David R. Henderson  

Partial Response to Yoram Bauman

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In his latest reply to co-blogger Bryan Caplan, Yoram Bauman writes:

If more economists like Bryan were upfront about their agreements with basic climate science then I would feel better about not having time to respond to people like David Henderson, who goes to great linguistic lengths in an effort to argue that global temperatures have not been increasing over the past century.

Bauman links, correctly, to my response to his question. But in case you didn't follow that link, here's my statement of his question [it's word for word what he asked] and my response:
Yoram: That global temperatures have been increasing over the past century?
David: No. "Have been" implies not only that they have increased but also have increased in the recent past. Global temperatures have increased over the past century. Of that fact, I can find no dispute, no matter which side of the issue climate scientists are on. But global temperatures have not increased for over a decade.

Bauman calls this "great linguistic lengths." I call it proper use of verb tenses. I bet you he does understand the difference.

In case some of the readers don't, though, let's get it away from global warming and look at a more neutral topic. Imagine that you are 70 years old and that when you were 10, someone told you that you should go to the dentist every year for a checkup. Imagine that you faithfully went every year for 50 years but haven't gone for the last 10 years. Someone asks you whether you have been going to the dentist for the last 60 years. What is the right answer?


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COMMENTS (25 to date)
Craig Richardson writes:

I think you both can be right- it is all a matter of your reference point. People who are thinking about the history of the world, think in terms of hundreds of years. Therefore a decade is a blink of an eye. Economists think of time frames far more narrowly, in months or quarters, so time is far more magnified.

If we changed the example to: Imagine you are 500 years old. You began getting cavities most years for the past 100 years except for the last ten years. Would you characterize the century as one with increasing cavities?

David R. Henderson writes:

@Craig Richardson,
Would you characterize the century as one with increasing cavities?
Yes, but read more carefully, Craig. The last century has been one with increasing temperatures. That was never at issue, as this statement from me above shows: "Global temperatures have increased over the past century."

Daniel Klein writes:

I think you are right, David.

Craig Richardson writes:

David,

I see- the issue for you is over a rate of increase vs. a climb to a new and higher level. This is a subtle point for many in the media and population at large- as the word "Global warming" itself connotes an ongoing *increase* in temperatures. It is more difficult to express a new higher average temperature as a catchy word or phrase.

We see this in the reporting of temperatures being higher than average for a decade but not higher each and every year.

Another analogy: If my frig slowly gets warmer due to a faulty condenser, from 45 degrees to 52, but then stops getting worse, such that my food spoils more quickly on average, it could still be a problem, but has a different solution than a frig temp marching towards 85 degrees.


David R. Henderson writes:

@Craig Richardson,
All good points, but not my point. My point is simpler: it really is entirely about proper use of verb tense. I’m quite willing to accept, in your fridge analogy, that just because your fridge has stopped getting warmer, that does not mean that it won’t get warmer. So the temp may indeed march toward 85 degrees.

nl7 writes:

The implication is that temperatures "have been" rising, and that this is an ongoing trend and are therefore likely to continue rising without some change or intervention. But obviously that's not true, since there is something of a plateau recently.

It would be better to say they "have increased." Though even this formulation can be used to imply, without asserting, that this is a linear trend that will continue without intervention. The issue is too complex to boil down to "believes the theory" or "disbelieves the theory."

gwern writes:

'Someone asks you whether the stock market has been rising for the last 60 years. What is the right answer?'

Yoram Bauman writes:

David sees important verb tense issues, and I see somebody who would cares too much about semantics to be worth spending much time on. If temperatures spike in the next year or two---as seems likely if an El Nino develops---then what will you say, David?

blink writes:

The dentist scenario is too different from the global warming situation. An appropriate analogy should at least have a cumulative variable. I suggest: Someone eats breakfast and lunch but skips dinner. How should the person respond when asked whether s/he has been eating today?

David R. Henderson writes:

@gwern,
'Someone asks you whether the stock market has been rising for the last 60 years. What is the right answer?'
Yes.
@Yoram Bauman,
If temperatures spike in the next year or two---as seems likely if an El Nino develops---then what will you say, David?
If that happens I will say that temperatures increased. I’m not sure why you ask, but that’s what I would say.

nshackel writes:

"David sees important verb tense issues, and I see somebody who would cares too much about semantics to be worth spending much time on." I'm glad Mr Baumann has continued to reveal his attitude to being careful about which propositions are true and false, his attitude to those he disagrees with and his character.

Scott Scheue writes:

[comment removed for rudeness. Email the webmaster at econlib.org to discuss editing the comment. --Econlib Ed.]

