In St.Thomas Aquinas' Summa Theologica, it said

But to know distinctly what is contained in the universal whole is to know the less common, as to "animal" indistinctly is to know it as "animal"; whereas to know "animal" distinctly is know it as "rational" or "irrational animal," that is, to know a man or a lion: therefore our intellect knows "animal" before it knows man; and the same reason holds in comparing any more universal idea with the less universal.

(Answer of Question 85(3))

Therefore, if anything is to be called by a name designating its property, it ought not to be named from what it participates imperfectly, nor from that which it possesses in excess, but from that which is adequate thereto; as, for instance, when we wish properly to name a man, we should call him a "rational substance," but not an "intellectual substance," which latter is the proper name of an angel; because simple intelligence belongs to an angel as a property, and to man by participation; nor do we call him a "sensible substance," which is the proper name of a brute; because sense is less than the property of a man, and belongs to man in a more excellent way than to other animals.

(Answer of Question 108(5))

So human being is defined as rational animal(or rational substance), and animal is sensible substance. However, androids with AI have complete rationality too, and they can be sensible with sensors. So is android a kind of mankind? Androids seems also rational substances, thus they are men by the definition. However in common sense they don't have souls, hence mustn't be mankind. That seems a paradox.

So my question: Are androids have souls? Are androids rational substances? If they are rational substances but don't have souls, are they mankind? Why?

Note: 'Android' in here means a kind of intelligent robot which is similar to ours, not a kind of Google's OS.


What is soul?

We must conclude, therefore, that the human soul, which is called the intellect or the mind, is something incorporeal and subsistent.

(Answer of Question 74(2))

What is rationality?

Reason and intellect in man cannot be distinct powers. We shall understand this clearly if we consider their respective actions. For to understand is simply to apprehend intelligible truth: and to reason is to advance from one thing understood to another, so as to know an intelligible truth. And therefore angels, who according to their nature, possess perfect knowledge of intelligible truth, have no need to advance from one thing to another; but apprehend the truth simply and without mental discussion, as Dionysius says (Div. Nom. vii). But man arrives at the knowledge of intelligible truth by advancing from one thing to another; and therefore he is called rational. Reasoning, therefore, is compared to understanding, as movement is to rest, or acquisition to possession; of which one belongs to the perfect, the other to the imperfect. And since movement always proceeds from something immovable, and ends in something at rest; hence it is that human reasoning, by way of inquiry and discovery, advances from certain things simply understood---namely, the first principles; and, again, by way of judgment returns by analysis to first principles, in the light of which it examines what it has found. Now it is clear that rest and movement are not to be referred to different powers, but to one and the same, even in natural things: since by the same nature a thing is moved towards a certain place. Much more, therefore, by the same power do we understand and reason: and so it is clear that in man reason and intellect are the same power.

(Answer of Question 79(8))

Therefore it seems rationality is intellect, and intellect is soul.

  • androids are fictional creatures. – Mozibur Ullah Apr 4 '13 at 0:59
  • @MoziburUllah Yes, they're man made creatures, but seems fit the definition of men(rational substance). – Popopo Apr 4 '13 at 3:02
  • Is this question off-topic? Or too localized? To downvoter: please leave a comment in order that I can improve my post. – Popopo Apr 4 '13 at 5:19
  • It's somewhat vague and unmotivated; you might consider specifying what exactly are you looking for someone to explain to you here. (What problem are you trying to solve?) What might you be reading or studying that's made this an interesting or urgent concern? What have you found out so far? Etc. – Joseph Weissman Apr 4 '13 at 5:25
  • @JosephWeissman Okay, I have edited my post. – Popopo Apr 4 '13 at 11:09

Are androids have souls? Are androids rational substances? If they are rational substances but don't have souls, are they mankind? Why? … the human soul, which is called the intellect or the mind...

The mind of an android to be equal to a man it should pass the a test like the mirror test and the Turing test. Nowadays the technology does not allow the creation of a mind like that of man. But who knows, one day? I do not know any impediment principle. As we get closer to the ability to create a non-human mind, perhaps we will also improve the forms of non human consciousness and intelligence's test.


Androids may lack the substance that we so dearly call soul. But with the development in AI, we may see the growth of such features in androids... who knows whether ancestors of the present life-forms on earth were not developed in a "laboratory" of an alien-planet, whose tech was far more advanced than that of ours today. After somewhat large-scale production, these ancestors of ours may have been sent to reside here, on earth, and due to the reproductive-mechanisms incorporated in our body, by these creators, we have flourished here on earth, with "no need" of interference of alien-activities.

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