OK, here we are at week six. The very last week of our course this week, we're going to have a bit of a romp.
We're going to start looking at phalluses. Fallacies are bad arguments that look like good arguments and can easily be confused for them.
OK, let's get started. Just a recap of last week, as always.
If you remember, we looked at what makes a deductive argument sound. And we looked at what makes such an argument valid.
So just a quick reminder for you. Would the argument be sound in this situation where it's valid but it has false premises?
Put your hands up if you think that sound. So it's a valid argument, but false premises.
OK. What about if it's an invalid argument with false premises?
OK. What, Walter, it's an invalid argument with true premises. And a valid argument with true premises.
Okay, good. Well done. It's only sound if it's a valid argument and it has two premises at it all, its premises must be true and it's valid.
Well done. OK. Now, here's the tricky one. OK.
The question is, could the argument be valid when it's got false premises and a false conclusion?
It could be valid. Well done. Could it be invalid? Well done, good.
Okay. What if it has false premises and a true conclusion? Could it be valid?
Put your hand up this time. Could it be valid if it has false premises and the true conclusion?
Could it be valid? OK.
Those few without your hands up. Is that because you don't know? Okay.
What about if it's got true promise isn't a true conclusion. Could it be valid then.
Okay. Could it be invalid then. Oh yes, it could be.
Okay. There is only one situation in which it couldn't be valid.
Only one situation which it couldn't be valid. And that's this one.
If it's got through premises and a false conclusion, it couldn't be valid.
Otherwise it could be it could be either valid or invalid. And the reason for that is because an argument is valid.
If and only if there's no possible situation in which all the premises are true and its conclusion false.
So it's a sufficient condition for an argument being valid that it there's no possible situation in which its premises are true, in conclusion, false.
And that's a necessary condition, too. And if you remember, I said to you last week that two things you've got to remember.
One is that it's the possibility, not the actuality of the combination of true premises and false conclusion.
That's important. And the other is it's the combination of true premises and false conclusion.
That's important. Okay, I gave you another test.
So if that was one test of validity and the other test I gave you is that an argument is valid.
If an only if it's counter example set is consistent and the example set is the sets consisting of the premises plus the negation of the conclusion.
So if you have if it's Friday, Marianne's wearing jeans.
It is Friday. Therefore, Marianne's wearing jeans. That's an argument.
An argument. If you take the conclusion Marianne's wearing jeans and negate it.
So you've got it's not the case that Marianne's wearing jeans. The counterexamples set then becomes if it's Friday, Marianne's wearing jeans.
Marianne Wear is wearing jeans. It's not the case.
It's not what the premises inclusion on it is Friday.
It's not the case that Marianne's wearing jeans. That's the counterexample set.
Now, listen, again, is that consistent? Could all these sentences be true together?
If it's Friday? Marianne's wearing jeans. It is Friday.
It's not the case that Marianne's wearing jeans. Could those be true together?
They couldn't. Could they? And that shows that the original argument is valid.
It shows there is no possible situation where the premises are true.
And the conclusion is false because the set consisting of the premises and the negation of the conclusion is inconsistent.
In other words, there is no possible situation where they're all true together.
That's why that test works well. So. Okay.
And I said to though, to test you will have understood the concept of validity.
Once you've understood, firstly, the paradoxes of entailment. And secondly, why this works.
If you understand why this works. You're getting there.
If you understand why the paradoxes of entailment are valid arguments, you will see why you've.
You'll have understood the concept of validity. Okay.
I can see there's still people worrying about the concept of validity.
But only if there is time for questions. We'll have a look at the questions that you might have then.
But we must go on today. I'm afraid so. We'll move straight on.
This week we're going to be looking at common fallacies.
And a fallacy is an argument that looks like a good argument can easily, easily be mistaken for a good argument.
But that isn't a good argument.
And you won't believe how many fallacies there are, fallacies that you can just identify and explain why their fallacies,
why they look as if they're good arguments and they're not. But I've listed a whole load of fallacies.
I've I've taken the form of a Web site that I've mentioned on the top and that there are I think they're four pages or something of fallacies all in.
I apologise for the smallness of the print, but they wouldn't have let me photocopy it if I'd put it any larger.
And I'd just like to point out the top one fallacy is now I've got my glasses on.
So it says something like, please note that the argument from fast talking on page eight.
That tells you that if somebody talks fast,
you haven't got a chance to work out for yourself whether the premises are true and the conclusion is valid.
And I'd just like to point out that I've gone through these ideas in these
lectures so quickly in some cases that there's no way you'll have had time to.
Stop and think about them as I've been talking,
and so you could say that the whole of these series of lectures has been a giant fallacy of fast talking.
I promise you it's not. And that if you go back and consider what I've said and of course, they'll all be on the podcast,
so you'll be able to actually go back and listen to what I've said again.
You'll be able to listen to all my mistakes as well as the things I've said correctly.
I hope we've identified all my mistakes as we've gone through.
