Indian Institute of Technology Kanpur. NP-TEL National Programme On Technology Enhanced Learning. Course Title Introduction to Logic

Transcription

1 Indian Institute of Technology Kanpur NP-TEL National Programme On Technology Enhanced Learning Course Title Introduction to Logic Lecture-08 Identification of Formal and Informal Fallacies by Prof. A.V. Ravishankar Sarma Dept. of Humanities and Social Sciences Welcome back in the last few lectures we talked about some other basic concepts in which we started we recognized arguments and we could recognize arguments only when there are some premise indictors are conclusion indicators suppose if these premise an conclusion indicators are missing then we are look for some kind of factual claim if it is there it is well and good and then we said that for identifying or recognizing an argument what is most important is the inferential claim. So if you can find the inferential claim then can say that they seems to be some kind of argument present in a given English language passage and once we indentified the arguments then we identified that based on how the conclusion follows from the premises we identified that a particular kind of argument is dedicative argument in which conclusion necessarily follows from the premises and there is no new information in the conclusion which is not stated in the premises. And then it is not considered to be implicative etc and all and we identified some of the other arguments in which the conclusion only probably follows from the premises and all and there is always some kind of new information in the conclusion which is not there in the premises and all so these are what we call inductive arguments and then we also said something about no arguments such as you know somebody is giving just a piece advice or suggestion or is just giving some kind of explanation or expository passages etc.

2 They are non inferential passage hence if w treaded them as non arguments so then we talked about one example with which one method with which we could find out whether a given argument is invalid etc and all that method is called as counter example method so then we spoke about one particular model of argumentation which is due to Stephen Tooling and with which you could find out what constitutes what is what do we mean by an effective argument and all. So there is a model which we have presented and then there we have seen that there are at least few components of an argument or a lay out of an argument which are important that is data and a claim and data and claim are supported by some kind of warrants and warrant needs to be supported by further backed up statements and then suppose if we come up with any claim each claim needs to be having some kind of qualifier and then it will have every arguments would have some kind of a rebottle and all. So this is what we have done so far and then now what we will do is this that once we indentified that they are deductive and inductive arguments and then both deductive and inductive arguments can be fallacies so in this lecture we will be talking about what we mean by fallacy and what kind of fallacies that we commonly come across in day to day discourse are when the arums is said to be making some kind of mistakes in the argumentation after all fallacy is nothing but a mistake or error or defect in the argumentation and all so why the arguer does this mistakes and all because simply because of this that all these fallacies are some kind of persevering mechanism and all. So we all the time want others to accept our claims and all in the process sometimes we will be logical sometimes we may not be logical and make some mistakes etc and that is what we are going to study in this lecture and all so in this lecture I will be focusing on 2 kinds of 2 different kinds of fallacies so that is formal fallacies and informal fallacies and then I will talk little bit about formal fallacies first and then we will move on to informal fallacies. (Refer Slide Time: 04:09)

3 Arises because of some kind of problems relevance and then I will talk about fallacies of weak induction and effort from this things there are some kind of fallacies which arise out of ambiguity in the language because English language is wage because fort example a simple words such as a predicate like tall can be represented in so many different ways and also ram is tall for example if you say that thing and the next question that comes to us is how tall he is. This is the case that 6.8 is consider to be should be considered to be tall or 5.8 is to be considered to be tall or what will happen to those cases in which fall between 5.8 definitely you know we considered that they are definitely you know taller and all and those cases in which you know they fall between 5.8 and 6.2 etc. So English language is little bit wage and all so we might make some mistakes in the argumentation especially when we shift the meaning of the word such a that we use in the argumentation the we talk about some kind of fallacies which arises out grammatical errors etc and all so these kinds of fallacies come into the category of fallacies arising out of ambiguity of language. So then we will discuss about deducting and avoiding fallacies this is a program this is agenda for under this fallacies so in this lecture I will be focusing on formal fallacies and the informal fallacies especially the fallacies of relevance so before I continue and let us talk about what we mean by a fallacy. (Refer Slide Time: 06:00)

