You’re basically running three arguments at once: (1) consent, (2) technical risk (off-targets / irreversible heritable change), and (3) slippery slope to enhancement. I’ll push back using the same structure, but also anchor it in what the data actually shows right now—not just theory. First, the “no consent from the embryo” point sounds strong, but it isn’t unique to CRISPR. Every reproductive decision is made without consent from the future person—IVF selection, choosing a partner, even basic prenatal screening. We already accept that society allows parents to make irreversible biological decisions for future children when the intent is to prevent serious harm. The ethical line people usually draw isn’t “consent vs no consent,” it’s “therapeutic prevention vs enhancement.” Second, on off-target mutations: this was a major concern in early CRISPR work, but it’s not where the frontier is anymore. High-fidelity Cas9 variants and improved guide RNA design have reduced detectable off-target editing to extremely low levels in many experimental systems—often below the limit of standard sequencing detection in optimized contexts. That doesn’t mean “zero risk,” but it does mean the claim “we are scrambling genomes unpredictably” is no longer an accurate description of the state of the technology. A useful comparison is somatic CRISPR therapy, not embryos: in clinical trials for sickle cell disease and beta-thalassemia, CRISPR-edited cells have produced functional cures or near-cures in the majority of treated patients (many trials reporting >80–90% elimination of severe symptoms after treatment). That matters because it shows the editing machinery can be precise enough to produce stable, life-altering benefits without widespread genomic chaos. Third, the “heritable irreversibility” argument is real—but it cuts both ways. Germline editing would indeed propagate changes, which is why no responsible regulatory framework currently allows clinical embryo editing in most countries. But it also means the risk has to be weighed against preventing a mutation that would otherwise propagate suffering through entire family lines indefinitely. For some monogenic diseases (like Huntington’s or Tay-Sachs), the “status quo” is not neutral—it is a guaranteed transmission probability in affected lineages. On preimplantation genetic testing (PGT/PGD), which already exists: in IVF, it can identify embryos without known disease-causing variants with high accuracy (often reported around ~95%+ for detecting known single-gene mutations, depending on the lab and condition). That already allows many at-risk couples to avoid passing on severe diseases without gene editing. So even the strongest pro-CRISPR argument isn’t “we need this immediately,” but rather “there are edge cases where selection fails or produces no viable embryos, and editing could expand options.” Finally, the “slippery slope to designer babies” concern is more about governance than biology. We already regulate stronger technologies with similar dual-use risks (nuclear tech, IVF, opioids, etc.) without banning the underlying science. The existence of a possible misuse pathway isn’t itself evidence that therapeutic use must be rejected—only that strict boundaries matter. So the core counter is this: the risks you’re pointing to are either (a) already substantially reduced compared to early CRISPR fears, (b) already partially addressed by existing reproductive technologies like PGT, or (c) real but governance-dependent rather than inherent to the idea of germline therapy itself. The strongest version of your argument isn’t “this is too dangerous to ever work,” but “this should be restricted until safety, equity, and regulation are far more mature.” That’s a much harder position to dismiss—and it actually matches where most of the real-world policy debate already is.

Start with your “nature vs invention” line. You’re treating CRISPR as if it introduces novelty into an otherwise stable system. Statistically, that’s not true. Every human genome already carries ~60–100 new mutations per generation that did not exist in either parent. Nature is not a preserved painting we carefully select from; it’s already a continuous generative process, producing changes that are unreviewed, unconsented, and permanently heritable. CRISPR is, in many proposed cases, not “inventing new sequences” so much as correcting known single-letter variants—swapping a harmful allele for a known benign or functional one. On your “we don’t understand downstream effects” concern: that’s valid, but it needs context. Roughly 70–80% of severe monogenic disorders are caused by well-characterized mutations in single genes. Huntington’s, sickle cell, cystic fibrosis—these aren’t mysterious systems with unknown causal structure; they’re among the most genetically mapped diseases in biology. The uncertainty is not “what does this gene do?” but “what else might this gene interact with across environments and time?” That’s where your strongest point actually lives—but it also weakens the “this is uniquely dangerous” claim. Because evolution already performs the same experiment, just noisily and without correction. The difference is not experiment vs non-experiment; it’s blind mutation vs targeted intervention. And IVF selection matters more than it first appears in your framework. You say IVF selects from what nature offers, while CRISPR creates. But selection is still directional pressure on the germline—just applied post-conception rather than pre-allele correction. Both are interventions in inheritance; they just sit at different points in the pipeline. The “every descendant carries our choices” argument is emotionally powerful, but statistically incomplete. Every descendant already carries ~3–5 new deleterious mutations per generation on average. We don’t treat that as moral contamination because it’s unintentional. The ethical question becomes less “are we introducing change?” and more “are we reducing predictable suffering or increasing it?” Finally, your romantic framing of imperfection is coherent as an aesthetic stance—but it doesn’t cleanly map onto disease burden. Sickle cell disease, for example, is not an aesthetic variant of human existence; it reduces life expectancy by decades and causes chronic ischemic pain cycles. Preserving that outcome in the name of “not perfecting nature” isn’t really defending nature’s integrity—it’s choosing to leave a known failure mode untouched while we have partial tools to address it. So using your own structure: If nature is already an uncontrolled generative system → CRISPR is not introducing the concept of variation, only shifting it from random to targeted. If irreversibility is the concern → irreversibility already exists via natural mutation rates and selection pressures. If intergenerational burden is the concern → current burden is already multi-generational and measurable in millions of cases per year for single-gene disorders. The real ethical distinction is not “natural vs engineered,” but “blind vs informed risk.” That doesn’t resolve whether germline editing should be done—but it does weaken the claim that it represents a fundamentally different category of biological action.

