In my article “The Absolutist Prolife Position: A Critique,” I argue against the view that a human being should be granted full ontological status from the point of conception. (Conception isn’t actually a point, of course, it’s an extended process. But let’s leave that aside for this discussion.) My argument centers on two scenarios:
Scenario 1: Peggy has intercourse after which she goes to Dr. White and requests the morning after pill. Dr. White prescribes the pill and Peggy takes it, thereby preventing the implanation of a fertilized human blastocyst.
Scenario 2: Sue gives birth to a baby boy. She goes to Dr. Black and requests that he euthanize the infant. Dr. Black administers a high dose of barbiturates resulting in the death of the infant.
According to the absolutist position, Dr. White’s action is morally equivalent to Dr. Black’s action. But Dr. White’s action is not morally equivalent to Dr. Black’s action. Therefore, the absolutist position is wrong. (Read the article for a more fulsome articulation.)
This kind of argument comes in many versions. Another familiar version is the burning fertility clinic: if a clinic is on fire and you only had time to save either 100 frozen embryos (room 1) or one crying human infant (room 2) which would you save?

While I have no survey data on how most people would respond, I suspect the vast majority would prioritize saving the infant. I know I would. And that response strongly supports the conclusion that human embryos like those pictured above are not ontologically equivalent to a human infant.
Catholic apologist Trent Horn is a well-known absolutist. In the following tweet, he attempts to rebut the burning fertility clinic version of the argument:
The "fire in the IVF clinic" scenario prejudices us against the unborn by putting them in an unnatural place (i.e. save 100 embryos in a cryotank or one 2-year-old). "Save 100 brain-dead, 6-week pregnant women who will give birth or one 2-year-old?" may provoke different answers.
— Trent Horn (@Trent_Horn) June 29, 2022
Keep in mind, this is just a short tweet. No doubt, Horn would have more to say. But a tweet is what we have to work with. So what should we think of his pithy rebuttal?
Let’s first deal with the allegation that the scenario “prejudices us against the unborn”. In response, let’s consider another scenario. In this case, a dog shelter is on fire: in room 1 are 100 dogs and in room 2 is one child. I am quite sure that Horn would say in that case we should save the child over the 100 dogs. And I agree!
Is the burning dog shelter scenario “prejudicing us” against our canine friends? Or is it simply clarifying our intuitions as to their non-equivalent ontological status to humans? The latter, I think. And the same is the case with the burning fertility clinic.
What about Horn’s next claim that the cryotank is an “unnatural place”? One problem here is that it isn’t clear whether by “unnatural” Horn only means “unusual” or “a state that does not occur in nature”.
Either way, I don’t see why that is relevant. Moral dilemmas arise from unusual circumstances all the time: for example, the Trolley problem is an unusual dilemma to face but it is a real dilemma and you could face it.
The same goes when we shift to the second interpretation of unnatural, i.e. the dilemma that arises from conditions created by human beings. For example, as human beings consider developing self-driving cars, they need to decide how to program them and that involves making decisions that are like a dizzying array of trolley problems to accommodate for the endless possible circumstances that can arise on the road: all of them are the result of states not occurring in nature (i.e. involving self-driving automobiles) but they are no less legitimate as moral dilemmas for that reason.
Horn concludes by attempting to draw our attention away from the contrast between a toddler and 100 embryos and on to the contrast between the toddler and 100 brain-dead 6-week pregnant women. But this seems to me obfuscatory rather than clarifying. First, it introduces the moral complexity of how we should think about brain-dead human beings. Second, it introduces the contrast between an embryo frozen at about 6 days (the original scenario) with a 6 week old embryo.
Ironically, if you are less sure about what to do in Horn’s latter scenario, that may actually count against Horn’s absolutist position given that you might be inclined to grant increased ontological status to a 6 week embryo over a 6 day embryo.
To sum up, I do not see in Horn’s admittedly brief comments any reason to question the intuitive strength of our response in the burning fertility clinic. We have excellent reason to think that 100 embryos are not morally equivalent to one small child (infant or toddler). And thus we have excellent reason to think that the absolutist prolife position is false.