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The Great Debates of Philosophy by Peter Kreeft

The Death of Socrates, 1787 (oil on canvas), Jacques-Louis David
The Death of Socrates, 1787 (oil on canvas), Jacques-Louis David

This is a 12-part lecture series by Dr Peter Kreeft on philosophy released from March to May 2023 on Word on Fire.

Lectures 1 to 11 compare two influential philosophers or schools of thought, one against its “opposite”. The two are not necessarily contemporaneous. Lecture 12 is Kreeft’s opinion of what he considers to be the best of the old and new, the “marriage” of the metaphysics of St Thomas Aquinas and modern personalism.

Although it is not absolutely necessary to listen to the lectures in order, it is recommended since some of the material builds on or overlaps the material presented in previous lecture(s).

Not surprisingly, the first five lectures involve Socrates, Plato, Aristotle, St Augustine of Hippo and St Thomas Aquinas as Kreeft considers these five to be the greatest. That order is obviously chronological. The subsequent lectures are loosely chronological, not necessarily in terms of the individual philosophers but their contrasting philosophies and how they impact society.

Like most of Kreeft’s books and lectures, they are easily accessible, enjoyable and educational, and he always examines the implications of the philosophy like what it means in practice and how it impacts society. Lectures range from around 25 minutes to 40 minutes in duration.

Below are some key points covered in each lecture. These are not intended to be summaries. The runtime listed for each lecture is approximate.

Lecture 1: “Socrates vs the Sophists on Ethics” (37m) – Kreeft gives a very brief historical outline of the “marriage” of philosophy to Christianity and its subsequent “divorce”. He then reviews what Socrates stood for against the cultural norms of his day as well as outlining some key similarities between Socrates and Jesus. Socrates sees truth as universal and objective, which is what the Greek word logos points to, whereas his enemies, the Sophists, do not and neither does the modern West which favors (moral) relativism.

Lecture 2: “Plato vs Machiavelli on Political Philosophy” (39m) – Plato presupposes the “idea” of objective and eternal principles and truths; for example, justice. For Plato, “ideas” are not merely subjective. This is encapsulated by the Greek word logos which means “cosmic order” or “cosmic reason” that gives meaning to everything, the source of wisdom, which Christianity later reveals its source.

Plato’s Republic (“public things”) is a Socratic dialogue about the ideal society (without implying achievability). Plato writes for the public about the common good whereas Machiavelli in The Prince writes for the self about how to be successful. The latter denies the divine and eternal “ideas”, in turn adopting materialism. Therefore, there is no objective morality as this is invented by man. It is all chance and power. Therefore, to be “good” according to Machiavelli is to use power for control for the benefit of the self.

Lecture 3: “Aristotle vs Kant on Epistemology and Ethics” (45m) – Kreeft gives a brief outline of Aristotle’s moral and life view, highlighting his metaphysical concept of “form”. This refers to “essence” or nature and one of the dimensions of form is the “end” or purpose.

Aristotle was the first to write a logic textbook, formulating what Socrates practiced. Aristotle’s epistemology is that we come to know forms or universals by inductive abstraction from particular examples, and we can deduce particular applications from these universals.

A contrary position is that of nominalism, that we cannot truly know things in themselves. According to Kant then, we can only know appearances so truth becomes subjective (without implying that it is arbitrary). What we know and can describe is then manmade structure, and this includes morality.

Lecture 4: “Augustine vs Sartre on the Difference God Makes” (45m) – St Augustine and Sartre both agree that God makes a difference to everything, for without God, everything is meaningless. Whilst St Augustine accepts God, Sartre rejects Him, and both men seemingly do so completely.

Most of the lecture is on Sartre’s philosophy, making general comparisons to St Augustine’s work. Kreeft explains Sartre’s two terms: “being-in-itself” and “being-for-itself”. The former, “being-in-itself”, has no consciousness and is complete or perfect, like inanimate objects. The latter, “being-for-itself”, first exists but without essence and exists to freely determine its own essence, like humans. The latter category is therefore incomplete or imperfect. Sartre rejects that anything or anyone can be both, therefore he rejects God for God is a person, a consciousness, who is also perfect.

