Psionics

 

Psionics is, in many ways, the 3rd type of magic (besides divine and arcane). Unlike magic, which is based on the environment, psionics is comes mostly from within, from your own spirit. In many ways it's the same as magic, in a few ways its different:

How is it the Same:

Most things that detect magic detect psionics also. Same with dispel, spell resistance, etc. Spellcraft is used as "Psicraft" and knowledge arcana can identify certain psionic elements. 

To your average peasant it's the same as magic (especially like spell like abilities that don't have components), so anyone who doesn't trust magic (like certain barbarian archtypes) would also distruct psionics. Most feats that affect spellcasters or casting defensively are equally usable against psions. 

How is it Different:

While there have been wild magic zones, psionics has been mostly unaffected. Likewise some magic dead zones may not affect psionics (though there may be separate psionic dead zones or areas where both are inhibited). 

While there is a huge mage's guild, which studies the "science" of magic, psionics are based more on the internal mind and spirit, and is harder to teach. As such, there are fewer guilds and schools that focus on it. True, there are psions in the mage's guild, and there are some that study at monasteries, but socially it is hard to teach in a classroom setting, so psions are still more rare.  

Thematically, divine magic comes from the gods. Arcane magic comes from the world (though having certain bloodlines may help you access the magic more easily). Psionics comes from the self. Divine magic can go anywhere your divine source is recognized (so certain alternate primes could suffer from a lack of faith in a god). Arcane magic can go anywhere that magical energy exists (so certain worlds may not have magic at all). Psionics can go anywhere you can go. 

While a psion can be mythic, there aren't as many mythic abilities that compliment a psion as there is a mage, and there doesn't appear to be mythic versions of psionic powers, so there's a negative. 

For creating magical items, psions create psionic items and spellcasters make magic items.