 to take a class of semester one and unit two argument and argument form truth and validity. In this unit argument and argument form truth and validity we have to discuss the basic concepts they are nature of argument, kinds of argument, argument and argument form truth and validity. Dear learners, before going into this class truth and validity argument and argument form you have to know also the concept a basic concept of logic that is what is logic. Now, dear learners you know the logic the very word logic is derived from the Greek word you see the Greek word logos L O G O S logos and it means thought or reason or law they are learners logic is defined as the science of reasoning this definition is not accepted as the real definition of logic because reasoning implies a special kind of inferring or inference. In inference they are learners we proceed from known to unknown again I repeat they are learners in inference we proceed from known to unknown known to unknown or you can say we can proceed from perceived to unperceived or you can say we can proceed from seen to unseen. Now, dear learners we can take a example that example is you see that there is smoke in the hill and that is the known case there is smoke in the hill or you can say it is perceived case or you can say it is seen case and from this perceived case we proceed to unknown case that is there is fire in the hill which is derived from the premise 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. Dear learners again we can define logic as the study of the methods and principles using distinguishing correct from incorrect arguments. So, you see this helps us to makes a distinction between correct and argument 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 arguments whether they are valid or invalid. It also helps us in our domestic discourse to argue systematically with others. Dear learners that logicians deal to it 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 logicians point of view. Now you see there are others as logic deals with correctness or incorrectness of argument. So, question necessarily comes what is argument and what are its kinds. Now dear learners you see argument consists of a group of propositions of which one is the conclusion and others are premises. You see argument consist of you see one is conclusion another is premises. Conclusion is derived from the premises. Dear learners you see again I repeat argument consist of a group of propositions of which one is the conclusion and others are the premises. Others are premises and you see of which one is the conclusion and others are premises which are regarded as providing support or grounds for the truth of the conclusion. Now you see their learners their premises provides support to the conclusion and you see premises are those propositions from which conclusions are derived and conclusions are those propositions which are drawn from the premises. So, you see their learners there is a necessary relationship between conclusion and premises. So, in an argument there is a necessary relationship between conclusion and premises. Now dear learners you see it will be clear to you when we go through the examples. Now dear learners you see the example all men are mortal all men are mortal. Then you can say another one Socrates is a man and therefore Socrates is mortal. Socrates is mortal. Now you see their learners this is an argument and here you see all men are mortal and Socrates is a man these are propositions or these are premises and the last one Socrates is a mortal this is conclusion this is conclusion because the premises all men are mortal Socrates is a man from which the conclusion is derived and that conclusion is Socrates is mortal in this example. Now dear learners you see so in an argument there is a necessary relationship between premise and conclusion. If we do not notice a necessary relationship between premises and conclusion then the argument will be invalid. Here you see their learners in this example in this argument or this argument is valid because the conclusion is necessarily derived from the premises like all men are mortal and Socrates is a man. So therefore dear learners these argument is a valid argument and dear learners you can take another example that is you can take all men are rational all men are rational and Socrates is a man therefore Socrates is rational this is the example of argument and another example you can take if rain comes if rains comes if rain comes we will not go out we will not go out and second one rain comes rain comes therefore we will not go out we will not go out this is also an example of a man so again you take another example that is A it is B and another example that is C you can take most actors are celebrities actors are celebrities and Amir Khan is an actor Amir Khan is an actor therefore Amir Khan is a celebrity now you see their learners these 3 examples A B and C the first 2 examples so that premises imply the conclusion the A and B this first 2 examples so that premises imply the conclusion and which is necessarily derived from the premises it means the conclusion the first one that Shibaji is rational and the second one we will know go out here the conclusion is necessarily derived from the 2 premises and the third one premises also supported the conclusion