Tuesday, July 07, 2015

Moral Derpitude

With the summer doldrums, ATTP going to conferences and the Greek crisis, it becomes necessary for Eli to borrow seriously in order to maintain paid readership (Damn Eli needs to monetize this blog but Brian will demand a cut).  Thus by way of Crooked Timber, Noah Smith on definitive derpiness, a subject he has deeply studied

It has to do with Bayesian probability. Bayesian probability basically says that "probability" is, to some degree, subjective. It's your best guess for how likely something is. But to be Bayesian, your "best guess" must take the observable evidence into account. Updating your beliefs by looking at the outside world is called "Bayesian inference. Your initial guess about the probability is called your "prior belief", or just your "prior" for short. Your final guess, after you look at the evidence, is called your "posterior." The observable evidence is what changes your prior into your posterior.

How much does the evidence change your belief? That depends on three things. It depends on A) how different the evidence is from your prior, B) how strong the evidence is, and C) how strong your prior is.

What does it mean for a prior to be "strong" really, really believe something to be true. If your start off with a very strong prior, even solid evidence to the contrary won't change your mind. In other words, your posterior will come directly from your prior. (And where do priors come from? On this, Bayesian theory is silent. Let's assume they come directly from your...um...posterior.)

There are many people who have very strong priors about things. For example, there are people who believe, very strongly, that solar power will never be cost-efficient. If you confront them with evidence of solar's rapid price declines, they will continue to insist that, despite this evidence, solar will simply never be cost-competitive with fossil fuels. That they continue to insist this does not necessarily make them irrational in the Bayesian sense; they simply have very strong priors. Someday they may be convinced - for example, if and when unsubsidized solar power starts being adopted on a mass scale. It'll just take a LOT to convince them. (A more entertaining example can be seen in this classic comedy video)

But here's the thing: When those people keep broadcasting their priors to the world again and again after every new piece of evidence comes out, it gets very annoying. After every article comes out about a new solar technology breakthrough, or a new cost drop, they'll just repeat "Solar will never be cost-competitive." That is unhelpful and uninformative, since they're just restating their priors over and over. Thus, it is annoying. Guys, we know what you think already.

English has no word for the constant, repetitive reiteration of strong priors". Yet it is a well-known phenomenon in the world of punditry, debate, and public affairs. On Twitter, we call it "derp"

Go read Noah and the comments

20 comments:

Magma said...

And there I was thinking such commenters pulled their arguments out of their posteriors. You learn something new every day.

Fernando Leanme said...

Solar power will be competitive when fossil fuels can't meet demand and prices climb to the point where the cost curves meet. However, the 64 trillion Venezuelan bolivar question is whether solar power can meet the power demand of 3 billion human beings.

Tom said...

Hi Fernando

The answer to your expensive question is undoubtedly yes, but undoubtedly not in the very near term. Doesn't settle much, does it?

Nigel Franks said...

Solar and wind power are already competitive in some markets, even with the fossil fuel subsidies. Thanks to the merit order effect they even bring down wholesale electricity prices.

Here you can see it happening almost in real time. https://www.energy-charts.de/price.htm Also note that the renewables are relatively well forecast, as the actual price matches the day ahead spot price quote well.

andthentheresphysics said...

I think Eli should be thanking his commenters for illustrating the point about how one's prior can influence one's posterior. Well done everyone.

Tom said...

There are bubble maps on the internet showing bubbles where solar power is cost-effective relative to other generating sources, some with some without subsidy. The bubbles are getting larger and will continue to do so.

But as a percentage of total inhabited area, the combined total of these bubbles is really, really small.

We all (well, most of us) hope this will change and change at an accelerating pace. But there's no real point in pretending that solar or wind is cheaper than coal, absent a large carbon tax. They aren't.

Bernard J. said...

"But there's no real point in pretending that solar or wind is cheaper than coal, absent a large carbon tax. They aren't."

They are. You just haven't accounted for the omitted, delayed and externalised costs of coal.

Russell Seitz said...

"Solar power will be competitive when fossil fuels can't meet demand and prices climb to the point where the cost curves meet. However, the 64 trillion Venezuelan bolivar question is whether solar power can meet the power demand of 3 billion human beings.'

the answer to Fernando's conundrum is to replace Zero Population Growth with Nano Population Growth.

By growing billions of people who weigh nanograms , the existing population of power-hungry giants can be rendered supernumerary by a new human nanopopulation , who can be warmed or air conditioned at milliwatt expense , allowing a square meter of silicon photovoltaics to serve a town of 100,000 or more , and six or seven hectares to provide for all humanity.

P.S

If you need change for a trillion Bolivars, I have plenty of Zimbabwe Dollars.


Tom said...

Bernard J: "They are. You just haven't accounted for the omitted, delayed and externalised costs of coal."

Umm, you do realize that that's the entire purpose of a carbon tax, don't you?

Bernard J. said...

Speaking of derpitude:

http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366%2815%2900239-4/abstract

Bernard J. said...

"Umm, you do realize that that's the entire purpose of a carbon tax, don't you? "

Two points.

