I'd appreciate your thoughts on this. I noticed a similar question in your web page, but it seemed to deal more with the Old Testament and the different kinds of literature there.
That is an excellent question. Your friend is obviously not the first one to notice such apparent contradictions in the Gospels. Back in the early church Tatian wrote a book called the Diatessaron (A.D. 172) that lined up the parallel passages and made an attempt to explain the differences. A couple of things should be said. One is that the early Christians had such respect for the text that they did not attempt to "re-write" any parts that looked different. Sometimes a scribe would try to harmonize, but there is a science called textual criticism which guarantees that the Greek texts we have are as close as possible to the original. One the other hand, given the fact that we have four different authors describing the same events it is quite remarkable that there are so few contradictions. Think of a time when you and few other people were eyewittnesses, say, to an accident. The Bible is the Word of God in the words of men. God uses human language, memory, culture, etc. as the vehicle for his saving truth. Regarding the specific question about how to harmonize the two accounts of the withering of the fig tree I do not have an answer. I bet by posting it, I will receive some.
Fr. Phil Bloom
Evidence That the Gospels Are Reliable
Physical Resurrection of Jesus: Hoax, Myth or Reality?
Homily on Resurrection