Can verbal spell components be fulfilled by sign language (or by a silent language)?

Question

I know this is a little broken or over powered, but please consider the following from a RAW or RAI point of view. Please make sure your answer reflects which you mean.

If a character happens to learn a sign language (currently the only one listed is drow sign language and is a secret language) would they be able to use that for their spell casting in place of verbal spell components?

Under casting a spell

To cast a spell, you must be able to speak (if the spell has a verbal component), gesture (if it has a somatic component), and manipulate the material components or focus (if any). Additionally, you must concentrate to cast a spell.

And since there is a silent language which is spoken by hands according to language rules

You are skilled at working with language, in both its spoken and written forms.

If there was some silent language, like a stone language (not terran) would that also work? As long as you "speak" can you fulfill that component?

Answer 1

No, because being able to gesticulate with your hands doesn't hold the same type of power as being able to actually say language out loud, in game terms.

Specifically:

Verbal (V)

A verbal component is a spoken incantation. To provide a verbal component, you must be able to speak in a strong voice. A silence spell or a gag spoils the incantation (and thus the spell). a spellcaster who has been deafened has a 20% chance of spoiling any spell with a verbal component that he tries to cast.

Answer 2

No

These spells are not able to be cast using non-spoken languages.

See text of the Silence spell, emphasis mine.

Upon the casting of this spell, complete silence prevails in the affected area. All sound is stopped: Conversation is impossible, spells with verbal components cannot be cast, and no noise whatsoever issues from, enters, or passes through the area.

As this spell prevents usage of Verbal components, we can infer that these components are unusable by any non-spoken language.

There are already multiple feats which can help with achieving the effect you are looking for.

Conceal Spell will allow you to hide the fact you are casting a spell, by dispersing the words throughout your standard conversation.

Silent Spell is a Metamagic feat that removes the need for Vocal Components.

---

See also the Mute Musician, who is unable to speak, but able to use nonverbal language without issues.

From the text of the Mute class feature:

A mute musician can provide verbal and somatic components for spells she casts via any musical instrument in which she has ranks in the appropriate Perform skill.

This does show that there must always be an audible component to a verbal spell, unless modified via metamagic.

Answer 3

This question is usually up to the DM but if you would like to have a second opinion I would be happy to oblige.

Although it may be a stretch to say that you can perform a spell using sign language can use other methods. A similar method would be to use a rune type of spell and make them with your hands. Another method of which you have already said would be to just use silent spellcasting however if I were DM I would not allow such a thing for it would give the person's character a leg up on other mage characters and unbalance the party.

I would go with making runes with your hands in the air as they do hold power just as words do.