Causes of Textual Variation

1. Unintentional Changes

A. From faulty eyesight or by careless inspection of the original

1) Substitution of similar letters and combinations of letters. 2 Peter 2:13 ΑΓΑΠΑΙΣ ("love feasts") and ΑΠΑΤΑΙΣ ("deceptions"); 2:18  ΟΛΙΓΩΣ ("scarcely") and ΟΝΤΩΣ ("really").

2) Omission of words between repeated phrases (homoeoteleuton). 1 John 2:23 "Whosoever denieth the Son, the same hath not [the Father; he that acknowledgeth the Son also hath] the Father."

3) Addition of letters by repetition (dittography). 1 Thes. 2:7 εγενηθημεν ηπιοι ("we were gentle") and εγενηθημεν νηπιοι ("we were babes").

B. From likeness of pronunciation or by incorrect spelling

1) ω confused with ο. Rom. 5:1 εχομεν ("we have peace") and εχωμεν ("let us have peace").

2) αι confused with ε. Mat. 11:16 ετεροις ("others") and εταιροις ("fellows").

3) ου confused with υ. Rev. 1:5 λουσαντι ("washed") and λυσαντι ("freed").

4) η, ι, υ, ει, οι, υι   all confused with one another, because they are all pronounced "ee" in later Greek (itacism). I John 1:4 ημων ("our") and υμων ("your"). A frequent variation in later manuscripts.

5) λλ confused with λ, νν confused with ν, etc. Mat. 27:35 βαλλοντες ("casting") and βαλοντες ("having cast"); Mat. 1:18 γεννησις ("birth") and γενεσις ("generation").

C. From errors of memory or anticipation

1) Substitution of synonyms and nearly equivalent expressions. Mat. 2:17 υπο Ιερεμιου ("by Jeremiah") and δια Ιερεμιου ("through Jeremiah"); Mat. 10:23 την αλλην ("the other") and την ετεραν ("the next").

2) Transposition of words to a more usual order. Rom. 1:1 "of Jesus Christ" for "of Christ Jesus"; Mat. 15:1 "scribes and Pharisees" for "Pharisees and scribes."

3) Transposition of letters. Mark 14:65 ελαβον ("receive") and εβαλον ("strike").

4) Addition of words from adjacent or parallel passages. Mat. 5:27 "to them of old time" added from verses 21 and 33.

5) Addition of expected pronouns. Mat. 14:15 αυτου ("of him") added after οι μαθηται ("the disciples") --a very frequent addition.

D. By incorporation of marginal notes wrongly taken as corrections

1) Addition of notes giving brief explanations. Mat. 10:3 "Lebbaeus, whose surname was" added before "Thaddaeus."

2) Addition of homiletic notes. Rom 8:1 "who walk not after the flesh, but after the Spirit." Rom 11:6 "But if it be of works, then is it no more grace; otherwise work is no more work." Mat. 27:35 "that it might be fulfilled which was spoken by the prophet, They parted my garments among them, and upon my vesture did they cast lots."

3) Addition of notes giving lectionary and liturgical adaptations. Luke 7:31 "And the Lord said" added at the beginning of the reading. Mat. 6:13 "For thine is the kingdom and the power and the glory forever, Amen" added to the Lord's prayer. Mark 16:20 "Amen" added to the end of the book.

4) Addition of notes giving quotations from related Scripture passages. Luke 23:38 "in letters of Greek and Latin and Hebrew" added from John 19:20; Heb. 12:20 "or thrust through with a dart" added from Exod. 19:13.

E. Through faulty interpretation of corrections in the margin

Chiefly by treating substitutionary corrections as additions (conflation). Rom. 6:12 "[in] its lusts" added after "obey it" rather than substituted for "it."

2. Intentional Alterations

A. To make the meaning more plain

1) Additions, omissions, and substitutions designed to simplify or correct the grammar. Mark 7:2 "they found fault" added to complete the sentence. 2 Cor. 12:7 "therefore" omitted from before "lest I should be exalted."

2) Addition of implied words. Mat. 12:35 "of the heart" added after "treasure." Acts 25:16 "to die" added after "deliver any man up."

3) Addition of natural supplements, often for the sake of emphasis. Mat. 6:4, 6 "openly" added after "will reward you."

4) Substitution of more idiomatic expressions. 1 Cor. 3:4 "carnal" for "men." Phil. 2:30 "not regarding his life" for "hazarding his life."

5) Substitution of definitions. Mat. 6:1 "alms" for "righteousness." Mark 7:5 "unwashed" for "defiled."

B. To harmonize related passages

Mat. 19:17 "Why do you ask me concerning what is good?" displaced by "Why do you call me good?" from Mark 10:18. --a very frequent kind of alteration.

C. To remove difficulties which would require tedious explanation

Mark 1:2 "in Isaiah the prophet" changed to "in the prophets."

John 1:28 "Bethany" changed to "Bethabara."

John 7:8 "yet" added to "I go not up to this feast."

Mat. 24:36 "nor the Son" omitted.

D. To emphasize or safeguard important teachings

Luke 2:33 "Joseph" substituted for "his father."

Luke 2:43 "Joseph and his mother" substituted for "his parents."

E. To reflect or promote monastic customs

Mark 9:29 "and fasting" added after "prayer" (similarly in Acts 10:30, 1 Cor. 7:5).