Roe v. Wade is often compared to the infamous Dred Scott decision, and much has insightfully been made of the parallels between the issues of slavery and abortion. These parallels are usually drawn more for the benefit of persuading the opposition than for the benefit of pro-lifers themselves—pro-lifers already know that abortion is evil without the helpful comparison to the evil of slavery.

I recently had occasion to revisit Frederick Douglass’s immortal “What to the Slave is the Fourth of July?” speech in a course I’m teaching on slavery, and I realized that one crucial parallel between the issues of abortion and slavery has gone mostly unnoticed, or perhaps has been unduly neglected. The reason for this is simple: It is a parallel that some pro-lifers may find unsettling or uncomfortable, and therefore one that few have been especially eager to find.

In this famous speech, Douglass imagines a member of his audience imploring him to “argue more, and denounce less”—to push rational discourse about the slavery issue toward acknowledging the wrong of slavery, and thereby to further the cause of abolition in a calm and civilized manner.

In response, Douglass asserts that “where all is plain there is nothing to be argued.” He then unleashes a powerful barrage of rhetorical questions on his audience: “Must I undertake to prove that the slave is a man? Would you have me argue that man is entitled to liberty? That he is the rightful owner of his own body? Am I to argue that it is wrong to make men brutes, to rob them of their liberty . . . to starve them into obedience and submission to their masters?” According to Douglass, the slavery issue has already been settled on the level of reasoned argument, and “it is not light that is needed, but fire; it is not the gentle shower, but thunder.”

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While there were in fact a variety of pro-slavery arguments current at the time, Douglass was of course absolutely right: The humanity of the slave was obvious, and the right to liberty was, and is, an obvious concomitant of this humanity. The practice of slavery wasn’t being upheld by the force of rational argumentation, but by slaveholders’ desire for self-preservation and non-slaveholders’ apathy or inactivity. The battle to be fought wasn’t a battle of ideas—that battle already had been won—but a battle of conscience.

The same, I submit, is true of the abortion debate today. While, as in the case of slavery, arguments have been and are given against the humanity or right to life of the unborn, the contrary is simply obvious to anyone willing to set aside ideology or narrow self-interest.

Excellent and highly sophisticated arguments for the personhood and dignity of the unborn from the moment of conception have been given by many on the pro-life side (by Robert George, Christopher Tollefsen, and Patrick Lee in particular), arguments clearly unmet by those in favor of abortion rights. Such arguments drive home this basic fact of human existence in a manner that effectively marshals the support of heavy-duty philosophy to the pro-life position. While this is a crucial task, in fact the argument may be settled by common sense and simple reasoning.

In a manner similar to the case of slavery as outlined by Douglass, there are two simple points that, once admitted, join to condemn clearly the practice of abortion: (1) the embryo is a human being from the moment of conception, and (2) all human beings have a natural right to life.

The second point, as in the case of the natural right to liberty, doesn’t require serious argument on the level of ordinary judgment, even though many pro-choice philosophers have tried to argue that only persons have a right to life, and the unborn, in their view, aren’t persons. To make such arguments, however, requires choosing an arbitrary cut-off point for personhood, as pro-life philosophers such as George, Tollefsen, and Lee have shown.

The first point is more often chosen as promising ground for challenges, but it too is plainly obvious to the unbiased mind.

Once conception occurs, the embryo is something other than the woman who carries it. The fact that the embryo requires the mother’s body to live is no argument against this—dependence does not exclude otherness, otherwise none of us would be distinguishable from everyone and everything else in the world upon which we depend in innumerable ways. The embryo is obviously something other than a part of the mother, but what is it?

This is where it gets easy, despite the messy, abstract philosophical arguments. The more appropriate version of the question is the following: What else could it be besides a human being? Is there a single example in natural history of sexual intercourse between two individuals of the same species resulting in something other than another individual of that species? Is it plausible to guess that sexual intercourse between two human beings might result in a fish, at least initially? Or maybe a frog? Such speculation is entirely fanciful and runs directly contrary to our experience of the world since the beginning of recorded history.

It should be obvious to anyone that the two points hold, and that the embryo is a human being possessing a natural right to life from the moment of its conception. The problem is that the younger and less developed the embryo is, the less it excites what some have called our “moral sense,” our sympathy with it as another human being like us. And as Hume correctly notes, human beings tend to be moved more by their passions and feelings, including the so-called “moral sense,” than by their intellectual understanding of the world when determining their actions. Even if our reason and common sense tell us clearly—as they undoubtedly do—that the embryo is a human being with the right to life, our moral sense or sympathy lets us off the hook.

So where does this leave pro-life advocates? How can we bridge the Humean—and human—gap between intellectual understanding and actual practice in our nation? The answer lies in the parallel between the issue of abortion and those of slavery and subsequent civil rights. The pro-life movement needs to model more closely in its organization and practices the antebellum abolition movement and the civil rights movement in order to achieve similar success in ending the evil of abortion. It needs to take up the mantle of these causes in a manner beyond rhetorical parallel or intellectual analogy and be prepared to undergo similar hardships before achieving its goals.

Both of these historical movements ultimately succeeded not by winning arguments, but by awakening the moral sense or conscience of a majority of the nation. Legislation relating to the provision of an ultrasound prior to an abortion, currently in place in some form in more than twenty states, is very well suited to this purpose. The dissemination of graphic images relating to abortion procedures, though controversial in pro-life circles, is also highly appropriate to this purpose.

The civil rights movement was driven forward significantly by television and photographic coverage of the inhuman treatment of protestors, as well as the publication of vivid written reports of racially motivated cruelties. Moral senses or sympathies are sparked most effectively by distasteful, unsettling, and shocking information; and when intellectual argument has had its day in trying to awaken consciences and has shown itself insufficient, recourse must be had to the level of moral sense and feeling.

The pro-life movement currently finds itself in the same place as the abolition movement at the time of Frederick Douglass’s great speech. If we are to experience similar success, we would do well to follow Douglass’s advice and focus our energies on awakening the moral sense of our fellow citizens. It would help to have another Douglass for our cause, but at least we still have his words: “The feeling of the nation must be quickened; the conscience of the nation must be roused; the propriety of the nation must be startled; the hypocrisy of the nation must be exposed; and its crimes against God and man must be proclaimed and denounced.”