Knowledge justification

Terms a prior and a posterior are usually used in philosophy to distinguish two types of knowledge, justification or arguments. A priori knowledge or justification is independent of experience as opposed to a posteriori knowledge which makes reference to experience and can be used for decision making processes [17]. 

Economists differ widely in their views on the practical importance of these market failures, on what remedies are appropriate, and whether governments can satisfactorily remedy the problem. One clear principle is that the problem be identified as precisely as possible and the assistance be targeted as closely as possible to the problem. For example, if information is inadequate, providing knowledge about options would be preferable to aiding a specific option. The three justifications for subsidies set a minimum test of aid that many programs fail to pass. 

If one pound of trifluralin containing 1 ppm NDPA were applied to, and left on, the surface of a one-acre field, 400 pg NDPA could conceivably enter the atmosphere over a several hour period. To calculate how much of that could be inhaled by a single person would require, among other things, a knowledge of dispersion rates, but without them it is apparent that some very small numbers would be encountered. We must resist the temptation, however, to casually equate small numbers with negligible risk without solid justification. 

There are many circumstances when a single-dose intravenous (IV) study can provide useful information for example, if the intended treatment route is intraper-itoneal (i.p.), or if the product will be administered to an open wound or injected into a muscle or a tumor, it might accidentally enter a blood vessel, and the knowledge gained from an IV study would be of value as well as one by the clinical route. Hence, if the intended clinical route is not IV, the absence of an additional study with IV dosing would require specific justification. 

One important criterion for determining whether an association is causative is whether it is biologically plausible. Although a justification of the biological plausibility of each of our observed associations is beyond the scope of this report, it is rather common knowledge that abundant evidence from other studies confirms the plausibility of a causative link between meat use and coronary disease (22). However, this study is the first major observational study to clearly show this relationship among U.S. subjects. The associations between meat and diabetes are certainly plausible, but there is considerably less evidence from other experimental or observational studies to substantiate such a relationship. 

There is clearly uncertainty in relying on knowledge of the same material in different applications or conditions. If performance is known under one set of conditions it may be a relatively modest step to predict performance under different conditions. As an illustration, if performance has been proven at 60 °C, the rule of thumb whereby reaction rates approximately double for each 10 °C rise in temperature, might be applied to estimate performance at 70°C (for a justification of this rule for many polymers see [8]). To what extent this approach proves useful or successful will depend on the closeness of the different circumstances and on a general understanding of the potential reasons for any discrepancy. 

Early attempts have modeled the positive frequency wing (v > 0) with the help of a Lorentzian, Eq. 3.15, because of a perceived similarity of the observed induced lines with the Lorentzian no theoretical justification was pretended. The negative frequency wing may then be described by exp (—hcv/kT) times that Lorentzian so that Eq. 3.18 is satisfied [215, 188, 414, 411]. Systematic deviations from this model were, however, noticed in the wings [75, 244]. Nevertheless, beautiful analyses of various rotational and rotovibrational induced bands were thus possible and significant new knowledge concerning the role of overlap and multipole induction, double transitions, etc., was obtained in this way [422],... 

As noted in Table 3.1, EPA often uses up to a factor of 10 for each of five areas of uncertainty in establishing an RfD from a NOAEL or LOAEL. In practice, however, the magnitude of any uncertainty factor is dependent on professional judgment. If EPA has resolved uncertainties in all areas, which usually is not the case, an uncertainty factor of one is used to estimate RfD. When uncertainties exist in one, two, or three areas, EPA can use an uncertainty factor of 10, 100, or 1,000, respectively. When uncertainties exist in four areas, EPA often uses an uncertainty factor of 3,000. When uncertainties exist in five areas, EPA might use an uncertainty factor of 10,000. The justification for reducing the uncertainty factor in the latter two situations is EPA s knowledge of interrelationships among the various areas of uncertainty. In these cases, the multiplication of four or five factors of 10 is likely to yield an unnecessarily low RfD. 

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