How Truthful is the “Proof of the Truthful”?

In the third Lyceum Institute Colloquium of the year, we present Dr. Catherine Peters, who takes up a controversy between the Islamic philosophers Avicenna and Averroes concerning the “proof of the truthful”:

ABSTRACT: The “Proof of the Truthful” is Avicenna’s most famous argument for the existence of God. Beginning with the essential possibility of creatures, he argues that there must be a first, necessary, cause: God. This argument came to be known as the “Proof of the Truthful” because it proposes an argument which is, in theory, accessible to any rational being (not just to the “wise” or religiously affiliated). In this way, it is the “most truthful.” Though compelling, Avicenna’s proof has not escaped criticism, most notably from Averroes, who rejected Avicenna’s conception of “possibility” and “necessity.” Rejecting these concepts can have far-reaching consequences, not only for the cogency of Avicennian metaphysics, but for any natural theology that seeks to employ these concepts. The present study, therefore, will first defends “necessary” and “possible” as formulated in the metaphysics of Avicenna. It will then show how these concepts serve as premises in the “Proof of the Truthful.” Third, it will address and refute Averroes’ criticisms.

Dr. Peters’ paper is now available at the Lyceum Institute. The live Question & Answer session will be held on 16 June 2022 (Thursday) at 6:00pm ET.


Colloquia are available at every level of membership for the Lyceum Institute — starting as low as $10.50/month.

See enrollment options here.

[Summer 2022] Semiotics: Thought and Contributions of John Deely

Semiotics—toward which human beings took their first explicit steps in the beginning of the Latin Age of philosophy, in the work of St. Augustine of Hippo (350–430AD), an age that culminated in the thinking of John Poinsot (1589–1644)—is that by which we begin in a true postmodernism. This is one of the key and perhaps surprising claims of John Deely (1942–2017). That is, often today what is called “postmodernism” is nothing more, in fact, than an ultramodernism: a fragmentary, distorted view of the world grown out of the errors of modern philosophical thinking, run toward its natural, incoherent conclusions.

Listen to a preview here

Preview – Semiotics as origin of genuine post-modernism.

In contrast, consider this description Deely gives:

In a word, postmodernism is the opening of a passageway from the age of classical modern philosophy to an epoch as distinct from the modern age as the modern age was from Latin times, or Latin times from the ancient Greek period. The opposition of modernity to Latin (and Greek) times eventually took the form of the opposition of idealism to realism in philosophy. Postmodern thought begins, properly speaking, not so much by rejecting this opposition as by transcending it, for in experience integrally taken, mind-dependent and mind-independent being assert themselves equally—not “equally” in the quantitative sense, but “equally” in the sense of components both asserting themselves in different ways at different times and in different proportions throughout the course of human life, both together making up the one fabric of our lives we call “experience”.

What was needed for philosophy to mature [to postmodernism] was not so much a shift as an expansion, an expansion of the notion of reality—and with it, being—to include the whole experience as the prior ground out of which human understanding arises and on which it throughout depends. From the start, being should have been an inclusive, not an exclusive and oppositional notion. Being is not only “that which can only be said in many ways” (Aristotle), but that out of which the division between what is and what is not independent of the mind arises (Aquinas), and not in any finally fixed way, but differently according to the time and circumstances of the one experiencing such a contrast among objects.

Deely 1994: New Beginnings (18–19).

To understand and affect this maturation into postmodernity, we will turn our attention in this seminar to the major contributions to semiotics given by Deely: the proto-semiotic history, an expanded doctrine of causality,  the retrieved and clarified notion of relation, the concept of physiosemiosis, the continuity of culture and nature, the notion of purely objective reality, and the real interdisciplinarity which semiotics fosters. This is an advanced seminar which provides a serious challenge to all participants.

July 2—27 August
Saturdays, 3:15-4:15pm ET /
7:15-8:15pm UTC
Tuesdays 10:00-11:00am ET /
2:00-3:00pm UTC

Lyceum Institute digital platform run on Microsoft Teams

In this seminar, lasting 8 weeks (with a break at the halfway point—see here for more information on all Lyceum Institute seminars), we will discover the enormous contributions to semiotics made by John Deely. The instructor for this seminar is Dr. Brian Kemple, who wrote his dissertation under Dr. Deely, and who is Executive Director of the Lyceum Institute. You can read more about Dr. Kemple here.

Lyceum Institute seminar costs are structured on a principle of financial subsidiarity. There are three payment levels, priced according to likely levels of income. If you wish to take a seminar but cannot afford the suggested rate, it is acceptable to sign up at a less-expensive level. The idea is: pay what you can. Those who can pay more, should, so that those who cannot pay as much, need not. Lyceum Institute members receive a further discount (see here for details).

[2022Su-B] Semiotics: Deely – Participant

Recommended for those who are currently students or with part-time employment.


[2022Su-B] Semiotics: Deely – Patron

Recommended for those in professions that do not pay as well as they ought and for whom continued education is especially important (including professors and clergy).


[2022Su-B] Semiotics: Deely – Benefactor

Recommended for those with fulltime employment in well-paying professions and sufficient resources to provide a little more in support of the Lyceum Institute and its mission.


