Aquinas and Beyond

Aquinas and Beyond

A Guided Tour of the Summa

What is Truth?

Is it God?

Alex Spieldenner's avatar
Alex Spieldenner
Jun 10, 2026
∙ Paid

This is the Guided Tour of the Summa Theologiae, a project for all paid subscribers of Aquinas and Beyond. In it, we are carefully reading through St. Thomas Aquinas’s masterpiece, with help from experts on Aquinas, to think like the universal doctor of the Church. Stop feeling intimidated by Aquinas, and subscribe so you can read along!


For the last 15 Questions, St. Thomas Aquinas has been discussing the different attributes in the classical account of God. Here, he moves to one attribute that is frequently asserted but rarely considered fully: truth.

Is God truth? What would it even mean for God to be truth? Does this mean, for example, that atheists must be relativists (no)? What is truth in the first place?

There is a lot of bad philosophy out there on truth, but this will clarify a lot.

a wooden block spelling truth next to a bouquet of flowers
Photo by Alex Shute on Unsplash

As always, here are some resources you might find helpful as we move forward:

  1. The Summa Theologiae itself. Buy Prima Pars here, and the whole Summa here. Read it for free here.

  2. If you have never read the Summa, it can be a little intimidating. But I put together a roadmap so that anybody can read it and understand it. Get it here.

  3. Here is the commentary I will be using from Walter Farrell, O.P.

  4. Here is the commentary I will be using from Brian Davies, O.P.

Now, let’s dive into truth.


Question 16: Truth

1. Is Truth Primarily In the Mind?

Aquinas states that truth is primarily in the mind, but you have to understand what precisely he means, because this could be misleading. You might think that Aquinas means that reality is primarily found in the mind when he says that truth if found primarily in the mind, which would seem to imply a kind of subjectivism. But Aquinas is not arguing that, at all.

Rather, Aquinas is pointing out that truth is, most properly, a property of beliefs, not things. Specifically, truth is the property of a belief that aligns with things. So my belief that “my hair is blonde” is true if my hair is, in fact, blonde. So truth is, as Aquinas argues, “the equation of thought and thing.”

So truth comes when our beliefs align with how things actually are. Or, as Davies writes:

Truth “lies in the comformity between intellect and thing (per conformitatem intellectus et rei). Here Aquinas means that we have truth in us insofar as we latch on to the way things are by having what they are formally in our minds. In this connection, Aquinas speaks of truth in our minds as bearing a likeness to what we know.1

But that’s not all Aquinas has to say about the nature of truth, and it makes God’s relationship to truth all the more vital…


This is a free preview of the Guided Tour of the Summa. To read the rest, join other premium subscribers who are becoming thoughtful, well-formed Catholic intellectuals through:

  • A guided tour through the ENTIRETY of Thomas Aquinas’s Summa Theologiae, which you are reading right now! Don’t miss out on forming your mind according to the Universal Doctor of the Church!

  • Founding Members get a FREE copy of my Catholic Philosopher In A Year Reading Plan, my ultimate reading list to get up to speed in Catholic Philosophy.

  • Blogs on the philosophy of religion (God, evil, free will, etc.) like this one about art and the problem of evil.

  • Reader’s Guides on the great works of Catholic philosophy, like last month’s guide on Jacques Maritain’s Art and Scholasticism.

  • Further reading recommendations on many posts, including free posts.

Stop feeling confused in the face of deep Catholic conversations and start thinking like a Catholic philosopher.


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