According to John Ioannidis, an epidemiologist at the University of Ioannina School of Medicine in Greece (in New Scientist via Zonk of Slashdot),

Most published scientific research papers are wrong, according to a new analysis. Assuming that the new paper is itself correct, problems with experimental and statistical methods mean that there is less than a 50% chance that the results of any randomly chosen scientific paper are true.

Ioannidis is speaking of medical research, but if something so "concrete" can be so often wrong, then by extrapolating to "fuzzier" fields (i.e., history, linguistics, education, sociology), I imagine that the percentage of "wrongness" should rise. What does this say about the academic endeavor?