But but that'll give you time to actually think about what I've said and work it out for yourself is actually.
Nobody can teach anybody else anything. You can learn from what I say.
There's nothing I can do to make you understand the concept of validity.
You've got to put that effort in for yourself. One thing I will promise you, though, if you do put that effort in, you will understand.
And if you still don't, after putting in a lot of effort.
Email me and I'll give you a tutorial all on your own, because it really is easy to understand once you've seen it.
And it really is just a question of looking at it in a slightly different way.
And I and you'll see it. It's it's one of those rather irritating things you'll probably remember from maths, from school.
Okay. So fallacy of fast talking. But the list of fallacies is down there.
Just for your amusement. Okay.
Here's a fallacy or rather his deductively valid argument.
And here's a fallacy that looks like it. Okay. Here's an example of modest pronouns you come across before.
I think you'll agree. Could these be true and this one false? If these two are true, could this be false?
No, absolutely not.
So if you negated that conclusion and took away the therefore, if you negated that conclusion, the set would be inconsistent, wouldn't it?
And that shows you it's a valid argument. Would you like us to do that there?
We can look at this counterexamples set. If it is snowing, the mail will be late.
It is snowing. The mail will be late.
And we're going to tack on it's not the case that which is just that symbol there.
OK. That's what that means. It is not the case that so we've got the set consisting of if it's snowing, the mail will be late.
It is snowing. It's not the case. The mail will be late.
Do you agree that's inconsistent, that there is no possible situation in which all those three sentences can be true together?
Okay, well, if there's no possible situation in which those three sentences can be true together,
then the set consisting of the premises plus the sorry, there is no possible situation where the premises are true and the conclusion is false.
Is that because that's what the counterexample says is the truth?
The premises, just as they are and the negation of the conclusion. OK.
That's why that test works. But look at this one. If it's snowing, the mail will be late.
The mail will be late. Therefore, it's snowing. Let's create the counterexamples set of that.
So tell me what to write. Somebody. If it's snowing, the male.
We'll be late. What do I write next? The mail will be late.
No, we do not put the therefore in because we're creating the counterexample set now.
We're just making a set of sentences. So I'm putting it is snowing. And then what do I do?
I put the negation sign in front of that and say it's not the case.
It's no. So we've now got the set consisting of the premises just as they are.
Plus, we're pretending the conclusion is false. OK, we're putting and not the case in front of the conclusion.
Pretending it's false now is that it could these sentences be true together?
Is there a possible situation in which all these sentences are true?
Where if it's snowing, the mail will be late. The mail is late, but it's not snowing.
Yes. OK. Give me a couple. The postal strike.
Yes, exactly, so. OK. Give me another one. If you can think of one.
The male van's broken down. Exactly. So there are all sorts of situations in which these two premises are true.
And so is the negation of the conclusion. Therefore, it's obvious there's more than one possible situation in which the premises are true.
And the conclusion is false. So making a counterexample set enables you to think about situations where the premises are true.
And the conclusion is false. And that's why it tells you whether the argument is valid or not.
So this is a deductively valid argument and this is a fallacy.
This is the fallacy of affirming the consequence. So if you like,
you take the consequence of the conditional instead of the antecedent and you put
that as the second premise and then derive the antecedent instead of the consequent.
It doesn't work, as you can see. Okay, so that's a formal fallacy.
And we're going to look at fallacies informally and some of the fallacies that we'll look at are actually formal fallacies.
But I'll talk about them informally because it's it's just as easy for you to understand.
Okay. We're going to have a look at three types of fallacy.
We're going to look at fallacies of relevance, parliament, fallacies of vacuity and fallacies of clarity.
And even then, we're just skimming the surface. Okay, so let's look at fallacies of relevance.
The first one is a non sequitur.
And you you commit a fallacy of non sequitur when you cite in support of a conclusion, something that's true but irrelevant.
Okay. So you cite in support of a conclusive one of your premises.
It's true. So that's fine. But it's irrelevant to the conclusion now.
You might be a bit worried about this, but let me just give you an example of non sequiturs.
That will be obviously non sequiturs. Bill lives in a large building.
Therefore, his apartment is large. OK. Is there any situation in which this premise is true and this conclusion false?
Hundreds of. Yeah. I mean, he may live in a large apartment, large building, but his apartment may maybe no bigger than a broom cupboard.
But it's so you can see that that isn't a valid argument. And the reason it isn't is because the premise doesn't matter how true the premises.
It's completely irrelevant to the conclusion, isn't it? You cannot derive the truth of the conclusion from the truth of that premise.
Now, I can imagine that you're thinking, well, what about those paradoxes of entailment then?
You surely that was a case, a paradigm Mattick case of irrelevance.
You remember I had grass is green.
Therefore, two plus two equals four.
OK, now, surely that premise is irrelevant to the conclusion.
But let me ask again. Is there any possible situation in which that premise is true and that conclusion is false?
