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Imagine that you are behind a two-way mirror looking in to a room where there is a furnace, a 5-year old girl, and a 5-day old human embryo in a test tube. In 1 hour one of the two will be thrown into the furnace. You decide which one it is. The girl cannot see you through the two-way mirror so you have no feelings of guilt associated with her looking at you and begging for her life. The embryo doesn't even know where the fuck it is, so don't worry about it. Which would you chose? I'm assuming you'd say the girl, and that makes sense. You believe that they are both worth the same, but you have to chose, and you decide to chose the girl. Great.
Now let's change it up a bit. Now there's 2 embryos in the test tube. Which would you save now? If you would save the embryos (because of reasoning outlined in the first paragraph) then we are indeed very different people. But I'm guessing that almost everyone, in their heart, would chose to save the girl. But what about 3 embryos? 4? 5? How many would it take to make you decide to kill the girl? What if just one test tube full of embryos would be killed to save the little girl? If that seems like a good deal to you, you'll need to justify how you decided that that one girl's life was worth more than the 500 million embryos that were in that test tube (yeah I did the math, I feel soo clever now I probably won't sleep tonight). I believe that most people would save the girl, despite whatever "moral" arguments have been pounded into their heads.
But this doesn't apply to the real debate you say. In the real world we can save both you say. However, that is incorrect. We do have a furnace in real life. It is called disease. It not only destroys little girls, but boys, women, men, fathers, mothers, sisters, brothers, best friends, husbands, wives, etc. By fighting against embryonic stem cell research you are effectively throwing the little girl into the fire.
As for me, I'd destroy all the 5-day old embryos I needed to save someone's loved one.