04 December 2008

What does a PhD mean

The trivial answer to the subject question is 'Doctor of Philosophy', which doesn't help us much. I was prompted to write about it by responses to Chris's comments on the pathetic petition over on Chris Colose's blog, wherein a reader seemed to think that once one had a PhD, one had received a grant of omniscience.

Ok, not quite. Rather, to quote Stephen (11 June 2008) directly: "...a person with a PhD is more apt to think critically before making a decision. Granted, it’s not true in every case, obviously, but someone with a PhD in any scientific field is statistically more likely to look at all of the information available to them." Unfortunately he never gave us a pointer to where those statistics were gathered -- the ones that supported his claim that PhDs in a scientific field were 'statistically more likely' .... I'm minded of the observation that 84.73% of all statistics on the net are made up.

The details of what a PhD means vary by advisor, school, and era. But for what's at hand, the finer details don't matter. One description of doctoral requirements is "an original contribution to human knowledge". This much being true whether we're talking about science or literature. The resulting contribution should (more so these days than a century ago) be publishable, and published, in the professional literature. Notions vary, but there's also a principle that someone who earns (or is a candidate to receive) a PhD should conduct the work with significantly less guidance than an MS candidate. And far less than an undergraduate. Again, true whether science or literature.

One thing you don't see there is 'more apt to think critically' about everything they comment on. You also won't find 'look at all information' about everything. The about everything is my addition, not the exact quote. But for the comments to be meaningful, they have to apply to the specific thing at hand, whatever it is that's at hand, whether it's the pathetic petition or other things allegedly about science.

The posession of a doctorate says, instead, that the owner is likely to be capable of making an original contribution to knowledge, without too much guidance from someone else. This is a pretty good sign. But it hardly means that the owner has been turned in to Mr. Spock. PhD holders are human still. We all have capabilities, PhD or no. And we humans don't always exercise the highest of our abilities. The area where you can bet (if not guarantee) that a PhD holder is more apt to think critically and consider all information is the area of their professional work. Outside that ... you're much better off to either ask if they brought full ability to bear, or to assume that they didn't.

In saying that, remember, I do have a PhD myself. It is possible that a PhD-holder is bringing full abilities to bear. If so, then they can fare better than most non-PhDs in evaluating things which claim to be science. I did, for example, take such a look at a couple of different scientific papers regarding left-handedness (I'm left-handed and interested in the topic). I thought they were very bad, for a number of reasons of 'how you do science'. The serious work, however, was done by the people who were in the field (PhD or no) and wrote the rebuttal papers for the peer-reviewed literature. They named many things that I got, and many more besides. Being a scientist got me about 1/3rd of the way through the list of errors that the original authors had committed.

On the other hand, many of the things I looked at and for in evaluating those papers were things I'm discussing here and seriously believe a jr. high student can learn to apply regularly.

So where are we? As Chris suggested in his response to Stephen: "From experience with my professors though, I wouldn’t ask many of them a question outside of their field, at least beyond 101 level stuff, so maybe not. But at the same time, none of them would go off signing petitions about things they know little about." Those are both good rules of thumb. Outside the professional field, a PhD-holder can't be presumed to know more than (or, depending on field, even) 101 level stuff. But most of us know this about ourselves, so toss the junk mail petitions where they belong when they arrive.


Philip H. said...

So where exactly does that leave those of us with a Master's in science? Are we less capable at analysis then a Ph.D. just because we didn't write a big enough paper to graduate? Seriously?

Good science (and for that matter good analysis of anything) isn't dependent on the level of academic training one receives. Some of the best taxonomists I have worked with had bachelor's degrees from 30 or 40 years ago, but had been practicing taxonomy all their careers. They had no need for further specialized studies, and they were leaders in their particular fields. I'd challenge many of today's Ph.D. taxonomists to do as well.

So, while Ph.D.'s do have their place (Especailly for academics), let's not kid ourselves that only Ph.D.'s can do the work. Many of your colleagues without Ph.D.'s would probably agree.

Robert Grumbine said...

Whew! I knew I should have put in that paragraph about Stommel.

An MS doesn't mean that you can't do original work independently. As I did allude, much of what I've done in looking outside my field was using ideas that could be learned far younger than that.

What I was addressing was minimal expectations, and, for that matter, how some people (when convenient) were granting too much to PhD holders. A minimal PhD should be able to do original work independently. A minimal MS may only have taken courses and not be ready for doing original work, or may not be ready to do it independently.

For doing science, what matters is to do science. Not the degree. A prime exemplar in my field is Henry Stommel. His undergraduate degree was in astronomy, and his final earned degree was a masters. Yet he was one of the great oceanographers of the 20th century. If you're of a mind to learn about the Gulf Stream, his book by that title (from the early 1960s) is still one of the best places to go.

So most of my colleagues with PhDs, and I, would agree that people without PhDs can do the work. The test is whether they do so. This stands in great contrast to the Stephen quote above, where a PhD in one field makes one qualified to comment on all fields.

Anonymous said...


There's exceptions to every rule (e.g., one of the pioneers in climate change history, G.S. Callendar, who worked with measuring early temperature trends, CO2 levels, and their connection was seen as an amateur by most professionals at the time), but it's rather rare to see a random guy off of the street make a radical contribution to the field. Part of the reason is that a pre-requisite to independent work and original contributions is to actually know what the current science says, and where the current problems are (it may be a bit of a formality in peer-reviewed papers that a qualitative introduction is given so that people at least know that the authors have the background in whatever problem is being addressed). Science often builds off of previous work (even "original contributions" use earlier work to come to conclusions) and it's in the process of earning a degree that people become familiar with that "earlier work." Academic training is only a backbone of course, but it does provide that skeleton upon which independent thinking works. It's like jumping into a calculus class without any algebra background and expecting to just pick up on what is being discuss.

