 Why has Whewell been misinterpreted by so many modern commentators? One reason has to do with the error of reading certain terms used by Whewell in the 19th century as if they held the same meaning they have in the 20th and 21st. Thus, since Whewell used the terms “conjectures” and “guesses,” some writers believe that he shares Popper’s methodology. Whewell made mention, for instance, of the “happy guesses” made by scientists (1858b, 64) and claimed that “advances in knowledge” often follow “the previous exercise of some boldness and license in guessing” (1847, II, 55). But Whewell generally used these terms to connote a conclusion that is not (yet) conclusively confirmed. The Oxford English Dictionary tells us that prior to the 20th century the term “conjecture” was used to connote not a hypothesis reached by non-rational means, but rather one which is “unverified,” or which is “a conclusion as to what is likely or probable” (as opposed to the results of demonstration). The term was used this way by Bacon, Kepler, Newton, and Dugald Stewart, writers whose work was well-known to Whewell. In other places where Whewell used the term “conjecture” he suggests that what appears to be the result of guesswork is actually what we might call an “educated guess,” i.e., a conclusion drawn by (weak) inference. Whewell described Kepler’s discovery, which seems so “capricious and fanciful” as actually being “regulated” by his “clear scientific ideas” (1857/1873, I, 291–2). Finally, Whewell’s use of the terminology of guessing sometimes occurs in the context of a distinction he draws between the generation of a number of possible conceptions, and the selection of one to superinduce upon the facts. Before the appropriate conception is found, the scientist must be able to call up in his mind a number of possible ones (see 1858b, 79). Whewell noted that this calling up of many possibilities “is, in some measure, a process of conjecture.” However, selecting the appropriate conception with which to colligate the data is not conjectural (1858b, 78). Thus Whewell claimed that the selection of the conception is often “preluded by guesses” (1858b, xix); he does not, that is, claim that the selection consists in guesswork. When inference is not used to select the appropriate conception, the resulting theory is not an “induction,” but rather a “hasty and imperfect hypothesis.” He drew such a distinction between Copernicus’ heliocentric theory, which he called an induction, and the heliocentric system proposed by Aristarchus in the third century BCE to which he referred as a hasty and imperfect hypothesis (1857/1873, I, 258).