Soundness and Validity 3


[ Music ]>>Welcome back. It may seem like a new topic, but we’re really
just focusing on soundness and validity again. Sorry. We’re dealing with deductive argument. Deductive argument has an
abstract major premise. Validity has to do with the logic of
stepping from one premise to the next. Soundness has to do with accepting
the premises and the logic as valid. So far so good. Should you have questions on
these, of course, ask me anytime. I’d be glad to try and clarify them. Stop by my office, I’d be glad
to talk to you about them. Let’s continue on, though. We’ll take another example. Here’s our new topic. A statement from a former attorney
general, which seems kind of surprising because he was an attorney general,
but let’s take the statement as read. The Supreme Court’s Miranda ruling, he
said in an interview, and we might remember that the Miranda ruling gives
defendants the right to have a lawyer present during questioning,
is wrong and only helps guilty defendants. Suspects who are innocent
of a crime should be able to have a lawyer present
before police questioning. But the thing is you don’t have many
suspects who are innocent of a crime. That’s contradictory. If a person is innocent of a
crime then he is not a suspect. So far so good. Take a close look at the writing. We’re going to reduce it to a few premises. So there should be something about
the writing that makes you ask what? Reduce it to a few sentences. Let’s see if I’ve got it. Guilty suspects do not deserve lawyers. If you were questioned by the
police you must be a guilty suspect. Therefore, those who are questioned
by police don’t deserve lawyers. The question surrounding these, of
course, are is it valid, is it sound? It’s kind of a complex paragraph,
a little bit of a complex argument, So we’ll take it apart and think about it here. Guilty suspects don’t deserve lawyers. If you were questioned by the
police you must be a guilty suspect. Therefore, those who are questioned
by police don’t deserve lawyers. What I would do, of course, is number these
statement so that you get them in a kind of order, and think about them
and how they relate to each other. What is the abstract rule here? It really does help to identify
the key major premises. And all I’ve done here is rearrange the
sentences so that the first sentence turns out to be if you were questioned by the
police you must be a guilty suspect. Now I’ve got all of my sentences
lined up, the abstract ones. The first one and the second
one follows from it, and then the third one has to be the conclusion. Sometimes with deductive arguments you have to
rearrange the writing so that you can get them in an order that makes sense to the argument. Okay. I haven’t really changed
anything materially. I’ve just shrunk it here so we
can take a close look at it. If you were questioned by the
police you must be a guilty suspect. Okay, let’s take a hypothetical. Now, these are all hypothetical. I’m not trying to accuse anybody in class. You were questioned by the police, given
a specific, since you were questioned by the police you must be
a guilty suspect, right? Therefore, you don’t deserve a lawyer because
guilty suspects don’t deserve lawyers. The argument so far is valid, and
that we’re going step by step. We’re going to step through the
thing if we apply it to you. But it’s unsound. Can you tell why it’s unsound? Can you see what the problem is,
what the potential problem is? If you don’t I’ll hint at it. It has to occur early on in the argument
in this case for it to be unsound. And you have to think about the major
premise and whether you accept it. But the validity of it is okay, step by step. That’s a straightforward argument. You want to be able to think
about whether you can explain why. Because the explanation calls
upon you to apply the vocabulary of deductive argument, and
that’s why we’re doing this. Let’s try a new one. You do get a lawyer. You must not be a guilty suspect. Does it follow that if you do get
a lawyer you must not be guilty? Look at that third sentence. We’re reversing the negative
on that third sentence. Therefore, those who are questioned
by police don’t deserve lawyers. Okay, so if you do get a lawyer, if
we go back through to the beginning, it must be that you’re not a guilty
suspect based on the second sentence. Sorry, not to the beginning
but to the second sentence. That’s actually using the logic here. And because it’s using negation
you can say it is valid. It is because you’re negating the
third and really the second sentence. Because you’re doing that you’re
pointing out how it couldn’t be true that you would be a guilty suspect. Still unsound, though, same reason as before. Do we know why yet? Have you been able to figure out why? In this one you want to focus
on the validity by looking at the last two pieces of the conclusion here. Let’s try one more. Same set of premises, same conclusion. You are not questioned by the police. You do get a lawyer. Are we given a rule for those who
are not questioned by the police? Of course the answer is no,
we’re not given a rule for that. We can’t conclude you do get a lawyer
and, therefore, the logic here is invalid because we don’t have actually
logic or any kind of rule for this. It’s still unsound, this
