Introduction:
Logic is a Greek word, which means Discourse. When we try to understand the word Discourse it suggest that it is a communication of ideas, information etc. The study of logic began in ancient Greece. Whenever man debates, discuss, and argue logic remains in the background. Whenever a man debates a matter in his own mind a silent logic plays role. No man can think without logic. If he will try to break logic will break him. Logic has created deep and long lasting impression on language and culture. Logic is the air, which we breathe. It is a connected thought expressed in words. Discourse with one self is called meditation. From what others have said or from what we ourselves have thought conclusions and inferences are drawn. They are the special concern of logic. Logic trains the mind to draw right conclusion and to avoid wrong. It always deals with serious statement.


Words related to Logic:
1. Logic: Reasonable thinking.
2. Logical: Decision based on thinking.
3. Logically: Think reasonably that there must be this.
4. Logician: Skilled in Logic.

Definition: From Aristotle to Mill several definitions of Logic have been suggested. Each and every definition is unique. They are closely related to each other.

According to oxford dictionary: “Logic is a science of reasoning.”


Discussion of definition: On the basis of above-mentioned definition it is necessary for us to know the relation between science and reasoning. The word reasoning indicates: “The drawing of inferences or conclusions from known or assumed facts.” If we want to represent any of our concept it is necessary that it must be based on sound explanation of Philosophy and it must be verified by scientific experiments. Such Philosophical argument, which is supported by scientific experiments, is nothing but Logic. So we can say that Logic is a beautiful coordination of Science and Philosophy. Unless a person knows science and philosophy deeply he will not able to reason any thing. No doubt he will have that power of doing argument but it will not consider as logical.

Relation between Science and Philosophy: According to Funk and Wan galls dictionary science in the widest sense includes: exact knowledge of facts, exact knowledge of laws obtained by correlation of facts, exact knowledge of proximate causes.

Philosophy is the general principle, laws, or causes that furnished the rational explanation of anything. Science and Philosophy are not antagonist but they are complementary to each other. Philosophy is a hypothetical interpretation. Science arises in hypothesis and flows in to interpretation. Science is descriptive but it divides one thing in to many sub categories. Like organs, parts of body, diseases, etc. philosophy is the criticism of categories. Science describes philosophy while philosophy teaches us to accept science. Every science begins as philosophy and ends as an art. If we want to develop the art of reasoning we must develop the art of thinking, perceiving, and proper interpreting. Reasoning is the minds eye. If we want to develop the power of reasoning we make the habit of reading in between the lines. Reading enables us to explain the different phenomena critically. It is the intellectual faculty by which conclusions are drawn from premises by connected thoughts. It teaches us how one judgment arrives from other judgment. Any process of inference is based on reasoning. So logic is called science of inference. It provides us light in the dark way of searching truth.

History related to origin of Logic: The demand for logic aroused in ancient Greece from the Sophistic movement. Sophists were pioneers of higher education. As a result there were disputes so they required rules for regulating discussion. Logic supplied the rules. Aristotle was one of the greatest thinkers of all time and he wrote on logic which includes:

Prior analytic. [Formal aspect of Syllogistic reasoning.]

Posterior analytics. [Deeper problems of inference.]

Topic. [Technique of arguments.]


Aristotle was first to see the problems of logic as a whole. Logic is not a royal road. It will not teach you the entire things clearly. But it will help you to acquire and retain knowledge and to detect an argument. It will teach preciseness which is the first fruit of study of logic. When we proposed something to someone discourse begins. So proposition is unit of discourse and terms. This propositions leads towards inference. Connected propositions yield towards Syllogism. All these are base of Aristotelian logic.

In a proposition there are two terms. 1. Subject. 2. Predicate.

Example: Silence is golden.