Is that any possible situation? Let me ask again in which that premise is true and that conclusion false.
Why not? You're right. There isn't. But why isn't the. We saw here that this premise can be true and that conclusion false.
Can't we? That's that's not a problem. That is a non sequitur. Commits the fallacy of irrelevance.
But what why it doesn't this one do that? That's all I got us.
The conclusion is dependent on the. Well, no, there's not one.
I mean, that's that's what's wrong with this one is that the premise and the conclusion are completely irrelevant to each other, aren't they?
So so why isn't that a problem with this one? The conclusion is necessarily true.
That's right. So so the reason this is a paradox is that the premise is completely irrelevant to the conclusion,
but it satisfies the definition of validity because there can't be any possible situation in which the premise is true and the conclusion false.
If there isn't any possible situation in which the conclusion is false. How can P and Q be true if Q isn't true?
If CU is necessarily false, then how can P and Q be true?
The truth of P just becomes irrelevant, doesn't it?
The truth appears is just unnecessary to the whole claim.
Are you with me? I'm I'm seeing light sort of going on here, but it's difficult, isn't it?
Okay, so this commits the. This is a non sequitur, whereas that's not that's a case of of of a paradox, of entailment.
And the difference between them is that two plus two equals four is a necessary truth.
It cannot be false. So how could the premise be true? And the conclusion false.
But if it can't be the case that the premise is true and the conclusion false, then it satisfies the definition of validity.
Whereas this doesn't. OK, here's another non sequitur.
Every year many people are supported through like life by their religious beliefs.
Therefore, their religious beliefs must be true. OK. Does that premise give any support at all to that conclusion?
No, I mean, perhaps your religious beliefs really do help you live a good life.
Live a life that's satisfying to you, too. That doesn't necessarily mean they're true because false beliefs.
If you believe false beliefs are true, they're going to give you everything that they would give you if they were true.
If you see what I mean. OK.
So those are two non sequiturs and we can see why a non sequitur is an invalid argument, that there's easily a possible situation, which.
That's true and that's false. Therefore, it's not valid. Again, the truth of that bears no relation to the truth of that.
So, again, the two arguments are not valid. Okay, what how to arguments like this work?
I mean, one of the things we've got to work for ever falling for fallacies.
I mean, we we argue incorrectly.
We either make fallacies, we argue fallacious ourselves, or we fall for the flat fallacies that other people offer us.
How do I talk to you about the principle of charity?
The principle of charity tells you that your interlocutor's silliness is less likely than your bad interpretation.
Okay. What does that mean? Okay. What's your name? I just think if the lady in front with a nice necklace, you've probably got a nice necklace too.
Okay. Margaret. Margaret and I are arguing. Margaret said something that I think is blindingly obviously stupid.
Okay. Now I've got two possibilities. I can think Margaret's just said something blindingly, obviously stupid.
I'm not going to talk to her anymore. You know, she's obviously not worth talking to because she said not P, whereas surely pee is obvious.
Now, what the principle of charity tells me to do in that case is to say, well, that's interesting.
Margaret says, not P? I think not P is definitely false.
Therefore, I must have misunderstood Margaret because her silliness is far less likely than my misunderstanding.
Her argument. Are you with me? Okay. So instead of saying to Margaret, you must be joking.
Oh, stupid. Can you get. Or anything like that. Or just saying to myself how.
Right. Okay. Thanks, Margaret. Nice to see you, etc.
I'm walking off. I say to Margaret. That's interesting. You think not pee?
I think pee. Why do you think not pee? And you give me your reasons and I give you read my reasons for thinking appear.
And we have a proper argument. We discover actually that pee and not pee are not in this case inconsistent.
That we've both got a slight misunderstanding. Let me give you an example. I don't know why use this example, but I always do.
So I'm going to do it again to rats in a cage. They both come from different cages.
And in one of those cages, one of the rats was given an electric shock every time a certain sound was made.
The same sound was resulted in the other rats being given a food pellet.
Okay, so the experiments are finished. They've now been put in the same cage and this sound happens.
Sounds. Sounds. Now, what's going to happen? One rat is going to rush, shaking into the corner of the cage, waiting for an electric shock.
And the other rat is going to be rushing up to the food bowl looking for food. Isn't it okay?
And then they look at each other and think, you're mad. You know, why have you done that?
What they if they were talking to this, I don't know. I and some I used this example.
If they were able to talk to each other, they would then discover that actually they both overgeneralise, too, didn't they?
Because one's experience was that whenever that this and the other's experience was
whenever that that they assumed that's all they experienced there was in the world.
And in fact, they've now got two counterexamples. That one is there in a cage where the sound goes off, nothing happens.
And the other is that there are places in the world where something completely different happens,
and it's only if they talk about it that they'll discover that.
So arguing is the life blood of of cooperating in the search for truth.
If you want to know what the truth is, you cooperate with other rational animals.
In other words, other people like us. And if you find that there's a constant contradiction.
