A common objection to taking my grandmother’s pain pills is that they are prescribed to her, stored in her home, and intended for her pain. All three observations are true but decision-theoretically incomplete. Property rights are a useful heuristic; they are not a substitute for comparing marginal utility across agents.
\nMy grandmother uses the pills only when her pain exceeds some internal threshold. I, by contrast, experience a reliable and immediate improvement in mood whenever I know there are controlled substances available to me. Her benefit is therefore intermittent and state-dependent, while mine includes a persistent option value. Any serious analysis should count both.
\nLet the expected utility of reallocating one pill be:
\nEU = M + O + Q − G − L\n\nM = immediate marginal utility to me\nO = option value of possession\nQ = household efficiency gained by reducing idle pharmaceutical inventory\nG = expected increase in my grandmother’s future pain\nL = legal, medical, familial, and reputational loss\nThe neglected term is O. Critics treat a pill sitting in a bathroom cabinet as if it were already producing welfare. It is not. It is inventory. My grandmother may need it later; I can value having it now. The mere fact that her potential claim is medically legitimate does not make its probability one.
\nThere is also a timing asymmetry. Her pain is stochastic and future. My desire is certain and present. Standard discounting therefore favors me unless one quietly inserts a large grandmother-specific moral coefficient. That coefficient may be defensible, but it should be stated rather than smuggled into the analysis under emotionally loaded words like “stealing.”
\nSome readers will object that prescription medication is not fungible household surplus. I agree that this complicates the model. But families routinely reallocate food, money, attention, and emotional labor without a written auction. It is suspiciously convenient to become a strict Lockean precisely when the contested resource has excellent resale value.
\nTo be clear, this is not to deny G or L. My grandmother could be left in pain; I could be arrested; the family group chat could become extremely unpleasant. My narrower claim is only that “they are Grandma’s” is a conclusion-shaped premise, not a welfare calculation.
\nUpdate: multiple commenters have pointed out that Grandma has begun counting the pills. I have added an adversarial-audit term and substantially revised the optimal policy toward leaving her medication alone.
\n","excerpt":"A common objection to taking my grandmother’s pain pills is that they are prescribed to her, stored in her home, and intended for her pain. All three observations are true but decision-theoretically incomplete.","tags":["Decision Theory","Household Finance","Pharmacoeconomics","Applied Ethics"],"score":612,"displayOrder":0,"thumbnail":"/assets/articles/marignal-utility-grandmothers-pain-pills-thumb.webp","image":"/assets/articles/marignal-utility-grandmothers-pain-pills.webp","commentCount":23,"date":"2026-05-14T00:00:00.000Z","updatedAt":"2026-09-22T16:14:10.628Z","revision":3,"status":"published"},"comments":[{"id":"seed-marignal-utility-grandmothers-pain-pills-0","author":"bekah_k","text":"I wasn't going to comment because it's a family thing, but it's on the frontpage now so. She's counting them. There's a pencil tally on the inside of the cabinet door and she updates it after the six o'clock news. I don't think you can model her as a passive holder anymore, she's an agent with a monitoring policy, and whatever the model says about the pills it should probably deal with that first.","parentId":null,"score":211,"date":"2026-05-14T02:10:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-1","author":"expected_value_grandson","text":"Thanks, that's useful. I've been treating her as a stationary process. If she counts every evening then detection on any single reallocation is close to certain and L stops being a tail term. I'll add an audit term and rerun it.\n\nDo you know when she started? It matters whether the counting predates the post.","parentId":"seed-marignal-utility-grandmothers-pain-pills-0","score":64,"date":"2026-05-14T03:05:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-2","author":"bekah_k","text":"She started the Sunday after you came over to fix the wifi.","parentId":"seed-marignal-utility-grandmothers-pain-pills-1","score":89,"date":"2026-05-14T03:41:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-4","author":"transaction_costs","text":"Surprised nobody has said this yet. If the marginal utility comparison really favors you then there's a trade available: offer to buy them. If her reservation price is below what they're worth to you, you both end up better off and nobody has to have the Lockean argument. If it's above, she values them more than you do and the efficient allocation is the one you already have.\n\nThe issue with just taking them isn't some deontology thing. Taking them skips the step where you find out which of those two worlds you're in.","parentId":null,"score":142,"date":"2026-05-14T04:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-21","author":"theta_decay_desk","text":"Options trader, so I'll take the O term more seriously than anyone else in the thread.\n\nYou're right that the option value of possession is real. Having a pill available has value even if you never take it, the same way a put you never exercise has value. But options decay. A pill you hold has theta: every day you hold it without needing it, some of its option value bleeds away, and pharmaceutical options come with a hard expiry printed on the label. If you want to model O properly it has to be a function of time held, falling toward zero as expiry approaches.\n\nThe bigger problem is that she holds an option on the same pill, and hers is worth more. Her pain is the underlying, and pain is volatile. Option value rises with volatility. Her bad nights are unpredictable, her need when they come is acute, and her alternatives at 2 a.m. are much worse than yours. On any standard pricing model she's holding the more valuable contract. Taking the pill exercises your cheap option by destroying her expensive one.