What determines a good argument? To determine whether an argument is strong and valid there are two questions that need to be asked
- Is there enough logical support for the conclusion?
- Are the premises true?
Arguments have three important components in the form of Facts, Evidence, and conclusion. While determining the strength and validity of the arguments it is essential to understand that strength refers to deductive arguments and validity refers to inductive arguments. In this section, we will understand how can we evaluate whether the premises provide enough logical support for the conclusion.
Deductive Arguments and Validity
In a Deductively Valid argument, the premises are true and provide enough evidence to support the conclusion. In this sense, a deductively valid argument succeeds in establishing conclusive support for its conclusion.
A deductive argument is invalid if it fails in providing conclusive support for the conclusion. Such a deductive argument is considered to be weak.
To determine whether a given deductive argument is valid or invalid one can use the following method. While evaluating the argument ask the question “Do the premises provide enough logical support for the conclusion?” if it does then answer "yes" if it does not provide a valid argumentation, you can answer "no".
Let's look at an example:
Patricia is wearing a Yellow Scarf, therefore her scarf is coloured.
In the above example, when we evaluate whether the premises provide enough logical support the answer is yes. In the argument above it is stated that Patricia is wearing a yellow scarf, which means that she is wearing a coloured scarf. In this argument, the premises are true and thus, the conclusion cannot be false. In fact, it is highly improbable for the premise (Patricia is wearing a yellow scarf) to be true, and the conclusion (her scarf is coloured) to be false. Therefore, the argument is valid.
Ramsay is famous. Ramsay is a chef. Therefore, Ramsay is a famous chef.
While some might say this is true, the argument presented above is Invalid. This is because the probability of the argument stating the same Ramsay is highly unlikely. It is possible that Ramsay might be a famous football player who is a chef but not a famous chef. It is thus possible for the premise of the argument to be true, but the conclusion false.
Arguments can be valid even if they do not make much sense. Look at the following example.
All Peacocks are purple in colour.
Anything that is purple is an bird. So all peacocks are birds.
The above example may sound nonsensical but because the premises provide enough support for the conclusion to be deemed as true. However, there is a need to be cautious with the word 'valid' here because in this statement valid does not mean good or bad, it just determines that the premises succeeded in providing conclusive support for the conclusion. The premises in this sentence are false but the argument is valid because there is enough conclusive support.
The Strength of Non-Deductive Arguments
When evaluating non-deductive arguments we do not look at the validity of the argument but the strength of the argument.
In this sense, a strong non-deductive argument is the argument that provides a probable, but not conclusive, logical support for its conclusion. A non-deductive argument is considered weak if it fails to provide any probable support for its conclusion. Another point to remember in non-deductive arguments is that it may become stronger or weaker with the addition of a new premise. So let's understand how can we determine if the non-deductive argument is strong or weak. non-deductive arguments strength depends on the context which means that the strength can be determined depending on or relating to the circumstances that form the setting for the statement or argument. Let's look at some examples.
96% of Americans became vegan in 2020. Janice is an American. Therefore, she became vegan in 2020.
In the above argument, if the premises are true, what is the probability that Janice became a vegan in 2020? It is 96%! However, Janice might not be a vegan, in fact, she can be from the small percentage of people who did not switch to veganism. Though the possibility of this being true is quite low, therefore we can conclude that the premises are true and therefore the possibility of the conclusion being true is very likely -it can be false but in this case the argument is strong.
Most Chinese
people have dark hair. Angela is Chinese. Therefore, Angela has dark hair.
In the above case, the statement is a strong inductive argument because of the word 'most'. The argument is strong, but may not be valid if Angela is not a Chinese who has black hair. However, because the premise is true the conclusion is ‘most likely’ true as well.