4 So it is used as synonym for any kind of position that is false or sometimes even deceptive are sometimes it is even applied to some kind of narrows sense to some kind faulty process of reasoning so we talked about different kinds of reasoning inductive and deductive reasoning etc so if both such kind of reasoning is defective then that is considered to be some kind of faulty process of reasoning and all. Or sometimes it and arguer might want to trick use some kind of tricks and all especially to persuasive the reader or listener or mostly these are some kind of specious persuasive and all so what is these all persuasive kind of mechanism and all so but logically speaking they are considered to be mistakes in the argumentation and all and hence they are called as fallacies so they might not be considered to be fallacy in the sense of a in a cytological sense etc and all. All these fallacies might be of some importance there but as far as logic is concerned they are considered to be fallacies in all so one most note that there are many arguments which are very persuasive and all they are all not good arguments and all so how to distinguish good argument from a bad argument etc this is a question that we will be we have asked in the last few lectures a well as we will be asking this lecture even we will be asking this question even in these lectures as well. So mere persuasive mechanisms will not serve as a good or effective kind of argument so they might be some kind of errors are defects are mistakes in the argumentation some times argue or

5 deliberately makes it sometimes the arguer might make it out of inner ignores or sometimes you know you just want to persuade is reader or listener to accept his claims. And all so fallacies in a sense it is nothing but some kind of mistake in the argumentation and all. These mistakes might arise in many different ways that is what we are trying to look into in a greater detail and all. (Refer Slide Time: 08:16) So a fallacy is a defect in an argumentation other than merely false premises so just because an argument as false premise does not mean that it is a it is consider to be a fallacy and all they are many arguments which have false premises but it these kinds of arguments are valid and all for example if you say all space are circles are circles are parallelograms all squares are parallelograms and all. So the conclusion seems to be obviously okay for us but the premises are obviously false that does not mean that there is a mistake in that argumentation yet this argument is considered to be valid and all since we do not want these kinds of arguments and day to day discourse so we do not use these kinds of arguments we invoke another kind of property which we have seen in the last few lecture under basic concepts that is the concept of sound ness a sound argument is a deductive argument in which it is valid as well as it as true premise.

6 So fallacy is term the term which is used for fallacy is none equivator that means it does not follow premise is invalid kind of argument is another name for fallacy and all mostly it is used in context of formal kind of fallacies so there are 2 kinds of fallacies that we commonly come across so one particular kind of fallacy is little bit straight forward and all just by seeing the form itself we make out that there is mistake in the argumentation and all. So once you extra the form and all and if it is invalid form obviously it is an invalid argument and all and hence it is a fallacy invalid arguments are automatically constructed to be fallacious arguments, so what is a formal fallacy a forma fallacy is in. (Refer Slide Time: 10:09) Again a error in error are mistake in the reasoning that involves the express it use of an invalid form for example instead of aim plus BA and B follows that is a more despondence rule which we have seen earlier instead of that we use A + B and B and it leads to A then that is constructed to be mistake in the argumentation and mistake in the very way we use the forms now we have

7 not used in the valid you are not used in a correct sense, so let say it is called as a formal fallacy so formal fallacy can be. Identified just the seeing form itself if you find invalid form obviously it is fallacious argument and it is called as formal fallacy informal fallacies on the other hand are not that easy to identify, so they do not have 6 form etc and all so informal fallacies are errors in reasoning they do not involve the express it use of an invalid form in the day to day argumentation it is not easy to extract form all the time it is not easy to identify what exactly the argument is trying to argue are intent to claim etc. A claim is constructed the conclusion so those kinds of fallacies in which I mean you can make out that there is a mistake in argumentation only by seeing or analyzing the content of an argument they are called as informal fallacies for example there is lots of examples we have seen already in the last few lectures for example if you say this room of an atoms, atoms are invisible so the room is invisible you know suppose if you say that particular kind of thing unless until you have analyze the content. Of the argument that means the words that you are using in your argument there is no way in which you can identify mistake in the argumentation, so detecting an informal fallacy requires an examination of arguments content you know unless until you analyze the content of an argument it is no way in which you can identify the mistakes in the argumentation, so these kinds of fallacies are called as informal fallacies to be simple in simple towns formal fallacies can be identified. By somewhat some mistake in the form and informal fallacies can easily be identified by not easily but it can be identified by analyzing the content of the argument, so how did we will get into this particular kind of some kind of interest in this fallacies you know we are saying that all fallacies are persuasive kind of mechanisms in all at the same time we are saying that not all persuasive kind of arguments are good arguments are efficient are not effective kind of arguments. You know so what are the characteristics of a good argument are effective argument so we already said about this thing, so it has to be deductively valid, so well and good if you if it is deductively valid are at least it should be inductively strong in the case of inductive arguments

