Ad captandum muscas..

[Hermes Trismegistus]

In terms of translation, what's the difference between 'ad captandum muscas' and 'ad captandas muscas'?!

 

[Matthaeus]

No semantic difference, only a matter of style or aesthetics, I guess. Also, the latter form, a gerundive, is found more often imo than a simple gerund.

 

[Puer Pedens]

So, when Caesar wrote, Ea quae ad effeminandos animos, He could've said: Ea quae ad effeminandum animos, too.

 

[Matthaeus]

...pertinent
yes

 

[Pacifica]

Very theoretically, but in practice classical authors never used a gerund with direct object after a preposition.

 

[Puer Pedens]

Discimus docendo, ok!

Discimus Linguam Latinam docendo, ok!

But, Discimus Lingua Latina docenda? is this correct, too?! if so, what's the logic behind it?

As usual, thanks in advance.

 

[Pacifica]

But, Discimus Lingua Latina docenda? is this correct, too?!

Yes.

if so, what's the logic behind it?

I think nobody is quite sure of the logic behind that use of gerundives. As I wrote elsewhere:

It is debatable how much of what appears should be the literal meaning of a phrase such as ad delectandos amicos, namely "towards friends needing to be amused", was still actually felt in a Roman's mind, or not; but for all practical purposes, it means the same as ad delectandum amicos, and translates exactly the same way: "(in order) to amuse friends".

 

[Glabrigausapes]

A (maybe) comparable example is to be found in Modern English, such as is spoken in my country anyway:

The confusion/redundancy of expressions like 'these things/this kind of thing/these kinds of things' has lead to such careless expressions as 'these kind of things'. In the case of Latin, it was simply easier to have the gerundival forms, which are patently some kind of o-stem in origin, agree with the nouns they govern/modify in the 'regular way' (cf. amicos amatos:amicos amandos).