“Rules for Demonstrations. I. Not to undertake to demonstrate any thing that is so evident of itself that nothing can be given that is clearer to prove it. II. To prove all propositions at all obscure, and to employ in their proof only very evident maxims or propositions already admitted or demonstrated. III. To always mentally substitute definitions in the place of things defined, in order not to be misled by the ambiguity of terms which have been restricted by definitions.”

The Art of Persuasion

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French mathematician, physicist, inventor, writer, and Chri… 1623–1662

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“Rules necessary for demonstrations. To prove all propositions, and to employ nothing for their proof but axioms fully evident of themselves, or propositions already demonstrated or admitted; Never to take advantage of the ambiguity of terms by failing mentally to substitute definitions that restrict or explain them.”

Blaise Pascal (1623–1662) French mathematician, physicist, inventor, writer, and Christian philosopher

The Art of Persuasion

“Rules for Definitions. I. Not to undertake to define any of the things so well known of themselves that the clearer terms cannot be had to explain them. II. Not to leave any terms that are at all obscure or ambiguous without definition. III. Not to employ in the definition of terms any words but such as are perfectly known or already explained.”

Blaise Pascal (1623–1662) French mathematician, physicist, inventor, writer, and Christian philosopher

The Art of Persuasion

“Rules necessary for definitions. Not to leave any terms at all obscure or ambiguous without definition; Not to employ in definitions any but terms perfectly known or already explained.”

Blaise Pascal (1623–1662) French mathematician, physicist, inventor, writer, and Christian philosopher

The Art of Persuasion

“Even if the absence of evidence for a given god were not evidence of its absence, it would still be evidence that the belief in that god is unreasonable. That's the only proposition that any atheist of any kind has to demonstrate in order to win the argument. Because anything beyond that… is just having fun.”

Scott Clifton (1984) American television actor, musician, internet personality.

God, Atheism and Evidence, as Theoretical Bullshit, hosted on YouTube. (11 January 2010) http://www.youtube.com/watch?v=9stJ8h2ilZU

“Ostensive demonstration is that which concludes directly to that which is in question. Reduction ad impossibile is that which, when something the opposite of that which is in question has been assumed, concludes with some other proposition directly to a known and manifest impossibility, from the opposite of which the investigator is led back to the original proposition in question. But there is a difference between ostensive demonstration and reduction ad impossibile, because the former proves from things prior in the order of nature but the latter from things posterior in the order of nature. When things prior in nature are better known in the intellect of the person making the demonstration the process is carried out ostensively; but when posterior things are better known to his intellect then the demonstration is carried out per impossibile… in demonstration carried out per impossibile the showing of the original thing in question is carried out by means of things posterior to it in the order of nature… And there is in the contrary, falsely supposed in predicate of subject, a connecting term by which something is implied to be which impossible in the nature of things.”

Robert Grosseteste (1175–1253) English bishop and philosopher

i. 17, f. 18<sup>r</sup>
Commentarius in Posteriorum Analyticorum Libros (c. 1217-1220)

“Theism is irrational by definition, because it is not based on reason and is not reasonable. There was no evidence indicating this conclusion, yet it is a firm conviction anyway, and believers are determined not to let any evidence change their minds either. The very purpose and existence of apologetics all by itself demonstrates how theism is irrational.”

Aron Ra (1962) Aron Ra is an atheist activist and the host of the Ra-Men Podcast

Patheos, Philosophistry http://www.patheos.com/blogs/reasonadvocates/2017/04/12/philosophistry/ (April 12, 2017)

“Those who assert that the mathematical sciences say nothing of the beautiful or the good are in error. For these sciences say and prove a great deal about them; if they do not expressly mention them, but prove attributes which are their results or definitions, it is not true that they tell us nothing about them. The chief forms of beauty are order and symmetry and definiteness, which the mathematical sciences demonstrate in a special degree.”

Aristotle book Metaphysics

Book XIII, 1078a.33
Metaphysics

“The " general" definition may give you no hint as to the way in which a particular assertion is meant to be interpreted. When, therefore, as in formal debate, a proposition is advanced by persons other than those who discuss it, clearness in defining is not sufficient. In such cases a definition must have two qualities: it must be clear, and it must be satisfactory to the persons addressed. They must know what the speaker means, and they must be convinced that his meaning is the correct one, — correct for that particular proposition at the time and place and under the conditions of that particular debate. Otherwise, they may object in the end that he has proved, not the given proposition, but another which he has substituted for it by means of arbitrary definitions.”

William Trufant Foster (1879–1950) American economist

Source: Argumentation and debating, 1908, p. 27; partly cited in: Branham (2013, p. 39)

“Changing a rod into a serpent and the serpent back into a rod may be clever magic, but how does such a demonstration prove that Moses spoke to God? If the only thing necessary to prove the truth of an extraordinary claim were to demonstrate an ability to bewilder, there would be no more mysteries to solve.
If a person claims that he can bring the dead back to life, and in proof of that power pulls a rabbit out of a hat, that is hardly a demonstration of the truth of his claim; it is merely an example of his ability in the art of deception. If he claims that he can fly without wings and without the use of mechanical help of any kind, and in proof of his ability pulls another rabbit out of another hat, that is not proof of his ability to fly, but of his ability to lie, and he will without much hesitation be condemned as a faker. The demonstration of one thing has absolutely no bearing in proving the truth of the other, when there is no relationship between them.”

Joseph Lewis (1889–1968) American activist

The Ten Commandments

“If philosophy aims at being a theoretical mode of thought and speech, can it have a rhetorical character and be expressed in rhetorical forms? The answer seems obvious. Theoretical thinking, as a rational process, excludes every rhetorical element because pathetic influences—the influences of feeling—disturb the clarity of rational thought. …
To prove means to show something to be something, on the basis of something. To have something through which something is shown and explained definitively is the foundation of our knowledge. Apodictic, demonstrative speech is the kind of speech which establishes the definition of a phenomenon by tracing it back to ultimate principles, or archai. It is clear that the first archai of any proof and hence of knowledge cannot be proved themselves because they cannot be the object of apodictic, demonstrative, logical speech; otherwise they would not be the first assertions. Their nonderivable, primary character is evident from the fact that we neither can speak nor comport ourselves without them, for both speech and human activity simply presuppose them. But if the original assertions are not demonstrable, what is the character of the speech in which we express them? Obviously this type of speech cannot have a rational-theoretical character….
Basic premises cannot have an apodictic, demonstrative character and structure but are thoroughly indicative….
Arche … cannot have a rational but only a rhetorical character. Thus the term "rhetoric" assumes a fundamentally new significance; "rhetoric" is not, nor can it be the art, the technique of an exterior persuasion; it is rather the speech which is the basis of the rational thought.”

Ernesto Grassi (1902–1991) Italian philosopher

Source: Rhetoric as Philosophy (1980), pp. 18-19

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