De not des?

Question

Je trouve qu'il a de bons arguments.I think he's got good arguments.In the example from this lesson, why is “de” used and not “des”?

Accepted Answer

Colin, the attached lesson will cover this for you - it is because ‘des’ becomes de when followed by a plural adjective preceding the noun.
 https://progress.lawlessfrench.com/revision/grammar/use-de-d-instead-of-des-in-front-of-adjectives-preceding-nouns-partitive-article 
PS Note for team - the title and first descriptive line of the article do not include the word ‘plural’ at all. Both should, I think.