Entry 0312: Knowledge of the First Indemonstrable Principle
The most basic formulation of the first indemonstrable principle is that it is impossible at once to be and not to be.
(6) See Ralph McInerny, "The Scandal of Philosophy: Reconciling Different Philosophical Systems According to Fides et Ratio," in "Faith and Reason: Friend and Foes in the New Millennium?" ed. Anthony Fisher and Hayden Ramsay (
Adelaide: Australian Theological Forum Press,
The axiom that it is impossible at once to be and not to be reflects the fact that any existing thing, by the very fact that it exists, excludes its simultaneous non-existence. That it is impossible at once to be and not to be is the law of the real. This is the metaphysical formulation of the principle.
There are other formulations of the first indemonstrable principle, but I will not treat them here since they all ultimately depend on the metaphysical formulation. For the sake of completeness, I shall just mention four other formulations: (a) "actuality in being cannot be denied and affirmed at the same time," (b) "it is impossible for the same attribute at once to belong and not to belong to the same thing and in the same respect," (c) "there is no affirming and denying at the same time," and (d) "it is impossible for two contradictory propositions to be both true or both false."
How do we acquire knowledge of the first indemonstrable principle?
Awareness that it is impossible at once to be and not to be is something that we learn from the world itself and not from propositions.
Saint Thomas Aquinas observed that "the first indemonstrable principle cannot be the conclusion of any demonstration." (1) And he stressed that "there cannot be strictly true knowledge if a right estimate of the first indemonstrable principle is lacking." (2)
The expression "right estimate" -- recta aestimatio -- is key here. In other words, all our discursive reasoning needs as point of departure a right estimate of the truth of the first indemonstrable principle. But this initial grasping of the truth of the first indemonstrable principle does not come via the explicit refined metaphysical formulations of the principle. An implied awareness of this standard of truth is all that is needed for us to begin to reason correctly.
Consider the following. A girl is aware of the truth of the first indemonstrable principle in the sense that, when she enters the classroom, she is aware that she cannot occupy the same chair that her classmate has already taken, but the girl has of course not yet discovered that what she knows is an impossibility and an instance of something much more general, namely, the non-contradictory character of being. (3)
This basic awareness of the truth of the first indemonstrable principle "is acquired through the impress of our world upon us. That world is a world in which things are separate, each thing is itself and not another. Each feature and quality of these things exclude other features. Our experience of the world affects our minds leaving permanent dispositions which explain our thinking." (4)
Indeed, the first indemonstrable principle is so self-evident that ordinarily most people take it for granted. In any act of knowledge, an implied awareness that it is impossible at once to be and not to be is always present.
Some have explained this by saying that a premetaphysical grasp of the truth of the first indemonstrable principle is necessary for us to be able to judge correctly. And they emphasize that the grasping or the expressing of this truth need not be made explicit for one to be able to use it. (5)
In more technical terms, the initial apprehension of the truth of the first indemonstrable principle is a direct reception of a habit. And more specifically, the dynamism of the awareness of the first indemonstrable principle consists of an ever-present, on-going activity and an ever-present, growing habit.
The activity is the immediate intellection of the being of things and the concurrent awareness of the non-contradictory character of the being of things. The habit is the disposition that this activity automatically generates and strengthens in our minds.
But the existence of this activity and the formation of this habit can escape explicit notice during our entire life.
Rarely, if ever, does the content of the knowledge provided by this activity and this habit come to the fore as the subject matter of an explicit actual consideration. Although this is possible, most people do not ordinarily engage their reasoning in this kind of philosophical reflection. Professional metaphysicians do.
Ordinary people do possess and constantly use the habitual knowledge of the truth of the first indemonstrable principle. And while minor lapses of inconsistency against this habitual knowledge are possible, ordinarily, no one rejects consistency, except those who explicitly choose to do so.
Our awareness of the truth of the first indemonstrable principle is prior to all our reasoning because this initial and habitual possession of the truth of the first indemonstrable principle is regulative of thinking as such, because it is first a truth about the non-contradictory character of the existence of the things that are. (6)
Anything that in any way whatsoever exists communicates to the knowing intellect the most fundamental content of knowledge, namely, the first indemonstrable principle that it is impossible at once to be and not to be.
The being of things cannot contradict itself. What exists cannot not exist. And so, the being of things affects our minds leaving permanent dispositions which explain our thinking. The most basic disposition that the being of things leaves in our minds is a habitual non-articulated awareness that it is impossible at once to be and not to be.
Knowledge of the first indemonstrable principle is a self-evident, automatic knowledge that one cannot not have. Though not explicitly articulated by most people, awareness of the truth of the first indemonstrable principle is something everyone uses, something everyone possesses.
Every human being is naturally predisposed to acquire a right estimate of the truth of the first indemonstrable principle.
(1) Saint Thomas Aquinas, "Summa Theologiae," part I-II, question 13, article 3, c: "Primum tamen principium indemonstrabile non potest esse conclusio alicuius demonstrationis."
(2) Aquinas, "Summa Theologiae," part II-II, question 23, article 7, ad 2: "Non potest esse simpliciter vera scientia si desit recta aestimatio de primo et indemonstrabili principio."
(3) See Douglas B. Rasmussen, "The Aristotelian Significance of the Section Titles of Atlas Shrugged: A Brief Consideration of Rand’s View of Logic and Reality," in "Ayn Rand's Atlas Shrugged: A Philosophical and Literary Companion," ed. Edward W. Younkins (
: Ashgate, 2007), 37. Burlington,
Aaron, "The Rational and the Empirical," in "Contemporary British Philosophy,"
Third Series (London: George Allen and Unwin Ltd., 1956), 3-20.
(5) See, for example, Joseph M. Christianson, "Aquinas: The Necessity and Some Characteristics of the Habit of First Indemonstrable (Speculative) Principles," "The New Scholasticism" 62 (1988): 249-296.