In other words, Sartre’s existentialism assumes atheism. He rejects God for he demands absolute freedom to determine his own essence or nature or truths. Kreeft emphasizes that Sartre’s idea of freedom is negative, the freedom “from” limits and other persons, whereas St Augustine’s idea of freedom is positive, the freedom to attain the end that God intends.

Lecture 5: “Aquinas vs Averroes on Faith and Reason” (38m) – Manifested as a “fake war” between science and religion in modern times, faith and reason are not seen as mutually exclusive in Christian thought. Kreeft reads excerpts from St Thomas Aquinas’s Summa contra Gentiles regarding the priority of truth, starting with the below:

The end of each thing is that which intended by its author. But the author of the universe is an intellect. The ultimate end of the universe must therefore be the good of an intellect. This good is truth.

Truth can be known in two ways: by natural reason and by divine revelation. It is the objective contents known by the two methods and not the subjective acts that can be married. The source of both, after all, is the same.

Irrationalists (“fundamentalists”), simply put, consider human reason to be useless and that whatever the divine says is true. This may extend to undercutting free will. Rationalists (“modernists”), when faced with problematic issues, may resort to symbolic interpretations that exclude the literal. Islamic theologians such as Averroes and St Thomas’s contemporary Siger of Brabant adopt a version of the latter, that what is true theologically may not be true philosophically or vice versa.

Lecture 6: “Descartes vs Bacon on Rationalism vs. Empiricism & ‘Man’s Conquest of Nature’” (27m) – Descartes exemplifies subjective thought in the sense that he aims for personal certainty, a sort of skepticism called “universal doubt”. As such, he focuses on the self (“I think, therefore I am”), and tries to apply the modern scientific method to philosophy.

Knowing comes from senses and reasoning. Rationalism prioritizes reasoning. Empiricism prioritizes senses (experience). Kreeft outlines how philosophers have defined and redefined reason over the centuries starting with Socrates. Descartes is a type of rationalist, narrowing reasoning to scientific reasoning. He emphasizes the mathematical and deduction aspects of the scientific method whereas Bacon emphasizes the empirical and inductive aspects.

Descartes sees the purpose of philosophy as not just about finding the truth for the sake of truth but as a means to be “masters and possessors of nature”. In this regard, Bacon is similar. Kreeft does not elaborate on Bacon’s position. He focuses on Descartes and warns of man’s desire for the “conquest of nature”, including of human nature.

Lecture 7: “Pascal vs Descartes on the Relation Between Philosophy and Science” (33m) – Kreeft continues to discuss Descartes in this lecture, comparing him to Pascal. Like Descartes, Pascal is a scientist, mathematician and practicing catholic but the two take very different approaches to philosophy.

Kreeft outlines twelve ways in which Descartes and Pascal differ, although he does not number them. Simply put, whilst Descartes emphasizes reason, Pascal emphasizes faith, albeit by narrowing his definition to something more personal. Descartes uses philosophy for applications (technology) to perfect the temporal world.

Pascal is rational too but takes a seemingly pessimistic but realistic starting point of appealing to our experiences in a fallen world. His philosophy is more focused on the “heart” (the intuitive seeing and the will­), aiming to find the meaning of God, ourselves, life and death.

Lecture 8: “Kierkegaard vs Hegel on Religion and Individuality” (32m) – Kreeft outlines Hegel’s approach before comparing it to Kierkegaard’s.

Kant reverses the traditional causal relationship between thought and its object, that the object conforms to our structure and labelling. Hegel takes this further by considering everything is thought, including reason, so all thought is then divine thought. He is in effect a rationalist pantheist. Since thought changes over time, the divine is not eternal (timeless). One of the implications is relativism since there are no universal and eternal absolutes. War and the state become the standard for judging and this is something Marx adopts for communism. Both Hegel and Marx focus on the collective rather than the individual, in effect denying free will.

