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Francis Garden - 1878 - Table of contents

Diccionario filosófico
Complete edition

Diccionario de Filosofía
Brief definition of the most important concepts of philosophy.


A Dictionary of English Philosophical Terms Francis Garden

Vocabulary of Philosophy, Psychological, Ethical, Metaphysical
William Fleming

Biografías y semblanzas Biographical references and lives of philosophers

Brief introduction to the thought of Ortega y Gasset

History of Philosophy Summaries

Historia de la Filosofía
Explanation of the thought of the great philosophers; summaries, exercises...

Historia de la Filosofía
Digital edition of the History of Philosophy by Jaime Balmes

Historia de la Filosofía
Digital edition of the History of Philosophy by Zeferino González

Vidas, opiniones y sentencias de los filósofos más ilustres
Complete digital edition of the work of Diogenes Laertius

Compendio de las vidas de los filósofos antiguos

A brief history of Greek Philosophy
B. C. Burt


A Short History of Philosophy





Hypothesis. From ὑπό and θέσις, a placing under. The Latin suppositio exactly corresponds in formation and meaning, and hypothesis may very well be explained by supposition.


Aristotle (1) supplies us with the following account of the preliminaries of reasoning. If we have a point of departure, as we needs must, which does not admit of proof itself, because it is the basis of proof, and is not an axiom, it is to be called a θέσις, position. A thesis or position may either state what the thing is, in which case it is a definition; or it may state that it is, or that it is not, and then it is an hypothesis.

The enunciations prefixed to the theoretical propositions of Euclid, together with his definitions, are the theses which render his demonstrations possible. That the radii of a circle are equal is the result of his definition of a circle, and is a thesis of which he makes continual use; that in a given proposition in the enunciation of which he has laid it down that the angle A B C is equal to the angle A B D, we are presented with an hypothesis, a supposition, on which he reasons. In the demonstration the angles are equal by hypothesis.

The word, however, without essential change of meaning, is used for the most part nowadays in a more especial sense. We mean by an hypothesis a supposition not proved, and perhaps not provable by itself, adopted in order to explain a set of phenomena. The history of physical science is the record of a succession of such. The Ptolemaic system was an hypothesis, so that of Tycho Brahe, so the Copernican.

We must not identify such hypotheses, as does Reid, with mere conjecture. Doing this, he treats hypothesis of every sort with unmitigated scorn, and pronounces that we should "despair of ever advancing real knowledge in that way." (2) This, however, is to fly in the face of all history. The right employment of hypotheses has continually furnished the steps by which real knowledge has been gained and a true theory arrived at.

How has hypothesis done this, and what is such right employment? The answer to the first question is that an hypothesis furnishes us with a reason for trying one set of experiments sooner than any other, and with some principle of selection in experiments we must be furnished if we are to make a beginning at all. We use our hypothesis aright when we use it for this reason, keeping steadily in mind its provisional nature, and holding ourselves in readiness to abandon it the moment the result of our experiments is adverse to it. It ought too to be credible in itself, not at variance with any knowledge that we possess, or any ascertained facts, whether in the sphere with which we are at present engaged, or in any other.

Hypothesis thus used is plainly a path of progress. Even should it ultimately prove untenable, it will have led to many experiments and much ascertainment of fact. If, on the other hand, it be found to explain all the phenomena, not only those which first stirred inquiry, but the additional ones which such inquiry has brought to view, if it do this with as much clearness in what might at first seem adverse as in favourable cases, and if nothing else can explain them, then the hypothesis may be regarded as established, and as providing us with the true theory of the facts to which it has been applied. The animal spirits and the vortices of Descartes have disappeared from the world of science, as has the astronomical system of Ptolemy, while that of Copernicus, at first as much an hypothesis as they, has taken rank with established truth. But surely the Ptolemaic system led to much important astronomical observation which would hardly have been made without its guidance.

As hypothesis ought not to be identified with mere conjecture, so ought it not to be with theory, which is a word of larger meaning (see Theory).


(1) Analyt Post. L. I. c. 2.

(2) REID on the Intellectual Poems, Essay I. cap. III.



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