1. Introduction to Philosophy Lecture 3a Evaluating an argument
By David Kelsey

2. Evaluating formalizations
In this lecture we learn a new 4 step method to formalizing an argument. This method will consist of 4 questions that you ask of the passage the argument is contained within.
Second, we will learn how to evaluate an argument.

3. 4 Simple steps to formalizing
Here is a quick 4 step process to formalizing arguments.
The first 2 steps:
1. Are there any terms you don’t understand?
Here you simply ask if there are any terms or words or vocabulary that is unfamiliar or unclear to you
2. What is the issue of the passage?

4. Finishing the 4 step method
The final 2 steps:
3. What is the conclusion?
The conclusion is always the answer to the Issue.
4. What are the premises?
Here I am asking you to work backwards, from the conclusion to the premises given.

5. The Argument from Evil A passage by J.L. Mackie:
In its simplest form the problem is this: God is omnipotent; God is wholly good; and yet evil exists. There seems to be some contradiction between these three propositions, so that if any two of them were true the third would be false. But at the same time all three are essential parts of most theological positions: the theologian, it seems, at once must adhere and cannot adhere consistently to all three...However, the contradiction does not arise immediately; to show it we need some additional premises, or perhaps some quasi-logical rules connecting the terms "good", "evil," and "omnipotent." These additional principles are that good is opposed to evil, in such a way that a good thing always eliminates evil as far as it can, and that there are no limits to what an omnipotent thing can do. From these it follows that a good omnipotent thing eliminates evil completely, and then the propositions that a good omnipotent thing exists, and that evil exists, are incompatible. (This passage is taken from the first page of J.L. Mackie's Evil and Omnipotence.)

6. Terms 1. Any terms that you don’t understand?
Omnipotent, Wholly good, Evil, Quasi-logical, Theology, Incompatible…

7. The Issue What is the issue of the passage?
Lets take a look at the passage to help:
“In its simplest form the problem is this: God is omnipotent; God is wholly good; and yet evil exists.”
You can see straight away that the author is concerned with God somehow. What is it the author wants to say about God though? Let’s look at the passage to determine this.

8. The conclusion What is the conclusion of the argument?
Since the issue is whether God exists or not, the conclusion is just the author’s answer to this issue.

9. The Premises What are the premises of the argument?
What must the author have to get to the conclusion that God doesn’t exist.
Have a look at the first sentence of the passage:
”In its simplest form the problem is this: God is omnipotent; God is wholly good; and yet evil exists…”
What are the 3 premises we can pull out here?

10. The premises continued
Now have a look at this bit of the passage:
“However, the contradiction does not arise immediately; to show it we need some additional premises, or perhaps some quasi-logical rules connecting the terms "good", "evil," and "omnipotent." These additional principles are that good is opposed to evil, in such a way that a good thing always eliminates evil as far as it can, and that there are no limits to what an omnipotent thing can do.”
Do we need these quasi-logical rules the author speaks of?
1. A good thing always eliminates evil as far as it can.
2. There are no limits to what an omnipotent thing can do.

11. The argument so far The argument so far: 1. God is omnipotent.
2. God is wholly good.
3. Evil exists.
4. A good thing always eliminates evil as far as it can.
5. There are no limits to what an omnipotent thing can do.

12. Structuring the argument
Now consider the following claims though:
1. God is omnipotent.
2. There are no limits to what an omnipotent thing can do.
3. God is wholly good.
4. A good thing always eliminates evil as far as it can.
If God did in fact exist and all of the above was true then what has to follow?

13. Finishing the Formalization
We can now add in the premise that if God exists, then evil doesn’t exist. Since this premise follows from the first 4, we add it as the 5th premise:
1. God is omnipotent.
2. There are no limits to what an omnipotent thing can do.
3. God is wholly good.
4. A good thing always eliminates evil as far as it can.
Thus, 5. if God exists, then evil doesn’t exist.
6. Evil exists.

14. The Finished Formalization
So far we have 6 premises. But if you notice, from premises 5 and 6 we can infer our conclusion that God doesn’t exist. So we get:
1. God is omnipotent.
2. There are no limits to what an omnipotent thing can do.
3. God is wholly good.
4. A good thing always eliminates evil as far as it can.
Thus, 5. if God exists, then evil doesn’t exist. (from 1-4)
6. Evil exists.
Thus, 7. God doesn’t exist. (from 5 and 6)

15. Evaluating Mackie’s argument
To evaluate a formalization you need to look for weaknesses or flaws in the argument.
Since the premises of an argument work to support its conclusion, we must aim to show there is a weakness in the premises.
We can do so by making a counterargument.

16. More on counterarguments
You are probably asking now what a counterargument is?
A counterargument is an argument against another argument.
A counterargument is to the conclusion that another argument is faulty, problematic or weak.
Thus, I might with a counterargument, argue that a premise of some argument is false.

17. Developing counterarguments
Developing a counterargument:
One rather common mistake I see is that my student’s will develop a counterargument to the conclusion of an argument! This is to miss the point entirely.
To show there is something wrong with Mackie’s argument I need to show there is something wrong with the argument Mackie gives in favor of the conclusion. This means I must direct my criticism at the support for his conclusion, not at his conclusion.

18. Finding counterarguments to Mackie’s premises
Now we can look to build counterarguments to Mackie’s premises.
To build a counterargument to one of Mackie’s premises you don’t have to utterly destroy it.
Instead, just provide good reason for thinking the premise might be false.
Think about this in relation to the burden of proof…

19. Replying to Mackie’s argument
We might for example present a counterargument against his premise that evil exists.

20. A second reply to Mackie’s argument
Other counterarguments:
Consider his premise that A good thing always eliminates evil as far as it can.
We might try to cast doubt about this premise by suggesting that a good being like God might have reasons for allowing evil to exist.