Tom Baldwin sets the boundaries

There are important questions about the proper boundaries to the use of PGD.
It is widely accepted that enabling couples to avoid having a child who would inherit a significant predisposition to cancer is very valuable. This type of disorder involves a serious physical condition, and one possible boundary would be a restriction of PGD to such disorders.

But there is strong evidence that some mental disorders (e.g. schizophrenia) are heritable. Supposing there to be a reliable genetic test indicating a significant predisposition to a mental illness, there seems no good reason why potential parents should not be able to use PGD to avoid having a child with such a predisposition. So a more defensible boundary condition would be a restriction of PGD to enable parents to avoid having a child with an inherited disorder leading to serious physical or mental illness.

Outside the boundary
The type of case which would trangress this boundary involves the use of PGD to enable parents to choose positively to have a child with a desirable non-medical characteristic such as high IQ.

At the moment this possibility is entirely speculative and in my judgment is likely to remain so; nonetheless we can consider whether it would be in principle acceptable to use PGD in this way.

The critical fact here is the power parents would have to determine the kind of child they will have. Opponents argue that giving parents this power is wrong: it violates the respect which parents owe to the fact that their children are individuals in their own right.

Although the principle which motivates the objection is correct, it is not clear that using PGD simply to enhance the possibilities available to a child would violate it. At present, however, the great majority of the public regard such a use of PGD with horror, and until it is clear that a positive use of PGD would have only a modest and beneficial enabling effect, it is sensible to maintain a firm boundary against it.

Professor Tom Baldwin is in the Department of Philosophy at the University of York