Keith Burgess-Jackson writes:
Howdy, Bill. According to Bryan A. Garner, "adviser is the standard spelling. Advisor is a variant form. Note, however, that the adjectival form is advisory." A Dictionary of Modern American Usage, 23. The Oxford American Dictionary and Language Guide (p. 15) says this: "Either spelling of the word is acceptable, although 'adviser' may be seen as less formal, while 'advisor' suggests an official position." You make it seem like one is correct and the other incorrect. That's incorrect.
Keith is right. I did make it seem like 'advisor' is correct and 'adviser' incorrect, and I was wrong to do so. After I wrote that post, but before I published it, I paid a visit to Mr. Webster and saw that both spellings are acceptable. But for some reason (laziness?) I let my original formulation stand. I suppose 'adviser' struck me as a newfangled spelling. Being a linguistic conservative, I looked askance at it. The connection between 'advisor' and 'advisory' also influenced me.
By the way, I am happy to hear any and all reasonable and well-intentioned criticisms. One of the things I am doing in this weblog is conducting my education in public. Some of the things I write about are things in which I can claim no special expertise, e.g. my recent post on Social Security. I write to learn. I go out on limbs that you are invited to saw off if you can.
Keith's message also got me thinking about quality control in the blogosphere. Although anyone can publish anything, with astute readers like Keith to keep one honest, there is no reason why weblogs cannot be of the same quality as good hardcopy journals.