Why is Shmoneh Esreh referred to as 18 blessings when there are actually 19?

Question

Originally Shmoneh Esreh only had 18 blessings, thus the name "Shemoneh Esreh." However, subsequently a 19th blessing was added of Velamalshinim regarding the heretics. If there are 19 blessings now, why do we not refer to it as Tisha Esreh (19 Berachot)? Why did we retain the original name of Shemoneh Esreh?

This was a question asked to me by my daughter.

I wonder if it was simply a sociological phenomena and that is why is stuck or if there was an actual idea that was being conveyed by keeping the name. As if to say it is only a temporary blessing or something along those lines.

Answer 1

The OU website gives the possible reason that we hope that beracha will not be needed anymore and there won't be any opponents to judaism,so we hope by calling it shmoneh esrei but have 19 as a relevant need.

Answer 2

See the discussion here: http://www.shemayisrael.com/dafyomi2/taanis/insites/tn-dt-13.htm

Note that even in the Geonic era, there were those versions of Shmoneh Esreh that consisted of 18 blessings despite the addition of Velamalshinim.

Even after the additional blessing was added, there was a practice to combine "Tzemach David" with "L'Yerushalayim". You can still see a remnant of this in the "Krovetz L'Purim" which is said in Shmoneh Esreh on Purim. The "Krovetz" is divided into 18 sections to correspond to both 18 words in a certain verse in Esther, and the 18 blessing in Shmoneh Esreh. In order to keep the number of sections to 18, one section corresponds to both "Tzemach David" and "L'Yerushalayim". See Yaakov Emden's siddur for more information.

Both the Talmud and the midrash Shocher Tov show a correspondence of the 18 blessings with the 18 occurences of God's name in Psalm 29. The Talmud simply excludes Velamalshinim because it was added later. But the midrash includes Velamalshinim and combines "Tzemach David" and "L'Yerushalayim".

Answer 3

Mechon Mamre says what I always thought,

One of the thirteen requests (the one against heretics) was added around the 2nd century C.E., in response to the growing threat of heresy (primarily Christianity), but at that time, the prayer was already commonly known as the Shemoneh Esrei, and the name stuck, even though there were now 19 blessings.