Philip H. said...

My problem is with the dismissal of the completion of an M.S. as not giving a person the ability to stay current on the science and thus contribute new and original science. I can read all the oceanography and marine science journals with as much understanding as the Ph.D. next to me. Likewise I can do robust statistical and experimental design and carry out the same laboratory and field experiments. So how, exactly, am I not positioned to contribute original science? Or, how is anyone with a Ph.D. better positioned then I am?

And Robert, as an oceanographer, I have to agree about Stommel.

Anonymous said...


Perhaps you could point out where Robert (or Chris) [dismissed] the completion of an M.S. as not giving a person the ability to stay current on the science and thus contribute new and original science and claimed that you are not positioned to contribute original science.


Anonymous said...


I am a student. In fact I'm working on a Bachelors degree, and at the same time I have a decent knowledge of climate science, a website, and am actually starting a book which I hope progresses nicely. I feel confident enough to tell "good science" from "bad science," and to question shady arguments. However, I am not yet in any position to make original contributions to the refereed literature, and there's still a lot of stuff in the atmospheric sciences at an undergraduate and graduate level that I can learn. Until I do so, I really will not think about telling professionals who have been in the field for decades that I have something to teach them that they never thought of. To me, that is actually a rather biazarre notion.

Now I'm sure that there are people my age much brighter than I am who could be a little ahead, but still, I doubt that many of them are in a position to really do much as far as "original contribution" prior to at least a Master's degree. I do not believe it is very plausible for such a person to have extensively studied and experimented in the way you speak of-- largely because of available resources and funding, the lack of guidance of an instructor, or because he missed out on basic knowledge which many primary articles simply assume the reader has. There are exceptions to the rule, but I do not rely on it.

Now if I did have an idea which I thought was unique I would take it up with a professional in the field (who more likely than not would just tell me to go read a textbook at one level higher than I was thinking), but in the off-chance I actually did have something unique to contribute, then good for me...I still have much to learn.

In any case, this is getting off the point of the OISM petition. I highly doubt that all of these deceased people and veternarians are doing the extensive pre-PhD research that you speak of, or that any of them are really in a position to declare the mainstream scientific community wrong. It might be good for a bridge designer or engineer to talk about what doesn't make sense to them at a dinner table conversation, but I think there is a lot of arrogance to start signing petitions that fly in the face of century-old physics.

Anna Haynes said...

In some cultural contexts "I have a PhD" is a handy shorthand for "I'm someone who spends a lot of time reading and thinking, so perhaps you might learn something from what I have learned, by listening."

I do feel a bit silly wielding mine, but if you're in a crowd composed largely of the clueless-but-unaware-of-it, and you yourself are not inherently poised and articulate, it may be the only tool you've got, to get people to accord your words any weight.

Anonymous said...

Bob, another issue is how all those people signed notwithstanding the incoherent language of the petition. It doesn't give one much faith in their grasp of the science.

"We urge the United States government to reject the global warming agreement that was written in Kyoto, Japan in December,[sic] 1997, and any other similar proposals. The proposed limits on greenhouse gases would harm the environment, hinder the advance of science and technology, and damage the health and welfare of mankind.

"There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gasses is causing or will, in the foreseeable future, cause catastrophic heating of the Earth's atmosphere and disruption of the Earth's climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth."

What a rhetorical train wreck.

(BTW, your "pathetic petition" link doesn't work.)

DeadFrog said...

Piled Higher & Deeper

John Mashey said...

1) Sayeth Lord Kelvin:

"When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge of it is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced it to the stage of science."

2) This discussions sounds like critical thinking and knowledge are mixed together, and I'm not sure there are rigorous definitions and measurements that I'd believe.

3) But even if there were, assertions about populations often fail in a common way:

Means are often worthless without distributions.

In particular, the (correct) assertion:

a) The average (something) of population X is higher than that of Y.

gets said as:

b) X is higher than Y.

c) And even with caveats, gets interpreted as "All (or most) members of X are higher than all (or most members) of Y.

4) Consider a well-measured case, that of height, by gender, within an ethnic group. Male average is higher than female average, and both groups are more-or-less normally distributed. But there is plenty of overlap.

So, even if critical thinking and knowledge were well-measured, I'd suspect there would be overlaps amongst the {BS, MS, PhD} distribution, and I would suspect that the distributions might be lognormal, rather than normal, i.e., more like weight than height, because the very best people in a field are really very, very good.

5) Scientists, especially towards ends of careers, sometimes go off into different areas. Sometimes they bring new approaches and contributions, but:

Good rule: get very nervous when a well-published scientist shifts into a different field, starts writing OpEds and other non-peer-reviewed material whose positions contradict the mainstream science in that field.

Examples (of varying degrees of reknown)
Nobel winner Linus Pauling & Vitamin C
Nobelist William Shockley & eugenics

Aurora physicist Syun-Ichi Akasofu (on climate science)

And two from the recent APS FPS brouhaha:

Nuclear physicist Gerald Marsh (on climate science, see list at RC.

Physicist Larry Gould, who has discovered Viscount Monckton as a climate expert.

6) Fortunately, many scientists remain sharp and careful for many years, and can be pretty good at moving to new areas, because they know what they know, and know what they don't, and know how sort out science from non-science and anti-science.

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