The following material, which was originally written for a Jewish history class in a yeshiva high school, is basically a direct continuation of my post on Shimon HaTzadik.
The Influence of the Greeks
The period that began after the death of Shimon HaTzadik was one of great turmoil for the Jewish people. The Greek presence in Eretz Yisrael increased, especially through the various Greek towns that were founded surrounding the Jewish population. One of the standard Greek strategies, begun by Alexander the Great, for solidifying their rule was the founding of cities that were settled by Greeks and by non-Greeks who had adopted Greek ways. In Eretz Yisrael, many such cities were founded, in most cases by changing an existing town into a Greek style government and society. Among the most important of these cities were Gaza, Ashkelon, Acco (Ptolemais), Jaffa, and Dor.
The establishment of these Greek colonies required large amounts of construction and generated tremendous profits for those who were connected to it. Thus, those Jews who had connections with the Greeks were able to use those connections to become wealthy. The increase in wealth and economic activity caused many people to admire the Greek society. Personal contact between Greeks and Jews, especially Jews from the wealthier and politically powerful segments of society, became more common. Over time, the Jewish people were increasingly influenced by the materialism and secularism of the Greeks and some even began to see the Greek way of life as superior. The word for this belief is Hellenism, and those who followed it are called Hellenists, or, in Hebrew Misyavnim.
The following material will discuss how the Misyavnim – the Hellenistic Jews – began and grew into a powerful political party that eventually succeeded in turning the Greek government against the Jewish people and led to the Greek oppression that eventually brought about the successful uprising of the Chashmonaim (Hasmoneans) which we commemorate on Chanukah.
The Generation of Antigonos Ish Socho
Antigonos Ish Socho, the disciple of Shimon HaTzadik who succeeded him as the head of the Sanhedrin, did his best to counter the harmful influence of the Greeks, and to teach the people to serve God without materialistic motives. As the Mishna (Avos 1:3) states:
אנטיגנוס איש סוכו קבל משמעון הצדיק. הוא היה אומר, אל תהיו כעבדים המשמשין את הרב על מנת לקבל פרס, אלא הוו כעבדים המשמשין את הרב שלא על מנת לקבל פרס, ויהי מורא שמים עליכם. (אבות א:ג)
Antigonos Ish Socho received from Shimon HaTzadik. He used to say, do not be like slaves who serve the master in order to receive a reward, but be as slaves who serve the master without expecting to receive a reward, and the fear of Heaven should be upon you.
This was a call to the Jewish people to abandon a mentality of materialism in their service of God. Rav Shlomo Brevda explains:
... לאחר תקופת שמעון הצדיק הצליחו היוונים להתחיל להשפיע על אחינו בני ישראל מיסודות חכמת הטבע. וידוע, כי איש הטבע דואג תמיד על קיומו ופרנסתו בעולם הזה. ועל כן מעשיו בדרך כלל נעשים על מנת לקבל פרס. כי תורה ועבודה, כולה לשם שמים, אין נמצאים אלא באלו השתולים על מימי התורה והיראה על טהרת הקודש. וזה פשוט. על כן בא אנטיגנוס איש סוכו בדורו להחזיק את העם בדבריו – אל תהיו כעבדים המשמשין את הרב על מנת לקבל פרס וכו'. ... אמנם חכמת הטבע השפיע על בני עמנו, לאחר תקופת שמעון הצדיק, לעשות חשבונות טבעיים במעשיהם בגדר על מנת לקבל פרס. ולכן במקדש נשתנה מצבם ממצב למעלה מהטבע למצב טבעי, פעמים דולק פעמים אינו דולק וכו'
After the time of Shimon HaTzadik the Greeks began to successfully influence our brethren, the children of Israel, with the wisdom of nature (secular materialism). It is clear that a materialist is always worried about his survival and livelihood in this world, and therefore, as a general rule, his actions [even his ‘spiritual’ activities] are all done with expectation of benefit. For Torah and service [of God] done purely for the sake of Heaven is only found among those who are “planted by the waters” of Torah and fear [of Heaven] in holy purity. This is clear. Therefore Antigonos Ish Socho came forth in his generation to strengthen the people with his words, “Do not be like slaves who serve the master in order to receive a reward…”
Nevertheless, after the time of Shimon HaTzadik, the wisdom of science influenced the people of our nation to make materialistic calculations in their actions, in the category of “in order to receive a reward.” Therefore, in the Temple their circumstances changed from one that was above nature to one that was natural, “sometimes it would remain lit and sometimes it would go out.”
