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Comment by yummyfajitas | Hacker News Reader

Whether or not something is a public good is a matter of technology. Trains are definitively a private good - they are rivalrous (you and I can't simultaneously occupy the same seat) and excludible (don't pay, they don't let you ride).

Roads are also rivalrous (you and I can't simultaneously occupy the same piece of pavement) and excludible (don't pay gas taxes, you get no gas, you can't ride).

If gas taxes were impractical, roads might be a public good.

We also collect plenty of taxes for transit. Our taxes just buy us 1/5-1/100 as much as every other country in the world, because our transit systems are incredibly inefficient.

https://pedestrianobservations.wordpress.com/2013/06/03/comp...

https://pedestrianobservations.wordpress.com/2011/05/16/us-r...

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Looking into the links you sent. Not sure if I am on board with "whether or not something is a public good is a matter of technology." I would say it is a matter of shared values and ideals. When you describe trains, you are talking about individual seats which are rivalrous, right? The train as a whole is a public good: it benefits everybody, has large positive externalities, and without subsidies it is not likely to be supported for profit. It is not rivalrous as a whole.

It's true that politicians talking about shared values and ideals can turn simple private goods into nightmarish public ones (e.g. US medicine). Have politicians created dumb laws like "the conductor may not kick someone off the train even if they don't pay" or "long trips must cost the same as short ones"?

The train is merely an intermediate capital good used to provide train seats. It's private at the level of capital goods which is also the level at which it's paid for - only one railway can use a piece of rolling stock (rivalrous) and that railway can prevent other railways from using it (excludible). You might as well say that a house or a car is a public good, since they are merely capital goods that provide a stream of an underlying consumer good (space to live, road trips).

What are the positive externalities of a train? If anything, it's externalities seem to be negative - it creates pollution and noise. (It might be less negative than driving but that's a different claim.)

A train seat is not the thing I am paying for. A transit company is typically chartered around provision of service regions and schedules, and it has the power to divert passengers to alternatives like buses if problems arise preventing use of some existing infrastructure. The customer is not there to "ride the train" but to reach a destination - the transit is judged upon how well this demand is satisfied.

Private property law allows owners to enforce their own rules(to a point). This both explains the private control over the train and tracks and lends weight to the possibility of being kicked off the train, as it is justified in terms of disruption to service and resulting monetary losses. To wit, a positive externality of transit service is economic gain from the population having improved market access(more goods, services, workplaces within reach). The transit company does not realize these gains, the public does. The company's enforcement of rules is guided by the premise that some amount of security and order is necessary to achieve its service goals.

Reaching your destination via whatever mechanism is still a private good.

To wit, a positive externality of transit service is economic gain from the population having improved market access(more goods, services, workplaces within reach).

This is a positive externality of any transit method, including privately owned cars.

Ultimately what you've stumbled across is the fact that nearly any good or service will create gains from trade that are not captured by the producer. E.g., video games, cakes and pies, pornographic videos, and kindles all make people happier and nicer to those around them. This is why encouraging economic activity is generally considered beneficial.

Does this make cakes, pies, video games, pornos and kindles public goods?

What is a public good by this standard? You and I can't breathe the same air at the same time. We can't drink the same water at the same time.

Physical reality is rivalrous--in general, matter excludes other matter. Seems like the concept of a "public good" needs to be more refined than whether the thing permits simultaneity.

Not being invaded by communists is neither rivalrous nor excludible. Similarly for not being killed by ebola, eaten by cannibals, or inhaling toxic nuclear waste.

Roads would be a public good in an era or country where gas taxes/odometer taxes/similar mechanisms were not feasible.

Lots of things are public goods.

So basically the absence of things, and things which have no user fee? If a subway system was 100% tax-funded with no user fee, would it become a public good in your eyes?

No, it would be a private good that was subsidized.

Something is a public good if it's not possible (or extremely difficult) to exclude non-payers from receiving it (as well as being rivalrous). The subway just doesn't qualify - turnstiles exist.

Public goods aren't just the absence of things. Basic research, public art, and similar things would be public goods. Or going back to my previous example, roads in a country where gas/odometer taxes are impossible to collect would be a public good.

Why do people have such a strong desire to attach the word "public good" to things which are rivalrous and excludible?

So if we take the turnstiles off the subway (which was implied in my comment above about no user fee), does it become a public good?

> Public goods aren't just the absence of things. Basic research, public art, and similar things would be public goods.

Oh ok, so everyone can benefit equally from basic research? There are no user fees for, say, cancer therapies based on government-funded research?

Everyone can view public art? There's no limit on how many people can be in a park or museum at once?

The reason I'm belaboring this point is that there is no difference in how we finance, build, maintain, or use mass transit and roads. Heck quite a lot of mass transit is based on roads, like city buses.

Basically I suspect you just prefer driving, and are trying to create a tortured definition of "public good" to give your preference a veneer of objective rationality.

No, just as sandwiches don't become a public good if I leave my kitchen door unlocked. Please just read the standard economic definitions of the terms.

Basically I suspect you just prefer driving, and are trying to create a tortured definition of "public good"

You sure got that one wrong. I haven't owned a car since 2000 and I hated it for all 6 months. The fact that I prefer mass transit and walkable cities doesn't mean that this preference deserves subsidies. (I'd be happy with eliminating the laws that make such things illegal and insanely expensive when legal.)

I understand the standard definition fine--what I'm pointing out is your inconsistency in applying that definition, like listing as examples research, public art, and free roads despite the fact that none of them satisfy the characteristics of non-excludable and non-rivalrous.

Even the wikipedia page is hilariously mixed up, listing a public lighthouse as a public good, even though a person needs to own a ship to benefit from the lighthouse (excluding most people), only so many ships can pass through a section of the sea at one time (making it rivalrous), and of course the government can just turn off the light whenever it wants (excluding everyone).

Edit to add: if a road or a park or a lighthouse can be a public good, then so can a subway. If a subway can't be a public good, then neither can a road, a park, or a lighthouse, since they all violate the definition in similar ways.

The government can't exclude people who don't pay for the lighthouse from using it. It's all or nothing - hence not excludible.

A subway can exclude anyone who doesn't pay while including anyone who does. To take the example of several subways I've been on recently (NYC, Delhi, Amsterdam, Boston), if you don't pay the turnstile won't let you through.

If you scroll up, you'll find me explicitly agreeing that roads are a private good which should be paid for via user fees (either gas or odometer taxes), and those who refuse to pay should be excluded.

Okay, I'll think about this. Thanks for the discussion. Have a good weekend.

You are using public good a bit unusually; a public good is a positive externality (and the term is sometimes extended to things that produce positive externalities), it's the opposite of a public (or social) cost, a negative externality.

Roads aren't a source of public good because odometer taxes are impossible, they are sources of public good because and to the extent that creating them provides benefits beyond those who make the choice to use them, whether or not those making the choice to use them pay directly for that use in accordance with their dirct, private benefit from the transaction.

I'm using the terms as defined in standard economics. Public = non rivalrous, non-excludible, private = rivalrous and excludible.

https://en.wikipedia.org/wiki/Public_good

https://en.wikipedia.org/wiki/Private_good

Suppose we attach the label "public good" to roads or trains. What implications - if any - do you believe follow from this?

Certainly the implication that the government should subsidize it does NOT follow. A good which is rivalrous and excludible is one that the market can provide adequate quantities of, in contrast to goods which are non-rivalrous and non-excludible which will be underprovided by the market.

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