Indy always reacted to events, and I don't mean that in a bad way.
In RLA, the government hired him because they knew the Nazis were looking for the Ark; unfortunately, even in RLA, he was reacting against Belloq to get the idol, and he still lost it. Interestingly, a scene cut from RLA shows Belloq and Indy in a Cairo bar (when Indy thinks Marion has died), and Belloq tells him that he lost the idol because the Hovitos weren't going to let him take it from them.
In TOD, it was an accident, but Indy discovered that the regent and child rajah at Pankot were using the stones for evil ends (besides kidnapping the village children);
In LC, he was hoodwinked by Donovan to look for his father (because 'Dad' had sent Indy his Grail Diary to keep it out of the hands of the Nazis), because his father was searching for the Grail and disappeared;
In KCS, Mutt convinces him to look for Prof. Oxley and his mom by showing the letter (not the kid's fault he didn't know his mom's real name, or that he didn't have the experience to guess the kidnappers allowed her to mail that letter to get Indy to do their dirty-work for them).
Which makes me wonder: what the heck? All those other archaeologists can't research their way out of a paper bag?! Indy's work is less reacting than deduction, which makes him an archaeological Sherlock Holmes.
Again, in KCS, Indy acted to prevent the Russians from using the Crystal Skulls for their own evil purposes (not that it mattered, 'cus the Skulls had their own plans...) (and to clear his name after that debacle at Hanger 51).
The implication in each instance is that a 'real' archaeologist has to have the education, the database (knowledge) to decipher confused stuff (Grail Diary, Ox's letter), and that the 'bad' archaeologists (Belloq, Nazis, Schneider, Spalko) didn't pay their dues by learning the basics--and they were searching with the wrong "intention" (power and profit, not knowledge). Both Ilsa and Mac died because they sought profit, not knowledge.
BTW, the history Channel has a great documentary running this month, titled "Indiana Jones and the Ultimate Quest," where a number of professional archaeologists credit RLA for igniting their interest in the profession, along with first-hand accounts of where their work differs and
resembles Indy's movies. Here's the link:
http://www.history.com/shows.do?episodeId=295858&action=detail
(Rats! Sorry, there are no repeats currently showing; there's no DVD listed, but I've sent THC an email asking if/when they'll feature it for sale on DVD. They got permissions from Lucasfilm to include excerpts of the movies, maybe LFL will box it with IJKCS when it comes out on DVD)