Proximate cause tends to be the least understood element of the case for negligence. It may be best to think of it as a catch-all: even with every other element satisfied, there might be philosophical or policy reasons to ask a plaintiff to show more. The “duty” element of negligence, as we have seen, has also served this role – a way of circumscribing liability through fiat, as a matter of law, and therefore early in a case. Proximate cause is harder to pin down; whether it’s been met can become a jury issue when a judge thinks it’s not an easy call. (Indeed, in the celebrated Palsgraf case for today, the dueling opinions differ on whether the hiccup found within the fact pattern is best categorized as one of duty (Cardozo) or proximate cause (Andrews).) Perhaps the best way to capture the essence of proximate cause is in a single word: fortuity. Sometimes only the barest fortuity ends up linking the other elements of negligence, and in those cases we stop to consider whether there should be liability. Our opening case of the year, Vosburg, saw the prospect of major harm from a simple kick to the leg in a classroom. Fair to have the defendant pay all? The law’s answer tends to be yes. Suppose I’m speeding recklessly, and a falling boulder strikes the car spontaneously from above, injuring my passenger. My negligence – represented by the speeding – was a but-for cause of the harm, since if I’d been going slower (or faster, for that matter), the boulder would have missed us. But it’s a mere fortuity that my negligent act caused the harm in question; the harm is not anticipated from the undue risk that makes my behavior negligent. Fair for me to pay for my passenger’s harm, if I wouldn’t be responsible if the boulder hit us when we were driving normally? The law’s answer tends to be no. Proximate cause comes up when fortuity is at work, and the cases we review today seek patterns in the spectrum from Vosburg’s “eggshell plaintiff” rule to the no-liability outcome of the boulder hypothetical.