Can an incorporeal creature execute a touch spell against a corporeal creature?

Question

I am going by the definition of the incorporeal subtype from Monster Manual Ⅴ (page 213) and have a hard time coming to a definitive answer. I believe that incorporeal creatures should be able to execute touch spells, but how it describes interactions between incorporeal beings and physical things is a little ambiguous:

[An incorporeal creature] cannot take any physical action that moves or manipulates an opponent or that foe’s equipment, nor is it subject to such actions.

Simply: it cannot do onto others what others cannot do onto it. This is confirmed by Libris Mortis (page 141) where it talks about how the 50% miss chance also applies to corporeal creatures when it is the incorporeal making an attack:

Incorporeal creatures must deal with the same sorts of limitations on their ability to deal damage to corporeal targets as corporeal attacks do when fighting incorporeal foes.

But – back to MM5 – touch spells specifically work on an incorporeal creature:

Even when hit by spells (including touch spells) or magic weapons, […]

Is there any specific reason to believe that an incorporeal creature cannot execute touch spells back? Is touch defined anywhere as having to be physical?

I am asking for RAW answers here, which is why I ask for definitions and not interpretations.

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Note that I am not talking about Ghosts. Ghost come into the Material Plane (while simultaniously staying on the Ethereal Plane) through the supernatural ability Manifestation. It is this ability that specifically bans using touch spells agains “nonethereal targets”.

Answer 1

Yes it can

The Wizards of the Coast 3.5 archive Glossary shows that Incorporeality is not Etherealness, as incorporeal creatures are present on the same plane as non-incorporeal creatures.

That Glossary entry (which references Monster Manual III, which has the updated Incorporeal Subtype entry from Libris Mortis; the same one cleaned and reprinted in Monster Manual V) says:

...An incorporeal creature's attacks pass through (ignore) natural armor, armor, and shields, although deflection bonuses and force effects (such as mage armor) work normally against it. Nonmagical attacks made by an incorporeal creature with a melee weapon have no effect on corporeal targets...

[Emphasis mine]

Spell touch attacks are magical attacks, as evidenced by the language used earlier in the entry, showing that spells are magical attack forms:

[An incorporeal creature] can be harmed only by other incorporeal creatures, magic weapons or creatures that strike as magic weapons, and spells, spell-like abilities, or supernatural abilities. It is immune to all nonmagical attack forms.

Later, the glossary says:

Magic items possessed by an incorporeal creature work normally with respect to their effects on the creature or on another target. Similarly, spells cast by an incorporeal creature affect corporeal creatures normally.

So the incorporeal caster can use touch spells as normal against corporeal foes.