Logical / Critical Reasoning

There can be two types of reasoning-inductive and Deductive. In the case of Inductive reasoning, we come from the premises to inference. Questions arises what is premise? And what is inference? Premises means those statements on the basis of which, we can derive an inference. These can also be called propositions which resemble sentences but all sentences can not be called propositions.

Propositions

There are only four types of propositions:

Categorical propositions

In this type of propositions predicate affirms or denies something about the subject e.g. A is B or No A is B. There is no condition in the case of categorical propositions.

For example

All cricketers are smart.

Hypothetical

Second type of proposition is called hypothetical proposition. It is a conditional sentence in which ‘if clause’ is in the present tense and the other clause is in the future tense.

For example

If it rains I will not come.

Disjunctive propositions

In these propositions in the first clause we make use of either and with the 2nd clause we make use of or.

For Example

Either he will get through or he will fail in the examination.

Relational proposition

Next type of Proposition is called relational proposition, Relational propositions establish some sort of relation between the subject and the predicate.

For example

Mr.Ahmed is greater than Mr. Naik.
Mr.X is the husband of Mrs.Y.

Term of the Thought

Propositions are made up of terms which mean a single word or a group of words that become subject or predicate of logical propositions.

Arguments

Corresponding to the four. Types of propositions, we have four types of arguments, categorical arguments, hypothetical arguments, disjunctive arguments and relational arguments. Different types of arguments are guided by different rules as far as the working out of the inference is concerned, so we will study these types of arguments one by one.

Categorical Arguments

Before we take up the rules concerning categorical arguments it is necessary to understand a few concepts related to categorical arguments.

Types of Categorical Proposition

There are four types of categorical propositions depending upon their quality and quantity. By quality we simply mean affirmative or negative and by quantity we mean universal or particular. Universal Affirmative proposition is called A proposition. In this case the subject is universal but the affirmative is affirmative.

For example

All Doctors are responsible people.

The Universal negative propositions are those subject is universal but negative.

For example

criminal is law abiding.

Particular Affirmative Propositions are those in which the subject refers to something less than all and the statement is affirmative.

For example

Some players are rich.

Particular negative are those propositions in which the subject is particular but the statement is negative.

For example

Some officers are not good.