Nevertheless, although the Greek attitudes did influence the Jews, in most cases this influence was limited to subtle changes in attitude, such as the attitude towards serving God for ulterior motives. Although this influence was certainly harmful, it did not mean that the general Jewish population was turning away from their basic belief in God and His Torah. Unfortunately, however, there was a small but powerful element in the Jewish nation that was influenced to a much greater degree.
The Beginnings of Heresy
Chazal tell us that around the time of Antigonos Ish Socho another development occurred which contributed to the rise of the Misyavnim:
אנטיגנוס איש סוכו היו לו שני תלמידים שהיו שונין בדבריו והיו שונין לתלמידים ותלמידים לתלמידיהם, עמדו ודקדקו אחריהן ואמרו מה ראו רבותינו לומר דבר זה, אפשר שיעשה פועל מלאכה כל היום ולא יטול שכרו ערבית? אלא אילו היו יודעין רבותינו שיש עולם אחר ויש תחיית המתים לא היו אומרים כך. עמדו ופרשו מן התורה ונפרצו מהם שתי פרצות צדוקים וביתוסים, צדוקים על שום צדוק ביתוסים על שום ביתוס. והיו משתמשין בכלי כסף וכלי זהב כל ימיהם שהיתה דעתן גסה עליהן. היו צדוקים אומרים מסורת היא ביד פרושים שהן מצערין עצמן בעוה"ז ובעוה"ב אין להם כלום. (אבות דרבי נתן ה:ב ע"פ נוסחת הגר"א)
Antigonos Ish Socho had two disciples [named Tzadok and Baisos] who studied his words (quoted above, "Be as slaves who serve the master without expecting to receive a reward.") and taught them to their students and the students taught them to their students. They rose up and examined these words closely and said, “What caused our teachers to say this thing? Is it possible that a laborer can perform his work for the entire day and not receive his payment in the evening? Rather, if our teachers had known that there was a world after this and a resurrection they would not have said this!” They rose up and separated from the Torah  and two sects separated from them, the Tzedukim (Sadducees) and the Baisusim. The Tzedukim were named after Tzadok, and the Baisusim were named after Baisos.  They used golden and silver vessels all their days for they were gluttonous. The Tzedukim said, “It is a tradition amongst the Prushim (Pharisees)  to afflict themselves in this world, and in the world to come they have nothing.” (Avos D’Rebi Noson 5:2) 
Thus, through the misinterpretation of the teachings of Antigonos Ish Socho, a heretical movement began which, because it denied the belief in reward in the afterlife and the resurrection of the dead, denied the Torah. There is some question, however, as to what degree they abandoned the Torah. Rav Yakov Emden, in his notes on Avos D’Rebi Noson states:
עמדו ופירשו מן התורה. נ"ב לפי הטעם משמע סתמו כפירושו שמכללות התורה פרשו, אבל בכ"מ בתלמוד נראה שהיו מחזיקים בתורה שבכתב, א"כ לא פירשו אלא מתורה שבע"פ. אפ"ה קרי לה תורה סתם שהרי הוא כפורש מכולה שא"א לקיימה אם לא ע"פ מסורת חכמים.
“They rose up and separated from the Torah” – This implies that they separated from the entire Torah, but throughout the Talmud we see that they adhered to the Written Torah, and they only separated themselves from the Oral Torah. Nevertheless, this is referred to simply as Torah for abandoning the Oral Torah is considered as abandoning the entire Torah because the Torah can only be fulfilled according to the tradition of the Sages.
Rav Yakov Emden was apparently of the opinion that the Sadducees truly believed in the authority of the Written Torah, and "only" rejected the teachings of the Sages. This also appears to be the position of the Rashbam (Bava Basra 115b):
צדוק ובייתוס תלמידי אנטיגנוס איש סוכו היו והיו שונין לתלמידיהן מה שקבלו מאנטיגנוס אל תהיו כעבדים המשמשין כו' וטעו התלמידים בכך שהיו סבורים דהכי קאמר עבדו למקום ואל תקבלו שכר ואמרו כמו שאין בו ממש בדבר זה כן כל דברי חכמים וטעו ופקרו בדברי חכמים ונקראו צדוקים על שם צדוק ובייתוסין על שם בייתוס באבות דרבי נתן:
Tzadok and Baisos were disciples of Antigonos Ish Socho, and they taught their students what they had received from Antigonos, “Do not be servants who serve etc.” The students erred in this and thought that he was saying, “Serve God and do not receive a reward.” They said, “Just as this makes no sense, so too all the words of the Sages.” They erred and they abandoned all the words of the Sages and they were called Sadducees after Tzadok and Baisusim after Baisus – [as is stated] in Avos D’Rebi Noson.
