Haute Lumière
Commerce · VII.11 · MMXXVI · daylight
TEN CONCEPT BRIEFS · Chapter VII.11 — What We Owe the Next Thing
One page each. A reader who reads only these ten pages has the chapter.
BRIEF 1 — The Intergenerational Balance Sheet
The idea. What one generation owes the next is not a sentiment. It is a balance sheet, and every line on it is already published by somebody.
Five categories, and almost nobody adds them together because each one lives in a different department:
public debt pension promises infrastructure stocks
sovereign funds the natural capital positionWorked example. The United Kingdom, per head of a mid-2022 population of 67.6 million. Public sector net debt of £2,700 bn is £39,941 per head. The net public service pension liability of £1,375 bn is £20,340. Accrued State Pension entitlement of £4,000 bn is £59,172. Household net wealth of £15,200 bn is £224,852. Public non-financial assets of £1,300 bn are £19,231. Natural capital as the ONS values it, £1,800 bn, is £26,627. Sovereign wealth fund: £0.
Seven real figures, each quoted in public by somebody winning an argument with it, and not one of them can be added to another in that form — which is the first thing this chapter teaches.
Why it matters. An obligation you cannot write down is an obligation you cannot govern, cannot covenant, cannot verify and cannot argue about productively. The account is what turns a value into an instrument.
You already know this because you have watched two people argue about whether a household is doing well while one of them was looking at the current account and the other at the mortgage, and neither of them was wrong.
BRIEF 2 — Consolidation: a Domestic Claim Is Not a Transfer
The idea. A gilt is a liability of the state and an asset of whoever holds it. Inside one country, most public debt nets out — it decides who inside the next generation owns the endowment, not how much the next generation has.
Worked example. About 28 percent of UK gilts are held outside the country. So of the £39,941 per head headline, £11,183 is a genuine external claim on the next generation's output and £28,757 is one Briton's claim on another. The internal part does not leave the country and does not reduce the national endowment by a penny.
The same move dissolves the accrued State Pension line as a debt. At £59,172 per head it is real and it is owed — but it is owed by the next generation to the one before it, and the matching claim on future labour income is booked nowhere. Enter one side of a two-sided entry and you have measured a convention, not an obligation.
Why it matters. The single most common sentence in intergenerational rhetoric — we are leaving our grandchildren a mountain of debt — is about a quarter true at the national level and entirely true at the distributional one. Separating the two is not a debating trick; it points at two different and equally real problems, each of which has a different fix.
You already know this because you have never thought a family was poorer because one sibling owed another sibling money.
BRIEF 3 — ΔM: What Actually Crossed the Boundary
The idea. Strip the internal claims and one question survives: is the endowment per person larger or smaller than the one this generation received?
Worked example. The ONS national balance sheet, 1995 to 2022:
UK net worth, 2022 £11,800 bn -> £174,556 per head
UK net worth, 1995 £2,800 bn -> £48,276 per head
1995 in 2022 prices (×1.87) -> £90,276 per head
----------------------------------------------------------------
ΔM, the transfer -> £84,280 per head
real growth per head, compound 2.47% per yearThe aggregate transfer is strongly positive. Per person, in constant prices, this generation is handing forward a little under twice what it received. Move the 1995 stock by a fifth either way and ΔM runs from £66,225 to £102,336 — it never changes sign.
Why it matters. Any argument about intergenerational justice that assumes the aggregate transfer is negative is arguing against an arithmetic result. The serious case is elsewhere, and this brief is what makes the serious case findable.
You already know this because you have stood in a city that plainly contains more infrastructure, more housing and more accumulated skill than it did thirty years ago, and you did not think anyone was lying about that.
BRIEF 4 — The Land Switch
The idea. A house that doubles in price has not become a better house. The buyer pays the difference. So is a land revaluation an addition to the endowment or a transfer between generations wearing the clothes of one?