Fall Seminars

The Lyceum Institute Fall Seminars will begin the first week of October. Brief descriptions and links with more details and enrollment options are below below.

More than Aesthetics: Ens Artificiale & the Philosophy of Art [REGISTER]

Matthew Minerd

What is the being of a work of art?  What is the nature of “poetic” knowledge, the experience of the artisan and the artist?  How should a Thomist speak about these matters?  This lecture series is devoted to these questions, taking as their principal guide, Jacques Maritain, who probed these questions in his works Art and Scholasticism, Creative Intuition in Art and Poetry, and Art and Poetry.  Other thinkers will be consulted along the way, presenting a synthesis which, however, uses Maritain’s texts as the primary guiding thread of the lecture discussion. [REGISTER]

Thomistic Psychology: The Meaning of Evil [REGISTER]

Kirk Kanzelberger

Every human being has some notion of evil, vague though it may be, as that which is opposed to a good:  the good that one desires, the good that one honors – or, perhaps, the good that one wishes one honored or desired more than one does.  Even those who lack an inclination to deeper questioning concerning the matter and the meaning of evil can nevertheless find themselves possessed with anger at states of affairs, ideas, and other persons they clearly judge to be evil.  Might there be some relation of dependence between the lack of deeper questioning and the frenzy of the anger, as well as the lack of humility it evinces?  For if we are honest, we must admit that, despite every good intention, we ourselves have some share in, and make some concrete contribution to, the mysterious reality of evil in the world.  This seminar aims to deepen our questioning concerning the meaning, that is, the intelligible reality signified by the term evil. [REGISTER HERE]

Metaphysics: God [REGISTER]

Brian Kemple

In the second Metaphysics seminar, we will engage in a deep Thomistic discussion of the intelligible discovery of the existence of God and the justifiable inferences which may be made concerning the Divine Nature.  This stands in corresponding opposition to the via resolutionis secundum rationem discussed in the first Metaphysics seminar, concerning the discovery of ens inquantum ens, as the via resolutionis secundum rem—according to the thing, according to the existential cause.  This will unfold further into a consideration of the attributes of the Divine which may be justly inferred from the resolution to a First Cause.  Thus, the primary reading for the course will be from the Prima pars of the Summa theologiae. [REGISTER HERE]

[2021 Summer] Science: Aristotle’s Organon

In order to be a proper ἀκροᾱτής (akroates), i.e., hearer or student of Aristotle’s, such that one might read and understand the Stagyrite’s treatment of specific subjects like nature (Physics), the soul (De Anima), ethics (Nicomachean Ethics), politics (Politics) or metaphysics (Metaphysics), one must first obtain a general understanding of Aristotle’s rigorous logical method. This method is disclosed in a set of works that, since Alexander of Aphrodisias (A.D. 200), has been called the  ὄργανον (organon) because it provides an account of the instrument of coming to know being or reality (οὐσία/ousia).

This seminar, Science: On Being, Language and Reason, and Cause in Aristotle’s Organon, treats Aristotle’s methodology for coming to know reality in two parts. In the first part, to be led by Dr. Daniel Wagner, students will gain understanding of the primary terms for defining (Topics), the classification of the most general concepts of the intellect (Categories), and the method of reasoning used for defining beings, which Aristotle calls induction (ἐπαγωγή/epagoge) and division (διαίρεσις/diairesis and ἀνάλῠσις/analusis) (Posterior Analytics). In the second part, to be led by Dr. John Boyer, students will gain understanding of Aristotle’s method of deductive demonstrative reasoning and explanation by proper cause (αἰτία/aitia), which constitutes scientific understanding (Posterior Analytics).

WHEN: Saturdays from 12 June through 31 July 2021, from 1:00-2:00pm Eastern Time US / 5:00-6:00pm UTC.

WHERE: on the Lyceum Institute platform run through Microsoft Teams.

In this seminar, lasting 8 weeks (see here for more information on all Lyceum Institute seminars), an intense inquiry into the means of defining and demonstration will be undertaken. The instructors for this seminar are Faculty Fellows Daniel Wagner, PhD, and John Boyer, ABD. You can read more about our fellows here.

Lyceum Institute seminar costs are structured on a principle of financial subsidiarity. There are three payment levels, with discounts for those who are professors and clergy (whose continuing education is not sufficiently prioritized by their institutions) and for students (who are already taxed excessively by the educational system). However, if you are part of the working world and wish to take a seminar but cannot afford the “standard” rate, it is acceptable to sign up at one of these discounted prices. The idea is: pay what you can. Those who can pay more, should, so that those who cannot pay as much, need not. Lyceum Institute members receive a further discount (see here for details).

[2021 Summer] Science: Aristotle’s Organon – Standard

Includes full access to the seminar and a free month at the Lyceum Institute. Price is suggested for those with full-time employment.


[2021 Summer] Science: Aristotle’s Organon – Professor / Clergy

Includes full access to the seminar and a free month at the Lyceum Institute. Discount is suggested for those employed as educators or clergy.


[2021 Summer] Science: Aristotle’s Organon – Student

Includes full access to the seminar and a free month at the Lyceum Institute. Discount is suggested for students or others with part-time employment.