Frequently Asked Questions

Philosophy proceeds by unaided natural reason alone; theology proceeds from revealed premises accepted on faith. The two can treat the same object — God’s existence, for instance — but by entirely different methods and evidence.

The syllogism makes explicit the structure every valid argument already has implicitly. Training in it sharpens the ability to spot bad reasoning — equivocation, false premises, invalid form — wherever it appears, including in ordinary speech.

Glenn’s course (Criteriology) argues that universal scepticism is self-refuting — to argue against the reliability of reason is already to use reason and trust it. From there it defends the basic reliability of sense knowledge and intellectual first principles.

Every other science studies some restricted kind of being — living things, quantities, minds. Metaphysics studies what belongs to anything simply insofar as it exists: act and potency, substance and accident, essence and existence.

No — philosophical cosmology asks about the nature of change, matter, and form at the most general level (why does anything change at all?), while empirical science measures and predicts particular changes. The two are complementary, not competing.

Philosophical psychology asks a different question than neuroscience: not how the brain processes information, but what kind of thing must exist to explain intellection and free will — a question about nature and causality that empirical method alone cannot settle.

They cover much of the same ground — Aquinas’s Five Ways appear in both — but natural theology (Theodicy) treats it as a conclusion of philosophical reasoning, prior to and independent of any appeal to revelation.

Natural law ethics in the Thomistic tradition is argued from human nature and its rational end, without appeal to revelation — it claims to be accessible to any reasoning person, which is precisely why Glenn treats it in the philosophy course rather than the theology tracts.

Because two acts can produce the same outcome while being genuinely different acts. Giving pain relief that may, as a foreseen but unintended side effect, shorten life is not the same act as administering a lethal dose because death is the goal — even if the physical result looks similar. The tradition’s principle of double effect exists to track this real difference, not to dodge hard cases with a technicality.

Natural law holds that personhood tracks what a being is by nature, not which capacities it happens to be exercising at a given moment — a sleeping person or an infant doesn’t currently exercise reason either, without anyone concluding their life stops mattering. On this view, a human being possesses a rational nature from the beginning of its existence as an individual organism, even though that nature is only gradually exercised.

Not quite. Subsidiarity holds that a higher body shouldn’t absorb a function a lower one can perform adequately — but it also obliges the higher body to step in when the lower one genuinely can’t cope. It’s a principle about the right level of action, not a blanket argument for smaller government.

No — the tradition holds two principles together: a real right to migrate grounded in the universal destination of created goods, and a real authority of political communities to regulate their own membership for the sake of the common good. Neither cancels the other out, and prudential questions about numbers and capacity are left to be judged on the facts, not settled by either principle alone.

Aquinas himself engaged seriously with Aristotle, the Platonists, and his contemporaries — seeing where a system goes wrong, and why it seemed plausible, sharpens understanding of the true position far more than being handed conclusions alone.

They overlap but differ in method: this branch treats the rational credibility of religion in general and Catholicism in particular using philosophy alone (miracles, the reasonableness of revelation), while the theology-site tract works from within faith to answer objections to specific doctrines.

It helps, since the Summa draws on logic, metaphysics, and ethics throughout, but Glenn’s Tour is written as an accessible bridge — you can start here and circle back to the earlier branches as needed.