Don't assume that the other person is wrong, because the only rational thing to assume is that one of you is wrong.
And even that might be false. But it certainly might be you.
And it's the principle of charity that you observe when you argue in order not to do the irrational
thing and to assume that the other person is wrong rather than assume that you've misunderstood them.
So that's what the principle of charity is. And what happens in this case and in the case of non sequiturs is that the principle of charity
can take you get you into the wrong place because you might not notice the irrelevance.
I mean, that that can happen if, for example, large apartment, large building,
you might think the two large is there is enough to make it relevant and you'll let the argument go through.
You wouldn't be right to do that. But it maybe is understandable. But sometimes when people are arguing, you might think, well, hang on.
I'm sure that was irrelevant, but it can't have been because, you know,
Margaret's too rational for it to allow and the relevance to go through non sequitur like that,
or you might just want to not be not admit that you can't see the connexion.
So the thing to do is to be aware that there should be an interest in any conversation.
The implication is that there's a connexion between premises and conclusion, like the sea is salts.
Melbourne's in Australia. When I gave you the context, you could see the connexion.
So if you can't see the connexion, ask for it. So don't be too generous.
Because it's possible that this person is putting forward a non sequitur and certainly don't be too proud to ask for the relevance.
If you can't see it. Okay. Here's an ad.
So this is the second fallacy of relevance.
So the second one is attacking the person is the second one we're looking at. There are many more than this.
You might attack the person making the arguments rather than the argument that's made.
And this is called an ad hominem fallacy. And you may have heard it was it's Miliband.
On the Today programme the other day talking. Now, who was he talking to, talking to William Hague.
And he accused William Hague of an ad hominem fallacy.
He said, you're arguing against the man, not against the arguments on your your stopping the man, not the ball or something.
He said it was a very good example. OK. Here's an ad hominem fallacy.
Nick Griffin is leader of the BNP. Therefore, his claim that some people worry about immigration is rubbish.
Now, I actually heard that fallacy loud and clear the other night on Question Time.
I'm sure you did, too. Does the truth of the fact that Nick Griffin is leader of the BNP bear at all on the claim?
The truth of the claim that some people worry about immigration.
And it could it be the case that Nick Griffin is leader of the BNP and some people worry about it?
Immigration. Course it could. Couldn't it?
Yes. OK. Here's another one, Von Duncan, that you may not even remember him.
He was the chap who wrote books about people coming from space and building the pyramids and so on.
His books about ancient astronauts are worthless because he's a convicted forger and embezzler.
Now he is actually a convicted for forger, an embezzler. Does that mean that his books are worthless?
OK. So could this premise be true and this conclusion false?
Yes. Could this premise be true? The conclusion false. So the arguments he uses, aren't they, they're both invalid.
There are possible situations in which the premise is true, inclusion, false.
They're not good arguments.
Now, it's very important when thinking about ad hominem fallacies to distinguish between ad hominem attacks and ad hominem fallacies.
And the difference between the two is this. You can attack somebody is right to say something.
So you can cast doubt on on why they're saying what they're saying by saying something about who they are.
And what you can't do is cast doubt on the truth of what they're saying.
So here's a different. The difference between the two. Here's an ad hominem attack.
Nick Griffin is a self professed racist. So you should take care when listening to his claims about immigration.
Now, that just seems sensible, doesn't it? That's an ad hominem attack.
That's not a fallacy at all. All you're doing is warning somebody that this person has a vested interest in making you believe something.
So you should take his claims with an extra pinch of salt.
But it doesn't say anything about the truth of the claim.
So here. Well, the only thing it says about the truth of the claim is,
is that you should be aware of the truth of trading claim because this person wants you to believe that.
And of course, that's not a good enough reason for believing it. Nick Griffin is leader of the BNP.
Therefore, his claim that some people worry about immigration is rubbish. That is a fallacy.
If you attack a person instead of what he says and your attack on the person is actually irrelevant to the truth of what he says,
in other words, your attack might be a correct attack.
You're not saying something false about this person. But the truth of what you're saying bears.
No has no bearing at all on the truth of what he is saying.
That's a fallacy. What do you what you could be saying is warning somebody so, so.
I've gotten your name again. Ashley comes to me and tells me that, oh, so-and-so came and told her that the coffee's ready in the common room.
And I say, yes, but I know why he told you that. That's because he likes everyone else to go to the common room first and then discover
it's actually being served upstairs today and he gets all the chocolate biscuits.
I mean that when I'm doing that, I'm giving her a reason for why he said something.
It doesn't actually bear on the truth of what, sir, but is a good reason not to to be sceptical about whether the coffees being in the common room,
you'd want to cheque with someone else that the coffee was in the common room before you went there, perhaps.
Or you wouldn't come down from your house in order to get coffee from the common room on the basis of what Ashley said or what what this person said.
Okay, so that's the difference between ad hominem. So I don't know if that's answered your question.