8 we can only talk about strength of the arguments so that is why it has to be strong and of course if it has true premises it is called as in the case of inductive arguments which is called as a quotient argument in the case of deductive argument. It is called as a sound argument a sound argument is a valid argument with true premises if that is the case of and it seems to be a good and effective kind of arguments are it has a validity and truth of the premises be evident as far as possible to the parties involved supposed two people argument with each other we know that some of the statements that in argue whereas used also happened to be factually true as, so that makes this arguments sound you know of course a validity does not require that the truth of the premises to be actually true and all. But if there is inferential claim that is well in good enough for set of the validity at all, so both parties that means. (Refer Slide Time: 14:23) So those who saver is engaged in argumentation should be able to find out that argument is valid as well it as true premises makes well and good, so that will constitute a good argument and the premises should be stated clearly using some kind of understandable language and making clear what the premises in the conclusions are etc and all these has to nicely let me say if the arguments has to be some kind of well crafted kind of argument you know, so if that is the case when if you know what premises.

9 Are what conclusions are when you will automatically know what seems to be supporting what etc and we need to avoid for a good argument in it in avoid circularity, ambiguity and sometimes we will be using lot of emotional language into the arguments and then basically our purpose is true to make the reader or listener accept our claims you know, so one is to ensured that there is a circularity in the argument one simple example could be for example somebody is arguing that I believe that a god exist is true you know. So suppose if you are asking why you believe that god exist is true you know so then we will say that this is what by this is then the next question that you will come across is what is a guarantee that wrote by this AC is true or what grown and Geetha says is true then you will argue that god is true if he talks of only truths and whatever he has written the bible is written Geta or Kuran or written by god only this god words only there obviously true etc then you again ask what is a guarantee. That these words are true I mean this is the statement that are there in the bible is true again you will say that god exist etc and all it leads to impacts some question at each and every stage you are and there it leads to some kind of circularity you know argumentation and all as far as possible we should ensure that there is no circularity in your arguments you know, hence it has to be relevant of the issue at hand and all, so for example if you say = 4 and then and move is made of green teas. And you will know 2 2 = 4 there is no relevance between movie is made up of green teas and = 4 and all although it looks like that from A and B you are deriving B but there is and make any sense to we do not make such kind of claims in logic in particular but although it is formally valid and it follows and all, but usually you know that is not constructed to be a good argument = 4 and moon is made of green teas and some movie made up of green from A and B, B follows so the next question that.

10 (Refer Slide Time: 17:21) Arises in our mind is that how this fallacies arises so people are often more interested in convincing rather than seeking the truth of the matter, so we might be in patient are we might be we want others to accept our claims in all so somehow we want to convince others you know we will forget about what whether the conclusion is true or conclusion it follows from the premises are is there any support of premises to the conclusion. All these things we will Sita said and then we will mix up these arguments with lot of emotions etc you know, so may be because of that this fallacies matter is are otherwise we often find in the argumentation these are the sound the arguments that you will often find it in the arguments of advertises in particular and advertising agencies wants customers to buy some particular kind of thing I mean people to buy some particular kind of item they will use some good solid advertisements. In all etc and all advocates use it in the codes politicians try to who is the customers who is the voters in particular so then they might use this fallacies as a persuasive mechanism are political funs its might use it in analyzing who is going to I mean political points might use it in some sense in a broad sense fallacies any argument that involves some kind of fault is reasoning as far as logic is concerned, so they might be they may follow physiological they might be physiological relevant in all.

11 But as far as a logic is concerned they are there all they construct mistakes in the argumentation so now let us going to the details of formal fallacies first and then we will move on to informal fallacies little bit later, so tools commonly. (Refer Slide Time: 19:21) These are the two commonly found kind of fallacies in the logic that is when these rules are used in proper way then it leads to formal kind of fallacies you know, so these fallacies are like this first one is. (Refer Slide Time: 19:40)

