Because of the simple fact that we are all human beings, and human beings understand things pertaining to them.
“Human beings are ends in themselves and never a means of resolving other problems.”
If one understands this GOLDEN SENTENCE, question on abortion would end automatically.
When you see red signal on the road-intersection, you know what it means. If you are not serious-minded, you can take individual words such as red, signal and so on and say red does not mean do not cross, it is just one of many colors given to man for his enjoyment... and signal means to me this and that ..... and so on. Fully convinced, you cross. Then the law-enforcement agencies will make you convince otherwise with absolute clarity. You will NEVER have any doubt thereafter!
Life is precious. You are free to play with it provided you are prepared to face its cosequences!