Did Jesus appear post-resurrection to twelve apostles?

Question

We see at 1 Cor 15:3-5:

For I handed on to you as of first importance what I in turn had received: that Christ died for our sins in accordance with the scriptures, and that he was buried, and that he was raised on the third day in accordance with the scriptures, and that he appeared to Cephas, then to the twelve.

But, we see Matthias being elected as replacement for Judas Iscariot only after the ascension of Jesus (See Acts 1:9 [Jesus' ascension] & Acts 1:26 [Matthias chosen]).

My question is: whom does Paul refer to as "the twelve" when there were only eleven apostles left in the group before the ascension of the Lord? What is the explanation offered by Catholic Church for the said statement of Paul?

Answer 1

While Matthias was not an apostle at the time that Jesus appeared to the other eleven apostles, the Scriptures do indicate that Matthias was a disciple during Jesus' ministry.

According to Peter’s words (Ac 1:21, 22), Matthias had been a follower of Christ throughout Jesus’ three-and-a-half-year ministry, had been closely associated with the apostles, and was quite likely one of the 70 disciples or evangelists whom Jesus sent out to preach. (Lu 10:1) After his selection, he was “reckoned along with the eleven apostles” by the congregation (Ac 1:26), and when the book of Acts immediately thereafter speaks of “the apostles” or “the twelve,” Matthias was included.​—Ac 2:37, 43; 4:33, 36; 5:12, 29; 6:2, 6; 8:1, 14; see PAUL. [article "Matthias" printed in "Insight on the Scriptures" by Watch Tower Bible and Tract Society of Pennsylvania]

So, Paul was recognizing Matthias as an apostle even though his appointment to that position had not be made yet.

(While not an answer from the Catholic perspective, this does give an answer from the Bible itself.)

Answer 2

In classical literature this is known as a figure of speech called a synecdoche. In this particular case, i.e. “the twelve”, the whole represents only a part. It’s common, even in our culture, to use words that refer to the entirety of something when one only is thinking about a portion of it.

I’ll let other people come up with modern examples in the comment section.

Answer 3

Both Paul and Luke refer to "the twelve" as the 12 apostles, including Matthias.

And that he was seen of Cephas, then of the twelve: 1 Cor 15:5

Some time after the ascension, there is a squabble mentioned early in Acts.

Then the twelve called the multitude of the disciples unto them, and said, It is not reason that we should leave the word of God, and serve tables. Acts 16:2

How do we know this phrase "the twelve" includes Matthias? It is because he was an eyewitness to Christ's resurrection during the 40 days from His resurrection to His ascension. He was selected as replacement to Judas Iscariot as an eyewitness.

Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection. Acts 1:22

That was the criteria for the replacement.

So, when Paul and Luke refer to "the twelve", this refers to the 12 living apostles alive at the time who witnessed the resurrection directly, including Matthias.

PS John writes of the twelve, but evidently as an expression known to those of the time and subsequent readers that includes all 12 living apostles who were eyewitnesses.

But Thomas, one of the twelve, called Didymus, was not with them when Jesus came. John 20:24

Answer 4

In Acts 1 Peter's conditions for a new apostle are that "one of the men who have accompanied us the whole time the Lord Jesus went in and out among us, 22beginning from John’s baptism until the day Jesus was taken up from us. For one of these must become a witness with us of His resurrection." Acts 1:21-22

So the new apostle was a person who had seen Christ in His resurrection, and could be considered one of the twelve, even though his official designation came after Jesus ascended.