In his Disputed Questions on Truth q. 1 a. 1 arg. 3, St. Thomas Aquinas presents an argument against "that the true (verum) is exactly the same as being (ens)." However, it seems to show that truth and being are the same:

3. Things which differ conceptually [ratione or "in reason"] are so related to each other that one of them can be understood without the other. For this reason, Boethius says that the existence of God can be understood if for a moment we mentally separate His goodness from His existence. Being, however can in no way be understood apart from the true, for being is known only in so far as it is true. Therefore, the true and being do not differ conceptually.

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^{Praeterea, quaecumque differunt ratione, ita se habent quod unum illorum potest intelligi sine altero: unde Boetius in libro de hebdomadibus dicit, quod potest intelligi Deus esse, si separetur per intellectum paulisper bonitas eius. Ens autem nullo modo potest intelligi si separetur verum: quia per hoc intelligitur quod verum est. Ergo verum et ens non differunt ratione.}

I object to the major premise of this argument. For instance, in mathematics a twin prime and a prime are different; however, one cannot grasp what a twin prime is without understanding first what a prime number is.

In his Disputed Questions on Truth q. 1 a. 1 arg. 3, St. Thomas Aquinas presents an argument against "that the true (verum) is exactly the same as being (ens)":

3. Things which differ conceptually [ratione or "in reason"] are so related to each other that one of them can be understood without the other. For this reason, Boethius says that the existence of God can be understood if for a moment we mentally separate His goodness from His existence. Being, however can in no way be understood apart from the true, for being is known only in so far as it is true. Therefore, the true and being do not differ conceptually.

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^{Praeterea, quaecumque differunt ratione, ita se habent quod unum illorum potest intelligi sine altero: unde Boetius in libro de hebdomadibus dicit, quod potest intelligi Deus esse, si separetur per intellectum paulisper bonitas eius. Ens autem nullo modo potest intelligi si separetur verum: quia per hoc intelligitur quod verum est. Ergo verum et ens non differunt ratione.}

I object to the major premise of this argument. For instance, in mathematics a twin prime and a prime are different; however, one cannot grasp what a twin prime is without understanding first what a prime number is. Thus, St. Thomas's argument does not seem to show that truth and being are not the same.

St. Thomas Aquinas presents an argument—against "that the true (verum) is exactly the same as being (ens)"—in his Disputed Questions on Truth q. 1 a. 1 arg. 3, which seems to show truth and being are the same:

3. Things which differ conceptually [ratione or "in reason"] are so related to each other that one of them can be understood without the other. For this reason, Boethius says that the existence of God can be understood if for a moment we mentally separate His goodness from His existence. Being [ens], however can in no way be understood apart from the true, for being is known only in so far as it is true. Therefore, the true and being do not differ conceptually.

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^{Praeterea, quaecumque differunt ratione, ita se habent quod unum illorum potest intelligi sine altero: unde Boetius in libro de hebdomadibus dicit, quod potest intelligi Deus esse, si separetur per intellectum paulisper bonitas eius. Ens autem nullo modo potest intelligi si separetur verum: quia per hoc intelligitur quod verum est. Ergo verum et ens non differunt ratione.}

I object to the major premise of this argument. For instance, in mathematics a twin prime and a prime are different; however, one cannot grasp what a twin prime is without understanding first what a prime number is.

In his Disputed Questions on Truth q. 1 a. 1 arg. 3, St. Thomas Aquinas presents an argument against "that the true (verum) is exactly the same as being (ens)." However, it seems to show that truth and being are the same:

3. Things which differ conceptually [ratione or "in reason"] are so related to each other that one of them can be understood without the other. For this reason, Boethius says that the existence of God can be understood if for a moment we mentally separate His goodness from His existence. Being, however can in no way be understood apart from the true, for being is known only in so far as it is true. Therefore, the true and being do not differ conceptually.

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^{Praeterea, quaecumque differunt ratione, ita se habent quod unum illorum potest intelligi sine altero: unde Boetius in libro de hebdomadibus dicit, quod potest intelligi Deus esse, si separetur per intellectum paulisper bonitas eius. Ens autem nullo modo potest intelligi si separetur verum: quia per hoc intelligitur quod verum est. Ergo verum et ens non differunt ratione.}

I object to the major premise of this argument. For instance, in mathematics a twin prime and a prime are different; however, one cannot grasp what a twin prime is without understanding first what a prime number is.

I'm reading "Disputed questions on Truth" from Saint Thomas Aquinas. He claims that truth and being are the same arguing that:

All things that differ in reason, are in a way that one of them can be understood without the other. Boethius says in his book De hebdomadibus, that it can be understood that God exists, if by understanding, it is momentarily separated from his goodness. In no way can being be understood, if it is separated from what is truth, that if understood is precisely because of being truth. Then what is truth and being are not different in reason.

My problem with the argument is it's beginning. For instance, in mathematics a twin prime and a prime are different; however one cannot grasp what a twin prime is without understanding first what a prime number is. Does it not contradict the first argument?

St. Thomas Aquinas presents an argument—against "that the true (verum) is exactly the same as being (ens)"—in his Disputed Questions on Truth q. 1 a. 1 arg. 3, which seems to show truth and being are the same:

3. Things which differ conceptually [ratione or "in reason"] are so related to each other that one of them can be understood without the other. For this reason, Boethius says that the existence of God can be understood if for a moment we mentally separate His goodness from His existence. Being [ens], however can in no way be understood apart from the true, for being is known only in so far as it is true. Therefore, the true and being do not differ conceptually.

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^{Praeterea, quaecumque differunt ratione, ita se habent quod unum illorum potest intelligi sine altero: unde Boetius in libro de hebdomadibus dicit, quod potest intelligi Deus esse, si separetur per intellectum paulisper bonitas eius. Ens autem nullo modo potest intelligi si separetur verum: quia per hoc intelligitur quod verum est. Ergo verum et ens non differunt ratione.}

I object to the major premise of this argument. For instance, in mathematics a twin prime and a prime are different; however, one cannot grasp what a twin prime is without understanding first what a prime number is.