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*Logic*is the science of necessary inference.*Reason*is the power and function of grasping necessary inference.*Argument*is a connected series of statements or reasons intended to establish a position.*Syllogism*is an argument of two premises and a conclusion with the predicate of the conclusion in one of the premises and the subject of the conclusion in the other premise, and a third term in the two premises.

The Logic Classroom site sets forth a basic course in traditional logic for students seeking to learn logic or improve their logic skills. The course divides along six brief studies described below. Each study ends with review questions and exercises.

The First Study describes the four standard propositional forms, their properties, and methods for translating nonstandard into standard forms of Traditional Logic. The Second Study investigates the properties of a number of Immediate Inferences. The Third Study outlines the characteristics of valid and invalid categorical syllogisms. The Fourth Study introduces the student to a number of additional valid argument forms and two basic formal fallacies associated with two of the valid argument forms. A discussion of truth table analyses of propositions and arguments is the content of the Fifth Study. The Sixth Study examines briefly the subject of informal fallacies and definitions.

For Downloads (Word & PDF) of all study exercises and answers go to the Answers Tab under Preview Tab or click HERE. For all posts of reviews of a variety of logic resources see BLOGICS .

A glossary of terms is indexed to the appropriate Study or Studies.

A Logic Quiz of 25 Items on basic logic can be accessed by clicking on the link below, but first it may be useful here to answer briefly: What is logic and why study it?

The First Study describes the four standard propositional forms, their properties, and methods for translating nonstandard into standard forms of Traditional Logic. The Second Study investigates the properties of a number of Immediate Inferences. The Third Study outlines the characteristics of valid and invalid categorical syllogisms. The Fourth Study introduces the student to a number of additional valid argument forms and two basic formal fallacies associated with two of the valid argument forms. A discussion of truth table analyses of propositions and arguments is the content of the Fifth Study. The Sixth Study examines briefly the subject of informal fallacies and definitions.

For Downloads (Word & PDF) of all study exercises and answers go to the Answers Tab under Preview Tab or click HERE. For all posts of reviews of a variety of logic resources see BLOGICS .

A glossary of terms is indexed to the appropriate Study or Studies.

A Logic Quiz of 25 Items on basic logic can be accessed by clicking on the link below, but first it may be useful here to answer briefly: What is logic and why study it?

Logic is the science of necessary inference. An inference is the forming of a conclusion from premises by logical methods.

A proposition is a form of words in which the predicate is affirmed or denied of the subject of a declarative sentence. A proposition is the meaning of a declarative sentence. Declarative sentences are either true or false. Propositions are the premises and conclusions of arguments. Other sentences, in expressing commands, posing questions, or conveying exhortations are neither true nor false. Some questions, rhetorical questions, are intended as propositions; but if a question is not rhetorical, then it is neither true nor false.

Arguments divide into two classes: deductive and inductive. The premises of inductive arguments provide incomplete or partial reasons in support of the conclusion. The premises of deductive arguments provide conclusive reasons for the conclusion. The conclusion of an inductive argument is said to be either probable or improbable. With deductive argument the conclusion either follows necessarily or it does not. If the conclusion of a deductive argument is a necessary consequence of the premises, then the argument is valid; otherwise, invalid. Given a valid deductive argument, if all of its propositions are true, the argument is

The study of logic is essential to correct thinking. The rules for correct thinking and methods for avoiding mistakes in reasoning belong to the subject of logic. Logic trains the mind to distinguish logical from emotional appeals, the latter often the only basis offered in support of a conclusion or a position in the absence of rational support. One source of faulty reasoning is to confuse emotional appeals with logical appeals. It is a fallacy to accept an emotional-inference as a necessary-inference. Logic is the irreplaceable means for correct thinking and avoiding fallacious reasoning.