Worked example. Land is about 60 percent of UK net worth. Hold it out:
non-land net worth per head, 2022 £69,822
non-land net worth per head, 1995 (2022 prices) £51,457
----------------------------------------------------------
ΔM excluding land £18,365 per head78.2 percent of the headline transfer is land. The same country, the same year, the same published accounts, and the transfer falls by more than four-fifths on a single accounting decision that no government makes explicitly.
Why it matters. This is the first of the chapter's two switches, and it is the one that is easiest to hide. A national account that does not separate land revaluation from capital formation is reporting a price change as an achievement.
You already know this because you have heard someone say their house made more last year than they did, and you noticed that nobody had built anything.
BRIEF 5 — ΔN and the Lower Bound
The idea. The natural position is the part of the ledger that is genuinely hard, and the honest treatment is to price what can be priced and to write UNMEASURED — never zero — where nothing can.
Worked example. UK territorial greenhouse gases fell from 700 to 417 MtCO₂e between 1995 and 2022. On a straight-line path between the published endpoints, the trapezoid mean is 558.5 MtCO₂e a year over 28 years: 15.64 GtCO₂e cumulative. At the Green Book's central carbon value of £269 a tonne, that is £62,228 per head.
And the change in Britain's non-atmospheric natural capital — soils, fish stocks, aquifers, habitat — over the same period has no consistent published series. It is recorded as UNMEASURED. Not zero.
Why it matters. A zero is a claim. A blank is not. Setting the unmeasured term to zero would have made this chapter's conclusion weaker, which is exactly why the temptation had to be refused: a fallback value is a lie with a default. Because of that refusal, ΔN is stated throughout as a lower bound on the natural deficit and never as a total.
You already know this because you have seen a survey report "no response" counted as "satisfied", and you knew immediately that the number had stopped meaning anything.
BRIEF 6 — θ: The Substitutability Parameter
The idea. Write the whole account as one line with one switch in it:
IGBS(θ) = ΔN + θ · ΔM θ ∈ [0, 1]θ is the degree to which manufactured and financial capital can substitute for the natural capital that was consumed.
θ = 1 is weak sustainability. Solow (1974) and Hartwick (1977): capital is capital, and a fund of bonds can stand in for a fishery, provided the rent is reinvested.
θ = 0 is strong sustainability. Daly (1990): some natural capital is critical and complementary rather than substitutable. Money does not cross the boundary. You cannot build a second atmosphere out of retained earnings.
Worked example. With ΔM = £84,280 and ΔN = −£62,228, the position at θ = 1 is +£22,052 per head and at θ = 0 it is −£62,228 per head. Same country, same year, same accounts, opposite sign.
Why it matters. Ernst Neumayer's survey of this dispute is in its fourth edition and has not resolved it, because it is not the kind of thing a survey resolves. What can be resolved is making the parameter visible. An account that hides θ is not neutral; it has chosen one and declined to say which.
You already know this because you have been in a meeting where two people agreed on every number and still disagreed completely, and nobody could say why.
BRIEF 7 — θ*: The Number That Decides It
The idea. Do not argue about θ. Compute the θ at which the sign flips, and hand that to the room.
θ* = −ΔN / ΔMWorked example.
with land θ* = 62,228 / 84,280 = 0.74
excluding land θ* = 62,228 / 18,365 = 3.39With land, the UK's position is positive if and only if you believe manufactured capital substitutes for the atmospheric sink at better than about seventy-four pence in the pound. That is a defensible belief and roughly the one a treasury acts on.
Excluding land, θ is 3.39 — outside the admissible range entirely. No degree of substitutability clears it. And that conclusion survives the whole sensitivity sweep on the least certain input: θ excluding land runs from 5.584 to 2.131 as the 1995 land share moves from 35 to 55 percent, and never approaches 1.
θ* is also sensitive to the carbon value, and honestly so: it reaches 1 at £364 per tonne with land and at £79 per tonne without. The UK government's own published 2050 carbon value is £378 a tonne — above the first figure. At its own number, even perfect substitutability does not clear the ledger.