[Subject] [Predicate]

Concept of various stalwarts related to logic:

1. Concept of Aristotle: Aristotle is considering as the founder of true logic because he systematically arranged different methodologies of logic and he is the father of both deductive and inductive logic. The most important logical work of Aristotle was organon. His method of logic was based on “Syllogism”. It is a Greek word. The meaning of this word is reasoning in general. To understand the basic concept of Aristotle’s logic it is necessary for us to understand certain basic principles.

a. Term: It is a word or a combination of words, which can stand by it self as the subject. This word was originated from a Latin word “Terminus” a limit or boundary. There is no order for terms in logic. For example in English we put subject first and predicate second. Example: Silence is golden. Here first word is subject and second is predicate. But this is not true according to Aristotle. Here order of term is not important but the meaning of proposition is important. About what are we speaking? That is the first question to ask. Answer to it gives the subject. The second question is what are we saying about subject? Answer is predicate. So in above example

1. What is golden? ----- Answer is Subject.

2. What is Silence? -----Answer is Predicate.

Types of Terms helpful to study Logic:

1. Abstract: Abstract means to take away or to omit. It is related to generalities or qualities and related to object, which cannot be seen and touched. Abstract terms are qualities or attributes of persons or things. The aim and use of abstraction is finding out what individual or group have common. Example irritability or anger etc.

2. Concrete: Concrete terms are persons or things, which are visible and tangible. Objects, which define shape, size, etc, are concrete things.

3. SingularTerms: Singular terms are individual. They are subjects of their propositions.
4. Common Terms: They are common to several persons or things. They are used by all so they are also called general terms. For example shoes, king, sheep etc.
5. Collective Terms: They apply groups of persons but not to individual. For example south Indian People.
6. Positive Terms: They are those, which suggest the presence of an attribute.
7. Negative Terms: They deny the presence of an attribute or suggest absence.

8. Probative Terms: They are those, which deny the presence of an attribute or suggest its absence where its presence was to be expected. For example Deaf, Dumb.
9. Infinite Terms: They are class of contradiction. For example this is not my pen. This indicates that as it is not mine it could be of any one.
10. Contradictory Terms: Opposite pairs of terms are contradictory when one is negative of the other it is called contradictory.
11. Denotation: This can be beautifully understood by example. What is house? We can paint any building and say that it is house. So here house denote all those buildings. This is nothing but denotation.
12. Connotation: Any one can say any building to house but no one precisely explains why it is house. It requires experts review. It is nothing but Connotation.
13. Intension: It is what you intend. Your term to mean. It is a statement of attribute.

b. Definition: To define something is a difficult task. To define a term is to state its limits. Connotation gives limits. So definition is the statement of connotation of the term. [Describe Precisely]. Rules for definition:

It must be adequate.
It must be precise and clear.
It must not contain a term equivalent to the term to be defined
It should not have negative attribute.

c. Description: It is a partial statement of the connotation of the term, sufficient to distinguish from other terms. It is an imperfect definition.

d. Division: It is a complementary process to definition. It is much like classification but in division. We start with whole and work down to parts. Where as in classification we usually start with parts and work up to the whole.

e. Propositions: They are important aspect of logic. Propositions propose something about something or something. Each proposition has two terms. 1.Subject and

2. Predicate. This can be beautifully understood by example. Do you like to be married with me? Here marriage is subject. Remaining whole sentence is Predicate. Here predicate is not isolated but it is joined with a word. This is known as “copula”.

Propositions come from the limitless human discourse. We can apply rules for logic at here. We select them from raw materials of sentences and prepare them for the process of logic. All propositions are sentences but all sentences are not propositions. It may be true or false. Prayer, wishes are not propositions. All propositions are not suitable for logical treatment. It they are unclear, deficient in subject, predicate form they are not helpful. There are mainly two criteria for converting propositions in to logical form.

a. Express the quantity of proposition.
b. Express the copula.
Example: All grass is green.

All--- Quantity. Is green---- Copula.
Propositions have either affirmative or negative quality. Quantity of proposition is same as that of its subject. There are four types of propositions.

Universal affirmative.
Universal negative.
Particular affirmative.
Particular negative.

1. Singular Propositions: They have singular term for subject. Example: Socrates taught Plato.
2. Enumerative Propositions: These are those propositions, which represent a limited number of class or members of a kind. Example: all red roses look beautiful.
3. Simple Proposition: It is a type of proposition, which is stated without condition.
4. Hypothetical Proposition: It states by supposition. Example: If rain falls I shall go out for wetting. It consists of two predictions: a. Supposition or hypothesis.

b. Consequences.

5. Modal propositions: Here the prediction is qualified by words such as may be, must be, possible, probable, necessary etc. For example: It may be possible that exam will be delayed.

f. Syllogism: Aristotle’s method of logic was based on “ Syllogism”. It is a Greek word. The meaning of this word is reasoning in general. It is a Greek word. The meaning of this word is reasoning in general. In Aristotle phase to syllogize is: “ To put two and two together” in regulated discourse and together from them something other. There are three parts of syllogism:

Data [premises].
Conclusion.
Consequence.