MG writes:

Prof. Henderson's punctiliousness is not a linguistic affectation. I wish Mr. Bauman were more open-minded to what the Prof. is pointing out. It is imperative that the last century's worth of temperature rises shows a continuing trend, since anthropogenic emissions have been concentrated towards the back-end of the century.

I also find it curious that Mr. Bauman's hypothetical retort would involve adducing an El Nino effect, which, as I understand, is a natural phenomenon that has preceded man-made warming. So Prof.Henderson's reply could have been: "Temperatures have increased. So what?"

Silas Barta writes:

"I ... have not been having ... sexual relations with that woman, Miss Lewinsky."

[@Editor: sorry for the topic matter; just trying to apply the tense distinction to an iconic quote.]

Yoram Bauman writes:

Sorry, let me rephrase my question: If temperatures go up in the next few years would you say "That global temperatures have been increasing over the past century?"

Josiah writes:

David,

I'm a big fan of your writings here, but in this case I think Yoram has a point. That post (and particularly the update) struck me as needlessly coy.

peter writes:

"Yoram: That global temperatures have been increasing over the past century?"

Take 100 years of temp data, and run a trend line through it. Is the trend positive?

I'm not sure why you decided to only look at a trend over the past 10-15 years, when the issue was a 100 year trend. I suspect if the 10-15 year trend was positive, but the 5 year trend was flat, you would have called out the last 5 years to make the same irrelevant point.

David R. Henderson writes:

@Yoram Bauman,
Sorry, let me rephrase my question: If temperatures go up in the next few years would you say "That global temperatures have been increasing over the past century?"
Yes.

John T. Kennedy writes:

David,

Easy-Peasy: The right answer is always Global Warming...

peter writes:

Actually, I want to make my critique of Dave even clearer.

Dave says:

Yoram: That global temperatures have been increasing over the past century? David: No. "Have been" implies not only that they have increased but also have increased in the recent past...But global temperatures have not increased for over a decade."

No. What "Have been" means is that our century trend analysis should include the most up to date data, and not data ending in say 2005 or 1995. It definitely does not mean that our 100 year trend analysis should only include data from the "recent past". If we were interested in just the trend in the recent past then Yoram's statement would have had to have been, "that global temperatures have been increasing over the recent past."

Actually, David's response is even more wrong/meaningless than I originally thought since "recent past" is so fungible. He chose 10 years since that gave him the answer he wanted. I'm going to say "recent past" is 20 years because it gives me the answer I want (yes temps have been increasing). I can even define "recent past" as six months. Since global temperatures have increased over the past six months this means that global temperatures have been increasing over the last century! WHAT?!?

Finally, the analogy that David used at the end of this post is wrong as well. Going to the dentist or not is a binary outcome and does not have a trend! Let's use a better analogy. Let's say that GDP fell from 2011-2013, and I asked, "Is it true that GDP has been increasing since 1913?" According to Dave the answer is "No" GDP has not been increasing since 1913 since it fell in the "recent past." Does anyone think that Dave's response would be a reasonable answer to this question?

David R. Henderson writes:

@peter,
Let's say that GDP fell from 2011-2013, and I asked, "Is it true that GDP has been increasing since 1913?" According to Dave the answer is "No" GDP has not been increasing since 1913 since it fell in the "recent past." Does anyone think that Dave's response would be a reasonable answer to this question?
I do.

David R. Henderson writes:

@Josiah,
I'm a big fan of your writings here, but in this case I think Yoram has a point. That post (and particularly the update) struck me as needlessly coy.
First, thanks.
Second, my guess is that our difference here has to do with the emphasis I put on proper, that is, non-misleading, use of verb tenses.

Daublin writes:

I see that many people are dismissing David, but not one person is saying why. I'm sad that David's point is getting attacked so heavily; it seems clear to me.

I wish obvious things like this could be conceded. There is something about CO2 control that puts people in a really dismissive frame of mind.

Josiah writes:

David,

As I recall, you did recently defend Bill Clinton's infamous "That depends on what the meaning of 'is' is" statement, so clearly this is a matter about which you place a lot of importance.

However, the verb tense thing wasn't the only instance in that post where you were being too clever by half, IMO.

Mark V Anderson writes:

I think the problem is that the question was rather vague, and David's objection was to this vagueness, which could have been answered either way. I would have liked to see Yoram rephrase his question to be more clear, so that we wouldn't get caught up in linguistic issues. He could have asked "Has the temperature increased over the last century?" or maybe "Is the average temperature over the last decade higher than the temperature of a century ago?" I believe David would have said "yes" to either of these.

The problem with agreeing to vague comments because you know what the writer really means, is that you may often get caught in the future when someone says you agree with something you really don't. I don't feel that David was being coy here; he was being precise. The Global Warming discussion is chock full of imprecise discussion. I think encouraging more precision is a good thing.

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