Aug 26 2009
By Definition
If you are not aware of Massimo Pigliucci’s excellent blog, Rationally Speaking, take a look. He covers the very important intersection of science and philosophy. His most recent post covers the concept of definitions in science and in general. It’s a great discussion that I wanted to expand upon a bit.
Massimo’s central point is that it is often not necessary, or even possible, to have a precise and unambiguous definition in science, and in fact scientific discovery is often exactly about exploring the nature of a thing.
To understand this we need to understand the nature and role of definitions in science and philosophical thought. At one end of the spectrum there is the fallacy that is called the “Socratic fallacy” (although Massimo points out that Socractes was not guilty of this fallacy) – the assumption that definitions need to be pristine to be useful. At the other end is the fallacy that definitions are hopelessly ambiguous and therefore of no value.
The reality is more complex, as it almost always is.
It has become a cliche of naive argumentation that whipping out a dictionary definition is the mark of a scientific rube. Dictionaries document current consensus – not anything useful in terms of scientific categorization. But they represent one type of “definition” – a meaning agreed upon by convention and useful for unambiguous communication. Dictionary definitions oversimplify and are not useful for scientific discussion.
Science simultaneously deals with two types of categorical definitions – operational definitions and conceptual categories. Massimo aptly characterizes the latter as:
…identified by philosopher of language Ludwig Wittgenstein, and known usually as “family resemblance” or “cluster” concept: it does not admit of a simple definition in terms of a small set of necessary and sufficient conditions. Rather, it is fuzzy, made of a number of conceptual strands that intersect in a complex fashion.
Categories in nature are sloppy – because they are more complex than our attempts at pigeonholing. Massimo uses species and planets as his prime examples, and they are good ones. Is Pluto a planet? That depends on how you define planet, and astronomers recently had to face the fact that there is no clear and unambiguous way to do this. There is a spectrum of objects orbiting our sun, with a variety of origins, fates, compositions, sizes, and relationships to other objects. There is no clean line to draw for planet, or dwarf planet, or planetoid, or whatever.
Species are also fuzzy around the edges – a population blends into a sub-species which blends into a species, which may retain tenuous genetic exchange with other “species”.
I would add an example from my own profession – that of the disease diagnosis. Diseases and disorders are often not discrete entities – they overlap with each other, there often are many subtypes, and there are many features which may or may not be present. This leads to an endless “lumper vs splitter” debate – whether you consider every subtype a different disease or just the spectrum of one disease. Diseases are often fuzzy.
Massimo points out that scientists can explore the origin of planets even without a clear definition – and likewise, physicians can treat a category of disease even without a precise diagnosis (as one may not be possible by definition). This often causes patients undue anxiety, as the common assumption is that treatment is dependent upon a precise label.
Massimo did not discuss, however, the role of an operational definition in science (including medicine). An operational definition is a list of criteria – if a patient has symptom A, B, and C but not D or E then they have syndrome X. Or – if a body has enough gravity to pull itself into a sphere, it orbits the sun, and it gravitationally dominates its orbit, it’s a planet. Operational definitions are partly convention – agreed upon nomenclature. But they do allow us to ask certain kinds of questions.
For example, If I want to know if a drug relieves acute migraine attacks, I need to have an operational definition of an acute migraine attack. This definition will necessarily not be perfect, it will oversimplify the complexity, it will exclude some episodes that may reasonably be considered migraines, but it creates a category that can be broadly and practically applied. It allows me to compare my results to a researcher in Japan, if they follow the same operational definition I spell out. (Often, central bodies will determine such operational definitions that everyone will use.)
Operational definitions are useful, often necessary. In some cases they may even exactly correspond to a real conceptual category. At other times they are an acknowledged approximation and oversimplification.
The trick is to use operational definitions, and nomenclature by convention, as they were meant to be used. Meanwhile, understand the nature of categories in science – they are approximations of a very complex reality. They should not constrain our thought, nor substitute for deep understanding. In fact, there is a useful interplay between our understanding of nature and the way that we categorize it. This is a process of creative destruction, not enshrined icons – like science itself.
