Lower spells in higher spell slots

Question

Can you place a lower level spell in a higher spell slot? In other words, can you place magic missile in a 4th level slot if you want to, without a metamagic feat?

This came up in our Pathfinder game last night. It was a sorcerer who had a 4th-level slot available — but that spell was of no use — and no lower slots to use for a lower level spell which would be of more use at the time.

I remember reading somewhere that this was allowed (maybe it was D & D) but I could not find anywhere in Pathfinder that allowed this. I also thought that the effect was the same but the save DC would be higher and the dispel check harder, as per the new spell casting level.

Answer 1

It's still the same in Pathfinder, as described in the "Arcane" section of the "Magic" chapter^[PFSRD]:

Spell Slots: The various character class tables show how many spells of each level a character can cast per day. These openings for daily spells are called spell slots. A spellcaster always has the option to fill a higher-level spell slot with a lower-level spell. A spellcaster who lacks a high enough ability score to cast spells that would otherwise be his due still gets the slots but must fill them with spells of lower levels.

Emphasis added

However, this doesn't mean the spell actually has the higher spell level. This means that even if you cast Magic Missile from a 4th level slot it would still count as a 1st level spell for all intents and purposes (e.g. being blocked by a Lesser Globe of Invulnerability or calculating its Save DC). If you want to have the spell being treated as a higher level you have to use Heighten Spell^[PFSRD].

Answer 2

If metamagic can force a spell to a higher slot, then I see no problem with moving one up by choice. It's the same as equipping a high level fighter with a common sword.