We know Paul went to Damascus twice (Gal.1) so he left twice as well. We should not need a text that explicitly says "Paul left Damascus twice". This should be obvious. Now, then. Paul describes one time he escaped from Damascus (2.Cor.12). Luke describes one time Paul escaped from Damascus (Acts 9). Each of these times must be placed at one of Paul's two Damascene departures. We should not assume both accounts refer to one escape. Logically, we must consider that it may just as well have been two separate and similar events.
(Now take a fresh look at the texts. Done? Let's continue.)
Luke's account shows Paul besought by Jewish authorities, upset because he'd been preaching in the synagogues, soon after his conversion. Luke omits all reference to Arabia, and so omits Paul's second departure. Paul's account does not give a reference to time, but Paul does mention two Arabians - Aretas and his ethnarch. If Paul's return from Arabia has anything to do with the ethnarch's (and/or his King's) desire to apprehend Paul, then this account best fits with Paul's second Damascene departure. Since no actual evidence suggests any other cause for the ethnarch's presence, and since the chronology of Roman events suggests Aretas' authority did not extend near Syria until after Paul's conversion, the ethnarch's pursuit is most likely related to Paul's return from Arabia. (Links are to my posts last year on this topic.)
Therefore, each account fits best with a different departure. Luke's account happened before Paul saw Arabia, while Paul merely shared of his second escape. This is the most natural assumption. Since the overall storyline clearly shows two different contexts, each befitting one of two distinctly different accounts, the burden of proof should fall on anyone wishing to conflate these distinctions. Which is more simple? To reconcile divergent texts, historical details and time lines, inventing either a cause for the ethnarch's involvement (if early) or else an omitted cause for Paul's first departure (if the joint pursuit was late)? OR - to place things where they most naturally seem to belong?
If the only problem with this view, as stated by some, is that we should not imagine the same trick being used twice, then I beg to differ in the extreme. A sneaky escape trick, successfully employed, would no doubt be the first and most prudent option for future escapes. No one could have seen the basket or rope being pulled up unless Paul was still physically nearby when they saw it. In that case, Paul would probably not have escaped. And the brothers who lowered the rope would be somewhat pleased with themselves for making the trick work so well. They would be extremely likely to try it again - especially if there was no better option.
Therefore, it seems Paul fled from Damascus two separate times, by the same method. Luke describes the first event in Acts 9 and Paul told the Corinthians about the second. Luke omitted Arabia to avoid weakening his case that anti-Paul bias by Jewish authorities played out consistently all over the empire. (I see this as spin but not outright deception.) However, Paul omitted the first escape for reasons I cannot practically fathom, unless he simply chose the one that most broadened his 'resume' and omitted the other to avoid adding confusion.
Any comments or questions? ;)