"Then" and "than" used to be on my "Hostage 50" list. I had a list of commonly misspelled words, and if students misspelled one of them in a major paper, their grade was held hostage at a fifty until they wrote specified sentences fifty times. For then/than the sentences were:
“Than” is used for comparisons: “She is taller than he.”For years it has bothered me that students confuse these two words, words that reflect distinct logical relationships. According to what I was taught, "then" reflects a temporal relationship (He washed the car, and then played ball.) or a conditional (If it rains, then the picnic is canceled.). "Than," on the other hand, implies a comparison (She is taller than he.). It may be my interest in the relationships between grammatical constructions and logic that has made me so sensitive to this question, but lately I've had to reconsider. Within the last week, I have come across two violations of this rule, both of which were made by widely recognized writers. I did not write down the first, but I think it was in Ayer. The second, by G.K. Chesterton, motivated this page, where I will attempt to collect any further such "violations." As with "But" at the beginning of a sentence, if enough examples are found, then [than?] perhaps the rule should be abandoned.
the bold emphasis on "then" or "than" is mine.]
"Jane Austen was born before those bonds which (we are told) protected woman from truth were burst by the Brontës or elaborately untied by George Eliot. Yet the fact remains that Jane Austen knew much more about men then either of them." [G.K. Chesterton, The Victorian Age in Literature. London: Oxford University Press, 1966. 47.]