My Little Pony XIX: I Emptied Your Thread

[Grif]

Indeed, which is why I think that would be a perfectly acceptable reason for her to use when dismissing Pinkie's sense or Zecora's "curse". Instead she uses the claim that "magic has predictable effects" which is blatantly wrong, just look at Rarity's cutie mark story and how she had no apparent control of her magic or its effect.

Again, she never heard of the story before, so she wouldn't know that. It's a reasonable assumption if we assume magic IS mostly predictable. Indeed I think ponies treat magic almost like a science. Which means predictable cause and effect.

I would say this is a case of wilful ignorance combined with lack of exposure to the wider world of Equestria. You'll be surprised how people cling to their beliefs even in the face of contrary evidence.