The concrete reasoning for Ebola is:
1) Positive claim: Ebola causes death.
1a) Death due to Ebola are probably easier to prevent than a random sample of death. This is because we can probably find a single procedure to prevent { ebola death 1, ebola death 2, ... }, while we cannot find a single procedure to prevent {shooting death 1, drowning death 2, ebola death 3, cancer death 4}.
1b) Thus, preventing death due to Ebola will likely be cheaper than preventing a random selection of deaths.
2) Normative claim: Death is bad.
2a) Preventing death cheaply is better than preventing death expensively.
3) Preventing ebola will reduce incidents of death by (1), and that will be good (by claim (2)). It will likely be cheaper to prevent deaths due to ebola than due to a random sampling of causes (1b). Preventing deaths cheaply is better than preventing deaths expensively, by (2a).
It's not remotely difficult to justify the normative claim that stopping Ebola is good. And you can now see my normative principles - if you believe death is good, we know why we disagree.
If we want to come to agreement, we now know we need to debate moral philosophy rather than empirical claims like "is ebola really a single disease".
Most of this conversation is me asking "what goes into slot (2)" and a bunch of people repeating to me what they put in slot (1).
