Is formal logic primary concerned with the form of arguments?

Question

Or is it the content of the argument? and what about Informal logic?

Answer 1

I would say yes to the first, since ALL logic is argument, formal or not. Logic, though, is neutral. If logic is used correctly, so long as the original premises are accepted by another, that other must also accept your logical conclusions. However, such perfect logic is difficult to construct.

Ok, think I lost myself LOL

Answer 2

It has been a while since I studied this, but I believe that formal logic deals with the forms of argument, reducing them to a quasi-mathematical format that couldn't care less whether you're talking about roses, galaxies, or dump-trucks. Informal logic concerns itself with the specific forms of things, the content of the argument, in which roses and galaxies and dump-trucks are very different by nature -- although it, too, makes use of formal structures, like classic syllogisms.

Answer 3

What's meant by 'informal logic' is the whole subject of reasoning other than the study of the forms of arguments.

There are three (not two) basically different sorts of reasoning: analogy, deduction, and induction. (Analogy is usually classified as induction, but it shouldn't be - it's basically different than what is usually referred to as induction.)

What's usually meant by 'logic' is the study of deductive arguments, and 'formal logic' is the study of the forms of those arguments.

What's special about deductive forms? They are, when they are VALID, the only forms that guarantee a true conclusion from true premises.

Logic and formal logic are mainly the study of how to tell a valid deduction from an invalid one.

Informal logic is mostly concerned with fallacies - ways arguments can be faulty. Apart from deductive fallacies (that is, invalid deductions) there are two main categories of fallacies:

1. Fallacies of CONTENT. The basic fallacy of content is a false premise. Apart from that, fallacies of content are basically fallacies of confusion - that is, of wrong identification. A prime example is the fallacy of 'double meaning', which is when a word is used in two different senses in the same argument. Here's an example:
Arnold is very healthy.
Smoking is not very healthy.
Therefore, Arnold is healthier than smoking.
(A silly example, but it shows why you must give just one meaning to the words in an argument.)

2. Fallacies of CONTEXT. Basically, this means either leaving something out of an argument that should be there because it is relevant, or including something that should not be there because it is irrelevant. A prime example of the latter is the fallacy of 'straw man', which means arguing against claims that are irrelevent because your opponent's argument does not make those claims - you have imported them into yours and your opponent's arguments, but they don't belong there.

Answer 4

According to web definition, the informal logic deals with natural language arguments while formal logic concerns itself with study of inference with pure, formal content. Visit the website for more interesting definitions of various branches of logic.

Answer 5

Formal logic is mostly concerned with expressive power of the language.

See for example such great logical results as:

Compactness theorem[1]
Löwenheim–Skolem theorem[2]

And a more recent AMAZING development:
Fagin's theorem[3] Which connected logic to computer science

All have to do with expressive powers of language.

Answer 6

No, it is not. Formal logic is about the truth-value of propositions and establishing that through knowledge of verifiable relationships between classes, terms and predicates.