Thus, according to the Rashbam as well, it seems that the Sadducees only abandoned the Oral Torah (because they rejected the teachings of the Sages), but they genuinely maintained their belief in the Written Torah. 
Maimonides, however, maintains that the founders of the Sadducees actually abandoned the Torah entirely, but they recognized that the general Jewish community would never accept such teachings, and they therefore claimed to believe in the Written Torah and only openly denied the Oral Torah. Maimonides explains (commentary on Avos 1:3):
והיו לזה החכם שני תלמידים: שם האחד צדוק ושם השני ביתוס. וכאשר שמעו שאמר זה המאמר יצאו מלפניו ואמר האחד לרעהו, הנה הרב אמר בבאור שאין לאדם לא גמול ולא עונש ואין תקוה כלל! כי לא הבינו כונתו. וסמך האחד מהם ידי חבירו ויצאו מן הכלל והניחו התורה. התחברה לאחד כת אחת ולחברו כת אחרת וקראום החכמים צדוקים וביתוסים. וכאשר לא היו יכולים לקבץ הקהילות לפי מה שהגיע להם מן האמונה, שזאת האמונה הרעה תפריד הנקבצים כל שכן שלא תקבץ הנפרדים, נטו להאמין הדבר שלא יכלו לכזבו אצל ההמון שאלו היו מוציאים אותו מפיהם היו הורגים אותם, רצוני לומר, דברי תורה. ואמר כל אחד לסיעתו שהוא מאמין בתורה וחולק על הקבלה שאינה אמיתית. וזה לפטור עצמם מן המצוות המקבלות והגזרות והתקנות אחר שלא יכלו לדחות הכל – הכתוב והמקובל. ועוד, שהתרחב להם הדרך לפרוש. כי אחר ששב הפרוש בבחירתם היה יכול להקל במה שירצה ולהכביד במה שירצה כפי כונתו אחר שאינו מאמין בעקר כלו. ואמנם בקשו דברים המקבלים אצל קצת בני אדם לבד. ומאז יצאו אלו הכתות הרעות ויקראו באלו הארצות, ר"ל מצרים, קראים ושמותם אצל החכמים צדוקים וביתוסים. והם אשר התחילו להשיב על הקבלה ולפרש הפסוקים כפי מה שיראה להם מבלתי שישמעו לחכם כלל, הפך אמרו יתברך, "על פי התורה אשר יורוך ועל המשפט אשר יאמרו לך תעשה לא תסור מן הדבר אשר יגידו לך ימין ושמאל" (דברים יז:יא)
[Antigonos Ish Socho] had two disciples, the name of one was Tzadok and the name of the second was Baisos. When they heard him make this statement [that one should not serve God for the sake of reward], they went out from before him and one said to his fellow, “Behold, the teacher has clearly said that a person has no reward and no punishment, and there is nothing to look forward [in the afterlife] to at all!” For they did not understand his intent. And one lent support to the other and they left the community and abandoned the Torah. A sect gathered around one, and another around his fellow, and the Sages called them Sadducees and Baisusim. As they were unable to gather communities based on what they actually believed – for this wicked belief separates the gathered, it certainly cannot gather the separated – they pretended to believe in that which they could not deny before the populace, namely, the [written] words of the Torah – for if they had expressed [their disbelief in the Torah, the populace] would have killed them. Each one said to his followers that he believes in the Torah but he disputes the [rabbinic] tradition for it is not authentic. They said this to exempt themselves from the traditional laws, decrees, and ordinances, as they could not [openly] reject everything – both Written and Received. Furthermore, [rejecting the rabbinic tradition] broadened the path of interpretation, for now that they were free to interpret as they wished, one could be lenient where he wished to be lenient and strict where he wished to be strict, according to his own purposes, since he did not actually believe at all. However, they only sought changes that appealed to at least some people. This was the beginning of these evil sects, who are called Karaites  in these lands, i.e. Egypt, and who were known to the Sages as Sadducees and Baisusim. They were the first to challenge tradition and to interpret the verses in any manner they saw fit without listening to a sage at all. This is the opposite of what He Who is to be Blessed (i.e. God) said, “According to the teaching which they will teach you and the judgment they will tell you, so shall you do, you shall not veer from the thing they say to you right or left.”  (Deuteronomy 17:11)
According to Maimonides, the leaders of the Sadducees were completely irreligious, and their claims to religious belief were only intended to attract ordinary Jews to their false teachings. The Sefer HaKabala of the Raavad adds that Tzadok and Baisos actually became leaders amongst the Kussim (Samaritans) at Mount Gerizim.
