How do I reconcile this doctrine with Aquinas?

I am having trouble with this infallible doctrine from POPE Adeodatus II, sometimes called Deodatus, was the bishop of Rome from 672 to his death, now I know this was before Aquinas . But anyways , Aquinas said there is one substance ( a human being ) and that there are not two Separate substances of a body and soul like Descartes believed , there is only the substancial form ( soul) and the Matter of it ( the body) . So with that being said how do I reconcile this doctrine in the Denzinger at #535 under Adeodatus II that says they are two separate substances : 535 Dz 284 -Likewise we believe that the Father, the Son, and the Holy Spirit are of one substance, but we do not say that the Virgin Mary gave birth to the unity of the Trinity, but only to the Son, who alone assumed our nature in the unity of His person. Also, we must believe that the entire Trinity accomplished the Incarnation of the Son of God, because the works of the Trinity are inseparable. However, only the Son took the form of a servant (cf. Ph 2,7) in the singleness of His person, not in the unity of His divine nature; in what is proper to the Son, not in what is common to the Trinity; and this form was adapted to Him for unity of person so that the Son of God and the Son of man is one Christ, that is, Christ in these two natures exists in THREE SUBSTANCES ; of the Word, which must refer to the essence of God alone, of the body, and of the soul, which pertain to true man…END… ( so in cases like these should i say his philosophy was wrong but isn’t that to say that a infallible doctrine is wrong ? Or does it not change the meaning behind it and I should rely on the speech act theory and say that the illocutionary act ( meaning ) remains the same even though it was language before Aquinas ? I am just skeptical to say he is wrong because it’s infallible .

Infallibility has only been claimed 3 times and this wasn’t one of them. That doctrine came from Vatican I, around 1870.


Oh ok thanks ! That makes sense . I’m new to Catholicism . I know a lot but I just forgot about that one . Thanks for reminding me lol

St. Thomas is hard to refute as well!

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This is off topic, but this is way wrong. Papal infallibility was not invented at Vatican I. It was not declaring something new–the Church can’t invent dogmas, which are part of public revelation which ended at the death of the last apostle. The necessary implications are included in this deposit of faith and their formulations can certainly be developed, but the substance is always there (papal infallibility, which can be argued to be found in scripture, is at the least a necessary implication of the primacy being a permanent element of the true Church).

At the First Vatican Council, when some bishops wanted to condition papal infallibility on the Pope following some procedure or using some formula, the relator for the Commissio de fide (charged with providing official explanations of Council documents to the Council Fathers) said this could not be done, because there were already so many instances with various procedures or even none at all:

But, most eminent and reverend fathers, this proposal simply cannot be accepted because we are not dealing with something new here. Already thousands and thousands of dogmatic judgments have gone forth from the Apostolic See; where is the law which prescribed the form to be observed in such judgments?


As for the OP’s question, this is essentially the mystery of the Trinity which is why it is hard to completely understand. One substance, but three persons.

In Christ there were two substances joined, without confusion–human (which included the soul) and divine, specifically the person of the Son.


Substance, here, means nature, it is not referring to a soul and body duality. Jesus Christ has two natures, and the human nature is composed of the soul-body.

“He has therefore, in Himself the twofold substance of His divinity and our humanity.” - Excerpt from the Creed of Faith, Council of Toledo XI 675 A.D.


Which is it?

My poor choice of words aside, the bottom line is that not everything said by a pope, or in this case Pope Adeodatus, is considered infallible.

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But 535 ( the doctrine I posted ) isn’t infallibly defined is it ? And I know Christ has two natures I was just wondering these words : Three Substances ( the body and soul being two different substances) I know this was before Aquinas came along . What are yalls thoughts ?

A judgment as to whether a proposition is a dogma is not the same as instituting the dogma. If I tell you the animal below is a horse and not a pig, it doesn’t mean that I have just now invented horses. I have simply judged that this animal is a horse. Horses pre-exist me. The Pope’s definitive judgments as to whether a proposition is a dogma or not are infallible. But the dogmas pre-exist him. Popes have made such dogmatic judgments many times.

The First Vatican Council itself explained how these infallible dogmatic judgments have historically come about:

  1. It was for this reason that the bishops of the whole world, sometimes individually, sometimes gathered in synods, according to the long established custom of the Churches and the pattern of ancient usage referred to this Apostolic See those dangers especially which arose in matters concerning the faith. This was to ensure that any damage suffered by the faith should be repaired in that place above all where the faith can know no failing [59].