Yeah, I mean, an ad hominem is an attack on the person making an argument,
not on the arguments he's making, and therefore that the attack, even if they attack, is justified.
It doesn't question the argument itself. So those were fallacies of relevance.
Now moving on to fallacies of vacuity. OK, the first one is a circular argument that we'll be looking at.
And what do you when you argue in a circle, you, Supai, sort cite in support of a conclusion?
That's a very conclusion. So your premise or your conclusion is amongst your premises here?
A second fallacy we're looking at here is the fallacy of question begging.
And thirdly, a self sealing argument. So let's start with circular arguments, then come back and look at these again, a circular argument.
The conclusion is one of the premises.
And the difference between that and a question begging argument is that here the conclusion actually is one of the premises, exactly the same thing.
And here the conclusion is assumed by one of the premises.
So you haven't actually got the conclusion amongst the premises, but you've got amongst the premises of a premise that assumes the conclusion.
So here's an example of a circular argument. All whales are mammals.
Therefore, all whales are mammals. Now, that argument valid.
Well done. You're absolutely right. It is valid. All circular arguments valid.
How could there be a possible situation? That's true. And that's false.
If there's the same thing. If that's true, that's got to be true, hasn't it?
So there's no possible situation in which that's true and that's false.
Therefore, that argument is valid. So circular arguments are always valid.
And what that tells you is that there's got to be more to a good argument than validity.
And what's more true premises, because this is actually a true premise as well.
So that's a sound argument, but it's not very good, is it?
It wouldn't convince anybody of anything. But do you remember last week I got myself into a bit of a tangle by trying to
draw truth tables on here and convince you that once you've got a premise,
once you've got a conclusion in amongst the premises, it doesn't matter what you add to the argument, it remains valid.
This is called the monotonic property of entailment.
And if I had lots of other premises to that, the circularity will no longer be as obvious as it is now, will it?
But actually, you are validity detected. That's what you are in virtue of being rational animals.
So somebody stands up in parliament and gives a circular argument that's long and convoluted and so on.
It's a valid argument. And you hear that.
You can tell that it's a valid argument that there is no possible situation where the premises are true and the conclusion false.
But what you don't see is that it's only valid because it's circular.
Do you see how it happens so nobody would put forward an argument like that.
But if they embed that premise in with the sorry, that conclusion in with the premises,
they've set up a situation in which there's no possible situation where all the premises are true and the conclusion false.
How could that be? Because it doesn't matter what other premises are there.
If all the premises are true, the conclusion must be true as well, because a conclusion is one of the premises.
So circular arguments are always valid and some secular arguments like this one are sound.
But that doesn't make them good. There must be more to a valid argument. Sorry to a good argument than just soundness.
In the final analysis, the point of an argument is to persuade someone of something.
So it's to persuade you. If you don't believe me, and I think you should believe me, I think peer's true and therefore you should believe it.
I put together an argument in the hope of convincing you that P. Okay.
So what I want from an argument more than anything else is that it should be persuasive.
Okay. But I do not want it to be persuasive because of a fallacy.
I actually wanted to be a good argument as well. And therefore, I want it to be sound and valid.
But if it sounds invalid, not persuasive. It's pretty useless for any practical purpose.
So you actually you can't have a productive argument with somebody unless you agree with them.
Didn't anyone tell me why that might be the case? Productive disagreement.
Always depends on on agreement. Which is why if you've really got two sides who absolutely disagree on everything.
You may as well forget it. Why should. Productive disagreements depends on agreement.
I can only argue with you if you're prepared to accept my premises, if you reject my premises,
then then I can't draw anything from those premises that's going to convince you of anything.
Can I? So I've got to convince you of at least one of my premises before we can even get started.
And of course, what I might do is say, will you agree to take this for the sake of argument and then take you through the arguments.
But of course, if you still don't accept the premise, really, you know, you're never actually going to accept the conclusion of my argument, are you?
So in order to disagree productively, you've got to agree on something.
You've got to agree on the premises. Okay, so that's a circular argument and it's a valid one,
but it's no good and it's no good because there's no possible situation which the premise is true and the conclusion false.
But that's because the conclusion is amongst the premises. OK.
Let's look at begging the question. Here's an argument. It's always wrong to murder human beings.
Capital punishment involves murdering human beings. Therefore, capital punishment is wrong.
What s question begging about this argument is.
Exactly. This, too, to talk about capital punishment as if it were murder.
Just to assume that capital punishment is murder is to assume your conclusion, isn't it?
I mean, most people say that actually capital punishment isn't murder because murder is illegal killing,
whereas capital punishment is legal killing, isn't it? Judicial killing.
So by talking as if capital punishment to murdering human beings are interchangeable here.
You're actually begging the question, aren't you? You're begging the question.
Well, hang on a second. You know. Why should I believe capital punishment is wrong on the basis of these two premises?
I do not accept that one at all. Because you're just assuming your conclusion here.
You with me.
So so when you say that an argument is a fallacy, you're not necessarily saying it's invalid, but you are saying there's something wrong with it.
