Critical thinking for Students (5 page)

The argument no longer works. The first sentence was needed for the second sentence to work as a reason (and vice versa).

There is another feature of showing the structure of an argument that we can introduce here. This is numbering the reasons. This time, whether or not the reasons are joint or independent isn’t the point: all we do is to give each reason a number to show their position in the sequence of the argument.

(R1) Teenagers are supposed to increasingly break free from their parents during adolescence. (R2) Texting enables the teenager to keep in touch with their parents, about the smallest detail of their lives. (R3) Teenagers need peace and quiet in their lives to develop into the person they want to be. (C) So the big increase in texting can be seen as restricting the psychological development of teenagers.

 

We’ve just had an argument with three reasons. There is no limit to the number that you can have in an argument.

In this argument, we have five reasons supporting the conclusion. You will perhaps have noticed that they are five independent reasons.

It might be helpful to have a brief recap at this stage.

There is one more feature of this process of inference which needs to be noted at this stage. We’ve seen that the process of inference can involve any number of reasons (so long as there’s at least one). But, perhaps oddly, the process of inference can involve any number of conclusions too. The oddness of this comes from how we described a conclusion. We said ‘it’s where the argument has ended up. It’s the final destination. It’s where the author of the argument wants to go’. This does seem to directly contradict the idea that there can be more than one conclusion.

To resolve this apparent contradiction, we need to see arguments as a bit like a journey. If you’re setting off to travel somewhere, you know where you want to end up, what should be your final destination. But you also know that you will pass through various places on the way. They are places you reach in order to get to where you want to go.

In this way, we can see that arguments might have inferences that are drawn on the way to drawing the final inference. Let’s look again at an example we used earlier.

The conclusion of this argument could be used to draw a further inference.

As you can see, what had been the conclusion of an argument has now become a reason for a conclusion in another. This is straightforward. After all, a conclusion is a claim that just happens to be used as an inference. But, because it’s a claim, it can be used to draw an inference. And so it can go on, with claims leading to
inference-claims
, which lead to further inference-claims, with no necessary end to the sequence.

If we put the last argument back on to the previous one, we can see what’s happening.

As we have seen, what was the conclusion of the argument has now become a reason for the new conclusion. But it’s important to note that, though it’s used as a reason to support the conclusion, it’s still a conclusion drawn from the three reasons. Because it’s now become a conclusion drawn on the way to another conclusion, it’s called an
intermediate conclusion
. An intermediate conclusion is one that is drawn on the way to the final or main conclusion. (Or, because there might be more than one, we can say that intermediate conclusions are drawn on the way to the final or main conclusion.)

So what does the structure of this argument now look like?

 

We discussed just above that there are no limits to the number of reasons in an argument. In that intermediate conclusions act as reasons, there must therefore be no limit to the number of intermediate conclusions in an argument. Of course there can be only one final or main conclusion. (You’ll see that this is given in the structure by ‘C’ to distinguish it from the intermediate conclusions.)

There’s another point that we need to consider here. Read the next version of this argument.

You will see that another claim has been put in between the intermediate conclusion and the main conclusion:
It is very important for teenagers to have the opportunity for
proper psychological development
. What function does this claim perform? It can’t be drawn as an inference from the intermediate conclusion. It does, however, act as a further reason from which the main conclusion is drawn. It was, as you might have spotted, sort of hanging in the air before we put it in. (This general point about reasons ‘hanging in the air’ will be looked at in detail in the next chapter.)

So, given that the new claim is a reason for the main conclusion, the structure of the argument will now look like this.

 

(You will see that IC and R4 operate as joint reasons.)

At this point, we now know how to unravel what’s going on in argument. We can reveal the structure and thus make sense of the lines of inference. That’s good, but we’re now going to meet something that’s part of the structure, but we have yet to see it. Weird? Read on.

We have so far concentrated on looking at the process of inference in two ways. We’ve looked at what’s involved in drawing an inference from a claim to create arguments. We’ve also looked at how arguments are put together, focusing on reasons and conclusions. In this way, we’ve got some understanding of how arguments work. Towards the end of the last chapter, however, we hinted that there might be something else going on. This was when we talked of a reason ‘hanging in the air’. We’re now going to look at such reasons in detail.

In looking at the process of inference, we see that someone judges that a claim is sufficient for an inference to be drawn. They have judged that the claim that supplies the reason (or claims that supply the reasons) justifies the conclusion being drawn. But it’s very likely that they’re relying on other reasons too, reasons that, as we have seen, are hanging in the air. Let’s look at an example:

This is a nicely simple argument. We have one reason (an evidence-claim) being used to draw one conclusion. The thrust of the argument is straightforward enough. Here are the age-groups that are a particular problem for crime, so we should target them with ‘strong deterrents’. Simple yes, but you might have thought that there’s quite a lot hanging in the air between the evidence-claim and the inference from it.

To uncover what’s hanging there, go back to the point we made in the first chapter. An evidence-claim just sits there as a neutral claim unless and until someone comes along and says ‘this evidence-claim has this significance’. This is no exception. And it’s when the inference is added, as you know, that the significance is given.

