Tag Archives: argumentum ad imperfectionem

Blinded by expertise

I asked my house guest, a real philosopher and therefore likely some kind of liberal, which major or even minor scientific view, endorsed by a majority of competent scientists working in their specific field of expertise, he doubted.  He said that he couldn't think of one.  Nor really can I.  For in the first place, I don't think my judgement in those matters so acute that it outweigh the work of all of those people working independently across time and space.  Secondly, I wonder why I would be so acute as to notice the faults of one particular view, without at the same time suspecting the every similar scientific activity be subject to the same kinds of failures.  But that's just me, and perhaps my house guest.

Now comes George Will, noted global warming denier.  His scientific acumen is so sharp–on the subject of global warming–that the Post continually allows readers to consider his judgement to stand alone, often without fact checking and usually without rebuttal.  And who says arguments are dialogues.

Today's global-warming-advocates-are-eating-crow provides yet another example of our newly discovered fallacy, argumentum ad imperfectionem–the argument from imperfection.  For more on that, see here.  Briefly again, the argument from imperfection, operates in the following way.  A person finds completely normal relatively minor errors (or inconsistencies, etc.) in a particular view, such as climate change, and alleges that those errors (consistencies, etc.) justify a kind of disproportionate skepticism.  So, for instance, the disagreement among scientists (which is what they do!) on the contours of this or that matter do not open the door to global skepticism. 

First here's Will in the only section of his op-ed that makes reference to evidence:

Global warming skeptics, too, have erred. They have said there has been no statistically significant warming for 10 years. Phil Jones, former director of Britain's Climatic Research Unit, source of the leaked documents, admits it has been 15 years. Small wonder that support for radical remedial action, sacrificing wealth and freedom to combat warming, is melting faster than the Himalayan glaciers that an IPCC report asserted, without serious scientific support, could disappear by 2035.

Jones also says that if during what is called the Medieval Warm Period (circa 800-1300) global temperatures may have been warmer than today's, that would change the debate. Indeed it would. It would complicate the task of indicting contemporary civilization for today's supposedly unprecedented temperatures.

Last week, Todd Stern, America's special envoy for climate change — yes, there is one; and people wonder where to begin cutting government — warned that those interested in "undermining action on climate change" will seize on "whatever tidbit they can find." Tidbits like specious science, and the absence of warming?

If you follow the links, you'll learn that Phil Jones has been grossly misrepresented (that reference to 2035 was a typo, by the way, and not integral to the case for anthropogenic climate change).  Here is Jones (read the entire thing):

G – There is a debate over whether the Medieval Warm Period (MWP) was global or not. If it were to be conclusively shown that it was a global phenomenon, would you accept that this would undermine the premise that mean surface atmospheric temperatures during the latter part of the 20th Century were unprecedented?

There is much debate over whether the Medieval Warm Period was global in extent or not. The MWP is most clearly expressed in parts of North America, the North Atlantic and Europe and parts of Asia. For it to be global in extent the MWP would need to be seen clearly in more records from the tropical regions and the Southern Hemisphere. There are very few palaeoclimatic records for these latter two regions.

Of course, if the MWP was shown to be global in extent and as warm or warmer than today (based on an equivalent coverage over the NH and SH) then obviously the late-20th century warmth would not be unprecedented. On the other hand, if the MWP was global, but was less warm that today, then current warmth would be unprecedented.

We know from the instrumental temperature record that the two hemispheres do not always follow one another. We cannot, therefore, make the assumption that temperatures in the global average will be similar to those in the northern hemisphere.

H – If you agree that there were similar periods of warming since 1850 to the current period, and that the MWP is under debate, what factors convince you that recent warming has been largely man-made?

The fact that we can't explain the warming from the 1950s by solar and volcanic forcing – see my answer to your question D.

I – Would it be reasonable looking at the same scientific evidence to take the view that recent warming is not predominantly manmade?

No – see again my answer to D

Now of course if you read only those portions of the discussion that confirm your pseudo-skepticism, you might take Jones to be dismantling his entire case.  But it ought to be obvious that the disagreements about the data, to Jones and the rest of actual scientists, are well known and do not constitute grounds for doubting the entire thesis, as non-expert skeptics such as WIll maintain.  Perhaps, however, Jones is blinded by his own expertise. 

But of course Jones is fully aware of the disagreements around the edges of the science.  That's what science is for those who don't know.


I think I might refine the definition of the argumentum ad imperfectionem somewhat today.  As I alleged the other day, ad imperfectionem fallacy occurs when one asserts that the minor errors in someone's argument may be justifiably exaggerated by opponents of that argument.  So, for instance, minor errors in a legal filing undermine one's entire case, not just those particular claims relevant to those errors.  For, after all, if there are a couple of typos, who knows what other kinds of serious errors there could be.  This, of course, is the response of a crazy person.  But not all crazy is the same, so it's worth it to take a closer look at the crazy.   

On this description, the imperfectionem is a variation of the ignoratio elenchi (IE).  The ignoratio elenchi, sometimes called "missing the point" or–get this–"non sequitur", is a kind of a catch-all category of fallacy: any other basic failure of informal entailment gets thrown in here.  Here, for instance, is the way Patrick Hurley puts it in A Concise Introduction to Logic:

Missing the point illustrates a special form of irrelevance.  This fallacy occurs when the premises of an argument support one particular conclusion, but then a different conclusion, often vaguely related to the correct conclusion, is drawn.


but in some ways it serves as a catchall for arguments that are not clear instances of one or more of the other fallacies.

Textbooks will often use examples of IEs with outrageous conclusions where more moderate ones are available.  So, for instance, given the inevitable shortcomings in weather forecasts, one ought not to listen to them at all.  That's dumb, as weather forecasts are predictions, and predictions can be wrong.  Again, the conclusion of a crazy person.  This conclusion, in that particular example, is driven by the idea that any imperfection, however minor, in the assertions of one party are sufficient to create doubt about that party's entire case. 

I think the argumentum ad imperfectionem is focused on the inference from the relatively minor shortcomings of one side to either (a) the truth of the opposite side (in which case it looks like a false dichotomy) or (b) to the conclusion that no one can really claim to know one's conclusion is true (in which case it looks like an appeal to ignorance) or finally (c) to the conclusion that the opposite side is relatively more justified. 

I can think of examples of all three of these.  But for today, here's an example of (a):

(a) in the minds of many, the various quibbles and revisions involved in the science of global warming justify skepticism of the entire thesis.  Here's an example of that from the Washington Post:

"What's happened here is that there's an industry of climate-change denialists who are trying to make it seem as though you can't trust anything that is between the covers" of the panel's report, said Jeffrey Kargel, a professor at the University of Arizona who studies glaciers. "It's really heartbreaking to see this happen, and to see that the IPCC left themselves open" to being attacked.

That's not an example of an actual argument, as it is a report of someone else's argument.  But people really do make that allegation, unfortunately.

Maybe if I'm motivated I'll find examples of the others later.