 In a way, it is true that abilities don’t change simply because the risks of exercising them do. To illustrate with a simple, non-medical analogy, consider a cooking student who has learned to make a perfect omelet and now succeeds in making one nine out of ten attempts. This is her current ability level and it does not change even if the consequences of failure change. In one case, perhaps, failure simply means she has no omelet, but only scrambled eggs, for breakfast, whereas in another case failure to make the omelet properly might cost her admission to chef school. But the odds of failure are the same in each case: 1 in 10. In effect those who favor an asymmetrical requirement think that it is fair to require a higher level of ability (and so a lower chance of failure) when the negative consequences of failure are higher. And this does seem to be about protection rather than ability per se.