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Premises

If you look closely at all the reasons and objections in Tutorial 1, you'll see that each one contains a claim.  A claim which is inside or part of a reason or an objection is known as a premise


This reason contains a claim. The claim is a premise.

Here is an alternative way to map the simple argument. It displays the premise as a distinct claim.
 
Discussion

Premise is a technical term.  In ordinary conversation people (mis)use it in many ways, but for us it has a specific meaning: a claim which is part of a reason or objection.

The key point right now is that if you look closely at reasons or objections, you'll see that they are made up of distinct claims, which we call premises.

 
New Concepts

A premise is a claim which is part of a reason or an objection.

Multiple Premises

Sometimes when people present reasons or objections, it is clear that they have provided two claims as part of a single complex piece of evidence. That is, they have provided more than one premise.  Consider this argument:

When there are two or more explanations for some events, the least complicated is to be favoured.  The least complicated explanation of the Apollo events is that the astronauts landed on the Moon. Therefore, the Apollo astronauts did in fact land on the moon. [based on 9.8-9]

In this passage, there is only one reason to believe the contention, but there are two distinct claims in that reason, i.e., two distinct premises.  The two premises "work together" to support the contention.

We could map the argument this way, lumping all the premises together in one reason box.

Or we could map it by putting each premise in its own claim box.  This shows much more clearly that there are two distinct claims.

 
Discussion

There are various ways to diagram arguments with multiple premises.  The particular type of diagram shown above follows the approach used in the Reason!Able software.  The crucial thing is that the diagram show that the premises belong together as part of one reason or objection. In the diagramming approach here, this is shown by the lines joining together before they connect to the contention

Co-premises

Multiple premises working together as part of a single reason or objection are known as co-premises. A co-premise helps connect ("co-nnect") the other premise to the contention

 
Discussion

Two premises are part of the same reason or objection when they are working together. Roughly, two premises work together when each one needs the other so that they can, as a group, provide evidence for (or against) the contention.  They don't stand alone; rather, they work hand in hand to show that the contention is true (or false).

Example:

You can see how when both of these premises are true, you have a reason to believe that the Apollo astronauts landed on the Moon.  However if either of them is false, the other one is not enough on its own.  Thus, the premises are working together.

Another intuitive way to understand this notion of co-premises working together is to think of a co-premise as what connects the other premise(s) to the contention.  It makes the connection or bridge between claims which otherwise might seem unrelated or only partially related. 

Don't worry too much if you're not 100% clear yet on this notion of "working together."  We will clarify it a lot in the following pages and tutorials.  However it is worth mentioning right now that this is one of the most difficult of all the concepts we will deal with.  Getting it right is one of the biggest challenges in argument mapping!

Technical point: The notion of co-premise is relative. Nothing can be a co-premise on its own, just as you can't be a husband or a sister on your own.  Husbands are only husbands in relation to wives, and sisters are only sisters in relation to their siblings. Likewise, premises are co-premises in relation to other premises, as long as are part of the same reason or objection.  Two premises are not co-premises in relation to each other if they belong to different reasons or objections.

Logicians use various terms to refer to co-premises.  Some others you might come across are:

Note for Reasonable software users: Reasonable uses the term "helping premise" where these tutorials use the term "co-premise." In other words, helping premises an d co-premises are the same things.
 
New Concepts

Co-premises: Two premises within a single reason or objection are co-premises in relation to each other.

Golden Rule

We now come to one of the most fundamental principles of reasoning and argument mapping: Every simple argument has at least two co-premises.  This is the Golden Rule.

The Lunar Roving Vehicle was 3.1 metres long by 2.3 metres wide, and 1.14 metres high. As the Lunar Module's descent stage was only 4.3 metres in diameter by 3.2 metres high, one might think this would not have left much room for the remaining equipment. [8.4]

An example of an argument with two premises. Notice how the premises "work together" as part of one reason for the contention.

 
Discussion

Notice the "at least two" in the Golden Rule.  Simple arguments can have more than two premises; we will see examples later.  However two premises is the simplest and most common case.

Now you can see the point of the technical definition of a reason mentioned in Tutorial 1.  Every reason is a set of claims (premises) working together to provide evidence for another claim (the contention).  That set always has at least two members. 

 
New Concepts

The Golden Rule: Every simple argument has at least two co-premises.

Hidden Premises

Usually when people provide reasons or objections they don't explicitly state all the premises.  In other words, people typically "hide" one or more co-premises.

Artificial lighting was used when the Apollo pictures were taken, and therefore the pictures were taken in a studio on Earth. [Based on 5.1]
 
In this simple argument, only one premise is provided.  Any others are currently "hidden."

