No, it does not. Now you're right back to the philosophical wankery where nothing is every certain. That way lies madness - hey, you can't trust your senses anyway, so maybe somebody is feeding you a simulated world, and everytime you do NOT kill 50 fake people, 50 REAL people are killed for you.
If you want to form an ethical value system, you have to start by assuming you can make decisions, and that your knowledge is good enough to do so. You're not going to make a perfect, 100% logical system, but you don't have to, because you can't. Just making a good effort is what counts.