So what significance has the author of this argument given the evidence-claim? The evidence, they think, shows that we can do something about the problem of crime, that it shows us a way forward: strong deterrents are the way forward.

But, when we look at the evidence, it didn’t in itself show us that. So how has the author moved from an evidence-claim to a recommendation? By adding in all sorts of other claims, claims that are necessary to bridge the gap between ‘here’s the evidence’ and ‘here’s what we should do about it’.

Let’s look at one of these:

You can see that, for the author to recommend that something should be done, they have to believe that this something hasn’t already been done. In this example, though the author of the argument hasn’t claimed that there aren’t already deterrents in place, they must accept or believe that they’re not.

So we’ve actually found another claim in the argument. Technically, it’s another reason, because that’s how it’s doing its job. Put it into the argument to see why it
must
be there.

What we have found is a missing reason, a reason that forms part of the argument, indeed a necessary part of the argument. But it’s not stated. We have found what is called an
assumption
. The author has assumed this reason rather than stated it.

Let’s see if there are any more of these assumed (unstated) reasons.

This has to be accepted by the author. As with the claim that there weren’t already deterrents in place, it’s a necessary part of the move from the evidence to the inference. If the author didn’t believe this to be the case, then their inference doesn’t follow. Let’s put it into the argument and see how it fits well.

Again, we can see that it is an essential part of the argument, essential in that it’s a necessary reason for the conclusion that’s been drawn.

Here’s one more:

If the author thought there were better ways, then their conclusion is an odd one. Why recommend strong deterrents, when other methods would work better? So here’s yet another additional, necessary reason.

We’ve so far found three claims that the author of this argument had to accept as an essential part of their argument. A useful way of thinking about assumptions is to picture an X-ray machine at work. When we see a person (or animal), we see only so much, only what’s presented to us. But when this person (or animal) stands in an
X-ray
machine, then we see much more. We see, in particular, their bones. When we see the skeleton, we realise that what we see on the outside is only part of the full picture. In fact, in all sorts of ways, what we see on the outside is only a small part. Without the skeleton, the body collapses.

This is what is going on when we look at an argument. We normally see only a small part of it. (This gives us another way of looking at what’s going on with assumptions – think of them like the biggest part of the iceberg, the part that’s hidden under the water.) When we look for assumptions, we’re seeing so much more. We’re seeing much more of the full content of the argument.

Let’s just be sure as to what assumptions are.

Because assumptions are necessary reasons, this means that they’re not to be confused with possible additional reasons that might be relevant to an argument but which are not required by it.

Here’s an example:

If we put this into the argument, it serves well as a reason for the conclusion.

However, it is not
essential
for the conclusion. We know this because the author could still argue the way they do by believing it not to be true. Let’s see this.

So here we have an important point. An assumption isn’t just relevant to an argument; it’s essential to it. This distinction between relevant and essential is crucial in looking for assumptions.

Let’s just return to the point we’ve just looked at, when we made the distinction between an essential reason in an argument and a relevant reason. You’ll remember that we tested for essential or relevant by putting the opposite version of a claim in the argument. We found that, if the author could still argue the way they did with the opposite position in their argument, then the reason was not essential, therefore was not assumed. However, if the opposite version made the conclusion an inference that simply couldn’t be drawn, then we have found an assumption. This is what is called ‘the negative test’ (a term I introduced some years ago). Let’s use it on the argument we’ve been considering.

We’ll put in the opposite of one of the assumed reasons we used earlier (shown in italics).

This negative version now makes nonsense of the conclusion: strong deterrents wouldn’t work, so introduce strong deterrents. You can see how, using the negative test, we can easily check whether a claim is assumed or not.

You might be wondering why it works. The answer is simple. Conclusions that are drawn from reasons that go in the opposite direction are rightly seen as nonsense (or odd, at the very least). It’s a straightforward point that arguments should not contain what amounts to a contradiction.

This, of course, stops you in your tracks. The conclusion goes the wrong way: presumably the UK could learn nothing from the Finns about how to increase the imprisonment rate for young people. Instead, given the evidence in the argument, the UK could perhaps learn from the US.

Assumptions are found not only in arguments. They’re also found in explanations.

Here we read of what Ms Turner-Stewart did in response to the problem of graffiti in her local park. It is an explanation of why she decided to be a councillor. There are, however, missing parts of the explanation which are needed to make sense of it.

Ms Turner-Stewart obviously slotted the second of these assumptions into her plan based on her understanding of the political reality of Surrey. In the 2009 elections, of the 80 councillors, 56 were Conservative and only one was Labour (with the rest divided between two other parties). Unfortunately, we don’t know if the graffiti in her local park was reduced as a result of Denise’s personal plan (but let’s hope so).

It’s important to note, before we move on, that finding assumptions in an argument is not an exercise in working out whether an argument’s good or bad. It’s a neutral exercise of finding missing reasons in an argument. When supposed experts tell you otherwise, they’re wrong, simply wrong. It might well be that we can look at what an author has assumed and go on to ask questions about this, but that’s not the same as simply finding them.