mlqurgw said:
I just wanted to say that I didn't for a moment think that what I said was what you actually believed. I should have said that in my earlier post. While we may disagree on some things I do emphatically consider you my brother in Christ, which is something I am very careful about.
Well, thank you very much for your words of encouragement. I too consider you a dear brother in Christ, and am happy and thankful that we have this forum through which might have fellowship.
mlqurgw said:
Now a question that you, I am sure, can answer concerning logic. Would you say that there is a difference in formal logic and the normal way people reason? That is, is all reasoning logic whether it is correct logic or incorrect logic? I ask becuse I am trying to learn something of what logic is as I said earlier. I am becoming more convinced all the time that the saying that you can't teach an old dog new tricks is true. I think I may have killed too many brain cells before Christ revealed Himself in me.
Okay, this is a good question. It is best to answer it by saying what "formal logic" is and then comparing it to the way we ordinarily think. Now, formal logic, as its name implies, speaks of the "form" of arguments. For example, there are four basic ways you can assert something. You can say, "All a is b," "No a is b," "Some a is b," or "Some a is not b." These are the four different "forms" of logic. They encompass every possible proposition.
Now, the science of formal logic tells us which combination of these forms are valid inferences. For example. If I say all dogs are canines, and Fido is a dog, then Fido is a canine. This is a valid inference because the form of the argument is such that the conclusion follows necessarily from the premises. Now, you can already see in this proposition how human thinking frequently fits into this form. Not all human thinking follows logical forms, though. In fact, I would venture to say that
most thinking
does not. Part of the reason is because we do not always think "propositions." Propositions are basically declarative sentences. "All dogs are canines" is a proposition. "Do I need to go to the store?" is an interrogative, a question. Here is an important distinction: propositions are the only forms of language that can be true or false. Questions, commands, exclamations, and other such non-propositional phrases are neither true nor false because they do not assert anything.
Given this information, we can see that much of our thinking is not "formally logical" because it is non-propositional.
And that is okay. Not constantly having "logical thoughts" is a part of being human. It is a part of language. The Scriptures are full of questions, commands, and exortations. Of course, we frequently think propositions that are irrational, too.
We might think, "Joe has been acting funny lately. He must be up to something because people act funny when they're up to something." This is actually a valid argument, but the premises are highly suspicious. To say that "all people act funny when they're up to something" is to say something that cannot possibly be demonstrated as true. Joe may simply not be feeling well or he may be having personal troubles. While the form of the argument is correct, the proposition is false. Notice that the argument is logical, but wrong. Logic does not dictate what is true. Instead, it only dictates what necessarily follows from a group of propositions. Now, if it were true that all people act funny when they're up to something, then the conclusion would also be true because the conclusion necessarily follows from the premises. But because the premises are false, the conclusion is also false.
Sometimes we use bad logic. We might say, "Everytime it rains, the ground gets wet. Now, the ground it wet, so it must have rained." This argument is formally fallacious. The fallacy is so common that it has been given the name,
affirming the consequent. The form of the argument is invalid, so the conclusion does not necessarily follow from the premises. Now, it might be true that it has rained and that is what made the ground get wet, but a different argument is needed to demonstrate that fact because this one is incorrect. This is similar to working an algebra problem incorrectly, but getting the right answer. Your teacher will still mark your answer down as wrong (if he is a good teacher, that is) even though you got the right answer. The reason the answer is wrong is not because the figure is correct, but because the solution was invalid.
I hope that helps to illustrate some of the principles of logic and how they relate to our thoughts.
Soli Deo Gloria
Jon