LOL! I never thought that the interface was that bad. But the main reason for the multiple threads is partly due to the fact that I haven't been able to do all of them at once, but rather in increments. Also, some good has come out of the multiple threads because if people have specific questions pertaining to a certain sections of propositional logic, they are able to place them in the appropriate area. But the main goal (at least of these logic threads) is to help people along with the material rather than putting the material out and leave it solely up to that person to get it. There are many logic text books and logic websites on the internet, but only a scant few that novices can easily adapt and learn from, as well as post questions and ask for practice problems if they wish.

But the idea of a online logic textbook is a great idea though. It would be neat to add another volume to the many that already exist. In my own opinion, that has been the big gripe with propositional logic which is there is not yet a defined system with set symbolization and so on. I have spent god knows how much time deciphering other peoples systems. I learned from three textbooks for propositional logic alone, which is utterly ridiculous.

Your tutorials are actually pretty good, although I'm not quite sure anyone could just beam up the page and really start understanding it though (not to say the same could be said of mine either). But anyway, good ideas though.

The issue with creating an ultimate logic textbook is the fact that you run the risk of just creating a new, more dilute system.

To be honest, your elaborations are just as confusing as many other logic sites around. Though it makes sense to some with previously developed knowledge of propositional logic and above, I wonder if a complete new comer would be able to sit down and comprehend your explanations on the first go. That was one of the reasons why I put the logic threads up in the first place. Anyone can do it, its just has to be conveyed in a down-to-earth way step-by-step "clearly and distinctly."

However, I do agree that many logic books don't go nearly as in-depth as to translations than they do other points. Its funny because it seems like the most useful thing to take away from this type of logical system.

There are always risks. The main issue is that there are no good online logic textbooks and definitely not in danish. It is very important for all persons to learn logic and the lack of good introductory books is a set off, especially when they don't come in the person's natural language.

Well. Sub- and sup-scripts are useful for many things. I'll mention a couple of examples: Distinguishing between two or more meanings of a single word e.g. atheism_1 and atheism_2. Formalizing certain sentences without resorting to second-order predicate logic, one can use P_1, P_2, P_3, ..., P_n instead of (∀P). (I'm not very familiar with second-order predicate logic and I hope I got this right.) I have proposed using sub-scripts to enable formalizing sentences that contain more than one alethic operator i.e. logical, physical and epistemic possibility and necessity. (See this essay which is a minor version of my danish essay on the topic.)

That's ok. My writings are not intended, so far, as a logic textbook. Only as supplementary to a person who already knows some logic.

The interface of this forum makes it annoying to read your textbook. Perhaps you should copy/pasta it into a single PDF file? Have you tried? It would be easier to spread it then.

I think the translation part is very important and it is a sad fact that many textbooks do not spend much time on this. It is not an 'exact science' to translate normal language into a logical language. It involves guessing the intended structure of the sentences etc.

To anyone else reading this. I did not start this new thread. A moderator moved some of my posts from another thread to this thread.

Logic is definitely is an important tool to know and utilize. As far as introductory logic books (at least in English), they are about a dime a dozen. All with different symbolization and so on. I'm surprised that there are not many logic books translated into Danish, or at least by Danish authors.

I'm sure they are. Actually, I know they are because one of my logic books "The Logic Book" by Bergmann et. al.) uses the same symbolisms. The issue comes when little Timmy (reading Bergamanns book) and old man Bob (reading Herrick's "Many worlds of Logic") come together to talk and find out their Q's are different from their P's. Especially as far as predicate logic, the universal quantifier comes off as merely (x).

But doesn't that seem rather redundant though to provide a basic text for someone already familiar with it to begin with?

It would seem more beneficial (to me) to impart basic information to people who don't know it to begin with. As to the forum and the interface, it would be neat to collect it all into one pdf file. However, I haven't even finished half of the propositional section let alone the predicate, modal, inductive, etc. sections.

Fair enough. On the subject, the closest I have come to a good introductory text book for most modes of logic is Paul Herrick's "Many Worlds of Logic." I have found it the most useful to reference and the inference and replacement rules are mostly as unified as it comes compared to some of the other books that I have. This one book, Bergmann's "The Logic Book," is complete garbage as far as basic accessibility is concerned, although it does possess a good deal more developed reasoning than Herrick's does, so it's good to use as a refresher every now and again. But damned if that book is universal though, which is the annoying think about it.

As far as symbolization, that has been a somewhat irritating hurdle to jump over every time someone has a question about logic. But not only in relation to that, but to proof organization and so on. As to the definition of the bi-conditional you had mentioned, I'm sure you can admit that many people are not as acquainted with the subtleties of connectives as others are, even though it's (most times) completely obvious. Its something I always have to come back to at one point or another for a lot of people who ask questions.

Wouldn't it be better to have a single thread and then create a single PDF file that people can learn from? Reading on this forum is terrible due to bad interface. In that way we'd have a somewhat complete online logic text book. I also have some logic material on my website.

Complete arguments
About the notion of complete arguments and how to properly present arguments clearly.

Inference and replacement rules
A resource on all the commonly used inference and replacement rules.

Logic symbols
A huge table of ready to use (i.e. copy) symbols that are used in logic.

P-list
A program that lets you easilier copy/paste the symbols in the above resource, and it let's you use hotkeys! I have converted the NumPad to a LogicPad.

Truth tables and their construction
About how to construct truth tables.