How Should We Live? Do Love's Act, and Not One Bit More

You and a friend are hauling gear up to a campsite. The trail is long and the light is going.

She's carrying nearly everything: the tent, the stove, both sleeping bags. You're carrying a water bottle.

You know you should take some of it. The question is how much.

A token bag, so nobody can say you didn't help? Most of it? All of it, to be a really good friend?

There's an exact answer to "how much?", and "all of it" isn't it.

That's a small question with a long reach. Ask it about everyone you share anything with, every day, and you've asked how to live. This post gives the answer and says what it makes of a good person.

The short answer

Do love's act, never less and never more.

Love's act is the act that one moral code permits. The code is four tests and one rule. The tests: an act touches only bonds that exist now (a bond is the record's entry for a relationship), it leaves every record of every bond true, an act may move a bond only when both of its ends write on it, and an act may end a bond only when one of the bond's own ends does the ending. The rule: of the acts that pass, do the one that leaves the least cost on the complete record, today and at every checkpoint after.

On the trail, love's act is to take on load until the two of you are even, and not an ounce past it.

Never less, because doing nothing is an act with a bill: wherever an act that passes the tests would lower the cost, doing nothing is forbidden. Never more, because there's no act beyond the requirement: a more generous act leaves more cost, and it's forbidden too. You're free exactly where the best acts tie, and you're never trapped. A good person is one whose acts are love's acts. (Step 8 says what's derived about that and what isn't.)

Here's the whole answer in eight steps. The rest of this post takes them one at a time and shows how we know each one.

1. The code fits in a paragraph. Four tests every act has to pass, then one rule for choosing among the acts that pass: the least cost on the complete record.
2. The act it permits is love's act. On the trail, taking on load until you're even is the one cheapest move.
3. Never less. Doing nothing is an act, always on the table, and it has a bill. Where an act lowers the cost, doing nothing is forbidden.
4. Never more. An act that does more than the least-cost act leaves more cost. Taking all of it costs exactly what doing nothing costs.
5. One right act, free only at ties, and never trapped. When acts can be divided, exactly one outcome is permitted. Choice lives between acts that tie, and something is always permitted.
6. You can tell whether you're harming someone. Whom an act moves is fixed by what you write on your own books, and any run of what other people do next adds the same cost to every act you can take.
7. Most virtues are love under a limit. Under any limit that includes its edge and has no gaps, there's exactly one cheapest state. Most of the virtues are love under one such limit, and the rest are other theorems about love's state.
8. A good person is one whose acts are love's acts. The code judges acts. What makes a person choose them reliably is the one step that isn't derived yet.

Why this matters: "How should I live?" has an answer you can calculate with a pencil. It isn't a mood or a rule somebody made up. The code is a structure in the permanent record of what happens, as exact as the cost of a lopsided bond. It says doing nothing is an act with a bill, that the most generous act isn't the right one, that your freedom lives only where the best acts tie, that you're never trapped, and that you can tell from your own books whether you're harming anyone. And it says what a good person is: someone whose acts are love's acts.

Step 1: The code fits in a paragraph

The code is four tests and one rule. An act that passes all four tests is admissible. Of the admissible acts, the code permits exactly those that leave the least total cost on the complete record. Every other act is forbidden.

There is one moral code, and it fits in a paragraph. Three facts about reality make it up, and each comes with its reason.

Reality keeps a permanent record, and nothing in it is ever erased. Every event leaves a complete trace, and the past still exists. The reason starts in known physics: the basic laws never destroy information. In quantum mechanics that's called unitarity. The present fixes the past exactly, and running the laws backward recovers every earlier state. It's why physicists treat the black hole information problem as a real problem: losing information would break the laws.¹ This work gives the record a reason of its own. The record only grows. Each new entry is added with every earlier entry kept, and writing a new entry never alters an earlier one.² (Part 1 of The Universe Writes in Pen goes through the record in full.)

