for proficient language-users. It is not an exaggeration to say that the rule depends as much on a deep understanding of one specific word's usage within a given linguistic community as it does on the logical relationships between terms in the rule itself.
A further difficulty introduced through natural languages is that of conversational implicature, among other discursive norms. Granted, this problem is far worse in conversation than in law, but that does not mean the problem is insignificant, even in that context. For example, when I tell my son, "Don't spit on people," I actually mean something closer to "under no circumstance is it permissible to spit on people." It is only through the practical experience of parenting two small children that I have come to learn that that particular implicature is entirely lost on some members of my own linguistic community. A more interesting example, potentially, is when I tell him "Don't hit people." I suppose that what I probably mean is more like "never hit a person unless they are physically harming you." I think this example is fascinating because it turns out that rules on justifiable harming are rather nuanced. In fact, I find myself struggling to specify precisely the circumstances under which harming others is appropriate. Of course, I should expect my kids to learn over time to account for considerations of preemption, proportionality, and necessity in developing a finer understanding of the rules against hitting others. Still, it is difficult to specify all the morally relevant considerations bearing on the justifiable use of violence, and I take it that these are relatively simple rules. Maybe I could just say, "don't hit others unless it is strictly necessary that you do so." But notice there that the phrase "strictly necessary" has introduced the very sort of ambiguity and subjectivity that one should hope to avoid with children and robotic weapons. I have argued elsewhere that children, especially teenagers, offer a useful parallel in guiding effective lethal autonomous weapons policy, a point which takes on an even greater significance in recognizing the linguistic demands of following the law.19
The Global Reasoning Problem
19 Kevin Schieman, "The Soldier's Share: Considering Narrow Responsibility for Lethal Autonomous Weapons," Journal of Military Ethics 21/3–4 (2022), 228–245, here p. 239.
Thus far, the problems that I have described are features of individual laws and legal terms that make it difficult to understand how the law obligates people. However, rules also present a problem collectively that I refer to as the global reasoning problem. Whatever challenges one might find in applying a single rule, rules are rarely, if ever, applied individually. Instead, following the law is usually a practice of reconciling any number of rules against one another, determining the appropriate hierarchical relationship between rules, weighing precedence, considering past cases, and rendering a judgment that strikes an appropriate balance between potentially counter-vailing considerations. In some cases, it appears to be impossible to apply a law in isolation from its broader legal and jurisprudential contexts. For instance, the law established as Article 23, Par. (b) of the 1907 Hague Regulations states:
It is especially prohibited...to kill or wound treacherously individuals belonging to the hostile nation or army.20
It might strike those unfamiliar with the conventional legal interpretation of this law as surprising that it has generally been interpreted as a prohibition against assassination whenever a state of war exists between parties. Louis Beres notes that there is a direct reference to Article 23(b) in Article 31 of the U.S. Army Field Manual 27-10, The Law of Land Warfare, dated 1956, which reads
This article is construed as prohibiting assassination, proscription or outlawry of an enemy, or putting a price upon an enemy's head, as well as offering a reward for an enemy "dead or alive."21
Beres also notes that this understanding of Article 23 was entered into customary international law as of 1939, suggesting something of a resolution, but also introducing a further complication for legal rule-following; namely, there is also a temporal component
20 "Convention with Respect to the Laws and Customs of War on Land," The American Journal of International Law 1/2 (April 1907 Supplement), 129-159, here p. 142.
21 Louis Rene Beres, "After Osama Bin Laden: Assassination, Terrorism, War, and International Law," Case Western Reserve Journal of International Law 44/1 (2011), 93-147, here p. 109.