The structure created minds is the same as his Creator’s. God is not insane; He is a rational being; the structure of God’s mind is logic. For these reasons, we say not only that logic is irreplaceable and universal, but logic is necessary and fixed. It is not one scheme of things among others. It is not something optional, for the mind was formed on the three laws of logic: principles of identity, excluded middle, and contradiction

These three laws of thought are universal, irrefutable, and true. Without these laws, it is impossible to imagine how anything written or spoken could be intelligible. These laws are the basis of necessary inference, for without them, necessary inference vanishes! By

Here is a brief statement of each.

*Necessary*in necessary inference or necessary consequence means there is no way to avoid the conclusion of an argument. An argument consists of one or more propositions in support of another proposition. The propositions in support of the other proposition are called premises; the proposition supported by the premises is called the conclusion.A proposition is a form of words in which the predicate is affirmed or denied of the subject of a declarative sentence. A proposition is the meaning of a declarative sentence. Declarative sentences are either true or false. Propositions are the premises and conclusions of arguments. Other sentences, in expressing commands, posing questions, or conveying exhortations are neither true nor false. Some questions, rhetorical questions, are intended as propositions; but if a question is not rhetorical, then it is neither true nor false.

Arguments divide into two classes: deductive and inductive. The premises of inductive arguments provide incomplete or partial reasons in support of the conclusion. The premises of deductive arguments provide conclusive reasons for the conclusion. The conclusion of an inductive argument is said to be either probable or improbable. With deductive argument the conclusion either follows necessarily or it does not. If the conclusion of a deductive argument is a necessary consequence of the premises, then the argument is valid; otherwise, invalid. Given a valid deductive argument, if all of its propositions are true, the argument is

*sound*; otherwise unsound.The study of logic is essential to correct thinking. The rules for correct thinking and methods for avoiding mistakes in reasoning belong to the subject of logic. Logic trains the mind to distinguish logical from emotional appeals, the latter often the only basis offered in support of a conclusion or a position in the absence of rational support. One source of faulty reasoning is to confuse emotional appeals with logical appeals. It is a fallacy to accept an emotional-inference as a necessary-inference. Logic is the irreplaceable means for correct thinking and avoiding fallacious reasoning.

The structure created minds is the same as his Creator’s. God is not insane; He is a rational being; the structure of God’s mind is logic. For these reasons, we say not only that logic is irreplaceable and universal, but logic is necessary and fixed. It is not one scheme of things among others. It is not something optional, for the mind was formed on the three laws of logic: principles of identity, excluded middle, and contradiction

These three laws of thought are universal, irrefutable, and true. Without these laws, it is impossible to imagine how anything written or spoken could be intelligible. These laws are the basis of necessary inference, for without them, necessary inference vanishes! By

*universal*, we mean allows for no exception.*Irrefutable*means that any attempt to refute them, makes use of them; thus, establishing them as necessary for argument.*True*means not only “not-false,” but not-false because they are grounded in the*Logos*of God, the source and determiner of all truth. Together, these laws establish and clarify the meaning of necessary inference for logic and all intelligible discourse.Here is a brief statement of each.

- The law of identity states that if any statement is true, then it is true; or, every proposition implies itself: A implies A.
- The law of excluded middle states that everything must either be or not be; or, everything is A or not-A.
- The law of contradiction states that no statement can be both true and false; or, A and not-A is a contradiction and always false: thus, not both A and not-A.

**The Logic Quiz**: Each True or False Item is worth 4 points for a total of 100 points.

Click Button for Logic Quiz. For Downloads of Exercises 1-6, Answer Key, or other logic resources, go to Exercise Answers page.

"In conclusion, the student should remember, for the rest of his life, that if he is logical, he will never go wrong -- unless he starts with false premises. Logic will not guarantee the truth of the premises, but without logic no progress is possible." (Gordon H. Clark,Logic, The Trinity Foundation, 1985, p. 116.

*This site contains copyright materials. Permission is granted to print and distribute the Studies provided that each reprint bears the copyright notice, author's name, and source, and provided that all such reproductions are distributed to the public without charge. The Studies may not be sold or issued in book form, CD-ROM form, disk form, or microfiche. Copyright ©Elihu Carranza, 1999, Napa, CA (Answer Key Page contains Form with Contact Information.)*