Unobservable entities

Extrapolation 1) An estimation of a numerical value of an empirical (measured) function at a point outside the range of data which were used to calibrate the function, or 2) the use of data derived from observations to estimate values for unobserved entities or conditions. 

Ian Hacking s philosophy of experimental realism integrated the epistemological sensibilities of the new empiricism into the practice-model of science by severing the theoreticist link between the truth of theories and a realist commitment to the existence of unobservable entities. As a form of entity realism , experimental realism allows experimentalists to be antirealists or instrumental-... 

Express their understanding of observed phenomena in terms of underlying aperceptual (unobservable) entities and processes... 

An important conceptual, or even philosophical, difference between the orbital/wavefunction methods and the density functional methods is that, at least in principle, the density functional methods do not appeal to orbitals. In the former case the theoretical entities are completely unobservable whereas electron density invoked by density functional theories is a genuine observable. Experiments to observe electron densities have been routinely conducted since the development of X-ray and other diffraction techniques (Coppens, 2001).18... 

Ideologies are elusive entities. Beliefs, like electrons, are unobservable they must be identified indirectly. To ask people about their beliefs is already to interfere with them, since what we seek generally is the spontaneous, unreflective belief rather than the self-conscious answer to a question. Moreover, to believe in something is not one single, simple modality. Children may believe in Santa Claus, and yet ask their parents... 

In contrast, the term transition state refers to the properties of an ensemble of molecular entities at a finite (nonzero) temperature it may be associated with the maximum along a simulated free energy profile for an elementary step. We consider it useful to distinguish the two concepts in view of the significant difference between them the one is microscopic and related to a feature of an (unobservable)... 

According to Ostwald, any metaphysical assumption about unobservable or undetectable entities (atoms, molecules, ions, and radicals) should be avoided. 

The difQculties of the descriptive problem are sometimes underrated, because it is supposed that inductive reasoning follows a simple pattern of extrapolation, with More of the Same as its fundamental principle. Thus one predicts that the sun will rise tomorrow because it has risen every day in the past, or that all ravens are black because aU observed ravens are black. This model of enumerative induction has, however, been shown to be strikingly inadequate as an account of inference in science. On the one hand, a series of formal arguments, most notably the so-called raven paradox and the new riddle of induction, have shown lhat the enumerative model is wildly over-permissive, treating virtually any observation as if it were evidence for any hypothesis. On the other hand, the model is also much too restrictive to account for most scientific inferences. Scientific hypotheses typically appeal to entities and processes not mentioned in the evidence that supports than and often themselves unobservable and not merely unobserved, so the principle of more of the same does not apply. For example, while the enumerative model might account for the inference that a scientist makes from the observation that the light from one star is red shifted to the conclusion that the light from another star will be led-shified as well, it will not account for the inference from observed red-shift to unobserved recession [ 14]. 

One of the main characteristics of single molecule spectroscopy is thus that it reveals details about individual entities that are otherwise masked in the ensemble. In the simple case of fluorescent molecules this includes e.g. such previously unobserved effects as the presence of discrete emission levels, spectral diffusion, etc. This is demonstrated and displayed in Figure 1, which shows an intensity time trace of the... 

However, the turning away from regarding the elements as unobservable abstract entities could not be sustained for long. The concept returned rather forcefully with Mendeleev s version of the periodic system of the elements. In fact Mendeleev repeatedly emphasized that in his classification of the elements, the emphasis was primarily on the unobservable sense of the concept of element . In some instances Mendeleev even called them the real elements and carefully distinguished this concept from elements as simple substances or Lavoisier s elements. 

The question for realism is altogether different if taken in the sense of the belief in unobservable scientific entities. In fact many philosophers of science currently favor some form of scientific realism in the context of quantum mechanics (Cao, 2003). 

The atomist, by contrast, disputes this on the basis of an appeal to unobservable theoretical entities ... 

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