I found some time to make a few diagrams that I believe accurately shows Benatar's misuse of counterfactuals in his asymmetry, as argued by Cabrera (see last post). I believe this is a very important issue that people with reservations against birth need to address, because Benatar is seen as like the Jesus of antinatalism, but a flawed argument is a flawed argument regardless. So, let us begin.
First, we have Benatar's asymmetry, here:
However, the absence of pain has the same arrow and comment - but if the absence of pleasure is not-bad, then how can the absence of pain be good? For whom is it good?
This is further shown by the next diagram, in which the stick-figure faces represent the use of counterfactuals (if we had a child, then the child would experience x):
in other words, non-existence is neutral, and only better in comparison to an existence filled with pain (bad). Non-existence by itself is neither good nor bad, it requires a comparison to actual existence to have any value.
But can you imagine Benatar creating his asymmetry in a land of sugar and spice and everything nice, where practically no pain existed and death was not a thing? I find it hard to believe that he would have an issue with childbirth in this alternate, possible world. The asymmetry quite literally would not apply, for the pleasure experienced in life would outweigh the pain avoided by remaining in non-existence. This shows that Benatar relies on the apparent fact that the world is quite nasty - and he spends a large portion of his book describing how horrible our lives are. If his asymmetry could stand independently of itself (which Benatar argues it can), he shouldn't have felt the need to include this pessimistic worldview.
As it happens, however, his pessimistic worldview is quite accurate. Since there is nothing wrong (nor good) in staying in non-existence, and because life has at least the potential of being quite unfortunate, it stands that we must abstain from birth. Nothing will be lost if we do so, and what pleasure is inevitably avoided is far less than the amount of pain avoided.
So, it seems that the lack of pleasure being not-bad in regards to non-existence stems from our emphasis on pain: it is not that it is not-bad that pleasure (and an entity to feel it) is non-existent, but rather that pleasure inevitably brings along with it great pains. The asymmetry is not in regards to non-existence and existence, but within existence itself - there is an asymmetrical relationship between the pleasure of existence and the pains of existence. There are far more pains than there are pleasures, and pleasure without pain seems impossible while pain without pleasure is possible and in fact rather common.
However, without the existence/non-existence asymmetry, any appeal to antinatalism based on a evaluation of life's values is inevitably subjective. This is why I believe Benatar created his asymmetry - it would function as a global heuristic, applied to every single life on the planet. In other words, Benatar knew that the human race could not be trusted to objectively rule existence in a negative light. Antinatalist would require an analytic heuristic to get it off the ground - and it seems to have done its purpose somewhat, even if it is ultimately flawed.