As usual, for philosophical and pedagogical reasons (among others),
I don't like to spend very much time discussing misconceptions
(about the nature of science or anything else). There's just too
many of them. It's like trying to kill bacteria by shooting them
with a rifle, one by one. It's too much work, and there's too much
collateral damage.
My preference is to get the right idea out there, explain it
properly, and move on. (Exceptions can be made for misconceptions
that are particularly prevalent or particularly destructive.)
What was a short paragraph has become a small section. It says:
]] The lattermost stages of any systematic investigation can often be formalized in terms of
]] hypothesis testing. What’s more, it is often possible to describe an already-complete
]] experiment by stating what hypotheses are ruled out by the results, and what hypotheses are
]] consistent with the results. One should not imagine, however, that all scientific work is
]] motivated by hypotheses or organized in terms of hypotheses. Some is, and some isn’t.
]]
]] Science -- and especially research -- usually involves a multi-stage iterative process, where
]] the results of early stages are used to guide the later stages. The early stages are
]] exploratory, and are not well described in terms of hypothesis testing, unless we abuse the
]] terminology by including ultra-vague hypotheses such as “I hypothesize that if we explore the
]] jungle we might find something interesting”.
]]
]] Typical example: When Bardeen, Brattain, and Shockley did their famous work, they started from
]] the hypothesis that a semiconductor amplifier device could be built. This hypothesis turned out
]] to be true, but it was neither novel nor specific. The general idea had been patented decades
]] earlier by Lilienfield. Indeed since vacuum-tube diodes, vacuum-tube triodes, and semiconductor
]] diodes were all well known, almost anyone could have come up with a vague hypothesis about
]] analogous semiconductor triodes. The problem was, all specific early hypotheses about how to
]] make such a thing actually work turned out to be false. Bardeen, Brattain, and Shockley had to
]] do a tremendous amount of iterative experimentation and theorizing before they figured out how
]] to build a transistor that worked.
]]
]] Example: When Kamerlingh Onnes began his famous experiments, he was not entertaining any
]] hypotheses involving superconductivity. He was wondering what the y-intercept would be on the
]] graph of resistivity versus temperature; it had never occurred to him or anyone that the graph
]] might have an x-intercept instead.
]]
]] Example: When Jansky began his famous experiments, he was not entertaining any hypotheses about
]] radio astronomy. He spent over a year taking data before he discovered that part of the signal
]] had a period of one sidereal day. At this instant -- and not before -- the correct hypothesis
]] came to mind: that part of the signal was emanating from somewhere far outside the solar
]] system.
]]
]] Example: At the opposite extreme, in a typical forensic DNA-testing laboratory, a very specific
]] hypothesis is being entertained: Either sample A is consistent with sample B, or it isn’t. This
]] may be “scientific”, but it isn’t research.
]]
]] As the proverb says: If the only tool you have is a hammer, everything begins to look like a
]] nail. Now, I have nothing against hammers, and I have nothing against hypothesis testing. But
]] the fact remains that in many circumstances, they are not the right tools for the job.
]] Scientists know how to use many different tools.
]]
]] It is common for people who don’t understand science to radically overemphasize the
]] hypothesis-testing model, and to underestimate the number of iterative stages required before a
]] good set of hypotheses can be formulated. It is a common but ghastly mistake to think that a
]] good set of hypotheses can be written down in advance, and then simply tested.
]]
]] Overemphasizing hypothesis-testing tends to overstate the importance of deduction and to
]] understate the importance of induction, exploration, and serendipity.
]]
]] As usual, it is a mistake to focus on the extremes:
]] * At one extreme, it would be a mistake to think that research is precisely guided by
]] pre-existing hypotheses.
]] * At the opposite extreme, it would be a mistake to think that
]] research is conducted at random, with no idea what to look for or where to look.