1) Nature is already doing the same thing at massive scale Every child already gets: ~60–100 new genetic mutations and across the world that’s billions of mutations every generation So the “unknown long-term effects” he worries about are already happening constantly—just randomly and without control. 2) Natural does NOT mean safer or more predictable Those natural mutations: are not tested are not targeted are not reviewed still get passed down for generations So under his own rule (“uncertainty + irreversibility = danger”): nature is actually the bigger uncontrolled experiment 3) CRISPR is actually more controlled, not less targets one known gene fixes a known problem reduces randomness So it’s not “adding chaos,” it’s trying to remove known genetic chaos One-line pressure point: If your argument is “we shouldn’t make irreversible genetic changes we don’t fully understand,” then you already have to reject nature itself—because it’s making far more irreversible, untested changes every generation than CRISPR ever would.

1) “Intention makes it a different category” — breaks under his own risk logic He says: nature is random, CRISPR is intentional But in his framework, the relevant variables are: how often changes occur how irreversible they are how well we can predict them Intention is not one of those variables. Population genetics fact: Every child already has ~60–100 new germline mutations That is ~8–14 billion new mutations per global generation So under his own risk criteria: the gene pool is already being “edited” billions of times per generation—just without control or targeting So “intentional vs random” does not change the actual risk structure he claims to care about. 2) “Nature has a filter (selection), CRISPR skips it” — incorrect under genetics He claims: natural selection filters out harmful mutations But this is only partially true and slow and incomplete: Key statistical reality: A large fraction of deleterious mutations are recessive or late-onset These are not removed efficiently by selection They persist for hundreds of generations Examples: Huntington’s disease persists because onset is post-reproductive Sickle cell persists due to heterozygote advantage Many metabolic disorders persist silently through carriers So under his own “filter” argument: nature does NOT reliably eliminate harmful mutations—it often preserves them indefinitely CRISPR does the opposite: removes known high-confidence pathogenic variants before propagation So the claim “nature filters, CRISPR doesn’t” is factually reversed in many real cases. 3) “CRISPR forces permanent choices on descendants” — nature already does this at scale He says: every descendant must carry our CRISPR choices But statistically: each generation already inherits ~60–100 new mutations they did not choose across billions of humans, that’s billions of permanent genetic changes per generation So under his own irreversibility standard: nature already imposes far more permanent, unchosen genetic decisions than any proposed CRISPR intervention The only difference is: nature = unreviewed, random, high volume CRISPR = reviewed, targeted, low volume (by design) 4) Consent argument collapses under his own applied ethics He says: embryos can’t consent, so CRISPR is wrong But under real applied bioethics (including his own IVF acceptance earlier): embryos cannot consent to IVF selection embryos cannot consent to prenatal screening decisions embryos cannot consent to being brought into existence at all So the consistent principle is not consent—it is: whether society is allowed to make irreversible decisions in the interest of preventing severe harm And that already exists in: IVF embryo selection prenatal screening vaccination policies applied post-birth So CRISPR is not a new category of consent violation—it’s a stronger version of an existing one. 5) The strongest statistical inversion (the core rebuttal) He frames it as: CRISPR = engineered permanent risk nature = neutral evolution But quantitatively: Nature: ~10 billion new mutations per generation CRISPR proposals: targeted edits at a handful of loci per embryo So under his own “scale of irreversible change” logic: rejecting CRISPR because it introduces irreversible changes is inconsistent, because nature is already introducing orders of magnitude more irreversible changes—without targeting, review, or benefit selection