Welcome back. We've covered stages one through three of argument reconstruction
namely, close analysis, get down to basics, and sharpen edges. In this
lecture, we'll cover stage four, which is organized parts. Cuz it's not enough to
isolate the parts and figure out what they are. We need to show how the fit together
in a structure so that they work together to support the conclusion of the argument.
To see how this works, let's start with an example. Consider this example. That
fertilizer won't help the roses bloom cuz there is already a lot of nitrogen in the
soil. So, the fertilizer will make the nitrogen levels too high. Of course, so is
a conclusion marker so one conclusion is that, the fertilizer will make the
nitrogen levels too high. And then, you might think that one might have put the
argument into standard form goes like this. Premise one is that fertilizer won't
make the roses bloom. Premise two is the nitrogen levels in the soil are already
high. And then, the conclusion is that the fertilizer will make the nitrogen levels
too high. But that doesn't really make any sense, if you think about it. How could
the fact that the roses won't bloom be a reason to believe that the nitrogen levels
are too high? This couldn't be a reason for that. So, we might just have the wrong
structure. However, there is another argument marker. This time it's a premise
marker, because. And that indicates that the claim that there's already a lot of
nitrogen in the soil is a premise. But what is the conclusion for that premise?
That's supposed to show that the fertilizer won't make the roses bloom. So,
we've missed that part of the structure if we put it in standard form, the way we
first thought. The trick here is that there are really two conclusions. One
conclusion is that the fertilizer won't help the roses bloom, and another
conclusion is that the fertilizer will make the nitrogen levels too high. But
each argument's just supposed to have one conclusion. So, how are we going to put
this into a structure? The solution is that there are two arguments. One is that
the nitrogen levels in the soil are already high. Therefore, adding the
fertilizer will make them too high. And the second argument is that, adding the
fertilizer will make the nitrogen levels too high, therefore the fertilizer will
not make the roses bloom. Now notice that one argument really builds on the other
because the conclusion of the first argument is really a premise in the second
argument. So, we can represent them as two separate arguments. But we can also put
them together in a chain. So that the argument says, the nitrogen levels in the
soil are already high. Therefore, adding fertilizer will make them too high. And
therefore, adding fertilizer will not help the roses bloom. Now, if we take that
whole structure and we try to represent it in a diagram, and we represent each
premise with a number, which is the number that was given in the standard form, then
we can simply have premise one with an arrow to premise two indicating that
premise one is a reason for premise two. And then, another arrow going from premise
two to premise three to indicate that two is a reason for three. In a way, we've got
two premises and two conclusions because that one kind in the middle, number two,
operates as a conclusion in the first argument and a premise in the second
argument. But overall, I hope the diagram, its clear. Well, I want to call this
linear structure. When you have one premise giving reason for a conclusion
which is then premise for another conclusion, then they form a line in the
diagram them in the way that I am proposing. Arguments can have other
structures, too. In particular, sometimes there's more than one premise associated
with a single conclusion. And this can happen in two ways. The first, we're going
to call the branching structure, and the second we're going to call the joint
structure. Here is an example of the branching structure. I'm not going to go
to the movie with you because I don't like horror flicks. And besides, I'm too busy.
The word beca use is a premise marker. So that indicates that the conclusion is
that, I'm not going to go to the movie with you. And there are two premises. One
is, I don't like horror flicks, and the other is, I'm too busy. Now, you might
think that, that could just be put in the old linear structure that we already saw.
But then, the argument's going to look like this. I don't like horror flicks.
Therefore, I'm too busy. Therefore, I'm not going to go to the movie. But, wait a
minute. The fact that I don't like horror flicks doesn't mean I'm too busy. That
doesn't make any sense. Oh, maybe it's the other way around. I'm too busy. Therefore,
I don't like horror flicks. Therefore, I'm not going to go to that movie with you.
That doesn't make any sense either. The fact that I'm too busy isn't why I don't
like horror flicks. The problem is, there are two premises here but neither one is a
reason for the other, as we saw in the linear structure. Instead, in this
branching structure, each premise is operating independently. There's one
argument. I don't like horror flicks, therefore I'm not going to go to that
movie with you. There's another argument. I'm too busy, therefore I'm not going to
that movie with you. And each premise by itself is a sufficient reason not to go to
the movie with you. I mean, just think about it. If I wasn't too busy, but I
didn't like horror flicks, I wouldn't go to the movie. But if I liked horror
flicks, but I was too busy, I still would go to the movie. So, each premise by
itself is enough, and they operate independently. That's what makes this a
branching structure instead of a linear structure. Let's diagram it and you'll see
why we call it a branching structure. One way to diagram it would be to simply draw
an arrow between premise one and the conclusion two. And then, there's a
separate argument, so you draw another arrow from one star, another premise, to
conclusion two. And that's okay. But, notice that it doesn't show you that both
premises are reasons for the same conclusion. So, to capture t hat aspect of
the structure, that both Premise one and Premise one Star support the same
conclusion, namely two. It's better to diagram it so that there's an arrow that
runs independently from both premises to a single instance of conclusion two, as you
see on the diagram on the screen. And that should show you why we're calling it a
branching structure cuz it kind of branches, it looks like the branches of a
tree. Okay. Well, it doesn't really look like the branches of a tree, but you get
the idea. We're going to call it a branching structure. Next, we have to
separate this branching structure from what we're going to call the joint
structure. The difference is that in the branching structure, the premises provide
independent support for the conclusion. Whereas, in this joint structure, they
work together and they're not going to have force independent of each-other. It's
like the joint in your leg, which joins together the calf with the thigh. And, if
you didn't have both, it wouldn't work very well. So, we're going to call it a
joint structure. Here's an example. For my birthday, my wife always gives me either a
sweater or a board game. This box does not contain a sweater. So, this time she must
have given me a board game. Now, notice that the argent marker, so, indicates that
the conclusion is, this time she must've given me a board game. And it's got two
premises. And you might think that they got a linear structure, and the argument
goes something like this. My wife always gives me either a sweater or board games.
