[Jan-Poo]

Originally Posted by Wanderer

I still hold the claim that any logic used about the "truth" of Umineko requires assumptions that other people can't accept, and are thus circular arguments.

And I still claim that an assumption does not necessarily implicate a circular logic. Frankly the last thing I think when I assume X is that by assuming X I can argue that X is true.
By the way you make it sound as if it is just something related to Umineko while many theories in physic are based on assumptions.
Actually one could say that the very scientific method is based on an assumption.

Originally Posted by Wanderer

Actually, now that I look at it, this whole argument you made here is demonstrably circular:

You see, Ikuko not being Yasu was necessary for your premise to be true because only if Ikuko is not Yasu can she exist as an example of someone other than Yasu.

• Implicit: Ikuko isn't Yasu.
• Explicit: (Therefore) Yasu didn't adopt an amnesiac <==(ONLY TRUE IF IKUKO IS NOT YASU, THUS THE IMPLICIT PREMISE)
• Explicit: Therefore Wanderer can't show that Yasu didn't do it without being circular, which is a fallacious argument anyway.
• Implicit: Therefore Ikuko isn't Yasu.

So there you go.

Your interpretation of my statement is wrong.
The whole discourse until that point was about commonalities between "Battler" and "Tohya" and "Yasu" and "Ikuko" to demonstrate which would be the case with more coincidential similarities.

"Ikuko" in this case refers to the person that goes by that name and that is presented with the specific sprite of Ikuko. No assumption about her identity other than that was made.

"Yasu didn't do it" refers to the fact that the one that we are certain (or that we both can agree that) is Yasu, didn't do that.

Therefore a relation cannot be established.

To make a comparison it's as if I said that Battler and Tohya are the same person because they are both amnesiacs. You'll be well entitled to argue at that point that excluding Tohya\Battler (whose identity is being argued) we cannot say that Battler was an amnesiac at all.
For the same reason excluding Ikuko\Yasu (whose identity is being argued) we cannot say that Yasu ever adopted an amnesiac nor that there is a hint that she would do that.

I hope it's clear now.

As a side note, just to be sure, I will not accept any kind of argument on the line: "If you do not accept my assumption that Yasu is Ikuko then you automatically assume she's not!"
This kind of reasoning would deny the fact that it's possible to make reasonings with unknown variables.

Originally Posted by Wanderer

"A well defined formal fallacy, logical fallacy or deductive fallacy, is typically called an invalid argument. An informal fallacy is argument that may fail to be rationally persuasive."

So in fact, not only do these two quotes not support your argument at all, but one of them actually supports mine.

That's still a long shot from claiming that an "informal fallacy" is a "valid logic" or that "fallacy" and "valid" aren't antithetic. All that you have proved so far is that an "Informal fallacy" is not "formally invalid" which is almost tautological since if the fallacy is informal that means there's no fallacy in the form.

Originally Posted by Wanderer

Of course it does. But as far as I can tell you've been arguing that circular reasoning is invalid by definition, not by opinion.

In the context of a discussion it's always invalid by definition. I think the article you asked me so many times to read is almost entirely focused on demonstrating that.

Originally Posted by Wanderer

What's your point? That there must be 2 or more premises? You can always decompress any argument into a syllogism or sequence of syllogisms, right?

And what's with you pulling a logic-related definition after claiming you're not using logic-lingo?

That's not just my point since I quoted a dictionary. You interpreted "jointly asserted" in the wrong way, by the way.
http://dictionary.reference.com/browse/jointly
What it means is that both parties involved in the discussion must agree that the premises (or the premise if it's one) are true.

Anyway I think I demonstrated that it is perfecly legit in english to state that a "logic is invalid" even in those cases where the fallacy is purely informal. Because even if you say that a specific termonology would require you to rather say that the "logic is unsound", it is a fact that "valid" and "sound" are generally treated as synonim.

Originally Posted by Wanderer

There are two ways I've got at the moment to approach the issue: 1) An appeal to the theme of miracles. 2) It's not a coincidence (as in, Yasu-as-Ikuko knew where Battler would be for some reason).

You can't talk about how your theory is more probable than mine if you appeal to miracles.

Originally Posted by Wanderer

By the way, what do you think Ryuukishi was doing with the 19ko pun?

The same thing that he was doing with the 34 pun. If Sayo isn't Miyo then Ikuko isn't necessarily Beatrice. "Spiritual successor" seems to fit nicely with both.

Anyway if you are arguing that Tohya isn't Battler, then you can no longer say that a number pun must definitely implicate that the characters involved are the exact same person.