Let's say that you and your friends are bored one day, so you decide to play a game of Russian roulette, which you find extremely entertaining (even pleasurable). You've done this several times before, and nobody has ever "lost" a game, so you have a good track record up to this point. Now, imagine that it's your turn to point the gun at your head and pull the trigger. You know there is only a 1 in 6 chance that the gun will fire, so you have a reasonable amount of confidence that you will be safe. However, it turns out that you got the chamber with a bullet in it, and when you pull the trigger, you die.

Now, would anyone deny that you are morally responsible for your death? You knew the risks, and you knew that your safety wasn't 100% guaranteed, but YOU, and only YOU, chose to pull the trigger anyway. Because you were directly responsible for the action, you are morally responsible for the consequences.

Let's take it one step further. Imagine that, to make the game even safer, you used a special bullet that only has a 10% chance of firing. Therefore, you not only know that you may not get the chamber containing a bullet, but you know there is a 90% chance that you will survive anyway. Unfortunately, when you pull the trigger, the bullet fires. You are still responsible! Unless you are 100% certain that you will be safe, you have moral responsibility, because you are in control of your actions and are the direct cause of the event.

This takes us back to the plane example. If you put your son on a plane, you have a reasonable expectation the he will be safe. If the plane crashes, however, it is not your fault, because you didn't cause the plane to crash. In the roulette example, and in instances of consensual sex, you are in control the whole time, and you always have the option to prevent pregnancy from happening by abstaining from sex or to prevent death by not pulling the trigger.

This also comes back to my argument that planes are not designed to crash, but sex is designed to produce children. Think about the roulette example. If you pull the trigger and the gun doesn't fire, then that's an accident! You may be happy with the result, but the reality is that if that gun had been working properly, you would be dead. The point is that if you take an action that is designed for a specific purpose while simultaneously trying to prevent it from accomplishing that purpose, you are morally responsible if your attempts fail.

On the other hand, if you use something for its intended purpose and it fails, you are not morally responsible, because you were not misusing it. I think this is where [my opponent] was confused. I am trying to prove that sex, and not failed birth control, is the cause of pregnancy. As the roulette example shows, decreasing the risk involved doesn't make it morally neutral. Guns are designed to fire, and if you happen to shoot yourself, you are responsible because you knew that ahead of time.