Objection 1. It would seem that Paul was not ignorant whether his soul were separated from his body. For he says (2 Corinthians 12:2): "I know a man in Christ rapt even to the third heaven." Now man denotes something composed of soul and body; and rapture differs from death. Seemingly therefore he knew that his soul was not separated from his body by death, which is the more probable seeing that this is the common opinion of the Doctors.
Objection 2. Further, it appears from the same words of the Apostle that he knew whither he was rapt, since it was "to the third heaven." Now this shows that he knew whether he was in the body or not, for if he knew the third heaven to be something corporeal, he must have known that his soul was not separated from his body, since a corporeal thing cannot be an object of sight save through the body. Therefore it would seem that he was not ignorant whether his soul were separated from his body.
Objection 3. Further, Augustine says (Gen. ad lit. xii, 28) that "when in rapture, he saw God with the same vision as the saints see Him in heaven." Now from the very fact that the saints see God, they know whether their soul is separated from their body. Therefore Paul too knew this.
On the contrary, It is written (2 Corinthians 12:3): "Whether in the body, or out of the body, I know not, God knoweth."
I answer that, The true answer to this question must be gathered from the Apostle's very words, whereby he says he knew something, namely that he was "rapt even to the third heaven," and that something he knew not, namely "whether" he were "in the body or out of the body." This may be understood in two ways. First, the words "whether in the body or out of the body" may refer not to the very being of the man who was rapt (as though he knew not whether his soul were in his body or not), but to the mode of rapture, so that he ignored whether his body besides his soul, or, on the other hand, his soul alone, were rapt to the third heaven. Thus Ezechiel is stated (Ezekiel 8:3) to have been "brought in the vision of God into Jerusalem." This was the explanation of a certain Jew according to Jerome (Prolog. super Daniel.), where he says that "lastly our Apostle" (thus said the Jew) "durst not assert that he was rapt in his body, but said: 'Whether in the body or out of the body, I know not.'"
Augustine, however, disapproves of this explanation (Gen. ad lit. xii, 3 seqq.) for this reason that the Apostle states that he knew he was rapt even to the third heaven. Wherefore he knew it to be really the third heaven to which he was rapt, and not an imaginary likeness of the third heaven: otherwise if he gave the name of third heaven to an imaginary third heaven, in the same way he might state that he was rapt in the body, meaning, by body, an image of his body, such as appears in one's dreams. Now if he knew it to be really the third heaven, it follows that either he knew it to be something spiritual and incorporeal, and then his body could not be rapt thither; or he knew it to be something corporeal, and then his soul could not be rapt thither without his body, unless it were separated from his body. Consequently we must explain the matter otherwise, by saying that the Apostle knew himself to be rapt both in soul and body, but that he ignored how his soul stood in relation to his body, to wit, whether it were accompanied by his body or not.
Here we find a diversity of opinions. For some say that the Apostle knew his soul to be united to his body as its form, but ignored whether it were abstracted from its senses, or again whether it were abstracted from the operations of the vegetative soul. But he could not but know that it was abstracted from the senses, seeing that he knew himself to be rapt; and as to his being abstracted from the operation of the vegetative soul, this was not of such importance as to require him to be so careful in mentioning it. It follows, then, that the Apostle ignored whether his soul were united to his body as its form, or separated from it by death. Some, however, granting this say that the Apostle did not consider the matter while he was in rapture, because he was wholly intent upon God, but that afterwards he questioned the point, when taking cognizance of what he had seen. But this also is contrary to the Apostle's words, for he there distinguishes between the past and what happened subsequently, since he states that at the present time he knows that he was rapt "fourteen years ago," and that at the present time he knows not "whether he was in the body or out of the body."
Consequently we must assert that both before and after he ignored whether his soul were separated from his body. Wherefore Augustine (Gen. ad lit. xii, 5), after discussing the question at length, concludes: "Perhaps then we must infer that he ignored whether, when he was rapt to the third heaven, his soul was in his body (in the same way as the soul is in the body, when we speak of a living body either of a waking or of a sleeping man, or of one that is withdrawn from his bodily senses during ecstasy), or whether his soul went out of his body altogether, so that his body lay dead."
Reply to Objection 1. Sometimes by the figure of synecdoche a part of man, especially the soul which is the principal part, denotes a man. or again we might take this to mean that he whom he states to have been rapt was a man not at the time of his rapture, but fourteen years afterwards: for he says "I know a man," not "I know a rapt man." Again nothing hinders death brought about by God being called rapture; and thus Augustine says (Gen. ad lit. xii, 3): "If the Apostle doubted the matter, who of us will dare to be certain about it?" Wherefore those who have something to say on this subject speak with more conjecture than certainty.
Reply to Objection 2. The Apostle knew that either the heaven in question was something incorporeal, or that he saw something incorporeal in that heaven; yet this could be done by his intellect, even without his soul being separated from his body.
Reply to Objection 3. Paul's vision, while he was in rapture, was like the vision of the blessed in one respect, namely as to the thing seen; and, unlike, in another respect, namely as to the mode of seeing, because he saw not so perfectly as do the saints in heaven. Hence Augustine says (Gen. ad lit. xii, 36): "Although, when the Apostle was rapt from his carnal senses to the third heaven, he lacked that full and perfect knowledge of things which is in the angels, in that he knew not whether he was in the body, or out of the body, this will surely not be lacking after reunion with the body in the resurrection of the dead, when this corruptible will put on incorruption."
Source: Summa Theologica (New Advent)