Feud wrote:I understand the logic you are using, but I disagree with it. Saying the if A then B is equal to if -B then -A looks good on paper, but doesn't translate well beyond it.
Let's use a differant example, "If I go to Grandma's house, then I will get cookies." The contrapositive would then be "if I don't want cookies, then I will not go to Grandma's house." This may not be true though, since I may have wanted cookies, but for what ever reason I didn't go, or I went, but she was not home and so I did not get any cookies. Granted, this example is somewhat silly, but it is just here as an example.
No. You are not using the correct logic. I don't think that you do understand the logic that I am using. The logic that I am using is basic, first-order predicate logic. If a statement of the form A -> B is true, then the contrapositive is also true (i.e. ¬B -> ¬A). The contrapositive has, and will always have, the same truth value as the original statement. So, the correctly apply the contrapositive to your statements:
A = I go to Grandma's house
B = I get cookies
¬A = I don't go to Grandma's house
¬B = I don't get cookies
A -> B = IF I go to Grandma's house, THEN I get cookies.
¬B -> ¬A = IF I don't get cookies, THEN I don't go (have not gone) to Grandma's house.
C = I do not want cookies
D = I will not go to Grandma's house
¬C = I want cookies
¬D = I will go to Grandma's house
C -> D = IF I do not want cookies, THEN I will not go to Grandma's house.
¬D -> ¬C = IF I go to Grandma's house, THEN I want cookies.
So, the contrapositive of "If I go to Grandma's house, then I will get cookies" is "If I didn't get any cookies, then I didn't go to Grandma's house." This statement is as logically valid as the original, and, if you try it out, holds true. The same statement can be made about the second example. As I said above, the truth value of a statement and its contrapositive are always
the same -- they are equivalent statements. The reason to switch them around, as I did above, with regards to your argument, is to make a rhetorical point.
Feud wrote:Your reasoning removes those who do not want children, but would not be opposed to thier coming. It also removes those who are unable to have children, but still have sex. While your logic makes sense in it's own sphere, it discounts so many variables that I don't think it has any rational basis in the real world.
No rational basis in the real world, eh? Wendryn and I don't want to get pregnant. We would be opposed to getting pregnant at this point in time, and if Wendryn got pregnant tomorrow, we would terminate. Wendryn is perfectly capable of having children if we wanted them. We simply don't want them at this point in time. There is at least one real world example, and I hardly think that we are unique.
That being said, I am
purposefully leaving out other groups, because they are not relevant to the point that I am trying to make.
The point of this being the following: sex is a part of human relations. People have sex. You can't prevent it from happening. Furthermore, not only does it occur in marriage, but it is a sanctioned part of marriage. It is sanctioned by every church, government, and culture that I know of. If you argue, as you have, that couples that do not want a pregnancy should abstain, then you are arguing that married couples, who have a sanctioned right to have sex with each other must
waive that right if they do not want to become pregnant, with 100% reliability. This is absurd.
However, as I have pointed out already, this is really tangential to the best arguments in favor of keeping abortion safe and legal.