I am writing this because I had a conversation that mentioned crazy pro-lifers (the kind that terrorize people walking into Planned Parenthood). We didn't even have a debate or anything, but the ideas are now stuck in my head. I need to get them out.  These are my reasons for believing what I believe.
 

Reasons for being Socially and Politically Pro-Choice

• Outlawing abortions only leads to more death. People who want to have an abortion will find a way to do it, legally or otherwise. "Back alley" abortions are extremely dangerous. Thousands of people across the world die from them. If you consider an abortion murder, then two people are dying. If all life is sacred, then one life and one death is better than two deaths. Therefore, outlawing abortion kills more people than it saves. Education on sex and contraception will save more lives and prevent more unwanted pregnancies than outlawing abortions ever could.
  
• People who are raped have been stripped of their free-will. They should not have to bear such a burden unless they choose to. If abortion is a sin in the eyes of your deity of choice, then the rapist should bear that sin.

Reasons for being Philosophically Pro-Life

• I personally believe that a fertilized egg is every much a human being than a newborn baby. Note: I did not say 'person.' I said 'human being.' One could argue that a baby is not yet a person. They are acting on instinct alone to survive. Memories and experiences are what shape people. Babies have none. Therefore, how is a fetus any different. Yes, every baby is different. Some cry more, some laugh more, but can they conceptualize ideas? Can they think logically? I would argue that babies' varying "personalities" are not the result of life experience (because they have none yet), but of their genetics. Finally, a baby, if cared for, will develop into a person. A fetus, if cared for, will develop into a person (baring, of course, any unforeseen events in both cases). Both are simply stages in the path of becoming a person. It is not possible (given current scientific knowledge and technology or without interfering with the natural order of things) for a fertilized human egg to develop into a squid or kangaroo. It will become a person.
• Every person already has a choice regarding their body: you may have sex or not have sex. If you have sex, you are accepting any and all consequences of your actions. (See above pro-choice arguments for rapes and why education is important)
• Babies should not be treated like objects. When a married couple decided to have a baby, they are congratulated when the woman gets pregnant. It is like getting a new car when you can afford one. People think it is great and want to drive (or hold) it. When a single woman gets pregnant, they are met with sympathy. "Oh, no. I'm so sorry." I liken this to getting a new car... because you were drunk and weren't driving safe. Getting this car is not a joyous occasion. Should babies be treated the same as cars? No. Human beings have an inherent higher value. Life is precious. Shouldn't we treat it this way even if it wasn't planned?
• Finally, draw a line on a sheet of paper. This line is the threshold of life. Situations above this line mean that there is greater happiness being experienced than would be without being alive. Below this line are things like being in a car wreck, having all four limps amputated, and being covered in burns which cause extreme pain at all times and will never completely heal. You are being fed through a tube because all your teeth were knocked out and your lips are burned off. Also, a bird ate your tongue for some reason. One could make the argument that it is no longer beneficial to be alive. This should ideally be a choice for the burn victim to make, but sometimes that is not an option. I cannot imagine a situation in which a person who is born to a single mom or grows up in foster shelters, then struggles through poverty their whole life could be in a position where they could say "Life is so hard. I have experienced zero happiness. I wish I had not been born." Even if this were the case, shouldn't they be the one making that decision? We can't predict the future. We can't just assume that an unplanned baby will experience a life so terrible that it is simply better to kill them before experiencing any of it. Are we really prepared to put their life below that line on the paper without actually knowing what will happen? Life may be hard at times. We aren't all privileged. But the vast majority of people would rather deal with some hardship than to have never existed. (This is essentially the argument I read in my ethics class)

Conclusion