16 Responses to “By Definition”
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Nice one…I find this a common area of misunderstanding about science. Because precision in measurement is something stressed in science (though never perfect), it is often assumed that precision in definition is also absolutely essential. This turns out to be both true and false, depending on which kind of definition a person is talking about. Precise operational definitions are required, as this promotes the precision of measurement science strives for, as well as the effective communication to the scientific community that is essential to evaluating and replicating the methods of any given study. But that is a far cry from the categorical, consensus-based definition of things that my students and the public in general expects. Your admonition not to substitute operational definitions for a deeper understanding is also laudable, but too often ignored. Consider the way intelligence/achievement test scores are reified by the educational system. Our brains are wired to simplify things into easily digestible nuggets. We crave categories, and we especially crave categories with clear and stable boundaries. Maybe this is why some people are so uncomfortable with science — it is always moving those boundaries as our knowledge expands, and upsetting the status quo.
Plato (through Socrates) was actually not stating that definitions had to be pristine, only that the interlocutor accept that there is some form behind ideas that could not be defined by perceptibles (in the early dialogues). His famous example is obviously that equals are never unequal except as when perceived. His main problem is that he treats definitons as monadic rather than as relational (see: Phaedo 74:b-c).
Wittgenstein made the bold statement that our knowledge of the world is through relation (anti-platonic) as opposed to having knowledge about objects. Heidegger added a nice little bit that complemented this theory by stating that language should be viewed by its use rather than its reference (semi-anti-fregean), which ties into his view of Das Man: when we treat the external world as objects outside of us (i.e. not during the act of their use by us), we become Das Man, a neutral observer trying to gain existential knowledge about objects. It’s not until we start to use poetic language to allow the objects to “talk to us” that we gain any sort of knowledge of objects.
To create a variation to the often quoted saying by Justice Potter Stewart, ” I know hostility when I see it.” That’s why I use dictionary definitions, to reach a form of consensus and end the circular bickering which occurs on the blog. Of course, you will never reach consensus on anything if the posters are “high” when they write their comments. But, I have noted some humorous results. Please note that legal arguments, like scientific arguments need a basis to begin discussions, and the major points/ issues must be agreed upon prior to engaging in lengthy discourse. Then you can have successful social intercourse.
It never hurts to hear from philosophers that have addressed the problem of definition through language in an article regarding definitions.
In order for science to function we need to have the possibility of experiment and attempts to replicate results.
For this to occur there needs to be extremely precise definition of each aspect of the experiment.
To say that science doesn’t need presice definitions is absurd. (“I mixed the stuff with the other stuff in the thingamajig for awhile and got some gooey stuff,”– is perfectly valid for nonscientists. But each term must be defined so well that another can attempt to do the experiment EXACTLY as was done before…)
Precise defintions are necessary for epistemological systems (in this case: science) based on formal logic and mathematics. However, the analytic philosophers of the 20th century showed that the actual process of creating the precise definitions in the first place is problematic. Specifically, the problems that arise are that of what exactly is the referent of a definition, is a definition really just a dead metaphor, and can all aspects of reference be expounded by denoting phrases (a Bertrand Russel hypothesis in his “On Denoting” article back in the early 20th century).
The “cluster concepts” that Steve referred to in this article was actually an issue that was raised before Wittgenstein, but of course, cluster concepts (family resemblences) are integral to Wittgenstein’s philosophy of language. In the end, Wittgenstein accepted the fact that all knowledge in the world is relational, and thus, our definitions are facts about objects, not definitions of the objects themselves.
Heidegger built a similar philosophy of language in which he referred to Das Man. In german, Das is the gender neutral specifier for nouns. Heidegger was pointing out that when we refer to the external world, we need to make sure that we aren’t trying to create a “grey world” that we are separate from. That would be the attitude of Das Man: to be a third person to the world when creating definitions. He would rather we use poetic language to allow a relationship to be established between the object and subject, thus creating a more plausible definition, because the relational definition will be more indicative of how we would really use the object.