They all are related to each other. Here conclusion follows other two.
Example:
The good are happy. ----- Premises.
The unselfish are good. ----- Premises.
Therefore unselfish are happy. ----- Conclusion.

There are other ways of reasoning but man does syllogize. Structure of syllogism is neat. It helps the man to seek and find truth. It corrects fallacies, promotes precise treatment. If the conclusion follows from the premises it valid and as a result syllogism is also valid even though it may not true to fact. For example all fish are cold blooded. Whales are fish. Therefore whales are cold blooded. This is valid syllogism but false fact. There are certain criteria to make a syllogism.

1. Total six terms are there and each occurs twice.
2. The subject of conclusion must occur in premises.
3. The predicate of conclusion must occur in other premises.
4. Middle term occurs in both premises but not in conclusion.


Aristotle had a formula to express the principles of syllogistic reasoning. It is:

“What is predicted about any whole is predicted about any part of that whole.” Still there are disputes on it.

g. Categories. It is a Greek word. Categorizing is a process of entering in to minute analysis of any object. He made ten categories.

Substance.
2. Quantity.
3. Quality.

Relation.
Place.
Time.

7. Situation.
8. State.
9. Action.
10. Passion.

Such categories answer the question what is this predicate in itself? The word Predicate means what its subject is. The wood “is” has different aspect here. Dictionary meaning indicates [In relation to Logic] to assert (something) about the subject of a proposition. Another meaning of this word is: to affirm as a quality, attribute, or property of a person or thing. This can be beautifully understood by example.

1. The fish is small.
2. The fish is fresh.
3. The fish is in net.
4. The fish is taking food.

All these statements are about one subject but they differ in character. Here the fish is a thing, which has different characteristics. So in technical terms it is a substance. Here substance is the first and most important category. It means that which exist in it. All the other categories may be viewed, as ways in substance exist. According to Aristotle there is nothing that exist cannot be brought under one or another of the ten categories. We cannot go beyond them. Aristotle’s categories are opened for criticism. It helps us to classify predicates, to understand fundamental features of discourse.

h. Predicable: Under predicable predicates are to be considered. Aristotle recognized five heads of predicable.
1. Definition: Statement of essence of anything.
2. Genus: Part, which can be predicated also of other thing.
3. Differentia: Distinguish from other species.
4. Property: Proper attribute, peculiar to subject not a part of an essence.
5. Accident: Attribute may or may not belong to subject.

These five heads of predicable can be understood by example of a man. When we classify man under such headings:
1. Definition of a man: He is a rational animal.
2. Genus of man: Animal.
3. Differentia: Rational.
4. Properties: Laughter, Tears, and Speech.
5. Accidents: Cooking food, while traveling.

Genus, species, group, family all these words are used in daily practice for individuals. Genus and species have long history. There are certain differences between them. First is between natural class and artificial class. The natural class in more properly called Genus. It is there where we classify mankind or animal kind. Artificial class doesn’t mould the member of class. Animal is genus. Man is species. These two terms are so related with each other that the connotation of the one includes the connotation of others

I. Analogy: The dictionary meaning of this word is “Similarity”. It is an inference from a resemblance between particular things. It may help us to establish a link between Inductive logic and Deductive Logic. It is distinct from logical inference. It also helps us to enter in the process of Induction. There is uniformity in nature and natural laws. Objects are alike in some point. We also by analogy conclude that they are also alike in other points also. Therefore analogy enters in to process of Induction.
Example: when we lie down to rest on analogy we expect to wake up next morning refreshed and to find the sun arising.

j. Fallacies: It is but natural that every human being does mistakes. Mistakes, which occur in logic, are named and listed. They are called fallacies. It is nothing but the deceptive arguments. To be made aware of them, to know their names, it is a part of discipline of logic. Aristotle distinguished fallacies in speech from other fallacies. He made two corresponding lists. His way of treatment is open for criticism. But his work on fallacies was invaluable during his days.

Characteristics Of Fallacies:

1. To use the word, which has double meaning, is not advisable. For example the word “Old”, it may be old age or old people or old time or old thing. Here it is necessary that we must use it precisely. Here this syllogism is fallacious.