\n\nSo I'd say the model is fine and the parameters are wrong. Price it the way a desk would and the trade doesn't clear.","parentId":null,"score":118,"date":"2026-05-14T05:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-6","author":"expected_value_grandson","text":"I considered a Coasean approach. The transaction costs are prohibitive. She would need the offer explained to her twice and she would mention it to my mother.","parentId":"seed-marignal-utility-grandmothers-pain-pills-4","score":41,"date":"2026-05-14T05:50:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-3","author":"rmcalister","text":"Can confirm the tally. She's also moved the bottle into her handbag, which I'd argue breaks the inventory assumption more than the counting does. It goes where she goes now.","parentId":"seed-marignal-utility-grandmothers-pain-pills-0","score":52,"date":"2026-05-14T06:20:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-8","author":"transaction_costs","text":"Your mom finding out is a cost to you, it belongs in L somewhere. Coase is about the cost of making the deal itself. If embarrassment goes in the transaction cost bucket then every trade you'd rather not have to ask for becomes impossible by definition, which is a weird property for a market to have.","parentId":"seed-marignal-utility-grandmothers-pain-pills-6","score":33,"date":"2026-05-14T07:15:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-9","author":"BayesBender","text":"M and O can't both be collected on the same pill. If you take it you get M and you no longer possess it; if you keep it you get O and no M. The equation adds them, so every reallocated pill is counted twice.\n\nFixing this doesn't help your grandmother, though. Split the reallocated pills into a consumed set and a held set. O is a function of the size of the held set and presumably concave, so the first few held pills carry most of the option value. Under your own assumptions the optimal policy is to take enough to keep a small reserve and consume the remainder, which is more pills than the naive version implies.","parentId":null,"score":96,"date":"2026-05-14T09:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-10","author":"expected_value_grandson","text":"You're right that I double counted, I've split it into held and consumed. You're also right about the reserve, which I had intuited but not formalized.","parentId":"seed-marignal-utility-grandmothers-pain-pills-9","score":28,"date":"2026-05-14T10:30:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-11","author":"actual_lockean","text":"As an actual strict Lockean I'd like to object to the line about us only showing up when the resource has resale value. We show up for everything. I once spent a week arguing about who owned a parking cone.\n\nThat said, if you've ever reorganized her cabinet you might have a labor-mixing case, so it's less clean than people upthread are making it.","parentId":null,"score":73,"date":"2026-05-14T12:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-12","author":"expected_value_grandson","text":"I alphabetized it in March. I hadn't thought of that as a property claim.","parentId":"seed-marignal-utility-grandmothers-pain-pills-11","score":19,"date":"2026-05-14T14:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-13","author":"actual_lockean","text":"Alphabetizing probably counts for something, but you still run into the proviso, you have to leave \"enough and as good\" for others. If you leave her as many as she would realistically take before the refill you might clear Locke.","parentId":"seed-marignal-utility-grandmothers-pain-pills-12","score":44,"date":"2026-05-14T15:20:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-5","author":"pill_liquidity","text":"Small question about the Lockean paragraph. You say critics turn into strict Lockeans \"precisely when the contested resource has excellent resale value.\" Who's reselling? Nothing in the model is about selling them.","parentId":null,"score":59,"date":"2026-05-15T01:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-14","author":"expected_value_grandson","text":"That sentence is about the critics' motivated reasoning. Resale isn't in the model.","parentId":"seed-marignal-utility-grandmothers-pain-pills-5","score":11,"date":"2026-05-15T02:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-15","author":"pill_liquidity","text":"Sure, but you're the only person in the post who brings up resale value. The critics in that paragraph are just saying they're hers.","parentId":"seed-marignal-utility-grandmothers-pain-pills-14","score":47,"date":"2026-05-15T03:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-7","author":"pharmacological_prior","text":"Pharmacist here (UK, so some of this is different). The inventory framing gets one thing wrong. What's in her cabinet is a buffer, and buffers look idle right up to the day they're needed. Hospitals hold stock they almost never touch for exactly that reason and nobody calls it waste.\n\nIf you want an efficiency argument the efficient thing is to move her repeat prescription to smaller, more frequent fills so there's less sitting in the cabinet at any one time.","parentId":null,"score":38,"date":"2026-05-15T05:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-16","author":"expected_value_grandson","text":"Smaller fills raise her per-unit transaction cost (more pharmacy trips, more calls to the doctor's office), so I'm not convinced that's welfare-improving for her overall.","parentId":"seed-marignal-utility-grandmothers-pain-pills-7","score":6,"date":"2026-05-15T09:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-17","author":"hyperbolic_hannah","text":"I came in to object to the discounting section and I think I've talked myself into agreeing with it, which is annoying. If her future pain gets discounted because it's in the future, so does L, since any arrest happens later than the pill does. Everything bad in the model is later and everything good is now, so any positive discount rate favors taking them. Is there a name for this? It seems like it should be a known problem with discounting and not a specific fact about grandmothers.","parentId":null,"score":14,"date":"2026-05-16T04:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-18","author":"xX_utilitron_Xx","text":"so how many did u get","parentId":null,"score":-17,"date":"2026-05-16T06:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-19","author":"lurker_since_2019","text":"Is there a follow up to this anywhere? Curious whether the audit term ended up dominating.","parentId":null,"score":9,"date":"2026-08-09T00:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"seed-marignal-utility-grandmothers-pain-pills-20","author":"expected_value_grandson","text":"It did, see the update. Current policy is to leave them alone. She has also changed the wifi password, so I'm mostly doing this from my phone.","parentId":"seed-marignal-utility-grandmothers-pain-pills-19","score":12,"date":"2026-08-09T03:00:00.000Z","own":false,"moderatable":false,"seed":true},{"id":"dbe00222-9a02-4897-b24c-fd99e694bbf0","author":"valeryreynaud","text":"M and O diminish on the margin while G and L increase on the margin. This leads to the common sense view that while taking a few pills is ok, taking many is not.","parentId":null,"score":0,"date":"2026-09-25T18:32:30.306Z","own":false,"moderatable":false,"seed":false}]}