Why did the KJV translate Jeremiah 29:11 as "to give you an expected end"?

The best answer I can think of is that when you look at the usage of those words ~400 years ago, they had [somewhat] different connotations than they do now.

Excepting someone finding the translators' crib notes for the passage in question, it will most likely remain a point of speculation.

The Hebrew words אחרית (acharit) and תקוה (tikvah) occur in the same phrase separated by the conjunction ו in three phrases:

• Pro. 23:18

כִּי אִם־יֵשׁ אַחֲרִית וְתִקְוָתְךָ לֹא תִכָּרֵת

• Pro. 24:14

כֵּן דְּעֶה חָכְמָה לְנַפְשֶׁךָ אִם־מָצָאתָ וְיֵשׁ אַחֲרִית וְתִקְוָתְךָ לֹא תִכָּרֵת

• Jer. 29:11

כִּי אָנֹכִי יָדַעְתִּי אֶת־הַמַּחֲשָׁבֹת אֲשֶׁר אָנֹכִי חֹשֵׁב עֲלֵיכֶם נְאֻם־יְהוָה מַחְשְׁבֹות שָׁלֹום וְלֹא לְרָעָה לָתֵת לָכֶם אַחֲרִית וְתִקְוָה

Gesenius (p. 37-38) states that the Hebrew word אחרית may also mean "posterity," citing Psa. 109:13, Amos 4:2, and Dan. 11:4.

I believe the solution occurs in Jer. 31:17 wherein we find the phrase וְיֵשׁ־תִּקְוָה לְאַחֲרִיתֵךְ, which could be translated as "and there is hope for your posterity." In other words, although the Israelites were in captivity, "they shall return from the land of the enemy" (Jer. 31:16) and "return to their border" (Jer. 31:17). God would punish them by captivity, but they would be liberated and return to the promised land.

Therefore, I believe Jer. 29:11 should be translated as "a posterity and a hope." The hope of a captive Israel remained in the fact that as long as children existed, a future was certain for the people of Israel.

I disagree that there is a contradiction here. It is more of a subtle difference in the meaning of the two words being compared, “expected” and “hope”. I do see how “expected end” can be a greater indicator of an actual end that the word hope indicates. But, it appears that you are assigning the secular meaning to the word “hope” which is really wishful thinking, which I totally disagree with. As a Believer we have a “hope” that is a rock solid assurance based on the Biblical evidence in many promises God has completely full filled.

Furthermore, I dislike the KJV because we pour a meaning that is different than what the writers meant into some words of that version, which of course causes confusion. In this particular case, and at this time in history, the KJV is probable more accurate than the modern versions. Using Strong’s Dictionary the word expected in Hebrew is “tiqvah” which is noted as H8615 and defined as, “hope, expectation, line, the thing that I long for, expected.” So you can see the connection between hope and expected.

While I agree with some of the other commenters, the “future” or the “end” is Heaven. If Randy Alcorn’s insight, as stated in his book Heaven, is anywhere near accurate, Heaven is going to be unimaginably wonderful way beyond our hopes and expectations. I highly recommend that book.

Several answers have pointed out that the KJV's word choice may be due to usage of archaic English. What has not been adequately explained, as far as I see, is why the KJV and, e.g., the ESV (cf. NASB) differ in the use of one vs. two noun here — "a future and a hope" (ESV) vs. "an expected end" (KJV). This variation is somewhat surprising given that both are relatively formal translations (i.e. they tend to preserve the syntax of the source when possible), and an explanation is warranted.

The Hebrew certainly includes two nouns, connected by a conjunction. The key to understanding the KJV's choice of a single concept is the notion of hendiadys. Hendiadys is a figure of speech using two terms linked by the conjunction "and", where a single idea is intended. This is a way of modifying a nominal (or verbal) idea with another noun/verb rather than using an adjective/adverb. While hendiadys exists in English (see the link for a few examples), it is much more common in Hebrew where adjectives are fewer. The KJV translators understood acharit wetiqvah here as a hendiadys, where tiqvah ("hope" or "expectation") functioned adjectivally and modified acharit ("end" or "future") -- hence, "expected end".

This line of thinking is expanded by E.W. Bullinger:

Here the A.V. gives "to give you an end and expectation" in the margin, and translates it "to give you an expected end."... All this is a recognition of the difficulty, without grasping or catching the spirit of the figure: "to give you the end, yes -- the end you hope for" : i.e. the end which I have promised and on which I have caused you to hope and depend. All this, and more is contained in and expressed by the figure Hendiadys.

_{E.W. Bollinger, Figures of speech used in the Bible, explained and illustrated, Eyre & Spottiswoode 1898.}

English has a long and venerable history as a language. Over time the meaning of words shifts. Different words come into common usage for the same meanings. Words can in fact reverse meanings. The King James Version, originally translated some 400 years ago, has seen all of these things happen to its words.

One commonly cited example is the word "charity". Today we would think of benevolence or giving to needy folks (or charities!), but in King James English it meant "love". Another one that has come up already on this site is that "kill" in the KJV means what we would today call "murder" and uses another word, "slay" for what we would call "kill".

In the case of "end" I can tell you just from having read other old English literature that the word did not always imply a terminal point as we might use it today. In fact today if we are careful we can even use it in this sense. The end of a book is not the end of most stories. If something comes to a good end it means they lived happily every after. "The ends don't justify the means." isn't referring to a terminal case, it's talking about results or final outcomes that live on.

Likewise the word "expect" wasn't used in the ambiguous sense that it is today where you could just as easily "expect the worse" as expect something positive. Think about Dickens and his famous book Great Expectations. That is a reference to a hopeful future, things were looking up. Somebody in those times with expectations had an inheritance or a profession waiting for them!

Again in modern usage, although we can use the term more versatility the default implication is positive. If you ask a woman or family if they "are expecting" and ... well expect them to smile if the answer is yes!

The phrase "an expected end" does conjure up in my mind a much anticipated positive future, a story that gets set straight just as today's phrasing of "hope and a future" does.

The thing with the KJV is that you have to remember that the vocabulary is 400 years (or in some updated cases 242) years old! You need to know how that language worked, not just the English you know today.

Perhaps there could have been a better way to translate it at the time, but many issues like this can be explained purely on the evolution of English.

See also: Why are there so many translations of the Bible?