Therefore, this box does not contain a sweater. Therefore, this time she gave me
board game. That doesn't make any sense, right? I mean, the fact that she always
gives me either a sweater or board game is no reason to believe this box doesn't
contain a sweater. Well, okay. Let's try it again. Maybe it's a branching
structure. That would mean that the argument looks like this. My wife always
gives me either a sweater or a board game. Therefore, this time she gave me a board
game. And, as a separat e argument, this box does not contain a sweater, therefore
this time she must have given me a board game. Neither of those arguments makes any
sense so it can't be a branching structure. Instead, what we have here is
the two premises working together. She always gives me either a sweater or a
board game. And, the second premise, this box does not contain a sweater. Those two
premises have to work together. It's only jointly working together that they can
support the conclusion that, this time she must have given me a board game. How can
we diagram this joint structure? We can put a plus sign between premise one and
premise two, then draw a line under them to show that they work together jointly.
And take a line from that line and draw an arrow down to the conclusion, just like in
the diagram. And this is what we're going to call the joint structure. So, we've
seen the linear structure, the branching structure, and the joint structure. And,
we can combine more than one of these structures into a single argument. To see
how to do this, let's just do a slight variation on the previous example. My wife
always gives me either a sweater or a board game. This is box is not contain a
sweater because it rattles when I shake it. So, this time she must have given me a
board game. This argument combines a linear structure with a joint structure.
There are two argument markers. One is a conclusion marker, so, and that indicates
that the eventual conclusion is that she must given me a board game this time. But
there's also that new word, because, which indicates that the fact that it rattles
when I shake means that it's not a sweater. So, the first stage of the
argument in standard form looks like this. Premise one, this box rattles when I shake
it. Therefore, conclusion, this box does not contain a sweater. Stage two says,
this box does not contain a sweater, my wife always gives me either a sweater or a
board game. So, the conclusion, this time, she must have given me a board game. And,
of course, the conclusion of that fir st little argument is identical with the
premise of the second argument, so we can put them together into a chain. We can
say," this box rattles when I shake it, so it must not contain a sweater." My wife
always gives me a sweater or a board game, so this time she must have given me a
board game. That's how we get a linear structure combined with a joint structure.
And we can use our diagram methods to diagram this argument the same way we did
before. We simply start with premise one, the box rattles when I shake it. Draw an
arrow down to its conclusion. Namely, the box does not contain a sweater. That's
two. An then, we show that those are joint by adding a plus, premise three. Namely,
my wife always gives me either a sweater or a board game. Draw a line under them
and an arrow from those two together down to the eventual conclusion, namely, four
that this time she must have given me a board game. The fact that the top arrow
goes from premise one to two, but does not go from premise one to three indicates
that, that premises is a reason for two but is not a reason for three. So when you
use this method to diagram arguments, you have to be careful where you draw the
arrows. And draw them only where there really is a rational connection. That is,
where one claim is being presenting as a reason for that particular claim that the
arrow is pointing towards. Now, almost all arguments can be diagrammed using these
three simple structures. That is, the linear structure, the branching structure,
the joint structure, and some combination of those three. You can add more premises
because you can always add one plus two plus three plus four if they're four
premises operating together in a joint structure. And, you can add extra arrows
if you have a branch with more than two branches. So, you can cover a lot of
arguments using these kinds of diagrams. The method can be described in general,
like this. You start by identifying the premises and the conclusions, and you
number them. So that you can just have numbers instead of having to write out the
whole sentence on the diagram. Then, when they work together, you put a plus sign
between them and draw a line under it to indicate that they're working together.
They're functioning as a group. Then, you draw an arrow from the claims that are
reasons to the claims that they are reasons for. And then, you move them
around on the diagram so that they'll form a line when it's a linear structure and
branches when it's a branching structure. But, it will be easy to rearrange them so
as to show how all of the different premises and conclusions work together in
a single argumentative structure. That's going to be enough to accomplish this
stage of reconstruction. Namely, to organize the parts and show how they work
together in the overall argument.