12 A B then B then it leads to A then there is a mistake in the argumentation that I will talk little bit later and the other one which you will commonly find is A B and not A and B so this is called as fallacy of affirming the consequent, we will talk about some example related to both these things. So these are called as formal fallacies, and this is called as fallacy which arises because of denial of consequent. So these are all invalid forms obviously they are invalid arguments, so we said that all invalid arguments are automatically fallacies and all. So now why where is what is the valid form of this one this is one which we should gives in a implies b is the case this is an hypothetical situation. And then if a is indeed true then we can inferred that b follows from these two things, and the other the correct usage of this one is this a implies b and denial the consequent and then you need to denial the antecedent one. So first of all, so this is called as antecedent, so this is the conditional statement and a is called as antecedent and b is called as a consequent. And then that makes this a implies b some kind of hypothetical statement and all. If it rains the grass is wet, so if this is assume to be true and then b is also assume to be true then we need to see whether a is true or false. So the correct forms are these two things but as you see here clearly instead of using this valid of form we are using invalid forms and all invalid forms are automatically invalid arguments, so that is why they are all fallacies and all, it is pretty straight forward and simple to identify these kinds of fallacy.

13 So formal fallacy is usually grouped in to two kinds of fallacy, one is fallacy of affirming the consequent instead of affirming the antecedent you are affirming the consequent and all, of course you might say that in day to day argumentation we will this seems to be some kind of valid argument and all. There is a kind of reasoning which we did not discuss in this particular kind of course. So that kind of reasoning is called as abdicative reason, so in that what we will do is that this kind of principle a implies b and b and then from there it seems to be the case a follows from this particular kind of thing. So these kinds of reasoning is one which we are not going to talk about and abdicative inferences are also called as inference to the best explanations and all. So it is like for example deductive or doctors who are diagnosing some kind of disease they use this kind of reasoning and all in day to day discourse. So there of the view I mean of course a deductive is trying to find out whether or not murder to place etc in a certain place etc and all. So he might find he will just hypothetically state a particular kind of statement a implies b if murder to place then here will be some kind of blood, stains etc, so then deductive first he will find some kind of blood stains etc and all that will make him infer that there was some kind of murder to place in the particular kind of room and all. It seems to be little bit sensible in the actual day to day situations and all but this kind of reasoning is a kind of fallacies reasoning term as for as logic is concern, since it is not used in a valid form and all we can always come up with a counter example in which a implies b is true and b is true but a can be false and all. But in day to day discourse you might find some examples where this seems to be convincing for you. A deductive might use this particular kind of thing and all, he has an hypothetical situation a implies b and then b is indeed the case and all at least in all that evidence conforms that this is the case and then from this he will explain that probably a might be the best explanation for these two things to be true and all. So this is called as inference to the best explanation, so this one now what we are trying to use here and all abdicative reasoning is not the one which we are going to talk about. So but here so these are the two fallacies in which in our logically invalid forms and all, so that is why they are automatically invalid kind of arguments and all. But the correct forms of this one is

14 these things a implies b and a and b follows this is called as modus phone rule and this is called as modus Toller. So these are somewhat letting names and all, but usually it is represented as mt and mp. Modus phones and modus tureens, so these are the correct forms these are the incorrect forms that whether they are invalid argument are automatically fallacies and all. So now we can come up with lots of examples for these particular kind of arguments that are there on the top of this thing. (Refer Slide Time: 26:11) So one example could be if 2,523 is divisible by 9 then it has to be divisible by 3 and all, so that is seems to be little bit acceptable to us and all, anything divided by 9 it should be divided by 3 also. And then you are saying that 2523 is divisible by 3 so it also happen that 2523 is divisible by 3. So then it is also divisible by 9 and all it may not be the case that it may not be divisible by 9 and all this is better example which you can take in to consideration. So this is like fallacy of affirming the consequent of consequent and all, so this comes under the category 2 sorry first one. So you are affirming the consequent and then you are affirming the antecedent and all here, the best example could be like this suppose if you are in Kanpur then you are in Uttar Pradesh because Kanpur is in Uttar Pradesh only. You have be in Uttar Pradesh only.

