This is being hotly debated in my household right now - frankly I’m not sure that I’m right or anyone else is as we’ve degraded in our conversation-
but I need to hear what other Dopers think it means -
not that I want to win this argument, I just want to be sure we all
understand it -
Examples are greatly welcome -
I’ll tell you what the argument is about after we’ve heard from the gallery -
And thanks in advance -
Circular reasoning is noting that A implies A, and concluding that A is true.
In other words, Circular reasoning is that reasoning which is circular.
Circular reasoning is using your point to make your point.
A perfect example. I used to heckle a nutty preacher on the Quad at University of Illinois (I know some of you know him – Mad Max). At one point he was going on about how the Bible is the true word of God. I asked how he knew. He said he knows because it says so in the Bible. I whipped out my notebook and wrote in big letters, “This is the word of God.” Therefore, my notebook was the word of God. I had just proved it in the same way he had – circular reasoning. How do you know it’s the word of God? Because it says so. Why should we believe what it says? Because it’s the word of God.
Okay, lets just say that for the sake of making “regular people” understand this concept, give examples - I don’t want algebra or the short terms - I want your experience with this - so I can explain it and why I think it’s a good argument or not - because I frankly have no defense at this point -
help!
Screw it, they left and took the argument with them.
Never mind. I’m going to bed.
Well, if you “regular people” can’t understand the concept of circular logic then explaining it again won’t help. Hell, I don’t even have to read your statement to know it will be wrong anyway.
Does the above help clarify? Because it should and therefore it must and follows on that obviously it did make things clear for you. 
Did you read David B’s post? It’s sort of classic circular reasoning.
An example by my definition: A kiwi is the color green. kiwis are green, If they are not the color green they cannot be kiwi’s, they must be something else.
Or try this:
“I am always right.”
“Why?”
“Because I said so, and I am always right.”
This is not circular reasoning if the following is true:
**That is, if by this you mean all kiwis are colored green.
René DesCartes’ proof of God’s existence always struck me as an example of circular reasoning. I roughly remember it as:
• God is by definition omnipotent
• If something that is omnipotent can exist, it will exist; otherwise it is not omnipotent
• Thus, God exists
I couldn’t find that particular formulation on the Web, but there are many expressions of it out there. One I found follows:
“Existence is a perfection, and as God is described as the most perfect being. It follows that God must exist.”
This is a case of a supposition crucial to acceptance of the argument being taken as fact, while it is really just a supposition, a supposition defined by the end result of the argument it supports.
Remember, this is the guy that gave us Cogito, ergo sum, “I think, therefore I am.”
That’s the Ontological Argument. Kant refuted it decisively.
Good on Kant. The point is that it is circular reasoning hinging on an a priori supposition.
The most common example of circular reasoning I can think of is when both parties fall back on circular arguments for creationism vs the big bang.
The universe was created when particles were under enough pressure and-
Where did the particles come from orginally?
I don’t know.
That’s because God created man and the universe-
Where did God come from orginally?
I don’t know.
And it continues thusly forever because no one, scientist nor theist, can come up with a logical way to explain the antecedent conditions to bring about a God or particles because it’s impossible for something to have come from nothing at all. That and wondering where the universe ends make my head hurt.
Actually, it’s not clear that this is true.
Not sure what you mean there. Are you offering that as another example of Descartes circular reasoning, or the reverse?
“I think” implies that “I am”, otherwise how could I think?
My definition of circular reasoning is the same as my definition of circular reasoning.
I think I meant it just as an observation that even one of the great thinkers could get himself caught up in a circular argument, as he did with the God proof.
When we talk about ‘reasoning’, we usually mean the process by which we progress from some stated pieces of information to a new piece of information we didn’t have at first.
Example A.
Statement 1: All my pens are blue.
Statement 2: You’re holding one of my pens.
Conclusion: You’re holding a blue pen.
The information in the Conclusion is not explicitly stated in either of the two statements we started with, but by reasoning we can manufacture or ‘synthesise’ the conclusion. The conclusion follows from the starting statements, but the statements don’t follow from the conclusion.
The term ‘circular reasoning’ refers to any argument which may seem to have the same form as the above, except that at least one of the starting statements follows from the conclusion, thus creating a loop. In its simplest form (1 statement, 1 conclusion) this tends to look trite and silly, and it seems no-one would fall for it:
Example B.
Statement 1: Because I’m always right, what I tell you is accurate.
Conclusion: Because what I tell you is accurate, I’m always right.
The circularity is evident from the fact that you could swap the ‘Statement 1’ and ‘Conclusion’ labels around without making the argument any stronger or weaker than it already is.
If you introduce a few more steps, the circularity can seem less obvious to some people.
Example C.
Statement 1: I’m always right.
Statement 2: I’ve written this book.
Conclusion: This book says I’m always right.
The only support for Statement 1 is the Conclusion.