1) A tax is not a direct costing of externalities, it's (a) a sometimes proxy for cost, and (b) sometimes just a skimming of cream.

2) Even if a tax is applied as a proxy for cost it is often an inaccurate mechanism for costing. A carbon tax is a classic example. If the real cost of carbon emissions over distant time and with respect to all ecological sequelæ (many of which are not valued or even understood by neoliberal economists, businesses, and politicians today) was applied to the burning of fossil fuels, renewables would be cheaper today.

A carbon price is an attempt to apply (a), although interestingly neoliberals frame it as (b).

You might think it's semantics, but there's a difference between a "large carbon tax" and a fully internalised and real carbon cost. That's the distinction I make, and I stand by my original statement.

Nigel Franks said...

"But there's no real point in pretending that solar or wind aren't cheaper than coal, absent a large carbon tax. They are."

There fixed it for you. Of course, one of the difficulties that renewables have in competing with coal is the fall in coal price... anyone like to hazard a guess as to why its price is falling?

hypergeometric said...

There is a result, possibly too technical for here, which shows that better objective results are had over a wide class of statistical problems using a slightly informed prior than a so-called "uninformed prior", as long as, of course, the slightly informed prior does not exclude the portion of the space where the dominant posterior probability lies.

My point is these things don't necessarily work in the way common sense suggests, and I also doubt what's going on in public debate about anything looks like Bayes Rule, however it is formulated. Just look at criminal justice, or, more specifically, jury trials.

hypergeometric said...

Also, on the wind and solar versus coal and other fuels debate, there's a set of wind and solar options which are being equivocated. There are essentially three: (1) off-the-grid local generation and consumption, where residents or villages generate, store, and consume energy from zero Carbon sources (wind, geothermal, solar); (2) wind and solar and others generated in all ranges of sources, from small scale up to large, industrial sized generation facilities, all distributed basically using the existing power grid, perhaps one souped-up a bit to deal with variations in power, and perhaps supplemented by various kinds of storage; and (3) wind and solar at all scales, but connection with a drastically different kind of grid and controls system, where high accuracy forecasts for production at each and every site are available the day before, and enough wind and solar capacity is built not only to power demand, but including overcapacity to cover for forecast imperfections in real time.

To the degree a zero Carbon solution is capable of providing energy at less than full network costs of fossil fuels, it is inevitable fossil fuel energy will eventually die. Most valuations of fossil fuel energy ignore their full network costs, which include costs of extracting, refining, extracting, etc. They often do so because of belief that the market price entirely reflects that cost. In fact and for example, most exploration costs are not borne by market prices and are, instead, offset by the increase in value they give to the "proven reserves" of fossil fuel companies. There are also heavy subsidies for fossil fuel companies, such as tax credits, which if totalled are 2x-5x credits for zero Carbon energies, and there are indirect benefits such as the ability to explore and extract on public lands and in public waters.

On the status of Carbon taxes, I see the debate here as largely irrelevant. The Pigovian tax, for which a Carbon tax is an example, is intended to correct for market inefficiencies like externalities. That said, and while I recommend it, it is not itself without problems. In particular, if the operations of government or individual incomes or even offsets to income taxes are based upon proceeds from such a tax, its success in reducing greenhouse gas emissions can cause a counterproductive situation in which people are collectively disincentivized to reduce them further. Moreover, the Carbon tax, as proposed by many, does nothing to penalize past actions for damage to atmosphere. I personally think such a tax should be imposed on emitters retroactively and I have some ideas about how it could be usefully applied. Such details are well beyond the scope of the present discussion. Also, even though I think that's what should be done, I'm sure it is an unpopular notion. That doesn't automatically make it wrong.

Hank Roberts said...

> English has no word for the constant,
> repetitive reiteration of strong priors

Prayer.

Susan Anderson said...

It is hard to convey to a lay audience how mindbendingly, stultifyingly boring the repetitive and dull claims of phony skepticism really are.

People make these claims, over and over, and deny and ignore the answers. When they are told they are ignoring the obvious and straightforward answers to their claims, they say telling them they are denying them is claiming they are equivalent to holocaust deniers and that is impolite.

Well, it is impolite to ask questions and not listen to the answers. It is stupid to ignore reality.

Repetitive claims that climate science is not honest are not interesting. They are not only destructive and dangerous, they are boring boring boring.

Russell Seitz said...

The trouble with climate bores is their predoctability.

EliRabett said...

Eli resembles that remark

cRR Kampen said...

"Repetitive claims that climate science is not honest are not interesting. They are not only destructive and dangerous, they are boring boring boring."

They are worse today. They are criminal or praise of criminality.

And it is absolutely terrifyingly ffing hard to convey this and your observations to the lay public, I got some bruises recently again for attempting that. So give me a climate revisionist to kick and abuse any time.

John said...

James Hansen recommends a "carbon fee and rebate". All funds raised by the carbon fee are distributed to the population. That means the effect on government spending is zero. This (Hansen hopes) eliminates some arguments against it.

So Hansen's idea is inot a tax, it's a fee and rebate.