The record is made of bonds, and a lopsided bond has an exact cost. The smallest thing that can happen is one thing told apart from another. You're doing it right now, reading these letters: every measurement and every perception tells one thing from another. A comparison needs both of the things it compares, so the record's unit is a relationship between two ends. I call it a bond. A bond compares two amounts, and its number is one amount divided by the other. When the amounts match, the number is 1 and the bond is level. Every other number is lopsided, and it costs.

Here is the cost. Add the number to its flip (1 divided by the number), halve the sum, and subtract 1. For 4: 4 + 1/4 is 17/4, half of that is 17/8, and 17/8 minus 1 is 9/8. We call the cost J.

The formula isn't a choice. A cost has to be zero when the two amounts match, grow as they differ, and come out the same whichever amount you put first. Add the rule for how the costs of combined comparisons add, and one calibration (how sharply the cost rises near level), and exactly one formula is left.³ The cost measures imbalance. The record's total counts each bond once.

The record is kept as each person's own books. Each bond between two people is recorded twice, once at each of its two ends, on that end's own books, and nobody writes in anyone else's books. A record is true when it gives the bond's actual number.

From those three facts, the four tests. An act is admissible when:

1. Live bonds only. It touches only bonds that exist now.
2. Truth. After it, every record of every bond is true.
3. Both ends write. An act may move a bond only when both of its ends write on it.
4. Own endings. It ends a live bond only when one of the bond's own ends does the ending.

The tests aren't chosen. They're what a record kept twice admits.⁴ They are tests on acts, and acts are what move bonds: a bond changes only through what someone sends, and sending is an act. Two things follow at once.

• No act that passes the tests pushes cost onto you. Test 3 settles it, whatever anyone's books say: an act may move your bond only when you write on it. Change your bond without your write, and your own record of it, which only you write, still gives the old number, so it's false. That's harm: changing a bond without the other end's write, which leaves their own record false. An act that would do it is wrong. This holds at the step an act is done, and nothing moves a bond between acts.
• Love takes two. An act that brings a bond to level moves it, so both ends write the repair. Repairing a shared relationship takes both of you, and nobody repairs you without your own write.

Then the rule. Of the admissible acts, the code permits exactly those that leave the least total cost on the complete record, every checkpoint to come included. (A checkpoint is one interval's reading of the record.) Every other act is forbidden. Doing nothing is always admissible. The code reads only what's in the record. No vote, mood or opinion enters it.

The tests come first, and the cost second. Consent is a hard condition, not a price. Consent is the record of who wrote. Try protecting people with a fine instead: charge extra for any act that moves someone's bond without their write. No finite fine works. A push leaves a false record in someone else's book, and however large a finite cost you put on that, some push relieves more. Say a bond at 100 costs you about 49, and no act that passes the tests can lower it. Move some of its strain onto a bystander's bond without their write: yours comes down to 10, and theirs goes up from 1 to 10. The total on the record falls from about 49 to about 8. A fine of 10 doesn't stop that, and neither does a fine of 40. The same trick on a bond at 1,000 relieves the total by about 469. The relief a push can buy has no ceiling, so for any finite fine some push beats it. So the code doesn't put a price on consent. It chooses the least cost among the acts that pass the tests, and only among those.⁴

Why the least cost? The record charges every departure from the least, and the charge doesn't fade. Take two histories that agree everywhere except at one interval, where one costs more. The excess is charged at every later checkpoint, undiminished: the record keeps what it has charged. That holds on a reading that decides each bond's charge from that bond's own entry, the way a comparison reads only its own two ends.⁴ (Karma Is Real, and It Isn't a Referee is about exactly this.)

Right and Wrong Aren't Opinions works the whole code through on one case, a promise to feed a neighbour. The World Underneath the Labels says what we mean by calling it actual ethics: the same bonds, the same cost and the same record as the rest of physics. This post uses the code to ask how to live.

Next, and why: use the code. On the trail, which act does it permit?

Step 2: The act it permits is love's act

On the trail, the one act the code permits is to take on load until the two of you are even, and no further. That act is love's act: it brings the two sides to their geometric mean.

