ordinary Zitate

In the application of the ordinary principles of geometry and trigonometry to such Astronomical measures… it may sometimes be expedient to resolve the process into several successive steps, and these steps may perhaps require different kinds of treatment. But… all are simple and within ordinary comprehension, and the only complexity arises from the circumstance that the student may find it

necessary to have a clear view of several such steps at once…

In conversing with persons who are not officially attached to Observatories or in other ways professionally cognizant of the technicalities of practical Astronomy but who nevertheless display great interest… these persons appear to regard the determination of measures like those of the distance of the Sun and Moon as mysteries beyond ordinary comprehension… [and] when persons well acquainted

with the general facts of Astronomy are introduced into an Observatory, they are for the most part utterly unable to understand anything which they see…
The measure of the Moon's distance involves no principle more abstruse than the measure of the distance of a tree on the opposite bank of a river. The principles of construction of the best Astronomical instruments are as simple and as

closely referred to matters of common school-education and familiar experience, as are those of the common globes, the steam engine, or the turning-lathe; the details are usually less complicated.

The fundamental thesis of ordinary conventionalism, represented for instance by Poincare, states that there are problems which cannot be solved by appeal to experience unless one introduces a certain convention, since only such a convention, together with experimental data, makes it possible to solve the problem in question. The judgements which combine to make up such a solution are thus not

forced on us by empirical data alone, but their adoption depends partly on our recognition, since the said convention which co-determines the solution of the problem can be arbitrarily changed by us so that as a result we obtain different judgements.
In the present paper it is my intention to make that thesis of ordinary conventionalism more general and more radical. Namely, we want to

formulate and to prove the theorem that not only some, but all the judgements which we accept and which combine to make up our image of the world are not univocally determined by empirical data, but depend on the choice of the conceptual apparatus by means of which we make mappings of those empirical data. We can, however, choose this or that conceptual apparatus, which will change our whole image

of the world.