Can you give a definition of “species” that precisely describes the qualities of each and every designated member of that group in a way that belies the fact that the designations were and had to have been to at least some extent arbitrary?
That question was for sonic.
I’m referring to the sonic that, in mistaking description for definition, would have one hell of a problem with keeping such a dictionary current for more than a second or two.
artfulD-
There are three problems with definintion-
1) We don’t really know what we are talking about in the first place. (This is usual in science- we study things that are not fully understood)
But as we learn the definitions get better.
“He died of consumption,” wouldn’t work today because of our knowledge.
2) It may not be possible to precisely define an essence. This problem was well confronted by Bohr. (I’ll assume you understand from here)
3) People get emotional/religious attachments to words, and when those words or concepts are seen to be untrue (or not useful)- the people want to just change the meaning of the word rather than admit the error.
Your question about species involves 1) and 3) (perhaps even 2))
Biologists can’t define life well- this is probably due to ignorance (but it could be that life is an irreducible– but that sounds like ‘elan vital’ and that produces bad emotional responses, so I’ll suggest that we stick with ignorance as the problem). Therefore we will have problems defining catagories of life.
Further, when the original biologists were catagorizing species they thought they were listing the special creations of god almighty.
Well it turns out that this is not a very usefull idea, but due to the emotion/religious nature of the word, I fear we will be stuck with a problem for sometime in the future.
I would suggest that certain words are so caught up in emotion and mistaken ideas that they loss usefulness. Species is probably such a word.
sonic, then you’re conceding that what Dr. N contends is not, as you first opined, absurd?
And also wouldn’t you then agree that “describing” (not “defining”) each aspect of an experiment precisely has little to do with the exactness of the definitions that may in fact have to change because of the preciseness of the well described experiment?
Also as to Bohr and any problems with the “essence” of atomic structures, it wasn’t so much with “defining” it as with the almost impossible task of unraveling the intricacies of the strategies which are essential to that structure’s internal consistency.
artfulD-
A description is only as good as the clarity of the words used in that description.
“We mixed the stuff in the thingamabob for a while,” could be perfectly precise– if we had exact definitions of each of the terms.
“Homeopathy is the only valid scientific healing method,” is a completely true statement- just use definitions that are non-standard– (You wouldn’t want to use a dictionary and prove your rubeness, now…)
There is no reason to use the word ‘species’ in any serious discussion about life. As a word it doesn’t describe anything. (This could be remedied with a clear defintion- which has been attempted a number of times- which has only lead to a further mudding of the term)… It leads to endless fruitless arguing about points that people may actually agree about.
It is possible to use the word ‘species’ in a way that is not vague- but it would need to be defined by the author clearly and the reader would have to agree in advance to use that definition for discussion.
To say that it is OK for a scientist to use a word that has many meanings without clearly defining in what sense the word is being used is a mistake.
Unclear thought is just that…
(The last time I sent a ‘scientific’ paper to my buddy who gets published he suggested we spend some months on the definitions that were going to use…)
sonic,
Ridiculous response. By your logic we couldn’t even communicate at all using language at its present stage of development. Of course the word “species” is conditional – that was part of the point, that in spite of this we use it in science quite satisfactorily, as everyone (except evidently yourself) is expected to understand the nature of its provisional status.
You write: “To say that it is OK for a scientist to use a word that has many meanings without clearly defining in what sense the word is being used is a mistake.
Unclear thought is just that…”
I suppose that then we must clearly define what we expect to clearly define, and so on down the line.
No wonder your buddy expected it would take you some months to get to the bottom of this effort.
Can any word be precisely defined? Wouldn’t that be a case of infinite turtles? This argument seems pretty obvious but I’m glad Steve made the point about operational definitions.
What is the definition of a house?
Our brain makes a mental image of a “house” which includes the most significant characteristics, visual, functional, etc. It’s not going to be the same house that someone else pictures but the major characteristics are the same so we are able to communicate effectively (based on the agreement of our mental image).
Scientific language can be no more precise than the lay language upon which it’s built. We get into the infinite turtles scenario when the subject is over-analyzed beyond practical value.