"Is it really killing?" I consider abortion 'Letting the thing die', not 'Killing it'. Depends on the method, ofcourse. Would you call miscarriages murder? I don't see anything wrong with killing non sentient organisms. Wait - I think I misinterpreted what you were trying to say. Nevermind. But - How can you be sure something isn't sentient? Run tests on it in a lab? Apparently, even plants can be sentient. http://www.environmentalgraffiti.com/plants/news-feeling-plants-how-sensitive-flora Plants react with no thought process which constitutes they are (by most standards) not sentient. http://www.merriam-webster.com/dictionary/sentient And what "standards" are you referring to? I think those plants fit the sentient definition rather well. Plants are not "aware" of their environment. They do react to stimuli but the reaction is impulsive, not conscious.