The fact it counts as a ranged basic attack is irrelevant.
Nothing relevant. Magic Missile does not have a range of 'sight.'
Nothing relevant. Magic Missile does not have a range of 'sight.'
Something relevant.
So reread the Line of Sight part.
It says: If you can't see the target (for instance, if you're blind or the target is invisible). you can't have line of sight to it even if you could draw an unblocked line between your space and the target's.
Again, this is irrelevant.
Without Line of Sight, you can't have Line of Effect, therefore you can't cast Magic Missile blinded without the perception check.
Your argument is based on the fact that ranged powers with a range of 'sight' require line of sight.
Magic Missile is not one of those powers. (Neither is ranged basic attack.)
Magic Missile's range is 20. '20' and 'Sight' are not the same thing.
Except you did not Demonstrandum anything to Quod Est.
It is a ranged power. The point of origin is yourself. So you need a single line of effect to the target. However, it does not have an attack roll, therefore concealment does nothing. All line of sight does for attacks is determine concealment.
You can use Magic Missile if you are blind just as you can use a Healing Word while you are blind. Magic Missile is a power with no attack roll that has an Effect line. (This is not technically the same thing as 'automatically hitting', tho you can grok it that way if you like) Healing Word is a power with no attack roll that has an Effect line. Unless that effect is explicitly negated by lack of line of sight (teleportation springs to mind) then there's no reason to believe Magic Missile behaves any different.
Moreover, one cannot hold the idea that Magic Missile cannot be used on a target while blinded, but that Ray of Frost can (with a -5 penalty.) It's already established that yes, you can make ranged attacks while blinded. Magic Missile benefits from that.
I humbly disagree because Magic Missile is a Ranged Basic Attack, AND/OR a Standard action.
I humbly disagree because bacon is not a vegetable.
Your points are irrelevant.
In order to do a standard action OR a ranged basic attack against a target you have to see what you're targeting because otherwise how will you know what to hit with the line of effect?
Nope.
1) Unless the enemy has made a stealth check against you, you are aware of its location. The rules are explicit about this.
2) Ranged attack specificly states that you can use it against an enemy you cannot see.
3) Nothing in Standard Action acts as an exception to either rule.
4) Nothing in Ranged Basic Attack acts as an exception to either rule.
You have line of sight.. you SEE it.. then you use that line of sight to use your line of effect. That line effect is your MM spell. Revert back up to what I said one page ago. If you cannot see it, you cannot effect it with the affect you're trying to effect it with.
Incorrect. Line of Effect is not dependant on Line of Sight, and Line of Sight is not dependant on Line of Effect. You're confusing 'making a ranged attack' with 'teleportation' which DOES behave as you state.
The only sort of ranged attack where this applies is with Gaze attacks and attacks with "Ranged sight"-range, which present an explicit exception to the line of sight rules
Magic Missile does not have that keyword, or that range.