By Dr. Johnny Sakr
Everyone agrees that stem cell–derived embryo models are not embryos. The harder question is whether that biological distinction is doing more ethical work than it can plausibly bear.
In my recent response in the Journal of Medical Ethics, I argue that much of the disagreement about embryo models turns on a quiet but consequential slippage: a failure to distinguish between properties that ground moral status and considerations that merely shape regulatory or social responses. Once that distinction is made explicit, many familiar arguments for treating embryo models as morally lighter begin to unravel.
The central claim of my paper is simple. If a stem cell–derived embryo model genuinely instantiates the organised developmental features that are taken to matter morally in embryos derived from fertilisation, then moral parity follows. If it does not instantiate those features, then the question of equivalence never arises. What cannot be coherently sustained is embryo-likeness without moral consequence.
Why this issue matters now
This question is no longer abstract. Advances in stem cell science mean that some embryo models now display integrated organisation, lineage coordination, and embryo-like developmental patterning. At the same time, regulatory bodies rightly emphasise that these entities are not embryos in the organismic sense and should not be described as such.
That caution is important for governance. But it does not settle the moral question.
Moral status does not track origin, symbolism, or research utility. It tracks morally relevant features. The risk in current debates is that the reassurance offered by the label “model” is doing covert moral work, allowing embryo-like entities to be treated as ethically lighter precisely because they are scientifically useful.
Diversity without moral differentiation
One response to claims of equivalence points to the diversity of embryo models. Some lack integration. Some lack coordinated developmental organisation. Some are clearly outside the moral space occupied by embryos.
I agree. But diversity matters morally only when it tracks differences in the properties that plausibly ground moral status. Variation as such is morally inert.
Where an embryo model fails to instantiate organised human developmental form, moral equivalence does not arise. Where it succeeds, diversity elsewhere does not justify treating it as morally inferior. Moral heterogeneity exists, but only at the margins.
Why plural moral values cannot do grounding work
A more ambitious response appeals to plural moral values. Relational meaning, symbolic significance, and instrumental usefulness are said to reveal morally relevant differences between embryos and embryo models.
These considerations are illuminating. But they do not ground moral status.
Relational and symbolic values arise from social practices, cultural meanings, and institutional histories. Instrumental value concerns what entities enable us to do. None of these explain why one entity should count as having lower moral worth than another when the underlying status-grounding features are shared.
Allowing such considerations to determine moral status risks collapsing ethical reasoning into policy convenience. Moral status begins to track what is useful or less controversial, rather than what is morally relevant.
Beyond binaries — without abandoning parity
I am sympathetic to calls to move beyond crude binary thinking in bioethics. But rejecting binaries does not require denying equivalence where morally relevant features coincide.
Moral equivalence is not a claim about full personhood, rights, or legal recognition. It is a claim about parity at the level of moral status. Different governance strategies may still be justified. Different regulatory constraints may still apply. What is not justified is treating embryo-like entities as morally lighter simply because they are models.
A clearer ethical landscape
If stem cell derived embryo models fail to model embryos in the morally relevant sense, then the ethical relief they offer is genuine. If they succeed, then their success carries moral consequences.
What cannot be sustained is the idea that embryo-likeness is sufficient for scientific seriousness and regulatory caution, but insufficient for moral parity. Ethical coherence requires us to confront that tension directly, rather than resolving it through conceptual ambiguity.
Paper title: Moral equivalence and the grounds of moral status in stem cell-derived embryo models: a response to de Graeff and De Proost
Author: Johnny Sakr
Affiliation: Prince Sultan University
Competing interests: None declared.
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