[You Are Gay]

Good point by Mzyxptlk and nod. Choice is the difference between the two acts of killing. I hadn't thought of it that way.

OK so how about this:

"Should society allow disabled babies to be killed if their parents so choose?"

and following that:

"Should society allow and encouraged disabled babies to be killed retaining the parent's right to choose."

and by encourage i mean financial gain. Something like x percentage of the money the child would cost society in caring / extra training support etc. This money might not be paid directly in sterling into an account of your choosing but rather be benefit in kind (fertility treatment, the possibility of additional child tax credits ... basically things that would encourage you to have more children).

For the sake of argument a baby is a child up to the age of 2 where they are still a "blank slate" (i don't know if that is scientifically correct but we'll just use age 2 as the example for this argument)