Telepathy vs Detect Thoughts
 

If you have telepathy, do you essentially detect thoughts at will? If someone has a language, you can just listen to their thoughts, right? Or is it more active communication?

I'm thinking of taking telepathy on one of my characters, and I kind of want detect thought as well. But beyond dealing with non-language based characters, I can't see a reason to do so.

Some sources of Telepathy in 3.5 require the target to share a language with the user, while others merely require that the target speak a language. I seem to recall at least one source that requires neither of those, requiring only that the target is of sufficient intelligence.

I'm not aware of any source of Telepathy (as the special ability) , however, that duplicates the involuntary thought-reading capabilities of Detect Thoughts or similar spells/powers.

Telepathy is the act of projecting your thoughts to the mind of another person. Reading some's mind is a different ability and merely allows you to read the surface thoughts of others.

So, in a way, detect thoughts gives telepathy toward you, but not you toward them.

The description of Telepathy in the Special Abilities section of the SRD (or MM) stongly implies that the resulting mental communication is two-way making no mention that such would require both participants to possess the ability.

I will reiterate, though, that the ability facilitates communication, not mind-reading.

I was making an anology.

You can read minds so it's like they are having onesided conversations and you can't reply back. Plus, I hadn't seen your post, as I was writing my own.

I think that if you have Telepathy, you can communicate with them (both ways) but that you can't read their thoughts against their will. It may just be one-way, though (or it may depend upon the source).

The SRD entry on Telepathy:
"A creature with this ability can communicate telepathically with any other creature within a certain range (specified in the creature’s entry, usually 100 feet) that has a language. It is possible to address multiple creatures at once telepathically, although maintaining a telepathic conversation with more than one creature at a time is just as difficult as simultaneously speaking and listening to multiple people at the same time.

Some creatures have a limited form of telepathy, while others have a more powerful form of the ability."


Note the lack of indication that the resulting mental communication is 1-way.
Note the strong implications that it is, in fact 2-way.

Telepathy is speaking mind to mind. Detect thoughts would be the ability to tell if their was a thinking creature nearby.

Consecutive rounds of concentration on a particular target eventually allow for the reading of surface thoughts.

This is my take on it. If your telepathy allows the receiver to communicate back to you by you listening to their thoughts, then any thought that the receiver concentrates on could be "listened" to. As a DM, I would probably houserule in a Will save to keep from thinking a certain thought, but to a telepath, thinking is the same as speaking.

Maybe.