 Welcome to the video class formal logic, argument and argument form, truth and validity. Dear learners, in this topic we will discuss the basic concept of logic. They are nature of argument, kinds of argument, argument and argument form, truth and validity. Taste yourself, summary of the class and references. Dear learners, before we discuss the topic, we have to know at first what is logic. The word logic is derived from the Greek word loges. It means thought or reason or law. Logic is defined as the science of reasoning. This definition is not accepted as the real definition of logic because reasoning implies a structural kind of inferring or inference. In inference, we proceed from known to unknown, perceived to unforeseen. Now we can draw the conclusion that there is fire in the hill, which is derived from the premise that there is smoke in the hill. But the important issue is that logic does not include the act of inferring or inference within the subject matter of logic. Again, we can define logic as the study of the methods and principles used in distinguishing correct from incorrect arguments. This helps us to make a distinction between correct and incorrect argument. That is why it is clear that logic is a tool or strategy by which we can find out the distinction between good reasoning and bad reasoning. The study of logic, therefore, enhances our reasoning power to test the argument whether they are valid or invalid. It also helps us in our domestic discourse to argue systematically with others. Logicians deal with validity or correctness and invalidity or incorrectness of arguments. While psychologists concern with mental process, that is why the traditional definition of logic as the study of laws of thought is not satisfactory from the logician's point of view. The learners will discuss what is formal logic. Aristotleian logic is formal logic. Formal logic is concerned exclusively with the principles of deductive reasoning and it is concerned with the forms rather than with the content of propositions. Deductive logic is formal logic as opposed to inductive logic, which is a non-formal logic or material logic. Deductive logic is a formal logic as the term validity, which is applicable to any kind of deductive argument, implies only formal validity. As logic deals with the correctness or incorrectness of arguments, so question naturally comes to our mind what is argument and what are its kinds, the learners. Arguments consist of a group of propositions of which one is the conclusion and others are premises, which are regarded as providing support or grounds for the truth of the conclusion. Premises are those propositions from which conclusions are derived and conclusions are those propositions which are drawn from the premises. So, there is a necessary relationship between premises and conclusions. It will be clear when we go through examples. Dear learners, you take the example. All men are mortal. Socrates is a man. Therefore, Socrates is mortal. Here you see the first two propositions, all men are mortal and Socrates is a man. These are two premises and the last one that is Socrates is mortal, that is, conclusion is derived from the two propositions, all men are mortal and Socrates is a man. The learners, the last proposition is known as conclusion because it is drawn from the first two propositions. So, in an argument, there is a necessary relationship between premise and conclusion. If we do not notice a necessary relationship between premise and conclusion, the argument will be invalid. As for instance, we can take three examples. Dear learners, you see, all men are rational. Socrates is a man. Socrates is rational. Dear learners, you see, if rain comes, we will not go out. Rain comes, then we will not go out. The last one you see, dear learners, most actors are celebrities. Amin Khan is an actor. Therefore, Amin Khan is a celebrity. The first two examples show that the premises imply the conclusion and which is necessarily derived from the premises. And in the third one, one premise supports the conclusion. Learners, now we will discuss what are the kinds of arguments. According to traditional logicians, there are two kinds of argument. First one is deductive argument and the second one is inductive argument. And accordingly, logicians have classified logic into inductive logic and deductive logic. In deductive argument, the conclusion is necessarily derived from the premises. Generally, we proceed from general premise to a particular premise in case of deductive argument. So, the conclusion is less general than the premises. Dear learners, we can take example. All babies cry, Moon Moon is a baby. Therefore, Moon Moon cries. Here, the first proposition, all babies cry, is a major premise. And the second proposition, Moon Moon is a baby, is a minor premise. The last proposition, Moon Moon cries, is the conclusion which is derived from the above two premises. So, this is called deductive reasoning. The technical terms, phallid and invalid, are used in place of correct and incorrect, in characterizing deductive argument. Dear learners, now we will discuss what is inductive argument. Here, in case of inductive argument, we proceed from particular premise to general premise. So, in inductive argument, the conclusion is more general than the premise. Inductive