15 So if I am in Uttar Pradesh so that is also consider to be the case then it follows that you are in Kanpur and all, you might be in any part of Uttar Pradesh and all but does not mean that you are in Kanpur and all. The first one I am in Kanpur is represented as a I am in Uttar Pradesh is represented as b and then I am in Uttar Pradesh is represented as b uniformly we represented with the help of some symbols then I am in Kanpur is the one which follows from these two one is the hypothetical statement and the other one is I mean the statement that I am in Uttar Pradesh. You might be in Uttar Pradesh but you might be in Agra or you might be in some other part of the city maybe some other place and all, Bareilly or some other place and all but you need not have to be in Kanpur and all, so that is the single counter example which shows that argument does not follow and all. So all the fallacies arguments are obviously all invalid arguments are automatically fallacies. They are formal fallacies and all, so other examples could be the same example can be represent in different way if I am in Kanpur then I am in Uttar Pradesh, so I am not in Kanpur then you are not in Uttar Pradesh and all, so that is the one which follows from this particular kind of thing or we can take another example to establish this thing that fallacy of denial of antecedent and fallacies of affirming the consequent leads to mistake in the argumentation. So they are all invalid arguments and all. If we get hit by a car when you are it six then you will die young obviously six anyone dies is die young only but you are not hit by the car when you six whether it is six then you will die young of six any one dies the young on the but you are not hit by the car when you are six this is does not mean that when you not die young or it may be by the next year or may be next incidentally mind die or nor so you could be hit by the trucker the age of seven or may be some other thing might happen might die out of this disease some incurable diseases something like that. So what is important here is this is that invalid form that means invalid arguments any invalid arguments are automatically fallacies so when a agreement is invalid this solvers if the case that you are always come off with premises through and a conclusion false error so it is possible that you know you can come off with premises true and convergence forms that makes this argument invalid.

16 For example to say grass wet if the drains the grass is wet so then you are saying that grass is wet so this because when the grass is wet does not mean that if it is rain and will this makes some mistakes in the arguments grass may wetting several other ways or may be somebody pour some water there etc. There is some leakages of water some tap some were etc all this things might be reasons for grass being wet so these are some of the formal there is some problems that the form usage of the form so that leads to mistaking argumentation pretty straight forward to identify all the things which I have mentioned it here or will come under the category of categorical which I am going to talk about little bit later categorical are special kind of arguments in which on the categorical propositions. And categorical propositions re just the propositions but they have a special feature that all this propositions being with all know some etc every all these things comes under categorical of categorical propositions for example if we say all may have motor some in have motor or when not motor some may not motor all these things are called as categorical propositions so now the once which have stated here all these things are invalid arguments because it has invalids form as I said in the counter example method whenever you have a invalid argument suppose if you start with some set which has all the things that you have out you obviously know that they are true or false etc and all. For example if we say all cats and dogs the statement is false anyone would be able to believe that the particular kind of things false all cats and animals since to be acceptable true statements so there are certain things which are obvious towards which we nobody could denial and all so those things which taken to consideration and then substituted for A, B. C etc and all. (Refer Slide Time: 32:10)

17 And C whether you could come whether you could come off with any counter since counter example and all counter example in the sense that you have true premises and false conclusion suppose if you say all A s are B s all C s are B s so all A s are C s so the actual valid form is all A s are B s all B s are C s and all A s are C s but here it is not used in the particular kind of form. (Refer Slide Time: 32:50) So that is why this is consider to be an invalid forms so that is why called as fallacies so what seems to be valid arguments are this thing all is this A s, B s can be a anything now for substitute for A and substitute for B and substitute for B donkey cat it is all B s are C s so then all A s are

18 C s so this is a kind of valid kind of arguments so valid form so that is why it is called as valid kind of argument. You might ask how do you know it is a valid argument etc so then the definition of validities is that the compression may silly flows from the premise that means you cannot come out of with counter example in which the premises are true and the conclusion is false whatever you substitute for A s B s etc and all B C s etc. Then if these two are assumed to be true the second one the whatever follows from these two things we also be true so the detective arguments the true has been conclusion necessary follows in the premises so the one which we have used here are all A s are B s it is like a all A s are B s somewhat like all C s are B s so all that is a all A s are C s so if you compare these two things this is consider to be valid forms and this is not an invalid forms. Suppose if you are not convinced with this particular kind of thing that when I say that it is invalid form it is invalid arguments this is valid form and this is valid arguments then the certain things which we are which we know that the obviously true obviously false etc so instead of in this one you substitute A for ct and B for animal or C for some kind of rat or something like that. Then you will see whether this follows so the example here is this that for A s we are taking the consideration dogs that is will dogs are animals this is obviously the case are the dog cannot be some other thing and all. (Refer Slide Time: 35:09)

