JauneFlammee wrote:I need to appear in court.
With "to appear" being the greek infinitive.
What would the differences in meaning be in this sentence if it was a present infinitive compared to a future infinitive?
In this sort of construction the future infinitive would not be used at all; it's mostly used in indirect statements - "he said that the general will go." (Normally better English is "the general would go.")
What would the differences in meaning be in this sentence if it was a aorist infinitive compared to a future infinitive?
I can make a guess at number 1. Present would show an ongoing need to appear in court (perhaps they are a lawyer)
That is correct. The aorist indicative means past time, but the infinitive, the imperative, the participle and the subjunctive and optative mean single action (or thought of as single event: for example, in the middle of a war, a battle is ongoing; 30 years later, the battle appears as one event).
So, present: I need to appear in court (duration implied);
aorist: I need to appear in court (single event).
I can't even make a guess at number two. Does the idea of a future infinitive even make sense?
Yes, but Greek doesn't do it that way.
Obviously if one needs to do something, then they are not doing it now and it has to be future regardless of tense?
That also makes sense, and that's what Greek does. So in a sentence like "I want to go to Greece" the future is very strongly implied, but the grammar is going to use a present or aorist infinitive.