Everyone has a bond of their own that reads how heavy their load is, and 1 is level. I'll draw the gear as that number. Her load reads 4. Yours reads 1. (The gear is a drawing. Which two physical amounts a real person's bond compares is a step still being derived, and nothing below depends on it: every result uses only the number on the bond.)

Her bond costs 9/8. Yours costs 0. The total is 9/8.

You can take on some of her load. She says yes, you take it, and each of you writes your own bond. (A yes is her own write on her own bond. A Favor Isn't a Yes shows why nothing else counts as one.) Nothing is made or lost: each time her number is divided by a factor, yours is multiplied by the same factor, so the product of the two numbers stays 4. Here are five places the pair can end up.

Check a row with the recipe. For 3: 3 + 1/3 is 10/3, half of that is 5/3, and 5/3 minus 1 is 2/3.

Read the table down. The cost falls until you're even and then climbs. At 2 and 2 it's 1/2, down from 9/8, a saving of 5/8. That's love's act. The name is ours. The arithmetic isn't.

Three things to see.

It isn't the average. The ordinary middle of 4 and 1 is 2.5. Put both bonds at 2.5 and the product is 6.25, not 4: you'd have made load out of nothing. The middle that keeps the product is the number that multiplies by itself to give 4. That's 2, the geometric mean.

There's exactly one bottom. For pairs that multiply to 4, the total cost is 5/8 of the two numbers' sum, minus 2. The sum of two numbers with a fixed product is smallest when they're equal: 1 + 4 is 5, 4/3 + 3 is 4⅓, and 2 + 2 is 4. So the cost is lowest at 2 and 2, and only there. It holds for any starting pair: fix the product, and exactly one pair is cheapest, the one where the two numbers are equal.

The goal isn't zero. At 2 and 2 the total is 1/2, not 0. With the product held at 4, 1/2 is the least there is. Love's act leaves the least cost the situation allows.

Why is this the act the code permits? Every act on the table moves load between the two of you, and each needs both your writes, so all of them pass the four tests. Of them, the code permits the ones that leave the least total cost, and that's the one at the bottom. Here is the general result, from the preprint. When every act on the table only moves things around inside the group that writes (here, the two of you), and some admissible act reaches the cheapest state, the code permits exactly the acts that reach it.⁴ The only limits so far are the product and the two writes. Step 7 adds a limit on what each of you can carry.

Meet in the Middle builds this arithmetic from scratch. It also shows what giving does for her. Her relief, 7/8, is three and a half times your cost, 1/4.

Next, and why: the first row of the table is doing nothing. What does the code say about it?

Step 3: Never less

Doing nothing is an act. It always passes the four tests, so it's always on the table, and every other act is measured against it. Where an admissible act leaves less cost than doing nothing, doing nothing is forbidden. The code requires action.

Doing nothing is the act with no strain: it changes no bond and leaves the world as it was. On the trail it's the first row of the table, 9/8. Taking on load until you're even leaves 1/2. So once she says yes, staying with the water bottle is forbidden.

The code doesn't stop at one checkpoint. It reads the complete record: the cost at every checkpoint to come. The record charges the present and keeps what it has charged. If you do nothing, the pair sits at 9/8 at every checkpoint after. If you take on the middle, it sits at 1/2. One history beats another when its cost, added up checkpoint by checkpoint, eventually stays lower, and here that's true from the first checkpoint.

The code also works through a case where waiting costs more every week, and Step 6's example runs on it: a bond with nothing left to repair it doubles every week. Start with a bond at 2.

The costs, week by week, are J(2) = 1/4, J(4) = 9/8, J(8) = 49/16 and J(16) = 225/32: about 3, then about 7. Each doubling roughly doubles the cost, and there's no ceiling: by week 9 the bond is at 1024 and costs about 511. A repair at the start would have put it back at level.