19 So that is satisfying the first statement and all C s are B s here C s considered to be cats so all cats are animals so from that all A s are C s for example all A s mean as means dogs all dogs are cats suppose if you say that particular kind of thing although the premises the first two premises are true that is all dogs are animals all cats are also animals but yet all dogs are cats then that conclusion is false given the premises are true. That means it could easily come off with some kind of counter example for that particular the cou7nter example is this that you have come off with the true premises you can come off with the false conclusion all dogs re cats so it is all of us it will be easily it is easy to say that cats are dogs are obviously false so like this whenever you come across and invalid form so you can all this come off with the counter incidents where you have true premises and false conclusions that means that argument invalid. A invalid arguments are automatically fallacies by form itself because we used invalid forms so that is why this arguments are invalid so like this we can come across the valid form is that one this is the valid form and all we have used in different ways and will so that is why it is invalid forms that is why it is invalid forms all A s are B s no C s A and no C s are B and all so whether this particular kind of argument is valid or invalid. And again you know the certain things which are quite obvious to us the substitute A for cat and B for animal and C for dog and then see what happens here so all A s are B s instead of all every there are all same one another same so you say all every cat is an animal as could have saying the

20 same thing all cats are animals so this is the first proposition and the second on is no C s is A that means no dog is a cat. A dog can be different from the ct and all so that satisfies the second propositions in the in this thing and then form that no C s is B that means no dog is an animal so you could easily come off with the counter example where the premises every cat is an animal is true no cat no dog is cat is also true but the conclusion no dog is an animal is false so like this whenever you have an invalid arguments I do not want to go in details of other arguments and all. There are invalid forms and all invalid arguments and this is the invalid arguments whenever you come across an invalid argument you can substitute these instances etc instead of A s B s and C s you substitute dogs, cats, animal etc without disturbing the truth value of the propositions and see whether you can come across with a counter example. I mean you can come across a false conclusion, true premises should not lead to false conclusion and all. A valid detective argument is one in which it is impossible for the premises to be true and the conclusion is false, even if you come up with a single instance where your premises are true and the conclusion is false then that particular kind of argument is invalid. So far we have seen that the arguments are invalid just because of the fact that there is having invalid forms and all. Life is not that simple and all, so we need to analysis the content of the argument to see whether there is any mistake in the argumentation ands all. So these kinds of fallacies are called as fallacies of relevance, sorry informal fallacies and one particular kind of fallacies which arises very frequently in day to day disclose, especially when to argue or engage in some kind of debate or when a arguer present some kind of thing to convince the reader or listener you will find these kinds of fallacies which arises out of the problem of relevance and all. I will talk about what you mean by relevance etc little bit later but so this fallacies of relevance arises involves the uses of premises that are logically. (Refer Slide Time: 39:42)

21 Irrelevant to their conclusion for an argument the basic structure is that your premise and then premise should provide some kind of adequate support to believe that your conclusion to be true and all but it does not provide any adequate reasons to believe that the conclusion to be true then there seems to be some kind of problem. Here the problem arises because the premises are not logically relevant to their conclusions and all. There are some other relevant factors which comes into picture and all, so these relevant factors maybe physiologically relevant factors and all it might by pretty, it might be anger, it might be frustration all these things are psychologically relevant factors and all, sometimes we do take into the consideration all these factors and sometime the argument may be a good argument as well. Sometimes we invoke some kind of patriotism and then it will infer some kind of thing but the argument maybe convincing for all us. So here the most important feature that you need to look for is that are they logically relevant or psychologically relevant and all. I am not saying that psychological reasons are not important or useless etc and all, as far as logical reasoning is concerned as far as a good arguments should be free from all these psychologically relevant factors and all. But in the day to day intercourse we do take into the consideration these particular kinds of factors etc, psychologically reasons and all. So here is the list of fallacy which comes under the category of fallacy of relevance you should note that you know there is no way in which you can classify this fallacy into a 1 group or another group and all different text books have different classification and all, so that the book

22 we are following is concerned into logic early. It seems that you know these things are classified into very nice way and all in this book. So we are referring to that particular book in which things are classified in a very nice way, so we believe that this is a very good kind of classification and all. So we follow this particular kind of thing, so what are fallacies of relevance there are different names and all and mostly these kinds of fallacies are already there right from antiquity and all that means right from Greeks onwards you will find. You might have come across from Greek period onwards these fallacies exist and it is existing even now also, so the 1st one is apply to force this is also called as argumentum ad Baculum they are Latin names and the 2nd one is instead of argues is argument you will attack him in person and all. So Adhominem argument when you invoke pity it leads to appeal to pity kind of fallacy, the other kind of fallacy which will commonly come across is appeal to people. And fallacy of accident, missing the point, Straw man Fallacy and Redherring Fallacy and all. In all these fallacies what is the problem is that the premises are not logically relevant to the conclusion but premises may be psychologically relevant to the conclusions and all. So let us look into each one these fallacies in some detail. The 1st one is a simple kind of fallacy which is called as appeal to force. (Refer Slide Time: 43:21)