Like many aspects of ancient history, it is probably impossible to know the precise nature of the relationship between the Hellenistic Jews and the Sadducees. However, it is clear that both movements appealed to the same basic population of wealthy and politically Jews with minimal commitment to traditional Judaism. In political terms, both movements served the same basic function of undermining the authority of tradition and of the Sages. The popularity of each movement seems to have risen and fallen depending on the political conditions of the time. When the Jews were under Greek rule, Hellenism was dominant. When the Jews were independent, Hellenism fell out of favor and the Sadducee movement rose in its place.
Thus, the group that was known as the Sadducees did not actually rise up as a significant sect until after the Greeks had been defeated by the Hasmoneans and an independent Jewish commonwealth had been established. Rav Yitzchak Isaac HaLevi explains (Doros HaRishonim Vol. 1, p.170):
בתחילה בשעה שמלכו היוונים בארץ פרצו כל גדר וגבול ויהיו לפושעים ומורדים ביד רמה והולכים בכל דרכי היוונים. ואחר זה, כאשר נצחו החשמונאים הגבורים ויגרשו היוונים מן הארץ ויעמידו את הדת על תילה, שבו גם אלו בהכרח מהיות עוד פושעים ומורדים בעמם והולכים בדרכי היוונים ויהיו רק למקילים בדברי סופרים.
In the beginning, when the Greeks were ruling the land, the heretics violated every boundary and they sinned and rebelled [against the Torah] publicly, and they followed the ways of the Greeks entirely. Afterwards, when the mighty Chashmonaim were victorious and they drove the Greeks out of the land and properly reestablished the religion, the heretics were also forced to cease their open sinfulness and rebellion and their mimicking of the Greeks, and they resorted to just being “lenient” in the words of the Scribes.
 Based on M’Nechemia Ad Atah, ch. 26, by R' Chaim Dov Rabinowitz.
 In his Kuntres L’Hodos U’l’Hallel b’inyanei Chanuka, p. 17.
 A reference to the Ner HaMaaravi and other miraculous aspects of the
Temple service which lost
some of their supernatural qualities after the death of Shimon HaTzadik.
 Some authorities maintain that Tzadok and Baisos themselves became heretics. Others believe that it was their disciples who eventually abandoned the Torah because Tzadok and Baisos failed to properly convey the teachings of their rebbe, Antigonos Ish Socho.
 Although originally there were two groups, they were so similar that they were generally seen as one. It would seem that the Baisusim were eventually absorbed into the general group of Tzedukim and they are not mentioned in other sources (such as Josephus and Philo).
 "Pharisees" (Perushim) is a term used to refer to the Sages. The term comes from the word “Parush” – separated. Maimonides explains (Pirush HaMishnayos, Sotah 3:4):
זה שהחכמים קוראין עצמן פרושין להיותם מופרשין מבני אדם שיש להם חסרונות והמדות הפחותיות והרדיפה אחר תאות העולם והם מיחלים לשכר העולם הבא ולמדות המעלות
The Sages called themselves Perushim because they are separated from people with deficient character and lowly traits who pursue the desires of this world, whereas they [the Perushim] look forward to the reward of the world to come and to virtuous traits.
 It should be noted that this statement in Avos D’Rebi Noson is the only reference in ancient literature to the origin of the Sadducees. The theories promulgated by secular historians have no basis in anything except their imaginations and ideological biases.
 One difficulty with the position of the Rashbam is that he implies that the Sadducees continued to believe in the afterlife and the resurrection. Yet, both the Talmud and Josephus indicate that the Sadducees denied this principle.
 The interpretation of this phrase is somewhat difficult. I have understood it to mean that the Sadducees did not make such radical changes that would have offended the entire population. Rather, they only made changes that had at least some popular appeal.
 The Karaites were a heretical movement that began in the 8th century, whereas the Tzedukim seem to have disappeared after the destruction of the Second Temple, in the 1st century. However, Maimonides (together with Rav Saadia Gaon and a number of other authorities) apparently believed that the Karaite movement was a resurgence of a remnant of the original Sadducees. Some of the early Karaites also appear to have held this opinion to some degree.
 This verse is speaking of the Sanhedrin and its decrees and the great Torah scholars of every generation.