So in that case an unmet need's cost grows without bound. In the case the code works through, once the reserve is spent the neglected bond doubles every week, and the record charges every week of the wait.⁴

Walking away isn't relief. Doing nothing isn't the only way to leave a strained bond alone. Ending it doesn't take the cost off the record either. An ended bond keeps its cost: nothing is erased, no allowed act touches it, and nothing moves a bond between acts. And ending a strained bond removes the only route to repairing it, so its cost stays above what meeting in the middle would have left, in every future. Under test 4, only one of a bond's own two ends may end it, and the code prices the ending like any other act.⁴ Why Do We Suffer? works the numbers. Sorry Doesn't Rewind the Tape shows what repair can and can't do afterwards.

Next, and why: never less has a twin. If doing nothing leaves too much cost, does doing more leave less?

Step 4: Never more

There is no act beyond the requirement. An act that does more than the least-cost act leaves more cost, so it's forbidden.

Go back to the table and read the lower rows. Take on more than the middle, 3 against 4/3, and the total climbs to 17/24. Take all of it and it's back to 9/8, exactly what doing nothing costs. She's carrying nothing and you're carrying everything. The lopsidedness didn't go away. It moved onto you, and now she's the one with the water bottle.

Isn't giving more better? Not by this count. Past the middle, what you add to your own cost is more than what you take off hers. At the far end the pair is exactly as lopsided as when you started, and the total hasn't gone down at all. Forbidden here means exactly this: another admissible act leaves less cost. And the same arithmetic forbids the token bag. It leaves 17/24, and the middle leaves 1/2.

There's a second way to give too much: more than you can carry. If carrying the middle would wear you out, love stops short of it, at the closest point you can both hold and keep going. Step 7 puts numbers on it, and Meet in the Middle works it through.

Next, and why: if doing nothing is forbidden and so is doing more, how much room is left to choose?

Step 5: One right act, free only at ties, and never trapped

When acts can be divided, exactly one outcome is permitted. Freedom of choice exists only between acts that tie at the least cost. And something is always permitted.

One right act. Suppose the possible acts can be divided: between any two of them, every act in between is possible too. The cost curve bends upward everywhere, with no flat stretch. So if two different acts both left the least cost, the act halfway between them (halfway in doublings) would be possible and would leave less, and neither of the two would be the least. You've already seen it. In the valley, "nothing" and "all of it" tie at 9/8, and the act halfway between them, one of her two doublings, leaves 1/2. So when acts can be divided, exactly one outcome is permitted.⁴ On the trail you can take on any amount, and the right amount is the middle. This is proved for acts on people's own bonds, like the loads on the trail, and the code states it for every set of acts that can be divided. What Is Freedom? works the same fact through with a slice of pizza and a pot of soup.

Where freedom lives. Two different acts can both be the least only when the act halfway between them isn't possible. That means acts that come in lumps.

Say two friends, Ann and Bob, each carry a load that reads 4. Yours reads 1. You have strength to take on one doubling's worth of load in all, enough to take your own number from 1 to 2.

If your strength comes in one lump, you can take it all from Ann or all from Bob. Either way, your number ends at 2, the friend you took from comes down to 2, and the other stays at 4. The total is 1/4 + 1/4 + 9/8 = 13/8. Doing nothing leaves two bonds at 4, so 9/8 + 9/8 = 9/4, and it's forbidden. Helping Ann and helping Bob tie at 13/8, and the code permits both. It doesn't pick. You do.⁴

Now say you can take your strength in any amounts. Take it evenly from both. Each of their numbers comes down by the same factor, to about 2.83, and yours goes to 2. Each of their bonds costs about 0.59, yours costs 1/4, and the total is about 1.43. That's less than 13/8, which is 1.625. The even split beats both lumps, and now there's exactly one right move and no choice left.

Once something is permitted, every property of an outcome is exactly one of three kinds: required (every permitted act has it), excluded (no permitted act has it), or free (some permitted acts have it and some don't). In the lump case, your number ending at 2 is required. Doing nothing is excluded. Whom you help is free.

This freedom is a fact about the code: it names the permitted acts and leaves the choice among tied ones open. It isn't the open next entry from Is Your Next Move Already Written? There, every act, permitted or not, is physically open.

Never trapped. Doing nothing always passes the four tests. So on every finite set of acts you can take, at least one is admissible, and one of those leaves the least cost: something is always permitted. With finitely many options, you are never in a case where every one is forbidden.