Whilst the likes of Hegel attempt to make life and religion easier by introducing relativism and reducing God to myth and pantheism, Kierkegaard counters this by making everything harder. He adopts Hegel’s dialectical which is a three-step process but his content is obviously different: man progresses from “aesthetic” to the “ethical” and then finally to “religious”. Kierkegaard focuses on the individual, emphasizing the importance of free will and choice.

Lecture 9: “Nietzsche vs Heidegger on ‘The Will to Power’ vs ‘Meditative Thinking’” (26m) – Kreeft first compares Nietzsche to Kierkegaard. Both are considered existentialists and passionate about their philosophy. But they are opposites for Kierkegaard was passionately christian and Nietzsche was passionately atheistic. Nietzsche considers Christian morality and values as weaknesses, including honesty and truth. After all, without God, there is no absolute to author and impost absolutes: “Why truth? Why not rather untruth?” For him, power and the will to power is the ultimate end, to go “beyond good and evil”.

Heidegger, like Nietzsche, does not believe in the Judeo-Christian God. But to avoid the implications of having no God, he accepts an absolute, some sort of “being” to be achieved. This is done by two methods: detachment and an openness to the mystery. Despite that, he saw nazism as a revolution, a new reality that he cheered for.

Lecture 10: “Hobbes vs Rousseau on Man and the State” (26m) – This lecture is about totalitarianism which Kreeft describes as a political philosophy that gives public political authority or authorities total power over human life. It is a rule of subjective will, not objective morals; the former is not subject to the latter as it is supposed to be.

Kreeft outlines two types of totalitarianism. Hobbes advocates a “hard” totalitarianism in which the rule is based on an absolute monarchy with no consent and using fear. Hobbes is a materialist, so he denies the spiritual and also free will.

Rousseau advocates a “soft” totalitarianism or a “democratic totalitarianism” which is the rule of the (opinion of the) masses. As such, there is “freedom” or so it seems. The term “democratic totalitarianism” is not a contradiction since totalitarianism refers to the degree that is distinct from its method. Rousseau admits spirituality but merely in a vague modernist subjective sense.

Despite their contrasting positions, both deny objective morality and the moral nature of man. Therefore, morality is invented by man. For Hobbes, the absolute ruling power resides in the monarch whereas for Rousseau it resides in the emotions of the collective.

Lecture 11: “Confucius vs Marx on Traditionalism vs Revolutionism” (42m) – In this lecture about society, Kreeft explores why Confucianism can be considered the most successful in the sense that it achieved relative peace in a large population for about two thousand years. He compares Confucianism to communism, a philosophy full of self-contradictions and is the worst society by every metric when put into practice.

In short, Confucius sees society as organic. He takes traditional values and tries to apply them to society, to bridge divisions. Marx, on the other hand, is a materialist who sees society and the individual as merely mechanical. Therefore, there is no free will and there are no universal values or morality or anything like Natural Law. He exacerbates divisions, seeing fit to use them to destroy the traditional.

Lecture 12: “The Marriage of Medieval Metaphysics and Modern Personalism” (39m) – Whilst pre-modern philosophy emphasizes objective reality, modern philosophy emphasizes the subjective. There is no actual contradiction between the objective and the subjective since God is the union of the two; “I am” contains both the personal (subjective) and being (objective).

Kreeft explains the distinction between existence and essence. He emphasizes that existence can be better stated as “existing”, an act rather than fact. Existence transcends essences and actualizes essences. In short, God is being, the ultimate existence, “being itself” and God is personal. Kreeft then explains what it means for God to exist and man to exist, addressing the issue from this angle.

Editor’s Note: To those interested, related to this topic is Chapter 4 – “The Nature of God” (p.96) of Handbook of Catholic Apologetics by Kreeft and Tacelli which discusses the attributes of God, particularly the subsection “God Is Transcedent and Immanent” (p.100).


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