original set of statements. Let’s try one more. You don’t deserve a lawyer. That seems to affirm the third and
concluding sentence of this set of statements. You don’t deserve a lawyer. Can we work backwards, though, and
say that you must be a guilty suspect? Is that how the logic works? Can we go in reverse? Think back to Alan [assumed spelling]
and to our example in the other video. Nope, this one’s invalid, too, because
unless we’re negating the conclusion we can’t work backwards. And we don’t have a rule for what
happens when we don’t deserve a lawyer. We only have a rule set up if we’re questioned
by the police and being a guilty suspect. It could be the case that rule is also
set up for not deserving a lawyer. But we can’t affirm the consequence
in this particular example. Still unsolved. It would seem to be more important to be valid
in these four examples, but that’s not the case. What we’re trying to do is apply the vocabulary to understand validity and
soundness and argument. In all of the examples you
can see that they’re unsound. Let’s try and figure out why they’re unsound
and take another kind of example altogether. If we restate the argument, if you were a
suspect then you are guilty which is kind of a shortening and tightening
up of that thinking that Edwin Meese started this all out with. We could have even applied it to
crazy examples like Kris Kringle for those who still watch old movies. Kris Kringle was a suspect in
the movie Miracle on 34th Street. He’s a suspect and, therefore, Kris Kringle
is guilty and doesn’t deserve a lawyer which isn’t what happens
in the movie necessarily. Yes, why would that be valid? Because it follows the rule. In fact, it calls the rules into question. How can that rule be right? Being a suspect does not mean
that you’re guilty in other words. In this case all I’m trying to say is that
oftentimes you’ll have an argument thrown out as valid, thrown out
into the world as valid, and they want you to examine
the validity of the argument. Because what they’re trying to draw attention
to is the unsound premises that’s at its core. It is unsound to treat suspects as if they
are guilty and undeserving of lawyers. And that’s the key thing that people
will want to question if they’re looking at the unsound premise in this argument. Why is it that we assume
that suspects are guilty? Why is it that it’s supposed to
follow that they don’t get lawyers? That’s because Edwin Meese is wrong. What he’s trying to say is
wrong, and he got called on it. And it’s a good thing, too, because
you cannot have the forces of justice in our society working on the principle
that people who are suspect and questioned by the police are all guilty
and undeserving of lawyers. To sum up, if a major premise is untrue in a
deductive argument and the reasoning invalid, the whole argument is said to be unsound. If the logical premises follow
one right after another in logical order the argument
is said to be valid. So valid and unsound — valid and sound
arguments we examine them because there are ways of describing deductive arguments
and making sense of how they work and the assumptions that they’re based on. If the argument goes one step to the next and
it goes in logical order we say that it’s valid. If it violates that we say it’s invalid. If we don’t accept the premises and the
logic seems invalid then we say it’s unsound. An argument has to satisfy both soundness
and validity in order to work in other words. And, in fact, we’ve seen good examples of this. We come back to the centerpieces,
the ones that are unlike Ed Meese that started this little video out with
these are ones that have been accepted by our society and by our culture. Do you remember these from our readings? Because we took a look at
them in some detail in class. Can you identify the deductive arguments
from their sound major premises? Such as we declare these
truths to be self- evident. At the time they were asking
the world to accept that premise as a sound premise and so,
too, with these others. We the people do ordain, another
part of that same declaration intent. Or how about this next one? We means me. Are women persons? We the people she says. Maybe you recognize that one where she declares that the we doesn’t just mean
property men, it means women, too. Something about the boat. It’s declared sound in part
because it’s warranted as decided by the populous that hears the speech. And it has to actually happen over the period
of time that people buying into the argument. Accept it and then they eventually vote on it. Or how about the argument that
we would have treated in class that we need to be dedicated to their cause. We need to be dedicated to their cause. Or that an unjust law is. That’s a little bit more obscure. But if you can think back to our
discussions and examples in the readings in class you might notice how these are the
deductive sound major premises that we have used to demonstrate how deductive logic works. All right. This is abstract reasoning. And I’m not trying to overwhelm folks. When you do get questions come and talk to me. I’d be glad to try and answer questions or work
through something that was raised in the video that you’d like further clarification on. Good luck. [ Music ]

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