2. If there is improper compounding of words or object of thoughts it is called fallacies.

3. Chances of accidents are there in fallacies. For example: The dog was a father and it was yours therefore he was your father. This is called fallacies of accident.

4. From something we have to simply say something and we have to say according to something.

For example: Opium is a poison. Physician gives their patients opium. Therefore they give their patients poison.

5. Instead of attacking the statement we attack man who makes it. When some of those who hear the statement but does arguments not by all there are certain arguments accepted by a group of people and rejected by others. It only becomes fallacy. A person who accepts it knows that others may reject it but he consider as it is universally accepted.

6. Trying to answer all questions at once is called fallacy of single answer.

7. There are certain words where there is only a fine difference in the meaning of them so if we are not able to apply the proper meaning at proper place it called fallacy. For example: A king was told that if he will attack on Paris he would destroy a big empire. Here the word empire has two different meaning, which have only line of demarcation.

Thus Aristotle’s logic was based on Inductive syllogism. Here induction means leading. The main business of induction is to lead on from particular to general.

2. Concept of Lord Francis Bacon [1561-1626]:

a. His life: He was associated with royal family of England. He left the Cambridge school by saying that these studies are useless. In 1618 Lord Chancellor arrested for taking bribes but queen pardoned him but he had to abandon public life. He is considering as founder of modern inductive logic and said it is the only method of scientific discovery. He also introduced logical systematization of scientific procedures. His two important major writings are: 1. Advancement of learning. 2. Novum Organum.

b. His ideas:

1. Knowledge is power.
2. Scientific investigations are necessary for achieving mastery over nature.
3. He suggested the basic difference between Philosophy, Theory and Science.
4. He had also introduced the Doctrine of double truth. Which indicates accepting two truths at a time i.e. reason and revelation.
5. According to him syllogism of Aristotle is only helpful for rearranging acquired knowledge but useless for scientific discovery.
6. For scientific inquiry unprejudiced observation is necessary.
7. Before any scientific investigation first investigate oneself. The prejudiced can be corrected only at the individual level by correcting the subjectivity of the individual. Only by introspection and knowledge.

8. He also introduced the various sources of prejudiced. They are:
a. Idols of Tribe: It occurs due to teleological presupposition. [Human mind has imaginations, images and ideas of God].
b. Idols of Den or Cave: It occurs due to social and family influence and peculiarities of individuals, dispositions, likes modes of education, reading habits etc.
c. Idols of Market place: It occurs due to language association of words, Its meaning and interpersonal transactions. [The real feeling and meaning in mind vary often cannot be effectively expressed].
d. Idols of Theatre: It occurs due to false theories of science and philosophy.

c. His Concept: According to Bacon there are two ways of investigating and discovering the truth. 1. Inductive Logic. 2. Deductive Logic.

1. Inductive Logic:
a. Introduction: The Inductive method in science is the application of the principles of inductive logic to scientific research. Lord Bacon originated this method. He set forth in his Novum Organum. John Stuart mill in his great System of Logic further developed it. It has been the inspiration, the basis and the instrument of every modern science.

b. Dictionary Meaning: The word has originated from the word Induce that means to tell someone to do something or to cause something to happen. The word induction suggests:

1. Logical Reasoning.
2. The process of being initiated.

c. Definition: “Inductive method in logic is the scientific method that proceeds by Induction.”

“Induction is a process of drawing universal conclusion from Particular premise.”

d. History related to Inductive Logic: Before lord Bacon’s time logic was used principally as an instrument for argument and disputation. Little or no attention was given to facts. Direct and systemic investigation of nature was unknown or ignored. Opinions, speculations, and theories were used as the material for constructing more opinions and theories. The search for truth ended nowhere.

Lord bacon called upon men to cease speculating and go direct to nature in their for truth. He demolished innumerable false systems and restores logic to its true place as the guide to truth.

According to Bacon [mentioned in Novum organum Axiom 19]: “There are and can exist, but two ways of investigating and discovering the truth. The one hurries on rapidly from the senses and particulars to the most general axioms, and from them as principles and their supposed indisputable truth derives and discovers the intermediate axioms. This is the way now in use. The other constructs its axioms from the senses and particulars by ascending continually and gradually till it finally arrives at the most general axioms, which is the true but unattempted way.”

e. Requirements To understand the Inductive Logic: There are four basic requirements to understand the inductive method of Logic.

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