As much as I enjoyed the recap of Francis Crick's and James Watson's unravelling of the structure of DNA I focussed on the wisdom of his musings about the attempted avoidance of error. Excerpts are quoted below:
Page 16 "I've known a lot of people more stupid than you who have made a success of it."
P 24 "Even a cursory look at the world of living things shows its immense variety."
"The second property of almost all living things is their complexity."
P59 "The failure on the part of my colleagues to discover the alpha helix made a deep impression on Jim Watson and me. Because of it I argued that it was important not to place too much reliance on any single piece of experimental evidence. It might turn out to be misleading".
"Jim was a little more brash, stating that no good model ever accounted for all the facts, since some data was bound to be misleading if not plain wrong. A theory that did fit all the data would have been 'carpentered' to do this and would thus be open to suspicion."
p65 "Our first attempt at a model was a fiasco".
P67 "What was important was not the way it was discovered but the object discovered - the structure of DNA itself. You can see this by comparing it with almost any other scientific discovery. Misleading data, false ideas, problems of personal relationships occur in much if not all scientific work."
P70 "In solving scientific problems of this type, it is almost impossible to avoid falling into error."
"Now, to obtain the correct solution to a problem, usually requires a sequence of logical steps. If one of these is a mistake, the answer is often hidden, since the error usually puts one completely on the wrong track. It is therefore extremely important not to be trapped by one's mistaken ideas. The advantage of intellectual cooperation is that it helps jolt one out of false assumptions."
P109 "The best a theorist can hope to do is to point an experimentalist in the right direction, and this is often best done by suggesting what directions to avoid. If one has little hope of arriving, unaided, at the correct theory, then it is more useful to suggest which class of theories are unlikely to be true, using some general argument about what is known of the nature of the system."
P113 "It is all too easy to make some plausible simplifying assumptions, do some elaborate mathematics that appear to give a rough fit with at least some experimental data, and think one has achieved something. The chance of such an approach doing anything useful, apart from soothing the theorist's ego, is rather small, and especially so in biology. Moreover I have found, to my surprise, that most theorists do not appreciate the difference between a model and a demonstration, often mistaking the latter for the former.
In my terminology, a 'demonstration' is a 'don't worry' theory. That is, it does not pretend to approximate to the right answer, but it shows at least a theory of that general type can be constructed."
P115 "I cannot help thinking that so many of the 'models' of the brain that are inflicted on us are mainly produced because their authors love playing with computers and writing computer programs and are simply carried away when a computer produces a pretty result. They hardly seem to care whether the brain actually uses the devices incorporated in their 'model'.
A good model in biology, then, not only should address the problem in hand but if at all possible should serve to unite evidence from several different approaches so that various sorts of tests can be made of it."
P139 "Physics is also different because its results can be expressed in powerful, deep, and often counterintuitive general laws. There is really nothing in biology that corresponds to special and general relativity, or quantum electrodynamics, or even such simple conservation laws as those of Newtonian mechanics: the conservation of energy, of momentum, and of angular momentum. Biology has its "laws," such as those of Mendelian genetics, but they are often only rather broad generalizations, with significant exceptions to them. The laws of physics, it is believed, are the same everywhere in the universe. This is unlikely to be true of biology. We have no idea how similar extra-terrestrial biology (if it exists) is to our own. We may certainly consider it likely that it too will be governed by natural selection, or something rather like it, but even this is only a plausible guess.
What are found in biology are mechanisms, mechanisms built with chemical components and that are often modified by other, later mechanisms added to the earlier ones. While Occam's razor is a useful tool in the physical sciences, it can be a very dangerous implement in biology. It is thus very rash to use simplicity and elegance as a guide in biological research. While DNA could be claimed to be both simple and elegant, it must be remembered that DNA almost certainly originated fairly close to the origin of life when things were necessarily simple or they could not have got going.
Biologists must constantly keep in mind that what they see was not designed, but rather evolved. It might be thought, therefore, that evolutionary arguments would play a large part in guiding biological research, but this is far from the case. It is difficult enough to study what is happening now. To try to figure out what happened in evolution is even more difficult. Thus evolutionary arguments can usefully be used as hints to suggest possible lines of research, but it is highly dangerous to trust them too much."
P141 " The principal error I see in most current theoretical work is that of imagining that a theory is really a good model for a particular natural mechanism rather than being merely a demonstration - a "don't worry" theory. Theorists almost always become too fond of their own ideas, often simply by living with them for so long. It is difficult to believe that one's cherished theory, which really works rather nicely in some respects, may be completely false.
The basic trouble is that nature is so complex that many quite different theories can go some way to explaining the results. lf elegance and simplicity are, in biology, dangerous guides to the correct answer, what constraints can be used as a guide through the jungle of possible theories? It seems to me that the only really useful constraints are contained in the experimental evidence. Even this information is not without its hazards since, as we have seen, experimental facts are often misleading or even plain wrong. It is thus not sufficient to have a rough acquaintance with the experimental evidence. But rather a deep and critical knowledge of many different types of evidence is required, since one never knows what type of fact is likely to give the game away."
A Guide to The Logic of Scientific Discovery (The Popular Popper)