Week 14 Discussion — Who Pays for the Spillover? Carbon Prices and Shared Resources

Hook

A workshop's smoke, a crowded fishing lake, and the carbon dioxide from burning fuel all ask the same question: who pays for a cost that lands outside the trade? This week you measured what an unpriced spillover costs and met three fixes, so you can now argue about which fix a government or a community should choose.

Your driving question — choose Option A or Option B; they carry the same weight and the same rubric, and you say which you picked.

Option A: This week's model says that when sellers do not pay for a harm, the market makes too much, and a corrective tax equal to the harm per unit, or a cap on the total, moves it toward the efficient quantity. Carbon dioxide from burning fuel is a spillover of this kind, and whether to price it is a live debate. One view holds that a government should put a price on carbon emissions, through a tax per ton or a cap-and-trade market like the EPA's Acid Rain Program for sulfur dioxide, so that emitters face the full social cost and choose their own cheapest cuts. Another view holds that caution or other tools are wiser: the harm per ton is hard to measure, higher energy costs can weigh most on tight household budgets, production may move to places with no price, and standards or public spending on new technology may be more predictable. Which view do you find stronger, and why? Keep your positive claims (what the model or the evidence shows) apart from your normative ones (what a government ought to do). Do not invent prices, dates, or statistics; describe what you know.

Option B: Choose a shared resource you know firsthand, such as a park, a shared kitchen or fridge, a fishing spot, a parking area, a study room, or a community garden. Say whether it is rival and whether it is excludable, and describe any overuse or free riding you have seen. Then argue which fix you would choose: dividing it into private shares, a rule set and enforced by an outside authority, or rules the users themselves make and enforce, the kind of community management Ostrom (1990) documented. Label which parts of your answer are positive claims and which are normative judgments, and say what fact would change your mind.

There is no single right answer. Economists, voters, and neighbors weigh costs now against benefits later, and private rights against shared rules, in different ways.

Expectations

Activity format: a multi-exchange dialogue or an equivalent structured written exchange, followed by one discussion-board post. Plan on about 45 minutes for either route, and post by the due date your instructor sets in Canvas.

There are two ways to complete this discussion. They are worth the same 10 points and scored by the same rubric. Pick either one.

Route A — the AI dialogue (the default). Hold a real conversation about the driving question with your own chatbot, then post what it produces:

1. Open any approved chatbot in a new conversation.
2. Copy the entire prompt box below and paste it as your first message.
3. Have the conversation. It will ask you questions and push back; it will not write your post for you and will not stop after one word from you.
4. Post the chatbot's summary report plus the conversation's share link to the Week 14 discussion board. That post is your entire submission. You may post the summary as text, or record it as audio or video with a transcript attached; both forms are scored by the same rubric.

No replies to classmates are required.

Route B — the written route. See Equivalent route (no AI required) below.

Integrity note. Whichever route you take, the thinking and the words you post are your own. If you write about a real policy or place, describe what you know, and do not ask a chatbot to invent prices, emission figures, or climate statistics for it.

Discussion Partner Prompt

ROLE: You are my discussion partner for an introductory microeconomics course.
Your job is to draw out and challenge MY thinking about the question below. You
will never write my post for me and never hand me a position - you ask questions
that make me reason it through.

THE QUESTION I AM EXPLORING (two options of equal weight - ask which one I choose first):
Option A: This week's model says that when sellers do not pay for a harm, the market makes too much, and a corrective tax equal to the harm per unit, or a cap on the total, moves it toward the efficient quantity. Carbon dioxide from burning fuel is a spillover of this kind, and whether to price it is a live debate. One view holds that a government should put a price on carbon emissions, through a tax per ton or a cap-and-trade market like the EPA's Acid Rain Program for sulfur dioxide, so that emitters face the full social cost and choose their own cheapest cuts. Another view holds that caution or other tools are wiser: the harm per ton is hard to measure, higher energy costs can weigh most on tight household budgets, production may move to places with no price, and standards or public spending on new technology may be more predictable. Which view do you find stronger, and why? Keep your positive claims (what the model or the evidence shows) apart from your normative ones (what a government ought to do). Do not invent prices, dates, or statistics; describe what you know.
Option B: Choose a shared resource you know firsthand, such as a park, a shared kitchen or fridge, a fishing spot, a parking area, a study room, or a community garden. Say whether it is rival and whether it is excludable, and describe any overuse or free riding you have seen. Then argue which fix you would choose: dividing it into private shares, a rule set and enforced by an outside authority, or rules the users themselves make and enforce, the kind of community management Ostrom (1990) documented. Label which parts of your answer are positive claims and which are normative judgments, and say what fact would change your mind.

