Imp Emissary said:
That's a good one. Though, with the reapers breathing down you neck, it can make it easier to chose. Unless you were completely on the fence.
For me, I just figured, if they infected them with the stuff twice, I think they can do it again, so why not just cure it now, and if they act up, infect them again! Plus I tursted Wrex.
To me, the "Salarian argument" - we need the genophage to keep the Krogan in check in the future - is not what made the decision difficult - although the game tries its best to frame this argument as to make it matter. At the time when you have to make the decision, you know that you're fighting in a war against the extinction of all advanced life in the galaxy, and your situation is desperate. Conflicts that might or might not arise after this war is won, if it is won at all, which doesn't seem likely in the first place, has absolutely zero relevance.
I doubt that even the Salarians think that the genophage was the morally right thing to do in itself: you're almost sterilizing an entire species, and the effect that this has on the fabric of society of this species were horrible. But they felt it was necessary, that is, they justify the genophage with the Greater Good. They adopt the utilitarian position: The ends justify the means. But now, the situation has changed: The Salarian position of not curing the genophage is not only morally wrong, and unambiguously so I would argue, it is now also detrimental to the Greater Good. The only thing that does matter from the utilitarian perspective now is not being annihilated, and keeping the genophage is reducing the Krogan war effort, and thus increasing the chance of annihilation.
Unfortunately, the Salarians are incredibly stupid, and that's not the decision the player has to make: He has to decide between curing the genophage, thus winning the Krogan support but loosing the Salarian support (or parts thereof, and only with some likelihood; you can't know whether they get some sense reverse their decision later), or not curing the genophage, thus winning the Salarian support and risk loosing the Krogan support (if they find out).
So you have to decide whether the Krogan or the Salarian support is more valuable for the war, and what the chances of gaining/loosing either are after your decision, i.e. which decision contributes more to the Greater Good, winning the war. And you also have to decide, if this assessment favors the Salarians, whether this difference justifies the (unambigously) immoral act of not curing the genophage, lying about it to the Krogans, and, at the end, killing a dear friend for it.
Here, some say every alternative is preferable to extinction, and thus move such moral considerations to the back seat - and indeed, utilitarian considerations tend to prevail in war, especially in total war, because the stakes are incredibly high - and I tend to agree with this view, but you can also argue that, if in order to survive you have to commit deeply immoral acts, it's not worth surviving. (To choose a real life example, think about cannibalism: is it morally permissible to eat fellow human beings to survive?)
The game pulls every emotional string to make you opt for curing the genophage, and so, if I remember some BioWare stats correctly, it's probably no surprise that 80% of all people choose the cure, but still, I found it damn hard.