Is science sometimes in danger of getting tunnel vision? Recently published ebook author, Ian Miller, looks at other possible theories arising from data that we think we understand. Can looking problems in a different light give scientists a different perspective?

Can you prove a theory to be true?

Many/most scientists would probably say, no, you cannot; all you can do is to falsify a theory, while you believe a theory to be true because all evidence supports it. This raises the problem, what happens when the evidence that contradicts the theory are suppressed?
Thus further to my previous posts, there were further subtle cues as to why cyclopropane did not demonstrate conjugation. For example, if you have a sequence of olefins, pronounced conjugative effects are demonstrated. On the other hand, while a cyclopropane ring adjacent to either positive charge, or to potential positive charge such as with UV transitions, gives effects similar to conjugative units, add a second cyclopropane ring to the first, thus have two in a row, and the second one has no noticeable effect. On the other hand, if we put three cyclopropane rings around a positively charged centre, the effects are very close to being additive, which does not seem to happen with cross-conjugation.
Similarly, with the cyclopropylcarbinyl carbenium ion, you would expect the bond to the carbinyl centre to either make an angle of 120 degrees to the plane of the cyclopropyl ring (as required by the Walsh MO treatment) or approach closer to this angle as the ion forms, but it does not. Instead, the centre moves towards the cyclopropane ring, as if there were an attractive force pulling it. That, of course is exactly what should happen with my polarization field. While the fact that cyclopropane stabilized adjacent charge was taken as proof of conjugation, the associated minor details that contradicted that proposition were ignored.
An observation can be used to prove a scientific statement, provided you can write it in the form: “If, and only if, theory X is true, then you will observe Y”. The observation of Y proves theory X is true, as stated. Of course it may be incomplete, but it will be true as far as it goes. The problem is to justify the ”only if” part of the statement, because how can you know that there is not an alternative that has not been thought of yet?
The reason I have been writing these blogs on cyclopropane conjugation is not to justify my own youth. From a personal point of view, I could not care less whether anyone believes me, although I do feel that everyone should have the opportunity to consider the issue for themselves. If people want to believe the Earth is flat, well, I cannot do much about that. But people cannot form reasonable views on such matters if the “trivial details” that falsify a theory are suppressed. A review should be critical and complete, not merely fashionable. But suppose, you argue, the reviewer does not know about these details? That is why I think we need a new form of review, like the wiki, where everyone can contribute, and a number of moderators bring order to what is produced. . What do you think?
One final comment on this. One reason why everyone said cyclopropane conjugates was because they expected it to, because molecular orbital theory, mainly the CNDO/2 version popular at the time, and also a more sophisticated version of MO theory championed by John Pople, said it would. Remember, molecular orbital theory starts by assuming total electron delocalization, and special reasons are required to produce bond localization. As Aristotle would have said, to find delocalization when you assume it in the first place is not a great achievement. More on this issue later.
Posted by Ian Miller on Mar 18, 2013 1:50 AM Europe/London

Share this |

Share to Facebook Share to Twitter Share to Linked More...

Leave a comment?

You must be signed in to leave a comment on MyRSC blogs.

Register free for an account at