Theory vs. Fact
By Joey - Posted on March 28th, 2007
Tagged: Definition of a Theory
Darwinism as theory:
It seems that we need to be clear about the difference between a scientific theory and a fact.
Am I right?
JS
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In science a fact is an objective and verifiable observation, in contrast with a theory, which is an explanation of or interpretation of facts. Some scholars in the philosophy of science question whether scientific facts are truly objective or are always "theory-laden" to some degree. Thomas Kuhn and others as well pointed out that knowing what facts to measure, and how to measure them, requires some presupposition about the facts themselves. In the field of science studies, "scientific facts" are generally seen as entities which exist within complex social structures of trust, accreditation, institutions, and individual practices.
Mark,
In your previous post you make the statement that a theory can be accepted as fact. Perhaps you meant to say also this is possible once a resonable amount of evidence accumulates in support of the theory.
Notably, esp. for String Theorists, a theory is only useful until another more sensible one replaces it. Test-ability is not a necessary requirement.
Nevertheless, even for non-testable theories, logic prevails, and if a fatal flaw emerges then the theory may be modified or discarded.
Do you agree?
JS
There is a point of view that mathematics is not a science in the sense that there are no test possible outside the framework of axioms upon which the construct is built and, therefore, theories in that world are not testable. My impression is that string theory uses more the layman definition of the word than the scientific variant.
I would contend that a scientific theory both fits the data as well as suggests new behaviors which can be tested. By the time a scientific theory achieves the THEORY (neon letters top-dog status), it is already pretty good. However, it can be abandoned (e.g., Ptolomy or Copernicius orbital models) in favor a cleaner and more parsimonious model (Newtonian physics) or supplemented as was the case with Newtonian physics and Einstein since the Newtonian variation is the one we use for normal every day situations since it is more tractable.
From a Dempster-Shaffer Theory (that word is everywhere) point of view, a conjecture has two aspects: support and plausibility. Support is the evidence in favor of it whereas plausibility is the lack of countervailing evidence. (We used this in a multi-sensor data fusion system I was developing in the early 80's.) We need to not confuse probability with plausibility. I wrote a sidebar a few years ago for an IEEE Spectrum article on Data Fusion that was never published which I'll try to post. (Separately, since I lost a long post a bit ago because I tried to resize this text window.
The summary, for me at least, is that testability is a very important aspect of a theory. My symbolic regression models have no value if they cannot be tested — i.e., used — at points other than where we already have observations. The ability to interpolate and extrapolate is critical.
Mark,
I agree, testability is critical for a theory. I think Darwin stated this too. He suggested the following:
"If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous successive, slight modifications, my theory would absolutely break down." 'The Origin of Species' by Charles Darwin, 6th edition 1988 New York University press (p154)
Can you think of other tests of Darwin's Theory?
JS
Mark,
I have moved my mouth near your head and am asking if anyone is in there? So, I quoted Charles D., did you have to go buy the book?
JS
Sorry Joey, I didn't see your post.
One test, of course, is whether we can observe evolution as a process. I hope we can agree that that has been demonstrated with examples ranging from controlled systems (bacteria, fruit flies, improving yeast strains) to natural systems (speciation, ring systems, etc.) to artifical systems (e.g., genetic programming, genetic algorithms, etc.)
Now the question is HOW does this happen other than the simple expression
Diversity Introduction + Survival-of-the-fittest = Evolution
Ring systems are a favorite of mine. There are a number of such examples. One of my favorites is gulls around the Atlantic Ocean. If you pick a gull and go in one direction a species may be able to interbreed with another species and that species may be able to breed with another one further down the chain, and so on. However, by the time you get back to your starting point, the species at the end of the chain — which has a sexual compatibility path all the way back to the beginning — can no longer breed with the species at the start of the chain.
Diversity can be introduced by sexual exchange, mutation, or in the case of some bacteria, actually by donating genes back and forth without any children
Selection can come about in a variety of ways ranging from not being eaten to being eaten (some spiders and praying mantis) to sexual selection (different species have different turn-ons) to cultural selection.
Cultural selection is actually quite interesting in that it turns out the "us vs. them" actually provides a mechanism for altruism to develop. Axelrod (inventor of the Prisoners' Dilemma) did a very nice keynote a few years back on that topic. Thus, we see speciations based upon belonging to the right church (Jews, Amish, etc. — Theresa's grandmother would be spinning in her grave if she knew that Theresa had married outside THE faith), country club, ethnic group (Serbs vs. Croats vs ...), etc.
I'd recommend reading Carl Zimmer's book, "Evolution: The Triumph of an Idea" as a starting point. It is very well written. The theory around cultural selection and memetics isn't as mature as the natural selection and genetics side of the process so I don't have a recommendation for that off the top of my head.
Mark,
Not to address all of your nice response. But, as a slight detour, I did work on the Biochip project, as did you. At the time I learned just what an amazing amount of gene hopping is going on all the time.
This concerns me in regards to specie integrity.
My concern is that we look a bit more carefully about what is "going on all the time anyway" - the evolutionists seem to assume that when crossing purple flowering peas with white flowering peas that they are crossing static genomes. OK, sometimes this works hence genotyping and phenotyping but this static picture seems to be tenuous.
What is our control experiment in this remarkably dynamic and gene swapping world?
Joey
P.S. I will comment on other points you make shortly.