The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXIV. OF THE SINS OF SPEECH COMMITTED IN THE ORDINARY COURSE OF LIFE, VIZ., OF INVECTIVE, OF DETRACTION (AND CALUMNY), OF WHISPERINGS, OF MOCKERY, OF THE CURSE (B)

(B)  
What is understood by detraction?

Detraction, in its strict sense, implies the intention of attacking the reputation of our neighbour, or of taking away wholly or in part the esteem in which he is held by others, whensoever there is no just cause for so doing (LXXIII. 1)
 
Is this a great sin?

Yes, since it is to take away unjustly from our neighbour a good that is more precious than riches which are taken from him by theft (LXXIII. 2, 3).
 
In how many ways may one commit the sin of detraction?

In four ways: in imputing to our neighbour things that are false or in exaggerating his defects; or in making known things unknown about him and which prejudice him in the eyes of others; or in attributing to him intentions that are of a doubtful and perhaps of an evil character, whereby all that he does with the best intention becomes vitiated (LXXIII. 1, Obj. 3).
 
Is there any other sin of detraction that is hurtful to our neighbour?

Yes, in an indirect way, by refusing to acknowledge the good in him, or by keeping silence maliciously concerning his good points, or by lessening their worth (LXXIII. 1, Obj.3).

Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXIV. OF THE SINS OF SPEECH COMMITTED IN THE ORDINARY COURSE OF LIFE, VIZ., OF INVECTIVE, OF DETRACTION (AND CALUMNY), OF WHISPERINGS, OF MOCKERY, OF THE CURSE (C)