23 Appeal to force or it is called as ad Baculum fallacy which occurs when a conclusion is defended by some kind of threat to the well being of those who do not accept it, so this threat can be sometimes explicit or sometimes it can be even implicit and all. So this argument has this particular kind of structure so you can draw the diagram for this particular kind of fallacy then you will come to know who seems to be committed this particular kind of fallacy. (Refer Slide Time: 44:04) So now here is an arguer he is presenting some kind of argument, so this is what called as appeal to force, so what is this? Here is your reader or listener R stands for reader or sometimes it can be listener also. That means you are reading a text or you are listening to some one argument and all. So now these arrows are important, so A threatens readers are listener and he poses this particular kind of conclusion. So A threatens readers are listener and he poses this particular kind of conclusion ultimately his purposes is that we wants the reader or the listener to accept is claims and all, so in process we might do it any several ways to pursue the reader or listener to accept this claims and all. So one way which he does in this case is that, he threatens the reader or the listener if he do not accept whatever he says to be true and all then he will say that there are some kind of consequence which follows and all.

24 So this particular kind of thing is called as appeal to force kind of fallacy and all, so basically this threatening can be some kind of physical threat you will directly say that I am going to beat you or something like that or he might say that pose some kind of mental threat and all, he will invoke some kind of fear in you, he might say that he will leak your information etc. So these kind of thing is called as appeal to force and all, here what you will see here is that the premises may not be relevant to the conclusion and all. So since he was incorporated threaten into picture and all, so they all may be psychological factors etc and all sometimes you might use it for the well being of reader or the listener or a person whom the arguer is trying to pursuer but not in all the cases it might be used for the well being of a reader or the listener and all. So the structure of these arguments is that of course it is premises and conclusions, premises could be this you can avoid harm by accepting this particular kind of statement and all, so that is why this statement is true. So what he says is that he threatens the reader or listener why threatens the reader or listener? He says that you are going to avoid some kind of harm etc and all, if you do not do this thing you will face music and all, so you have to attract some kind of fine or it might be or you will be punished etc and all so this is the one which we commonly come cross day to day disclosure so where what the arguer is trying to do is that you can avoid harm by accepting this particular kind of statement. So what is the statement that you want his reader and listener to accept and all that is a conclusion it is bothering some kind of conclusion if we do not accept the conclusion then he says that there is some harm is going to happen particular kind of person so out of fear. The reader or listener might accept is claimed but here the premises are nothing to do with a conclusion so threat is what is making him to believe the conclusion so some examples which take into consideration and then it is we will understand this kind of in threaten. (Refer Slide Time: 47:58)

25 Now here the arguer is telling the reader or listener and then ultimately what intensi0on of the arguer is that reader or the listener accept whatever the conclusion that is making just to accept this particular kind of statement which is there is conclusion so now who is said to committed mistake in the argumentation A is said to be committed fallacy. If someone presents this particular kind of argument and all then we should be immediately in the position to say that since A has used as threading and all kinds of things and all there should be relevant to believing this particular kind of statement so some examples is where we will see later in detail so this is scenes. (Refer Slide Time: 48:49)

26 Thinks about organized crime etc children arguing with parents or children arguing with each other and not with the parents one example is like this Mr. salaam you helped us import the drugs somebody is arguing like this somebody is threading salaam for this the boss is obviously grateful and all. But now say your entered into 45 percent of the profits so now started claiming in shade and all now boss is very angry on this particular kind of thing the boss says that you are entered through 10 percent you are then excess given although you helped us in importing some legal drags etc and all okay that is fine well. And good and all but now you are asking you deserve only 10 percent but you are asking 45 percent so boss is very angry etc thi9s is what you seeing in the organized drain and all so the next statement is unless you see things boss that means if you do not listen to what the boss is trying to say be happy with 10 percent of shade etc. So than is what is unless you see things and boss way you are going to have very nasty kind of accident boss might give you or he might do something or other some kind of harm is going to happen in the middle if some kind of broker kind of person is trying to convince the reader or the listener. Let you know if you accept you know what ever boss says he is happy with 10 percent now threat is going to happen to him otherwise he is going to face some kind of nasty accident he will