Why it matters. θ* converts a philosophical dispute into a threshold a board can vote on. That is the whole trick, and it generalises to every argument where two camps agree on the facts and disagree on one elasticity.
You already know this because you have priced a break-even before, and found that the break-even was more persuasive than any of the forecasts around it.
BRIEF 8 — The Four Cells
The idea. Publish the account as a two-by-two, never as a point estimate.
weak (θ=1) strong (θ=0)
------------------------------------------------------------------
with land +£22,052 −£62,228
excluding land −£43,863 −£62,228One country. One year. Four answers, and two signs. Nothing in that table is a modelling error. Every cell is arithmetically correct given a premise somebody serious holds.
Worked example of the failure this prevents. A ministry publishes +£22,052 per head and calls it the intergenerational position. It is not wrong. It is one cell of four, and the three it did not print are the ones that would have been argued about. The four-cell format makes that omission visible, which is the only enforcement mechanism a voluntary disclosure standard ever really has.
Why it matters. Every check in this edition states its denominator — what it did not look at. The four cells are this account's denominator statement. A single figure with unstated switches is worse than no figure, because it will be quoted.
You already know this because you have seen a chart with a truncated axis and known instantly that somebody had chosen it on purpose.
BRIEF 9 — The Delivery Date
The idea. The failure is not the size of the inheritance. It is when it arrives and to whom.
Worked example. The Institute for Fiscal Studies finds inheritances on course to be worth about 16 percent of lifetime income for those born in the 1980s against about 9 percent for those born in the 1960s — a rise of 1.78 times. The median age at receipt is about 61.
Take a forty-year-old and the Green Book's own 3.5 percent rate. Twenty-one years of waiting is a discount factor of 0.4856:
handed over £84,280 per head
received at 61 £40,924 per head
---------------------------------------------------
destroyed by the wait £43,356 per head (51.4%)And on the conservative assumption that half the cohort receives anything material, those who do receive about £168,561 each, and the rest receive the debt without the estate.
Why it matters. Moving a receipt forward costs nothing in aggregate — the sum transferred is unchanged — and changes what a generation can attempt at the age when attempting is possible. This is the largest and cheapest available gain in the whole account, and it becomes visible only once the account exists.
You already know this because you know the difference between being given help at twenty-five and being given the same help at sixty.
BRIEF 10 — The Intergenerational Covenant Bond
The idea. Attach the account to a signature. A two-way sustainability-linked note whose KPI is the issuer's published per-head intergenerational balance sheet, with two triggers of different kinds: a money trigger (per-head comprehensive net worth, real, non-declining over a rolling five years) and a physical trigger (a named critical natural stock non-declining in physical units, not in value).
The second trigger is the strong-sustainability constraint written into a contract. It is the reason this is worth building rather than buying an ordinary green bond.
Worked example. On a $2,000 m ten-year note at 5.00 percent, a 25 bp two-way step is $5.0 m a year, $50.0 m undiscounted, $38.6 m in present value at 5 percent. Uruguay's step — the first sovereign two-way step, in 2022 — was 15 bp, which here would be $23.2 m. Verification at $400 k a year costs $3.1 m in present value, leaving the covenant net-positive to the issuer at $35.5 m. Spread across the United Kingdom, an account of this kind costs about £0.0047 per person per year.
The honest negative, stated first. That 25 bp step is 0.0022 percent of the £1,400 bn the Climate Change Committee estimates UK net zero requires to
- This instrument finances nothing. Sell it as climate finance and the
first analyst who divides two numbers will not read the second page. Sell it as a priced, dated, externally verified commitment to publish a number that does not currently exist anywhere, and it is cheap, honest and unusually hard to abandon quietly.
You already know this because you have kept a promise you would have let slide, purely because you had written it down somewhere another person could see.