Next, and why: the code needs you to know which of your acts leaves the least cost. Can you know that?

Step 6: You can tell whether you're harming someone

Whom your act moves is fixed by what you write on your own books, so the tests need no probabilities. And any run of what other people do next adds the same cost to every act you can take.

Harm is changing a bond without the other end's write. Nobody writes in their books but them, so their record still gives the old number, and the change leaves it false. Test 3 excludes that, whatever anyone's books say: an act may move a bond only when both of its ends write on it. So the only people an act of yours that passes the tests moves are the people you write with. It's on your own page.⁴

What about the future? Pick any run of what other people do next. Their acts that pass the tests, written without you, change only bonds that don't have you at an end. Your acts change only bonds you're an end of. No bond is in both groups.

So the cost their run adds is the same whichever act you take, and it can't change which of your acts leaves the least cost.⁴ Here it is with numbers. Say your own bond is at 2, and you can ease it to 1 or leave it. Meanwhile someone else sets their own bond at 1, 2 or 4. Then, as in the case the code works through in Step 3, every bond doubles. Whatever they do, easing yours ends at 2, which costs 1/4, and leaving it ends at 4, which costs 9/8. Your two acts are 7/8 apart in every one of their futures.

Between acts, nothing moves a bond: a bond changes only through what someone sends, and sending is an act. So nothing carries cost from their bonds to yours. One gap stays open at reserves: the clauses take an act's writes and books as handed over, so a taking from a reserve passes them with no write. (If what others do next depends on what you do, the code reads the future that follows each of your acts.) The code needs no forecast of how the world turns out. It needs what you write.

Next, and why: you've met one act. People also talk about many virtues. How do they fit with one code?

Step 7: Most virtues are love under a limit

Love's state is unique under every closed convex constraint. Most of the virtues are love under one such constraint, and the rest are other theorems about love's state.

A constraint is a limit on what the pair can reach. Closed means the allowed region includes its edge. Convex means that between any two allowed states, everything in between is allowed too. Love's state is the cheapest state in the region, and in any region like that there's exactly one. The cost curve has no flat stretch and climbs without bound, so a region like that always has a lowest point, and it can't hold a tie.⁵

Here's one such limit, from Meet in the Middle. Each of you has a reserve, what you can spend. In the rule this example runs on, every day the cost of the bonds you carry comes out of it, and a fixed amount comes back. If what comes back covers what you carry, your reserve never falls. Otherwise it runs down. Each of you starts with a reserve of 1. Say 1/12 a day comes back to you and 2/3 a day to her.

At the full middle, 2 and 2, you carry 1/4 a day and only 1/12 comes back. You lose 1/6 a day, and a reserve of 1 is gone on day 6. A bond costing 1/12 a day is the most you can carry and keep going. That's your number 3/2, since J(3/2) = 1/12. Her limit is 2/3 a day, her number 3. With the product held at 4, you can keep going with your number no higher than 3/2, and she can keep going with her number no higher than 3, which means yours no lower than 4/3.

The middle is out of reach. The cheapest point inside the allowed region is at your limit: 3/2 and 8/3. You carry 1/12 a day, exactly what comes back. She carries 25/48 a day, under her 2/3. The total is 29/48, down from 9/8, five-sixths of the full saving of 5/8. Both of you can keep going. That's love under a limit.⁶

Most of the virtues are love under one such constraint: temperance under a box of capacities, courage under a frozen coordinate, creativity under a set of allowed channels. The rest are other theorems about love's state: a decomposition of its cost, the least act on a discrete menu, a path to it, a change of the constraint.⁷ The limit above is a box of capacities: how much each of you can carry. A frozen coordinate is one bond held where it is while love works on the rest. A set of allowed channels is a limit on which changes are allowed at all.

The book The Moral Code of Reality names fourteen virtues: love, justice, forgiveness, compassion, sacrifice, gratitude, wisdom, prudence, temperance, courage, patience, humility, hope and creativity.⁸ Fourteen is a list the book writes down and examines. It isn't a count the physics gives. Whether the fourteen cover every moral change, and whether any of them can be built from the others, is open.