There's something wrong that means it's not persuasive. It shouldn't persuade you.
Often that'll be the case because it's invalid, but not always. And certainly with cases of circularity and question begging, that isn't the case.
Okay. Any other question? We'll move on now.
Okay, let's. Okay. Where are the question begging premises in each of the following arguments?
Let's do it. So intoxication. Intoxicated beverages should be banned because they make people drunk.
Let's set out the arduous logic bookstall. Before we do that, we might need to suppress Froese.
So what's the argument here? Think about it for yourself and then put your hands up when you when you've put out the argument.
Logic books style. Yes, being drunk is bad or something like that, or beverages that make people drunk should be bad.
That's probably the right one. Beverages that make people drunk should be bad. Should be banned.
Intoxicated beverages, beverages make people drunk. Therefore, intoxicating beverages should be banned.
What's the question? Begging bit. Which premise would you reject?
You couldn't have a beverage that's intoxicating without having your beverage.
That would make you drunk because an intoxicating beverage is exactly a beverage that makes you drunk, isn't it?
The fact is, you're not going to be able to reject that argument because it's is assuming its conclusion in its premises.
So beverages that make people drunk should be banned.
Intoxicating beverages make people drunk, therefore, intoxicating beverages should be banned.
It's a valid argument, but it's not ever going to persuade you. Well, let's go back to this one.
Let's go back to Candy. Can you see that?
Now, you might be for capital punishment or against it, but anyone who made this argument is clearly against capital punishment, aren't they?
Okay, so they would be making the argument in order to try and persuade someone who is for capital punishment or neutral either way,
to agree with them that capital punishment is wrong. Right. OK.
And the problem with the argument they offer is that it's not going to convince anyone who isn't already convinced of the argument.
Is it because I might say I'm against capital punishment?
Sorry, I'm no, I'm for capital punishment. I might accept that premise.
There's a is our starting point of agreement. But as soon as we get to that one, I'm going to say, boy, what?
Hang on. Hang on. No. Why? Why should I set that? You're assuming that capital punishment is wrong in making that premise.
You know, if you change that premise to capital punishment involves killing human beings, that's fine.
But then your argument isn't valid. The only way you make your argument valid is by putting murdering in.
And then it's valid because it begs the question. OK.
And therefore, it's not persuasive. So in exactly the same way.
If somebody was making this argument, say, I didn't believe whales were mammals.
I thought whales were fish. Whales, obviously fish, aren't they? I mean, we've discussed this before anyway.
They told me whales are mammals. Okay. So I don't believe whales are mammals.
And you're trying to convince me if you offer me this argument and say, well, here's a good argument of whales being mammals.
I would say no. No, that's not a good argument at all.
Why should I agree with you on that premise, in that premise?
You're just assuming your answer the obvious or your conclusion. So you've got a valid argument, but it's hopelessly unpersuasive.
Therefore, it's not a good argument.
And this one is only slightly difference in its instead of the the premise actually being the same as the conclusion,
the premise assumes the conclusion.
So if I actually if I'm if you're arguing using this argument against me, it's not going to persuade me of anything is it.
And that's what's wrong with it. Not that it's not valid. So we're looking at fallacies of vacuity.
OK? We've looked at fallacies of relevance. We're now looking at fallacies of vacuity.
And we've looked first at circular arguments where the the the conclusion is one of the premises.
Why? Tell me again why that would convince anyone if you've made an argument whether the conclusion is amongst the premises because
it's valid and because the fact that the conclusion is amongst the premises may be hidden amongst all sorts of other premises.
So you just don't notice that the conclusion is there.
Okay, then we looked at question bagging arguments and we tied ourselves in knots or I tied myself in a knot.
But the idea here is this.
Instead of the premise, the conclusion being amongst the premises itself, there is amongst the premises a premise that assumes the conclusion.
That's the difference between those two. And finally, we're going to look at arguments.
This is self sealing. Okay. A self sealing argument.
Two weeks from today at two forty five, you're going to be doing exactly what you are doing.
Well, it will be a true statement, won't it? I mean, yeah, that couldn't be false, could it?
But it's not a persuasive argument. Why not? It's completely vacuous.
It says absolutely nothing doesn't it doesn't give you any prediction. It doesn't limit the possibilities at all.
It just tells you you're going to be doing whatever you're going to be doing, which has to be true, not persuasive.
Here's one that that actually lots of people do think is persuasive. We must respect all moral beliefs.
Therefore, relativism is moral. Relativism is true. This is called vulgar relativism by chuckle Bernard Williams, famous philosopher.
And the reason that's a self sealing argument is that is a moral absolute.
We must respect all moral beliefs. You cannot derive moral relativism from a moral absolute.
If that premise is true, then that conclusion is false.
And if the conclusion is true, the premise is false. So it's it's a bad argument because it goes around in circles.
It's self-defeating, actually self-defeating rather than self sealing. Yes.
