Printed from http://tektonics.org/ecclauth.php
Tradition unanimously ascribes Ecclesiastes to Solomon, but the evidence here is admittedly thin, so much so that even some evangelical writers are content to ascribe it to the period between 400-200 BC (that is, about 600-800 years after Solomon). But as usual we have found a diversity of opinion on key points, and here we are left at worst with uncertainty -- and may note as well that the NT at least does not say that Solomon authored this book.
So let's look at the factors cited in this discussion:
- The thought question. Once the philosophical thought of Ecclesiastes was supposed to be evidence of lateness, and of influence of Greek thought from a later period. This argument is no longer in favor ("still moot" as Murphy puts it -- xlii), and that is as it should be (see next factor).
- Tone and style. Ecclesiastes is readily identified with ANE wisdom literature of the sort found in the ascribed time of Solomon, but some writers find complications.
Whybray [5-6] notes that Ecclesiastes is different in that it doesn't merely advise one to be wise; it discusses "the practical use of being wise." It offers a depth analysis otherwise unknown from ANE wisdom literature; as such Whybray classifies it as a "new kind of literary composition" and supposes it must be from a "very late stage" in the history of the wisdom tradition.
Such theorizing sounds plausible only on the presumption of evolution in a straight line. There is nothing improbable about an especially wise person (like Solomon) take wisdom lit "a step further" beyond his time. By such reckonings Akhenaten should not have existed until the time of Jesus, and DaVinci should not have been able to exist until this century. Human thought does not follow convenient straight lines, and Whybray's argument is therefore hardly persuasive.
- Internal evidence. Longman supposes that Ecclesiastes has internal markers against Solomonic authorship [Logman, 5].
1:12 being in the past tense ("I the Preacher was king over Israel in Jerusalem.") is taken to indicate Solomon could not have written this, but no Hebrew king ever retired to a life of leisure to be able to write such works; the phrasing is "anomalous" on any account. If a later writer made such a "mistake" then why could Solomon himself have not spoken this way?
1:16 ("[I] have gotten more wisdom than all they that have been before me in Jerusalem") is regarded as strange, for only David and Saul ruled before in Jerusalem: it is supposed that this cannot refer to other previous rulers like the Jebusite kings, but why this would be "passing strange" is difficult to see -- indeed one may argue that it would be a point of pride to have exceeded the previous pagan rulers.
4:1 ("So I returned, and considered all the oppressions that are done under the sun: and behold the tears of such as were oppressed, and they had no comforter; and on the side of their oppressors there was power; but they had no comforter.") is regarded as improbable since Solomon himself oppressed the people with conscripted labor, but we know well enough that politicians are not always sensitive to their own inconsistencies (even the wisest ones) and at any rate the Hebrew word carries implications of criminal action (it elsewhere means "defraud" or "deceive") and however oppressive Solomon's conscription may have been, it was legal under the prerogative of an ancient king -- this objection is anachronistic.
10:20 ("Curse not the king, no not in thy thought; and curse not the rich in thy bedchamber: for a bird of the air shall carry the voice, and that which hath wings shall tell the matter.") is said to be improbable because it assumes the king is a "suspicious bully," and Solomon would not say this about himself, but it is hard to see why the "suspicious bully" description is warranted. Longman's objections are more creative than practical, rather like the objection that Empedocles could not have committed suicide by jumping in a volcano because he never mentioned volcanoes in his writings.
- The language question. This is the biggest one of all: The Hebrew of Ecclesiastes is different -- very different -- from that of any other Biblical book, and very difficult, so much so that Whybray calls it "at first largely incomprehensible" .
Ecclesiastes is much a puzzle in this regard, for if it had to be placed on a linguistic evolutionary "scale" for Hebrew, it would have to be dated after the first century -- which is obviously out of order, since we know it existed for at least 150 years before that. [Ibid., 5] There are 27 unique words and 40 unique grammatical structures. [Crenshaw, 49]
Various studies have debated the presence of Aramaic, Phoenician, Ugaritic, and Canaanite linguistic features, to little avail for agreement thanks to the paucity of comparative Hebrew literature from the period.
The conservative commentator Delitzsch is often quoted as saying that if Solomon wrote this book, then "there is no history of the Hebrew language" [Seow, 11] -- one may ask rather whether we could say, "has a more complex history than we realize." As a whole the discussion involves techincal grammatical niceties beyond the scope of anyone who is not an expert in Hebrew, and we can say little more on this subject.
On a lesser scale, foreign words are few. There is no hint of knowledge of Greek (though to be fair, there is none in evidence in the Qumran documents either), other than that the phrases "under the sun" and "to see the good" are sometimes regarded as Greek in origin (though as Crenshaw responds, they are also found in Semitic - 49).
There are two words deemed to be Persian [ibid.]: "parks" (2:5 -- interestingly, found elsewhere only in Nehemiah and the Song of Solomon) and "provinces" (2:8, 5:8 -- found frequently in Daniel, Esther, and Ezra-Nehemiah, but also in 1 Kings, Ezekiel, and Lamentations). Persia however was not "born yesterday", so these two words are rightly not considered decisive.
Crenshaw  notes the presence of what he calls late vocabulary (for example, "season," Eccl. 3:1) but such arguments do tend to be assumptive and have been held only until such time as other documents discovered later show the word to have been in use even earlier. In this case, "season" has been found as early as the 5th century BC, only 400 years after Solomon; why is it not assumed that Ecclesiastes offers evidence of the word being used in Solomon's time?
Other unusual words (surplus, deficit, assets) may just as easily be attributed to the lack of need to use them in other materials -- we would not expect words like "economic forecast" in a military report.
Beyond these matters, do we have positive evidence for Solomonic authorship? External evidence (tradition and other writers) are unanimous in a Solomonic ascription. Internally the book is credited to a son of David who is king in Jerusalem (1:1), who specializes in wisdom.
Whybray, though he dates it to the Ptolemaic period, sets the book as written at a time of "unexampled prosperity" and "intense economic development" [9-10] -- which fits the time of Solomon's brief expansion as well. Of course one may note that "authorship" in the ancient world did not always mean "I wrote it personally" -- various anomalies (such as the shift in persons) are easily attributable to the commonplace use of a scribe.
In conclusion: The evidence here is thin, but an attribution to Solomon seems as good as any.