What does the term "tov" (good) mean? I am asking especially in how it relates to God.
I.e. what does "tov" mean and what does it mean that God is "tov"?
An example where God is ascribed "tov" is in Derech Hashem ch.2:
ובהיותו הוא לבדו יתברך הטוב האמיתי, לא יסתפק חפצו הטוב אלא בהיותו מהנה לזולתו בטוב ההוא עצמו שהוא בו יתברך מצד עצמו, שהוא הטוב השלם והאמיתי
("in that He alone is the true good...")
I am addressing what it means that G-d is "tov", and particularly how to understand the quote from Derech Hashem (along with other such quotes). The following is as was explained to me by a close student of R' Yaakov Hillel and R' Nochum Lansky (both noted and recognized in the world of Kabbalah), as well as made explicit in R' Chaim Friedlander's notes to Da'as Tevunos, Iyunim [2] and [19].
G-d in His essence has no positive attributions. He has no limitations and no definitions. The only thing that we can know about the nature of His essence is that it is שלם (Derech Hashem 1:1:2). Furthermore, all middos (attributes or characteristics) that we ascribe to Hashem are only a description of how He acts in the world, and not a description of His essence, which cannot be limited by such things (source and translation).
This extends to any description of attributes that one might apply to Hashem, including His being "good." "Good" happens to be distinct from other middos of Hashem, in terms of it being the most primary רצון (will) at play in creation, but even "good" and the desire to do good were in themselves things that Hashem created and chose to employ. Thus the Ramchal always uses terms such as מה שנוכל להשיג (that which we are capable of grasping)(Da'as Tevunos Siman 18) and מה שנודע לנו (that which has been made known to us)(Klalei Pischei Chochma V'Da'as Klal Aleph) when discussing these concepts.
Some read the words מחוק הטוב להטיב and think this means that Hashem is, in His essence, defined as being "good" and therefore "must" do good, or does good as a result of being good. In addition to ascribing specific limiting qualities to Hashem's essence, this is also a violation of Hashem's kadmus, which puts Hashem as preceding any other existence or concept, and being completely unbound in His רצון (sourced here). R' Yaakov Weinberg was very happy about the publication of the R' Friedlander Da'as Tevunos for clarifying exactly this very dangerous misunderstanding.
Therefore, what it means that G-d "is" good is that the most basic and underlying רצון that Hashem created and chose to act with in creating the world was "good."
From what I understand God is not good in the sense that anything else is. For example when I say "that piece of chocolate cake is good" I might mean well constructed, or tasty, or visually appealing etc. Judaism holds that the very definition of 'good' is God. The Rambam states this fairly explicitly when he describes the 'good' that is hidden away for the righteous as being "deriving pleasure from the splendor of God's presence". The Ramchal in 138 Entrances to Wisdom likewise indicates that the greatest 'good' is God and therefore the greatest gift God can give to others is to give of himself.
Based on malbim Torah v'mitzva shemos 20:12 - Tov is a human reference term which is used to mean "as opposed to ra". The discussion comes up by the first set of luchos, which as the gemara points out , is lacking the letter 'tes'. The 'tes' represents Tov and the gemara has a peculiar back and forth trying to figure out why that is.
(Source: http://thoughtsonparsha.blogspot.com/2014/01/parshas-yisro-ten-commandments.html?m=1)
Rabbi Kaplan in Handbook of Jewish thought chapter 3 #11-18 discusses Hashem's goodness. In paragraph 18 he quotes that line from Derech Hashem and explains it according to what he just finished saying, to mean the goodness of free will and the pleasure that comes from accomplishments that recognizably come from that free will. These are his words: Since the ultimate good is God Himself, the greatest possible good that He can bestow is Himself. There is no greater good than achieving a degree of unity with God, the creator of all good. Since God desires to give man the greatest good possible, He gave him the ability to resemble Himself.
From Rabbi Kaplan's Handbook Of Jewish Thought, chapter 2, paragraph 3.
As creator of the universe, God's existence can't depend on any of His handiwork. Judaism therefore rejects any definition of God as an abstract ethical force or social convention.
In footnote #2 he writes: "Thus, God cannot be defined as love, truth, justice, goodness, or in any other human terms. While these are attributes of God, they are not God Himself".
Goodness means existence. We consider something good when it promotes existence. Although we call things good when they aren't really good, that is just our perception. Since Hashem is מחויב המציאות, He is the ultimate good. See the Maharal on the Gemara about Rav Tuvyumi for more.
Saying that Hashem is good is basically after the rule that we must learn from Hashem's ways and to strive to be good too. For example, just as Hashem suffers the actions of the wicked, so too are we expected to continue doing good notwithstanding evil. The sefer Tomer Devora gives more examples
I think that G-d miraculously formed the world, and placed in it what the Bible calls “very good” things, what we call the laws of nature. From this reading, we learn that the laws of nature are good.
Can we say G-d is “good”? There are many commentators who differ. I like to take the approach of Maimonides (Rambam) who says that we cannot refer to anything about G-d, all we can say is silence. We cannot say anything positive about G-d, only negatives. For example, we know that G-d is not plural. In fact, we may not even use language, nor attribute a single word to Him. Even praise is not appropriate. For example, to say G-d is “good” would place Him under the same category of good people, the difference being merely quantitative when G-d is beyond languages.