That's actually should be in a slightly different category. But here's another one that you may have variants of.
It will have caught you out at some point.
I'm sure global economy is controlled by Jews and any parents to the country is the result of Jewish cleverness.
Women are stupid, and any appearance to the country is just because they're quite good at covering it over sometimes, you know?
So, again, a self sealing argument because you know that you can't be refuted because whatever happens,
you've got some reason for why what you're saying is is true.
So some self sealing arguments move back and forth from interesting but false claims.
For example, you might say all human beings are selfish and you won't say, well, hang on, that's not true.
Lots of people are altruistic. Then they do things for other people.
And then you say, oh, yes, but they still do. It does. They want to. I mean, Mother Teresa.
I mean, she wouldn't have helped all these people. And if she wanted to. And you say she did it out of duty.
And so you say, well, yes, she wanted to do her duty, didn't she?
I mean, she still wanted to do what she did. So the only thing she did was what she wanted to do.
So she's as selfish as everyone else. And her you know what's happening here?
Well, what's happening is that someone's moving from an interesting but false claim to a true but vacuous claim.
And what they'll do is they'll move backwards and forwards between the two until you've got yourself thoroughly tied in a knot.
And what do you need to do is separate, separate out the two claims that are being made and show why one of them is meaningless, even if true.
So three ways that an argument can be self see the ceiling. It can invent ad hoc ways to dismiss criticism.
So if my prediction didn't work, it's because there are negative vibes in the room.
Okay. You know, it's all your fault. It can attack its critics as unable to see the benefits of the position.
So, you know, the only reason you don't see that the world's being taken over by Jews or women
or or blacks or whatever is because you've been taken in by them or another one.
There is you know, you're in denial. Therefore, you you don't understand what I'm saying about your appalling desires and what have you.
It can also redefine key words. So it's selfish to always be doing just what you wants to do.
Well. It depends what how you interpret just what you want to do there.
If you interpret so you've Mother Teresa was doing just what she wanted to do, then you might need to have another look at what you mean by selfish.
OK. And finally, we're going to look at fallacies of clarity. And I want to lose you some time for questions.
Sorry, you've got a question. Well, on on the on this one.
As soon as you have the feeling that you're being moved from between two different propositions,
one of which is false, an interesting and the other is is safe.
Ask for time out. If you can, because that's the only way you're going to do it.
And of course, this is what you won't get. And try and identify what the two propositions are.
So in this case, you want to say, OK. The meaning of selfish is usually isn't interested in what anyone else wants.
In which case, Mother Teresa wouldn't be selfish because she is interested in what other people want.
Then you say, but then your other claim is that somebody is selfish.
Only if they saw something. It's sufficient for being selfish that somebody acts on what they they themselves want.
And actually, that's not usually the definition of self.
So identify the weasel words and get out the two definitions and then show that somebody is flipping between one and the other is the way to do that.
OK, fallacies of the heap. If you have only one penny, you're not rich.
If you're not rich and I give you a penny, then you still won't be rich. Doesn't matter how many pennies I give you, then you won't be rich.
OK. Is that a good argument? No one not.
I mean, is that false? No.
OK. Is that false? Is that new, is not false, is it?
I mean, that's true. If you gave me a penny, sadly, you wouldn't make me rich.
Sir, fully, you know. Okay, so that's true.
And that's true. Is that true? Okay. Is this valid?
Is there any possible situation where those two are both true and this is false?
Yes. Okay. This is actually not a valid argument at all, is it?
It's it's trading on the fact that many words are vague.
They admitted borderline cases. So any word you can think of, like tall, fat?
Clever. Can you think of a few others? Richard is one of them.
Yes. Long. Poor. Yep.
And any word that admits of of degrees Mitsu borderline cases.
You can construct a heap of arguments for the fallacy of the heap.
And so that's the fact the words do admit are borderline cases.
And the idea that a series of insignificant differences can't result in a significant difference.
And of course, it's this one here that's that's at fault because a series of insignificant differences.
If we take blue at this end of the stage and read at this ends of the stage, they're two different colours, aren't they?
But we can go from one to the other in a series of gradations where you would say in each case of the same colour,
the same colour, the same colour, but so A and B, the same B and C are the same.
But ANC are not the same. OK. The intransitive.
So when you're making an argument, you should try and avoid words that are grading words, scaling words.
And how would you stop these being vague if you had John has a nice income.
What might you say instead of that Set-aside again, some new good.
John, this is in the top ten percent tenth percentile of income earners or something like that.
Yeah. Okay. Cocaine is a dangerous drug. Cocaine is addictive or cocaine.
And cocaine. You could say the same sort of thing.
Yep. Or whatever. Exactly. That's what you're trying to do, is eliminate the vagueness by being more exact in some way or another.
So Mary is a clever woman in just say Mary has got three degrees and APHC or something like that.
Jane is a terrific tennis player. Jane is what?
Yes. Okay, good. That easy. Slippery slope fallacy.