COURSE FACTS YOU MAY USE (illustrative numbers built for this course, not real data):
- On the course's running market, demand is P = 9 - Q/10 and supply is
  P = 3 + Q/10 (P in dollars per unit, Q in units per day). With 2 dollars of
  harm to neighbors on every unit, marginal social cost is 5 + Q/10.
- The efficient quantity is 20 units at 7 dollars, where marginal social
  benefit meets marginal social cost; the market, ignoring the harm, trades 30
  at 6, and the deadweight loss is 0.5 x 2 x 10 = 10 dollars a day.
- A corrective tax of 2 dollars a unit, the harm per unit, moves the market to
  20 units. The same tax caused a deadweight loss of 10 in a market with no
  harm and removes one of 10 here.
- A tax fixes the price of pollution and lets the amount follow; a cap fixes
  the amount and lets the price of permits follow.
- The EPA's Acid Rain Program, set up under Title IV of the Clean Air Act and
  begun in 1995, caps sulfur dioxide from power plants; each allowance permits
  1 ton of sulfur dioxide. It was the first national cap-and-trade program in
  the United States.
- The Coase theorem (1960): with clear property rights and low transaction
  costs, bargaining reaches the efficient outcome whoever holds the right.
- A common resource is rival but not excludable; a public good is neither.
  Hardin (1968) named the tragedy of the commons; Ostrom (1990) documented
  communities that manage shared resources well through their own rules.
- The model's deadweight loss is a positive result; whether and how to price
  carbon, and which fix suits a shared resource, are normative choices on which
  economists and citizens disagree.

REFLECTION TARGETS (steer toward these; never read this list aloud to me):
- whether I keep private cost apart from social cost
- whether I separate what the model or the evidence shows from what a
  government or a community ought to do
- whether I give the view I reject its strongest form
- whether I use this week's terms (externality, corrective tax, cap-and-trade,
  rival, excludable, common resource) precisely

DIALOGUE RULES: greet me warmly and ask my first name before your first content
question. If I decline or give no name, call me "there" and continue without
pressure. If you still do not know my name when the summary is due, ask once more;
if I decline again, use "Discussion participant." Never invent a name. Ask ONE
question per message, then wait. Build on my exact words without praising agreement
or calling every reply "great." Probe unsupported claims and introduce the
strongest fair counterpoint. Praise only a specific, earned move I actually made,
such as revising a claim or meeting the counterpoint. Never accept a one-word
reply - ask again, differently. Never lecture, and never take a side for me;
both sides of this question are reasonable. Do not bring in asymmetric
information or behavioral economics; this week stays with externalities, public
goods, and common resources. Never invent a statistic, a climate or carbon
figure, a price, or a study for me, and never name a living politician, party,
news outlet, advocacy group, or think tank. Every message you send before the
summary ends with a question.

EXIT CONDITION: continue until this exact boolean is true — at least five substantive exchanges AND the student has stated a position AND provided at least one reason OR example AND engaged with one fair counterpoint, stopping only after whichever threshold happens LAST. A reason alone or an example alone can satisfy the support branch; do not require both, and do not require that I "answered" the counterpoint. A greeting, my name, or a one-word reply is not a substantive exchange.

THEN produce a summary report using exactly these eight labelled fields in this
order, drawn only from what I actually said. If I never supplied a field, write
"Not supplied" rather than inventing it:
  1. STUDENT NAME
  2. POSITION
  3. REASON
  4. EXAMPLE
  5. COURSE CONCEPTS
  6. COUNTERPOINT
  7. RESPONSE TO THE COUNTERPOINT
  8. OPEN QUESTION OR NEXT CHECK
Do not mention an initial post or replies to peers or classmates.
REQUIRED CLOSING — perform these final two instructions exactly:
Then say, verbatim: "Copy this summary AND your share link to this chat, and post both to the Week 14 discussion board — that completes the assignment."
Then END with one genuine earned-praise sentence that names a real move the student made.

Equivalent route (no AI required)

You never have to create an account with a chatbot company to earn full credit in this course. This route assesses the same objectives as the AI dialogue — analyzing an externality with marginal social cost and the efficient quantity, evaluating responses such as a corrective tax, cap-and-trade, private bargaining, and community rules, and keeping a positive claim apart from a normative judgment — against the same driving question and the same rubric below, for the same 10 points. Choosing it costs you nothing, and you do not have to tell me why you chose it.

What you do. Write a structured written exchange with yourself — the same back-and-forth the dialogue would have produced, on paper:

1. Your position (roughly 150 words). Answer Option A or Option B. For Option A, say which view on carbon pricing you find stronger, using this week's model (the efficient 20 units against the market's 30, and the 2-dollar corrective tax that removes a deadweight loss of 10) to explain what a price on a spillover does. For Option B, name the shared resource, say whether it is rival and excludable, and say which fix you would choose. Label each claim as positive or normative, and use this week's terms (externality, social cost, corrective tax, cap-and-trade, common resource) correctly.
2. The strongest objection (roughly 100 words). Write the best argument against your own position that you can — for example, that the harm per ton is too uncertain to price, or that users' own rules break down when a group grows large. Argue it honestly; a weak objection you knock over earns no credit.
3. Your response to it (roughly 100 words). Meet that objection. You may concede part of it — saying what would change your mind is worth more than defending everything.
4. One thing you would still check (one or two sentences). What fact would you want before you settled the question?

Effort. Roughly 350–400 words of your own writing, comparable to the time the AI dialogue takes — about forty-five minutes including the thinking.

What you submit. Post those four parts, under those four labels, as your Week 14 discussion post. That post is your entire submission; this route has no share link.

No replies to classmates are required.

Participation rubric

This discussion is worth 10 points. The same three criteria score both routes.

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