Formal and Informal Logic

Jazzn makes a distinction between "reason" and "logic."

So I suppose we can call reason "informal logic" and what he's referring to as "formal logic." Not being versed in formal logic, I can't speak of it.

But I and everyone else knows what I mean when I speak of "informal logic" or Reason. The question is whether the sort of reasoning I habitually employ has any validity, and if not, why not? Here's a sample:
Brute or Blackguard

I am well aware that there are some puzzles in the above argument, but one does what one can. This is a sample of what I call "informal logic."

My reasoning is the reasoning of people in general, not of someone who specializes in "logic." What makes it seem so important to me is that I think of it as a handle on reality. If this handle is broken, then I am out of touch with reality. This is why I reacted so strongly to the idea that I "don't understand logic." If I don't understand logic, then I am living in a mad maze. I have no handle on reality. Informal logic has to have some validity in order for the handle to be real.

Thread moved here from the Proposed New Topics forum.

A warning to all who will participate in this thread.

There is already a personal tension level attached to this topic and I'd appreciate it greatly if everyone participating would remember what the Encylopedia Brittanica says about debate.

Usually, in a well-conducted debate, speakers are either emotionally uncommitted or can preserve sufficient detachment to maintain a coolly academic approach.-- Encylopedia Brittanica, on debate

Please preserve detachment and try to maintain an academic approach.

Pay special attention to rules #4 and #10:

#4 - Points should be supported with evidence and/or reasoned argumentation. Address rebuttals through the introduction of additional evidence or by enlarging upon the argument. Do not repeat previous points without further elaboration. Avoid bare assertions. #10 - Always treat other members with respect. Argue the position, not the person. Avoid abusive, harassing and invasive behavior. Avoid needling, hectoring and goading tactics.

If this turns into a personal scrap or overall brawl, I will shut it down in a heartbeat.

Let the discussion begin.

Might what you call "informal logic", or "reasoning" just be "common sense"?

You know, the common snese to not put your hand on a hot stove.

Common sense has some validity, as far as figuring things out.
2 + 2 = 4 makes sense, and could be "common".
the earth is flat makes sense, and is "common".
It makes sense that the earth is flat--after all, you never see it curve, so long as you're on the surface.

Common sense also says things like "don't get wet and cold--you'll get sick".

Some of this is quite valid, some quite erroneous (flat earth). As a general idea, I would say that common sense is valid.

Maybe some others can expound further on this.

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All a man's knowledge comes from his experiences

Help me remember the context here robin. What was the thread that motivated you to start The problem with EVC? I would like to see if we can look at some more examples.

In general:

nformal logic has to have some validity in order for the handle to be real.

The problem is that informal logic is subjective. Informal logic may subjectivly tell us that Galois theory is totally crazy. It allows us to abstract down the entire known universe of number spaces into a few well understood parts that you might say shouldn't be done because we "loose our handle on reality". Formal logic though allows us to prove that such an abstraction is valid though and by doing so we use this to map mathematics to the known universe with somtimes suprising accuracy.

Also, as soon as you introduce a subjective (ie. informal logic) assumption into the discussion you can no longer speak with the authority that your conclusions are supported by the process. A subjective assumption might be made on the basis of the universe making sense but sometimes reality DOES NOT make sense.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

I think there is some misunderstanding in what informal logic is. First of all, it doesn't deal with facts, whether the facts are derived intuitively or imperically. The examples you provided...

quote:

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2 + 2 = 4 makes sense, and could be "common".
the earth is flat makes sense, and is "common".

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have nothing to do with informal logic. These are either known or unknown facts.

Informal logic deals directly with how language works and how a conversation can make sense to everyone. In other words, informal logic deals more with how facts backed up rather than what the facts are.

For example, 2+2=4 does not involve logic, but statement like "2+2=4 because it is a mathematical axiom." Another logical statement is "The Earth is flat because all our observations seem to indicate that it is flat and there is no evidence that we know of that say otherwise." Simply saying the Earth is flat is not logic. It is simply an assertion.

So, in response to your suggestion, I would say that logic, whether it is formal or informal, is very different than common sense. Logic deals with conversation and how facts are presented while common sense deals more with one's own intuition of what the facts are.

apparently people were right when they said I had no common sense.

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All a man's knowledge comes from his experiences

The problem is that informal logic is subjective.

I don't see why informal logic need be subjective. I suppose a standard syllogism is objective (though perhaps outmoded formalism), and informal logic uses deduction in this syllogistic fashion, though written in an informal style.

