It would be better for both of you if you explained to her how medicine worked.
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WormuIus, Sun 17 May 2009, 19:15,
archived)
Sister: "I had a stomach ache, and was feeling fatigued and took such and such a homeopathic remedy and felt much better afterwards. Ergo it works"
Me: "No you didn't. I replaced your such and such homeopathic remedy with pure sugar pills a week ago. What you took was a placebo. Ergo homeopathy doesn't work"
Sister: "Oh. What a fool i've been. Thanks for enlightening me with this marvellous ruse"
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applehead herp derp, Sun 17 May 2009, 19:18,
archived)
If she really believed in homeopathy she could argue that by redcing the chance of an active ingredient you have actually made the medicine stronger ;)
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WormuIus, Sun 17 May 2009, 19:20,
archived)