Why-necessary explanations

Of course, Dray s concern was human history, but the claims carry over into natural history. They enable us to see how reductionism might be vindicated, among biologists at least, as an ultimate how-possibly explanation gives way to proximate why-necessary explanation. Let us see how. 

In the period after Murray first produced his models, molecular biology has provided more and more of the proximate why-necessary explanations that the reductionist demands for the historical facts about butterfly eyespots. 

Insofar as science seeks to complete this (really) real explanation for historical events and patterns on this planet, it needs to pursue a reductionists research program. This is, biology can nowhere remain satisfied with how-possibly ultimate explanations, it must seek why-necessary proximate explanations, and it must seek these explanations in the interaction of macromolecules. 

Explanations of why a notification was considered necessary and all supporting materials used to develop the notice ... 

I believe that the explanation of these facts is provided by the three-8 W. Weizel, Z. Physik, 59,320 (1929). Weizel and F. Hund [ibid., 63, 719 (1930) ] have discussed the possible electronic states of the helium molecule. Neither one, however, explains why He Is2 + He+ Is form a stable molecule-ion, nor gives the necessary condition for the formation of a three-electron bond. In earlier papers they assumed that both atoms had to be excited in order to form a stable molecule [W. Weizel, ibid., 51,328 (1928) F. Hund, ibid., 51, 759 (1928)]. 

Not only are there substrates for which the treatment is poor, but it also fails with very powerful electrophiles this is why it is necessary to postulate the encounter complex mentioned on page 680. For example, relative rates of nitration of p-xylene, 1,2,4-trimethylbenzene, and 1,2,3,5-tetramethylbenzene were 1.0, 3.7, and 6.4, though the extra methyl groups should enhance the rates much more (p-xylene itself reacted 295 times faster than benzene). The explanation is that with powerful electrophiles the reaction rate is so rapid (reaction taking place at virtually every encounter between an electrophile and substrate molecule) that the presence of additional activating groups can no longer increase the rate. ... 

Despite these problems it remains necessary to attempt some explanation in terms of differential NT antagonism, of why clozapine is so effective (see Reynolds 1997) in that it causes fewer EPSs, reduces negative symptoms and is effective in some patients refractory to other drugs. Considering these benefits in turn ... 

It may be argued that although, in answer to a how-possibly question, all that need be mentioned is the presence of some previously unsuspected necessary condition of what happened. [NJevertheless, this does not amount to a full explanation of what happened. Insofar as the explanation stops short of indicating sufficient conditions, it will be said to be. .. an incomplete explanation, which can only be completed by transforming it into an appropriate answer to the corresponding Why . 

Antireductionists will differ from reductionists, not on the facts, but on whether the initial explanation was merely an incomplete one or just a how-possibly explanation. Antireductionists will agree that the macromolecular genetic and biochemical pathways are causally necessary to the truth of the purely functional ultimate explanation. However, they don t complete an otherwise incomplete explanation. They are merely further facets of [the] situation that molecular research might illuminate (Kitcher, 1999, p. 199). The original ultimate answer to the question as to why do butterflies have eyespots does provide a complete explanatory answer to a question. Accordingly, how-possibly explanations are perfectly acceptable ones, or else the ultimate explanation in question is something more than a mere how-possibly explanation. 

Why is it necessary to perform sodium nitrite titrations invariably in an acidic medium Provide a plausible explanation based on chemical reactions. 

Is one specific treatment comparison important . .. any aspects of multiplicity. .. should be identified in the protocol adjustment should always be considered.. .. an explanation of why adjustment is not thought necessary should be set out in the analysis plan. (ICH E9, Section 5.6)... 

It is generally agreed that blind examination of fetuses is an unnecessary source of error for regulatory studies. No explanation is given why the FDA considers this precaution to be necessary for food additives, but not for pharmaceuticals (10). 

Groves (1978) provided an intuitive explanation based on a mechanical model in which water penetrates into the oil/surfactant system, forming liquid crystals but, more to the point, considerably expanding the interface. This is the reason why it is necessary to postulate that water is inconsiderable excess. The surface expands so that instead of a negative interfacial tension what we have is a positive surface pressure. At this point it is not unreasonable to visualize the surface expanding and stranding as postulated in the Gopal model. 

It is clear that the selectivity relationship has broken down and it becomes necessary to explain why such an extremely rapid reaction should occur with positional selectivity. The explanation offered is that the rate-determining step is formation of an encounter complex (12, p. 506).84 Since the position of attack is not determined in the rate-determining step, the 5/6 ratio is not related to the reaction rate. Essentially the same idea was suggested earlier85 and for the same reason (failure of the selectivity relationship in some cases), but the earlier explanation specifically pictured the complex as a it complex, and we have seen... 

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