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Facts don't need "theory" -- against a fact there is no argument.
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Maybe you've forgotten all the hundreds of posts already made, like 50-plus reasons, just getting started.
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On the other hand, your failed hypothesis has zero support, because the earth isn't "flat."
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What do you believe is the single most compelling piece of evidence to help prove the earth is a globe?

What do you believe is the single most compelling piece of evidence to help prove the earth is a globe?

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For the purposes of this discussion, the fact that you are incapable of learning anything is proof positive the earth is not "flat."
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Very compelling!
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Let's see now, about your manifest errors: 
The horizon does not always appear "flat" 360 degrees around the viewer regardless of elevation, even while flat-earthers say it does.
The horizon does not always "rise" to the level of the observer, even while flat-earthers say it does.
The natural physics of water is not to seek its own level, even while flat-earthers say it is.
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Any more false statements you can dream up, Truth is Transitory?
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Dear Meg,  "Most" you say but most others say "globe" and they do mean the same things, ball does not mean flat for sure. Not only in words does she say ball/globe but she is pictured holding a globe, as St. Catherine said so.  

Anyway since I consider and am trying to live and die a Catholic I will put my Faith on the Blessed Mother with God's grace.  All Catholics should why?  Because they can't go wrong that is why.  

Dear Meg,  "Most" you say but most others say "globe" and they do mean the same things, ball does not mean flat for sure. Not only in words does she say ball/globe but she is pictured holding a globe, as St. Catherine said so.  

Anyway since I consider and am trying to live and die a Catholic I will put my Faith on the Blessed Mother with God's grace.  All Catholics should why?  Because they can't go wrong that is why.  

Maybe you can find the original words of St. Catherine, in French. Then we might be able to determine more clearly which word it might be. 'Golden ball' and 'globe' might be the same thing, but maybe not.

Maybe you can find the original words of St. Catherine, in French. Then we might be able to determine more clearly which word it might be. 'Golden ball' and 'globe' might be the same thing, but maybe not.

   I'm not worried about it.   She did not say anything that might resemble "see this flat earth" etc. 
I am sorry for you and other Catholics who doubt her, perhaps you might consider wearing her medal if you don't already.  

  I'm not worried about it.   She did not say anything that might resemble "see this flat earth" etc.
I am sorry for you and other Catholics who doubt her, perhaps you might consider wearing her medal if you don't already.  

Of course you would accuse me of doubting Our Lady. Sedevacantists are mean and spiteful that way, and can't seem to keep from saying things like that.  

Of course Our Lady didn't say anything about a "flat earth" to St. Catherine. We know that.

Of course you would accuse me of doubting Our Lady. Sedevacantists are mean and spiteful that way, and can't seem to keep from saying things like that.  

Of course Our Lady didn't say anything about a "flat earth" to St. Catherine. We know that.

I didn't mean to be spiteful, however, why do you keep insisting or looking for other words that she must have said or meant instead of what she did say. It is very clear!  
Anyway, it is you who has a mean outlook on anyone who claims to explain the Roman Catholic Church as being in the state of Sedevacantism.  This topic has nothing to do with sedevacantism and yet you insist that Sedevacantist are mean and spiteful.  You are mistaken, most don't even care what you or your ilk think about the shape of the earth.  
For myself the answer is right there especially for Catholics no matter how you want to slice it, Blessed Mother talks about the earth being a globe-like shape. Forget the science!   She should know for she has traveled from earth to heaven during her Assumption into heaven and her many apparitions back and forth, as the children have seen her coming and going, up into the heavens.