What is the hidden co-premise?  What claim "works together" with the stated premise so that both together can provide evidence?

Here is one suggestion as to what the hidden premise might be.

 
Discussion

If, as the Golden Rule says, every reason or objection has at least two co-premises, why do people usually hide some of them? Often, co-premises are obvious or uncontroversial and don't really need to be explicitly stated.  However there are many other explanations.  People tend to be one or more of the following...

When people hide co-premises, they are leaving it to us, as listeners or readers, to fill in the gaps.  This often involves a lot of effort and skill.

Since argument mapping is all about making the structure of reasoning explicit, if we are doing our job in a completely thorough way, we will identify all co-premises, which means identifying all hidden premises.  This is one of the biggest challenges in argument mapping.

Logicians also use various other terms for hidden premises.  Some you might encounter include:

 
New Concepts

A hidden premise is a co-premise which is not actually stated when an argument is presented.

Rabbit Rule

In the remainder of this tutorial, we will explore some simple principles which help us identify all the co-premises in a simple argument.

The first principle is the Rabbit Rule.  It says that any significant term or concept which appears in the contention must also appear in one of the premises. 

This classic, simple argument conforms to the Rabbit Rule.

This simple argument from Tutorial 1 violates the Rabbit Rule. It is not yet properly mapped.

 
Discussion

The Rabbit Rule is one of the key principles of structure for simple arguments.  A fully articulated simple argument MUST obey the Rabbit Rule.

Why is it called the Rabbit Rule?  The idea behind the rule is that you can't pull rabbits out of hats just by magic.  If a rabbit appears above the hat, it must have been put in there previously.  In argument mapping terms, nothing can magically appear in the contention; it must have been put in the premises first. 

The Rabbit Rule is a very simple idea.  However, properly applied, it has an amazing - almost magical! - effect in forcing hidden premises out into the open.  But the simplicity of the Rabbit Rule is in a way misleading.  Applying it properly is often a lot harder than you would expect.

Corresponding to the Rabbit Rule there is the Rabbit Test.  This is a simple test to determine whether you have a properly structured argument.  To apply the Rabbit test, just examine the contention to see if there are any significant terms or concepts which appear there but not in any premise.  If there are any, the argument fails the Rabbit Test.

Applying the Rabbit Test will give you clues as to what is going to have to go in any additional co-premises required to make the argument properly structured.

 
New Concepts

The Rabbit Rule: every significant word, phrase or concept appearing in the contention of a simple argument must also appear in one of the premises.

Using the Rabbit Rule

The Rabbit Rule helps us identify co-premises by telling us some of the key terms or concepts which should appear in them.

In this example there are two terms or concepts which currently violate the Rabbit Rule.  Since they don't appear in the first premise, they will have to appear in some additional co-premise(s).


Using a little creative thinking, we come up with something which uses the key terms and concepts and seems to be the right kind of claim for the job.
 
Discussion

The Rabbit Rule gives us strong clues as to what the missing co-premise should be, but it doesn't mechanically determine the outcome.  We still have to think hard about it to come up with a proper sentence which uses one or more of the terms or concepts from the conclusion, and also makes sense in the context of the argument. 

When adding co-premises, you do need to be careful what you add.  A poor choice of co-premise will create as many problems as it solves, for as we will soon see, any terms or concepts in the premises also have to be properly tied in to the rest of the argument. 

Holding Hands Rule

The second principle is the Holding Hands Rule, which says that if something appears in a premise but not in the contention, it must appear in another premise. That is, premises need to hold hands with each other!

This classic, simple argument conforms to Holding Hands (as well as Rabbit).

 
Discussion

Where the Rabbit Rule helps ensure that the contention is appropriately tied to the premises, the Holding Hands rule helps ensure that the premises are appropriately tied to each other.

Corresponding to the Holding Hands Rule there is the Holding Hands Test.  This is a simple test to determine whether you have a properly structured argument.  To apply the Holding Hands test, just examine the premises to see if there are any significant terms or concepts which appear there but not in the contention or any other premise.  If there are any, the argument fails the Test.

Applying the Holding Hands Test will give you clues as to what is going to have to go in any additional co-premises required to make the argument properly structured.

 
New Concepts

The Holding Hands Rule: every significant word, phrase or concept appearing in a premise of a simple argument but not in the contention must also appear in some other premise.

No Danglers

[Tutorial_2/9_No_Danglers/no_danglers_text.htm]

Summary

[Tutorial_2/Summary/summary_text.htm]