This is another fallacy of ambiguity. Humans are rational.
Sorry if in clarity human irrational because they act for reasons radiator's turn themselves on when it's cold.
Therefore radiators are rational. Now don't laugh because actually lots of people try and convince me of this because I.
I do not believe animals are rational. And people always told me that I should believe animals rational because they act for reasons.
And some people want to say that even radiator's irrational because when it's cold they turn themselves on except in Rowly House.
But I mean, it's usually the case.
And therefore there is it has a belief that it's cold and a desire that it should not be cold and therefore it acts.
Why isn't that rational? But again, we're doing the same thing, aren't we,
because here are radiator's down at one end of of acting for reasons and here are human beings up at the other end of acting for reasons.
And we're saying that there's no difference between the two. So any slippery slope argument can fall foul of that.
Just quickly, slippery slope. Depends on the idea that we shouldn't distinguish between things that are not significantly different.
And the belief that if A isn't significantly different from B and B, not significantly different from C, then A isn't significantly different from C.
And again, that's true. Only if you've got something that's transitive.
And there are many, many things that are not transitive. Of course, sometimes.
And you I mean, one way of avoiding a slippery slope is actually to define something.
We have to use slippery slope sometimes, don't we?
When we think about, you know, well, why should we have the age of being allowed to marry at 16 without your parents permission or whatever it is,
or the age of being able to drink whatever it is.
I have no idea which this 18. Is it right.
And what happens between the last day that you're 17 and the first day that you're 18?
That makes it possible for you to drink on one day and not drink on the other. Legally.
I mean, this is just daft, isn't it? Well, it is daft, of course.
But but here you you have to make a Cut-Off point at some point.
And what the slippery slope is, it can say, well, OK, there isn't an obvious difference,
but we have to make it on somewhere or that we can just make one by regulation or whatever.
But slippery slopes trade on this particular problem. Here's another one.
Mary had a little lamb. He followed her to school. Mary had a little lamb.
Then she had a little broccoli. We can see that that's an equivocation.
It's not actually clear what it's an equivocation on, is it? Is it lamb or is it had.
Or little well, and little actually, isn't it, because had means possessed, whereas in the first one and the second one, it means AIDS, doesn't it?
Little Lamb in the first one is a bit different from Little Lamb in the second one.
And so on. And here's an equivocation. Yep.
Okay. A feather is light. What is light cannot be dark. Therefore, a feather cannot be dog.
What's the equivocation there? The word light.
In the first case, it means light as a feather weight wise.
And the second case, we're talking about light as opposed to dark.
So that's the fallacy of equivocation. There are three types of ambiguity, lexical.
So what's wrong with that one? I thought it was rum. Is that rum is itself ambiguous.
That's a word that can mean different things. The second one, Berts, was a fat stock breeder.
What's the ambiguity there? Give me the two understandings of that term.
Right. Either Bert was fat or the stock was fat.
That's right. So is the scope of fat. Just so Bert was fat and Bert was a stock read breeder.
Or is it the fat goes with stock breeder? So Bert was a fat stock breeder.
Those are the two. And then finally cross-reference my wife's cousin engaged for her former husband.
What's the ambiguity there? So either my wife's cousin's engaged to my wife's former husband or my wife's cousin is engaged to the cousin Chey,
the wife's cousin had before now that she's married for the second time to the same person.
Okay, explain the ambiguities in this sentence. These sentences, no one likes Oxford and Cambridge as students.
Good. Okay. Nobody likes students who've been to Oxford and Cambridge or nobody likes Oxford students and nobody likes Cambridge students.
Oh, yes. No one likes Oxford and no one likes Cambridge students.
Yes, that would be another one. OK. Every nice girl loves a sailor, actually.
If you were able to formalise things, you would find it very easy to do this,
because this could mean there is a sailor such that every nice girl loves him or every nice girl is such that there is a sailor whom she loves.
With me. So every girl is such sorry. There is a sailor such that every girl loves him or every nice girl loves some sailor.
OK, so in the second case, there are lots of different sailors in the first cases, just one sailor who is loved by all the girls.
So that's a structural ambiguity. Our shoes are guaranteed to give you a fit.
I can see you've got that one. Okay. Irritating children should be banned.
That's right there. What are we banning? Children who are irritating or the irritating of children.
Okay. What about the last one? Can anyone tell me what the ambiguity is here?
This is more difficult. You'll kick yourselves. But but you'll also think that I've cheated you.
Why do swallows fly south for winter? Why do swallows fly south for winter?
Why does swellest vice south for winter? Why do swallows fire south for winter?
Is that ambiguous? Okay. And all it was is the intonation there.
I managed to give it lots of different meanings.
So you shouldn't think that actually the ambiguity might just be in this in the lexicon, in the structure and in the cross references.
Sometimes you can put it in just by the tone, the emphasis you give on the words that you use.
Right. Okay. That's it for the lectures. Thank you.
Thank you. Well, thank you to.