27 come across some kind of nasty accident so you have entered into10 percent only so ultimately he saying got my point or not do not get a point you are going to be punished and all. So what is happening here is that there is some kind of argue or here sir salaam here is the reader here the arguer is someone argue is the favor boss the boss don or something so who is committed in this mistake the arguer who is arguing for the boss who is arguing that it is a only 10 percent etc so he seems to be committing this particular kind of comparison why he as committed. Because all these things are not relevant for this particular kind of thing that whatever is claiming that is 45 percent profits etc and all so instead of here all the relevant things are like this and it is a broker who is arguing in favor of the arguer so trying to threaten the threaten salaam so he is saying that in order to you will accept a boss whatever boss is saying then you are going to invite some kind of problems. So here the first one is that threaten nasty accident has no logical relevance on the conclusion that the salaam is entitled to 120 percent there is nothing to do wi9th this particular you know the physiological your relevant tools but bet this is used as some kind of processing mechanism if you are this can still be used as some kind of postulates mechanisms the broker who is arguing for some kind of boss and all that he is ultimately he is trying to negotiate with salaam that he is written person rather than 45 percent if he claims 45 percent. Then broker is saying that you know you will say some kind of problems etc he is trying to negotiate or postulate that reader or listener by invoking some kind of threat so suppose in this case the arguer is said to be committed this particular kind of this particular kind of fallacy is called as appeal the force kind of fallacy so the postulates is this that we can avoid harm by accepting this statement is reserved 10 percent so this statements are based on thread. (Refer Slide Time: 53:06)

28 So it says statement is true then this tends to some mistake in the argument so this is what happens here premises see is that we can avoid harm by accepting this statement the conclusion is that hence that statement is proven the premises are relevant to the conclusion and hence leads to fallacy relevance and this fallacy of relevance further classified into fallacy of relevance which arises due to appeal to the force. (Refer Slide Time: 53:31)

29 Sometimes this thread arguer threads the reader or listener and posses a conclusion this particular kind of thread can be even enclosure the mental kind of thread so this is what you commonly see in organization in particular where secretary is arguing with this boss so he is saying his particular kind of thing I deserve promotion increments etc all that time you know worried about his increments etc. And all he have got some how he is claiming with his powers that should be promoted this particular theorem so he says till here it is find all but claim is based on some other irrelevant factors is goes on and says that after all he know how friendly I am with your wife and sure you do not want her to find out what kind of affair has been going between you and that of us somehow you have to develop some kind of religious with his wife. And that she does not know boss is wife does not know treating the boss you know if you do not revolt me all I am going to expose everything to you wife you know so I know you are being lying to your wife about what your what is way about where you go on and Wednesday afternoon etc all these things are irrelevant for promotion unless you want her to know where you really go it is time for you to realize. That you have no choice than raising my salary or you promote me or else you are going to leak all the information so this is some kind of psyclogical threat that secretary is trying to some kind of black milling he is trying to do so here in this case secretary is seem to a committed fallacy the mistake is argumentation.

30 Because all this factors there the boss is having relation with someone else extra all these things there is nothing to this promotion, promotion what is relevant may be achieved something some other things might play a curial role in the promotion etc so the thread to expose the lie no way constitutes evidence for any one s promotion there is nothing to this particular kind of thing so this is the problem of relevance and then we continue with other kinds of fallacies in the next lecture. Acknowledgement Ministry of Human Resource & Development Prof. Phalguni Gupta Co-ordinator, NPTEL IIT Kanpur Prof. Satyaki Roy Co Co-ordinator, NPTEL IIT Kanpur Camera Ram Chandra Dilip Tripathi Padam Shukla Manoj Shrivastava Sanjay Mishra Editing Ashish Singh Badal Pradhan Tapobrata Das Shubham Rawat Shikha Gupta Pradeep Kumar K. K Mishra Jai Singh Sweety Kanaujia Aradhana Singh Sweta Preeti Sachan Ashutosh Gairola Dilip Katiyar Ashutosh Kumar Light & Sound Sharwan Hari Ram

31 Production Crew Bhadra Rao Puneet Kumar Bajpai Priyanka Singh Office Lalty Dutta Ajay Kanaujia Shivendra Kumar Tiwari Saurabh Shukla Direction Sanjay Pal Production Manager Bharat Lal an IIT Kanpur reserved