Formal and Informal Logic

Fair enough but I don't understand why there is a problem.The specific discussion was about the logic.
The actual subject matter of free will was just a convenient example of its use and whether formal logical deductions were valid or not in that context.It is a little difficult to discuss logic without a medium through which it can be applied.

The way it was being discussed got confusing.Jazzn made the claim that all informal logic is subjective, but I don't think he's made much of a case at all for his position.

I could arbitrarily change the name of 'heads' to 'tails' and vice versa. I could even call them 'faces' and 'symbols'. It would make no difference whatsoever. However, there being a God or an infinite universe cannot be swapped so simply around since there is a lot more to it than that. Created by eternal being and eternal universe are not indistinguishable except for their names. When you applied your logic you did not justify your use of the principle of indifference.

I'm not entirely sure I have even seen a decent example of what "informal logic" even is.We have defined formal logic pretty well but so far the informal examples seem kind of fuzzy and poorly defined. I mean the concept of informal logic rather than the actual arguments.

It's logic written in an informal style (normal prose).

That sounds just like formal logic but possibly not as well laid out. With a little refining the two would appear to be equivalent. ie. you can easily make this kind of "informal" logic into formal logic with a bit of thought and planning.I agree with asome of your points earlier in this thread where Jazzns was saying that you weren't using logic when in fact you were laying down the premises on which your logic is based. In such cases it does not matter whether your premises are true or not. They just must be assumed in order to perform the logical deductions on them. That is the same way that I worked the free-will discussion with Iano.As for "subjective" as a definition of informal logic. I'm not so sure about that.
We certainly cannot say that ALL informal logic is subjective if we take your definition of informal logic = "normal prose" because what you have there is possibly poorly defined formal logic that can quite well be totally objective.I would like to see an example of this subjective informal logic or of your normal prose logic so that we can discuss them in detail.

See the link in the OP.

OK but let's take it in small stages and see if we can convert your reasoning into a formal argument. To do that we will probably have to resolve each part as we go through it.
I see that Jazzns attempted to reduce the entire thing a little earlier but doing that is probably not the best way to go. First of all we have a couple of premises defined in this statement. it can be easily condensed to....

• God exists AND he is the one commonly accepted in Christianity
• The fall is true and explains all evil in the world

You go on to say.. This, on the face of it is a bare assertion. Let's see if it can be backed up with evidence. OK this is pretty convincing evidence I would say. It looks like you have a strong case for the impossibility of the fall and evolution co-existing.
The trouble is that now we have a major logical impasse.
In your premises you stated that the fall DID happen so that means that if you are correct and the fall is incompatible with evolution then under the rules of formal logic, evolution DIDN'T happen so it totally undermines your argument.Do you see the problem here?You either have to go back and change your premises before continuing or abandon all evidenciary deductions that sprang from anything remotely connected to evolution.

I don't see where he said that the Fall DID happen.

He said it right here. Then he goes on to talk about this being incompatible with evolution.
If you read the whole thing it is quite obvious that he used this as a given premise.
All I did was to formalize the argument.

No, I said that IF there was Fall, then it still does not provide an explanation for pre-Fall animal pain. I didn't have to mention the Fall. I did so as an anticipatory answer to the traditional Christian view.The argument is conditional: If there was a fall, if evolution is true.(however, I assume that evolution is in fact true).

Not at all. He's just saying what the Christian view is. He doesn't share it. To him it's completely hypothetical. Not at all. It's all hypothetical.Or as he said, a conditional statement. He doesn't accept the Fall. He believes in evolution.Edited by Faith, : No reason given.

I know you said IF.
That is the nature of a premise followed by a logical deduction.
IF this.... THEN that.
That is the way it works. There is no reason to actually believe your premise is true. This is actually two different arguments since you have already argued that these two are not compatible with each other.
If you advance both of these as initial premises (arguments if you prefer) then you kill your logic dead because it cannot continue beyond the paradox of them being mutually exclusive. I realize that but it is entirely beside the point from a logical perspective.In order to make your logical arguments you have to have

1. A solid starting point. (not necessarily a true one)
2. a valid logical progression from that starting point.

What you appear to have here is a starting point with 2 divergent paths. One if the fall is true and one if evolution is true since you also make the argument that they cannot both be true.
That is perfectly acceptable but you cannot use the conclusions from one path to affect the other since they are totally seperate.

I'm not doing that. The argument I was setting forth was that what might be called the "moral argument" against God is flawed because our morality is subjective. A subjective judgement cannot be evidence of anything, such as evidence that the traditonal good God cannot exist. So we can't disprove the existence of such a God by callng the happenings in the universe "cruel."

Logical premises ARE hypothetical. I know those are not his views but they lay down the framework for the logical progression from those premises.
He says....IF the fall is true (premise) THEN argument (logical progression) ---> Answer (Logical conclusion)Nobody says you have to believe your premise to be true. That is the entire point of formal logic.
The vast majority of formal logic arguments take hypothetical premises, then explore the outcome by making the assumption that they are TRUE for the duration of the logical argument.In order to work with formal logic, all parties must agree to the original premises before the discussion can begin. Just as you yourself have attempted to do with biblical literalism.The only point is that the formal logical argument must be free to Question the premises if the original outcome makes no sense or reaches a point where it disagrees with evidence.For example I could start with the premise that 2+2=5 then attempt to argue a mathematical equation to see where it comes out. I think you will agree that it will pretty soon become evident that the premise is wrong.Edited by PurpleYouko, : Corrected formatting