Impossible to prove or demonstrate: a seemingly valid but indemonstrable hypothesis.

in′de·mon′stra·bil′i·ty n.
in′de·mon′stra·bly adv.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


incapable of being demonstrated or proved
ˌindeˌmonstraˈbility n
ˌindeˈmonstrably adv
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌɪn dɪˈmɒn strə bəl, ɪnˈdɛm ən-)

incapable of being demonstrated.
in`de•mon′stra•bly, adv.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
For, on Aristotle's account, the "what it was to be" of an entity is that very entity understood as an immediate and indemonstrable explanatory ground and principle.
(4) Morgan thought it a fiction insofar as it would be "difficult, if not impossible, to demonstrate the[] proposition[] by factual evidence[,]" and that, to the contrary, it "might be somewhat easier, by the kind of evidence we usually require for the proof of any debatable proposition, to demonstrate that men are not created equal...." (5) But Morgan thought it "not inappropriate" to call equality a self-evident truth because such a designation "implies our commitment" to equality and "protects [it] from challenge." (6) All societies, Morgan suggests, are built on cornerstone commitments that are ultimately indemonstrable. "[T]o challenge" our commitment to equality, says Morgan, "would rend the fabric of our society." (7)
First, far from being self-grounding, our knowledge of the indemonstrable first principles that we need for the act of reasoning is but one testimony that reason is in fact groundless precisely because, at its base, we find not bedrock but light.
This was the principle or origin of all things; understood as the ultimate indemonstrable principle.
It is in this sense that 'depth psychology's dream theories exert violence since the beginning, both on the dream state and on what is dreamed, by means of biased and abstract conceptualizations/.../ based on completely indemonstrable propositions' (Boss, 1977: pp 7-10).
William of Auxerre, in charge of purging the Libri naturales by Aristotle, showed in his Summa aurea that the relation between the indemonstrable premises and the scientific conclusion is identical to the relation between the articles of faith and the theological conclusion: "[...] a theological science, according to Aristotelian criteria of scientificity, so is the ideal that subsidizes [...] the Summa aurea" (LIBERA, 1993, p.
(14) In the Third Critique he then subdivides these ideas into "aesthetic ideas," which are "representations of the imagination" to which no "determinate thought" is "adequate," and "rational ideas," which are "indemonstrable concept[s] of reason" that cannot be given a material form, such as freedom or God.
Westfahl also takes what he admits is an indemonstrable position, which is that the original Star Trek television series may have had a "subliminal impact" on space program planners that in some way contributed to the Challenger disaster in 1986, as NASA may have unintentionally viewed the shuttle "as its own version of Star Trek" and so on some level may not have paid the sort of careful attention to detail that might have caught the problematic O-rings that caused the ship's explosion (138).