  2. The Roman pontiffs, too, as the circumstances of the time or the state of affairs suggested, sometimes by summoning ecumenical councils or consulting the opinion of the Churches scattered throughout the world, sometimes by special synods, sometimes by taking advantage of other useful means afforded by divine providence, defined as doctrines to be held those things which, by God’s help, they knew to be in keeping with Sacred Scripture and the apostolic traditions.

  3. For the Holy Spirit was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles.


The intent here is to say that the two natures exist in the union of the Word, of the body, and of the soul. Adeodatus was not trying to impose his philosophical articulation that these are 3 substances. Aquinas agrees that the Divine Word is united with the human, which consists of body and soul. His philosophy counts body and soul as one substance, which is probably more in line with the earlier doctrine than the “3 substances” proposed by other philosophies.

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That’s what I was wondering if I should take this as speech act theory , that the illocutionary act ( meaning ) is the same but the locutionary is different . Therefore even though the Pope used different philosophical terms to describe the form and matter as distinct substances, it’s ok if Aquinas disagrees as long as the illocutionary meaning is agreed on ? The intent was still The same regardless of philosophical terms. But I guess this would leave me to two other questions : 1. Is this a infallible declaration ? And 2. Can a pope error in Philosophical terms even though he can’t error in the intent or meaning ?

No, that is wrong. And it is way too simplistic of an answer for the OP. Pope’s have spoke ex-cathedra before the First Vatican Council. Ithe council did not confer a new capability on the Pope, simply defined an existing one. The Church has many more infallible teachings than three.

I am not enough a philosopher (it sounds like good understanding of metaphysics is needed) to parse exactly what Pope Adeodatus II was saying without sitting down and really focusing for a while. But the simple answer that it was not a infallible claim is simply dismissive.

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That is certainly the case, but why just say the answer to a diffucult question is “that pope was likely wrong.” Which is exactly what you seem to be claiming.

I think so. :wink:

This is contested by some people. St John XXIII in his opening Address to Vatican II endorses the idea that the meaning of dogma is one thing, the way it is expressed is another. Pius XII seems headed the other way in Humani Generis.

Probably not an infallible declaration, but a repetition of affirmations of the two natures in Christ.

Can a Pope say the sun rose today? That is erroneous in that it relies on a geocentric view. But the reality is there. (Not something he could say infallibly, but analogous enough, I hope)

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Oh, sorry, I see what you’re saying now. I think substance is being used in a less technical sense–flesh and spirit can be said to be different substances. Just like, say, hair and blood are different substances, even tough they pertain to the same one person. If you keep reading from the same text, the next paragraph (285) begins: “He has therefore, in Himself the twofold substance of His divinity and our humanity.”

As for the status of this text, it is from a profession of faith issued by the Council of Toledo, a local Council. However, it acquired universal authority through acceptance throughout the universal Church, including by the consent of the Pope in Rome. In that sense–properly read–it is without error.

I think this is an example of the problems with language and its evolution and the different meanings words can have. For example, even the Homoousion was first condemned by the Council of Antioch in the Sabellian sense before being inserted in the Creed by the Council of Nicea only a half century later. It’s why we have and need a living teaching authority in every age.

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Yes, well put.

You are up against the common misconception that the Church progressively invents truth or even supersedes one truth with another. It is one of the most dangerous consequences of modern defective catechising.

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I was just wondering because the Denzinger says it’s a compendium of creeds , definitions and declarations on matters of Faith and morals. So that to me sounds like ex cathedra .
So I’m not sure if everything in the Denzinger is infallible or not But I’m new to Catholicism still . I sent a email to Edward Feser on this . Hopeful he gets back to me with his ideas . I like your thoughts on all this though. I was kind of leaning toward that view also ( speech act theory). I also know this was before Aquinas came into existence lol . I just wonder about the infallible part and how to reconcile language that might be contrary to what the church teaches with Thomistic metaphysics, if it’s in deed infallible then we have two problems , either we have to admit the pope errored in his Philosophical language only or that Thomas Aquinas was wrong . And that would be problematic for the church teachings in thomistic metaphysics.

Thanks for pointing out the beginning with 285. Like you said He clearly says two fold substance therefore it seems Like he is Later saying the human substance Is made up of two substances ( body and soul) if we emerge this the early statement of a twofold substance then i guess it can be reasonably said that the claim is they emerged ( body or aka matter and soul) into one human substance . Even though I still don’t like that language because atoms would be a separate substance but not body because body is already part of the substantial form once the matter is formed… so It would have been better to instead say matter is and separate Substance because on matter becomes the body it is the same substance . But then again the matter is the body so. I guess you could say they are two substances that become one substance in a way. I just wanna stay away from Descartes substance dualism because that’s clearly not what Thomas believed .

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