Occasionally someone confronts me after a talk with this comment, “The embryo and fetus are not human beings anymore than an acorn is an oak tree.” I even recently saw a form of this claim while studying academic pro-choice authors. The statement often accompanies a stunned disbelief that this basic fact eludes pro-life advocates. A friend shared a video on social media of a pro-life advocate on the street being challenged by a woman demanding to know if pro-lifers also believed the eggs we buy at stores are chickens. Obviously that woman is deeply confused about what she is eating at breakfast, so we’ll stick to the acorn analogy for the moment.

There are two problems with this objection. The first should be obvious. The pro-life position doesn’t require anyone to believe an acorn is the same as an oak tree. Seeds aren’t trees. However, an oak acorn is an oak in an early stage of development. Mature oaks began as seeds (acorns), and then sprouts, then saplings, then mature trees. Oak is the kind of thing it is throughout that process and acorns represent oak life at the seed level of development. This objection confuses kinds of things with the developmental stages of things.

I don’t know any pro-life advocates confused enough to believe that embryos are the same as infants or toddlers. We understand very well that each developmental stage exhibits predictable and demonstrable differences in capacities. I can do things my 10-year-old daughter cannot. My 16-year-old son can do things I can no longer do at 48. Different developmental stages enjoy different abilities and limitations. Embryos and fetuses obviously can’t do things that infants and toddlers can just as children cannot do things that adults can do.

What we actually argue is that just as every oak starts as an acorn and predictably moves through certain stages of development every human life begins as an embryo and moves through certain stages of development. The oak has a life arc and it remain a living oak through it all. The human being has a life arc and it remains a living human through it all. Again, these objectors are making a category mistake, types of living things versus the developmental stages of living things.

The second mistake they make is confusing intrinsic value versus extrinsic value. The value of any particular tree in our life is generally determined extrinsically. That means it isn’t the nature of the tree that dictates how we treat it but conditions and aspects external to the tree. In this view, it makes perfect sense to believe an acorn is far less important than a mature tree. The tree can provide needed shade, helps generate oxygen, can beautify the area it is in, and add to its habitat in multiple ways an acorn can’t. If a friend stomped on an acorn we probably wouldn’t think twice about it. If the same friend unnecessarily destroyed a mature and healthy oak, that might raise reasons for concern. It is at least understandable how maturing could make an oak more extrinsically valuable.

Human beings are intrinsically valuable. Our value isn’t derived from our capacities or contributions to our environment. Our value is grounded in the kind of thing that we are. All human life deserves to be treated with dignity and respect. It would be grotesquely immoral to weigh the value of other human beings in the same manner we would a tree. We can’t use a human being’s lack of productivity or failure to contribute to or beautify their environment as justification for killing them. Intrinsically valuable things do not get more valuable as they mature like trees do. Yanking a sapling out of the ground doesn’t compare to unnecessarily destroying a mature oak in the same way killing a toddler morally compares to killing an adult. When my kids step on acorns in the driveway I think they are being silly. When an adult on Twitter expresses their pro-choice bona fides by declaring a willingness to stomp on human embryos I think they’re disturbed.