arguments deal with inductive logic. In case of inductive argument, the conclusion is derived only with probability from its particular premises. The premises serve as evidence for the conclusion. Inductive arguments involve the claim that the premises provide some grounds for the truth of the conclusion. Now, dear learners, it will be more clear when we go through examples. Pinky is a baby and it cries. John is a baby and it cries. Paul is a baby and it cries. Therefore, all babies cry. Dear learners, now we will discuss the another basic concept of logic that is truth and phallidity. Truth and falsity, phallidity and invalidity are the fundamental notions of logic. A proposition is true when it corresponds to reality. As for instance, grass is green is a true proposition because we see that grass is green in reality. We know where she that grass is white. Again, another example, dear learners, you can take that is milk is white. We never can see that milk is green, milk is black. Therefore, this proposition is true. On the other hand, the proposition, all animals are immortal is a false proposition because we never perceive immortal animals. Truth and falsity are the attributes of propositions and validity and invalidity are the attributes of arguments. A valid argument can have true premises or false premises. If the conclusion in an argument is false, still the argument can valid because the premises may imply the conclusion. Again, in a valid argument, there can be false premises. Yet, the argument can be valid provided the conclusion follows from the premises. Dear learners, we can take some examples in order to show that a valid argument can have false premises and an invalid argument can have true premises. All dogs are cats, all cats are horses. Therefore, all dogs are horses. Dear learners, now you see this argument shows that the premises are false but the argument is valid. Next example, dear learners, you see all dogs are animals, all cats are animals. Therefore, all cats are dogs. Learners, now you see this argument is invalid although the premises are true. Now, the next example, dear learners, you see all human beings are rich, all businessmen are rich. Therefore, all businessmen are human beings. Dear learners, now you see this is an invalid argument because the premises in the argument are false. Dear learners, now you can take another example. All men are rational, no cats are rational. Therefore, no cats are men. Dear learners, now you see this is a valid argument because this argument shows that the premises and the conclusion are true. The above discussion holds that the truth and validity are the basic concepts of logic. Validity and invalidity of argument become independent of the truth and falsity of the premises. From the above mentioned examples, it is clear that a valid argument can have false premises. Similarly, an invalid argument can have true premises. Again, validity and invalidity of arguments are not concerned with whether the premises are empirically true or not. Dear learners, a noted logician, Erwin M. Kopi, he significantly states that to determine the truth or falsity of premises is the task of scientific inquiry in general. Since premises may deal with any subject matter at all, but determining the validity or invalidity of argument is the subject of deductive logic. Logicians, dear learners, are concerned with the question of validity and invalidity of arguments depending on the logical relation of the premises and conclusion. Dear learners, after going through the topic formal logic argument and argument form, truth and validity, you have to test yourself. Therefore, there are some questions are given to you. Question one, what are the two kinds of argument? What is deductive argument? What is inductive argument? Given an example of deductive argument, what is argument form? And the last one is given an example of argument form. Again, protest yourself, state whether the following arguments are true or false. Number one, deductive logic is also known as exact logic or formal logic. Number two, in deductive argument we proceed from general premise to particular premise. Number three, the technical terms valid and invalid are used in inductive logic. Number four, the correctness and incorrectness of argument is associated with the subject matter of reasoning. Dear learners, after going through these most basic concepts, we can summarize or we can highlight the points of this topic. These points are basically logic is derived from the Greek word loges. It means thought or reason or law. Logic is defined as the study of the methods and principles used in distinguishing correct from incorrect argument. There are three laws of thought respectively, law of identity, law of excluded middle and the law of non-contradiction. Argument consists of propositions. Conclusion is necessarily derived from the premises. Argument implies a relation between premise and conclusion. An argument form is a symbolic representation of proposition. Arguments are generally divided into two kinds, deductive and inductive argument. Truth and falsity are dealt with propositions and validity and invalidity are concerned with arguments. Dear learners, to know more about the topic, you can take help of references which are mentioned below. Thank you, dear learners.