ABE: If a flawed syllogism is written, one can easily recognize it without any training in "formal logic." Surely that recognition is not subjective.

Edited by robinrohan, : No reason given.

I don't see why informal logic need be subjective.

Lets see if we can work with an example. Can you help me remember what thread came before the "Problem with EvC" thread?

Alternativly, can you rehash your argument for the equivalency between God and FSM?

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

Lets see if we can work with an example

I've already given you an example in the link in the OP.

Edited by robinrohan, : No reason given.

we can work on that one too. I had in mind the ones that motivated the Problem at EvC thread because that is where all this started. I just didn't remember what the original thread was. That MAY be it. Can you confirm.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

There's that "odds of God existing" thread which I took such grief about. But when I do a search I can't seem to find it. I'll look some more.

Here it is:

I said in another thread: So according to my scheme, there is a 50/50 chance that God exists.
Another poster said: I would really like to see this scheme layed out (perhaps in a new thread?)

So here it is:

There are 2, and only 2, possibilities for the origin of the universe: 1. it was created by an eternal Being 2. The universe has always existed in some form All other possibilites can be reduced to these two. A Pagan-style God, for example, a God that arose from nature, would reduce to option #2. Such a God would be logically unnecessary. It we say that perhaps the universe came into existence as a result of some other universe, that also reduces to #2. The options are Nature (an eternal thing) or a god (an eternal being). Now, if all we consider is the fact of creation (rather than the nature of that creation--problematical to say the least), there is no reason to choose either option 1 or option 2. We might as well flip a coin. The odds are 50/50.

Edited by robinrohan, : No reason given.

That sounds more familiar. I had in mind the discussion of the equivalence of God and FSM. I seem to recall that that is where I got my motivation to reply in the Problem at EVC thread.

I am working on your OP link now.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

Let me try to provide some perspective here.

An argument using logic is expected to be of the form:

premise 1;
premise 2;
...
conclusion A;
conclusion B;
...

Here each statement is either asserted as a premise, or follows from the preceding statements in accordance with the rules of logical inference. These rules of inference are based on the form of the statements.

When you present a logic argument, then there is a sense in which your argument is protected. Specifically, your argument can only be challenged in one of two ways:

one or more of the premises can be challenges;

you can be challenged if your argument did not properly follow the rules of inference (that is, if you committed a fallacy).

It is okay to say "logic implies X" or "X follows from simple logic". That would be an informal argument. However, if somebody disagrees with your informal argument, they might challenge it. And they would normally challenge it by demanding that you show the logic (present the argument in logical form). At that point, you have two choices. You can either withdraw the claim that you were using logic, or you must present the argument in logical form (so that the person who disagrees can either find a fallacy or challenge your premises).

My recollection of earlier threads, is that you made some informal arguments. But then you insisted on the protection of logic without actually exposing your premises or the details of your argument to challenge.

The point about FSM had to do with what kind of entity FSM was supposed to be. In order for the satire to work, FSM had to be a concept on the same level as the concept of God (possibly non-extraneous). If FSM is the Creator, then he's just another name for God, and so the satire would seem pointless. If FSM is without question extraneous (not possibly necesssary), then the comparison would not hold.

Hopefully this will be an accurate summary of the argument at the link in the OP.

1. Starting from a belief/acceptance in evolution.
2. Given the Christian God and the concept of the fall.
3. Evolution and the fall are incompatable because if not then God is cruel.
4. God being cruel is equivalent to God not existing.
5. Without the existance of God, morality is subjective.
6. Without an objective morality we cannot judge if God is cruel.
7. Therfore to judge that God is cruel requires that God exists.
8. Thus if God does exist he must be cruel.

Somehow I don't think I captured it right because 8 seems out of place considering 4. I guess I don't really see a conclusion here. I see more of a quandry then anything that we could call informl logic leading us to a conclusion.

Beyond that most of everything in there is TOTALY subjective. Maybe you can how me how if anything in there IS ACTUALLY objective.

1. Evolution may be wrong, but that is a small point and unlikely.
2. Has many subjective elements.

• God may not be the Christian God.
  
• The concept of the fall may not be true.
  
• Christian theology does not require the concept of the fall.
  

3. This entire premise is subjective and you even outline it as such later in 8.
4. Also entirely subjective as you also show specifically to be in 8.
5. Entirely subjective on its own. There very well may be a logical way to construct a morality without God depending on what "morality" is defined as.
6.
7.
8. All depend on the previous.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)