances of certainty are high in deductive logic (100% if all the premises and the conclusion are true, and the argument is valid).
Inductive Arguments, on the other hand, involve probabilistic reasoning.
Deductive arguments are either absolutely correct or out-rightly wrong, whereas inductive arguments are only stronger or weaker.
In simpler words, the inferential claim of deductive arguments is stronger.
This does not, however, dismiss the importance of inductive reasoning. In fact, inductive reasoning is a pre-requisite for progress in science, among other fields. Even though it fares low on certainty as compared to deduction, it makes a large variety of arguments possible, because deductive arguments with universal truths are hard to come by (in contrast to induction).
Conclusion
Good reasoning is an art, as well as a science. It is a mental process that we perform as well as understand. Giving reasons for our benefits comes as second nature, but the real skill is in the art of building arguments and testing them, which requires practice. In this article, we have gone over the basics of arguments, their types, their nature. One who has understood and strengthened these concepts is more likely to reason correctly than one who has never thought about the principles involved.