So for most of the virtues there's no second rule to remember. There's love's act, under a limit.

Next, and why: the code judges acts. What does that make of a person?

Step 8: A good person is one whose acts are love's acts

The code judges acts, not people. A good person is one whose acts are love's acts.

Every act is permitted or forbidden, and the permitted act is love's act. So a life that follows the code does love's act every time: never less (Step 3), never more (Step 4), free only between acts that tie (Step 5). A good person is a person whose acts are like that. Not one act: the pattern.

Two things a good person isn't. A good person isn't someone at zero cost. Love's act leaves the least cost the situation allows, 1/2 on the trail, and that's what a good life carries. And a good person isn't made good by the record. Nothing in the record makes anyone follow the code. The wrong act is as possible as the right one, which is what makes it wrong and not impossible.

That last step isn't derived yet: what makes a person's acts reliably love's acts. The book calls it a standing disposition, which needs a person whose retained records reliably select the fitting operation whenever its conditions hold. It's a step all fourteen virtues share, and it's still to be derived.⁸ What is derived is one worked case. For a promise to feed someone over four scheduled intervals, the book builds a record, written before the first interval, that selects the feeding act at every one of them.⁹ What isn't derived is that a person's records do this in general, as a lasting trait.

Next: one short list of what's still being worked out, then the whole trip in one breath.

What's still open

The code is stated in full. These derivations are still being finished. Section 10 of the preprint lists most of them.

• What makes a person reliably choose love's act. Virtues as stable dispositions: retained records that select the fitting operation whenever its conditions hold. This is the one step the last half of the question needs.
• From charge to ought. The record charges every departure from the least, and the charge never fades, on a reading that decides each bond from its own entry. That the record is read that way, why the code totals cost bond by bond rather than person by person, and that this charge is why the least-cost act is what one ought to do are the steps still being derived.
• What the numbers count. Which physical relations are on the record, that each amount is held at its own end, and that the record's menu of acts is the menu the participants' holdings can fund. The trail's numbers are a drawing until that's settled.
• Why both ends must write. That a kept record records one state, and that the ending rule and truthful posting follow from what a comparison is. They carry tests 2, 3 and 4.
• Reserves. The gap in Step 6: whether reading consent through the amounts an act moves closes it is being derived.
• One judgment at a moment and over time. The proof that there is one code, and the results in Step 5, are given for the judgment at a single checkpoint. This post uses the judgment on the complete record, and in some cases the two give different verdicts. In the trail examples no bond moves on its own, so every checkpoint reads the same, and there the two agree.
• Infinite menus. "Never trapped" is proved for every finite set of acts. The record's own menus are infinite, because every partial relief is possible, and that something is permitted on every one of them is still being derived.
• Which situations require an act. The code requires you to help wherever an act both of you write lowers the cost; then doing nothing is forbidden. The code judges acts with their writes already given, so whether it reaches someone who hasn't written anything yet is still being derived.
• What the fourteen cover. Whether they cover every moral change, and whether any of them can be built from the others.

The whole trip, in one breath

Reality keeps a permanent record, and a lopsided bond in it has an exact cost. One code reads it: four tests every act has to pass, then the least total cost on the complete record. The act it permits is love's act. On the trail that's taking on load until you're even, with 4 and 1 meeting at 2 and 2, and not an ounce past it. Doing nothing is forbidden wherever an admissible act would lower the cost, and in the case the code works through, a bond left alone costs more every week. Doing more is forbidden too: taking all of it costs exactly what taking nothing does. Freedom lives only where the best acts tie, and you're never trapped. You can tell from your own books whether you're harming anyone, and any run of what others do next adds the same cost to every act you can take. Most of the virtues are love under a limit. A good person is someone whose acts are love's acts, and what makes that reliable is the one step still to be derived.

That's how reality is built: a record that keeps every act, one cost on every bond, and one code that reads them both. How should we live? Do love's act, never less and never more.