These concepts are difficult to discuss for several reasons: there is no inherent good or evil in nature, most humans are coerced in their moral corset from an early age.
Most humans comply with the conventions they evolve in and which they tend to accept as a moral compass albeit, all too often rather reluctantly. Morality spill over into the legal sphere.

When asking what "the good", I think most people are looking for some ideal outside of themselves - an intrinsic good. Why not ask, "good for whom and for what?" If your answer to that question "good for me and for my flourishing", then the purpose of defining the good can be very beneficial.

I think, like most of philosophy, there are a number of ways of going about answering this question.
Also, addressing the questions themselves:

1. "What is the purpose of trying to define the good?"
   2."What is the point of trying to define "good" or "bad?"

That is simple. The purpose, or point, of trying to define good and bad - is to develop a definition of the two.

But I think I understand that your question might be geared a bit deeper than that direct answer and is calling for an answer to a different, but related question like one of these (or maybe a combo):

• What do we get out of having a definition of good and bad?

• What is the cause for our desire to define the the two?

If these are questions you might want answers to...

The latter could be answered by explaining sociobiological evolution...how and why we came to develop such questions in the first place in terms of biological and sociological context.

Another might be to explain it in terms of virtue. What values lie within answers to these questions and how or why the may motivate us to find such answers in the first place.

The former can be addressed by explaining -again - in the sociobiological context. How, or what it is that our bodies find that these answers have utility in terms of society and anatomy/physiology.

Or, by considering the utility the definitions have when addressing motives and developing plans.

Not sure this helps, but here it is. I would like to converse some more about this, so feel free to open up more about it all. Thanks (:

Hi all - thanks for the various responses.

We each have different time-frames and approaches to discussion and in my case, between work and some non-work that is also sort of work, it will take me awhile to hold up my side of things and offer some further thoughts, so just noting as a bookmark.

Two other quick things:

• Yes, I meant "the good" as used in morality and ethics discussions, and not in aesthetics discussions. Exact wording can matter in discussion, but in this I am trying not to get too hung up. I just mean - what is the point of trying to say what is moral or morality. (I'll break down quickly and make an obvious cheap side-joke about not letting our desire for perfect wording be the enemy of ....)

• I did not ask "What is the good?". This may be obvious, but to underscore: I asked what is the purpose of trying to define what is good. My point is largely that I see no point in getting to a discussion of morality if we haven't really discussed what is the point of morality, or put another way, I think if we ask what is the point of morality, that will lead us (or me anyway) ultimately to a discussion of morality that is different than the usual. Or, put another way, if we do skip just to the usual discussion of morality, I think it will just beg the questions around "Yes, we have a claim that thus-and-such is "good" but why is it defined that way?" and so ultimately I think those questions will lead us back to "What are we after here, and trying to say such things... to what end?"

[edited for a few things.]

One of the key difficulties is due to equivocation. "Good" can be used in either an aesthetic or a moral context, and these two uses are distinctly different. Failure to grasp this fact leads to the confusion philosophers call "a category mistake."

I believe the intent of your question is to address "good" and "bad" as moral evaluations. Here the context is specifically interpersonal activity, and has to do with living as social beings.

At heart we are all selfish anarchists, but we choose to conform to the social order. In so doing, little sacrifices are made for the sake of relationship. It is in this sense of relationship where most values reside. Their function is not merely personal but trans-personal, they establish the guidelines and the rules.

The dysfunctional elements of society cannot be avoided or denied, this is not a failure of a value system but a failure of the individual. All societies whatever their political and economic colour have developed their own police and legislator to control and contain such disruptive elements.

The second, and more profound problem we have has to do with the terminology, and this is due to our cultural mindset of which we are generally not conscious. The very words we use to frame our understanding are seeped through and dripping with ontological presupposition. In the Western World the prevailing perspective is that of Hellenic Idealism. We think of things like "good" and "bad" as absolute abstractions, We forget that meaning is only strong enough to carry a local address.

The "good" is what we perceive as enhancing our well-being and the well-being of others that we feel a connection with.

To me doing "good" needs to transcend anthropocentrism. Our species is destroying the natural world so many species need to live. Doing good needs to try and turn that around. In the end we humans are also vulnerable and prone to extinction.

Kant's Categorical Imperative addressed this. The potted version is that Good is achieved by The Golden Rule. I.e. Don't do what you wouldn't want done to you. However, motive is the driver, if a shopkeeper doesn't rip off his customers in case he gets found out is not the same as he who doesn't because it is not the correct thing to do. More to Kant's philosophy than this but one of the important premises.

There is no defining to it. Our ideas of "good" and "bad" are all developed in our phyche. We are imprinted from birth with the value system and morals of the community we are raised into. What I believe Jung called the "persona". Later as we get older we all "rebel" against some of the things we were imprinted with but hold on to those that got lodged in there really deep. Some of us are eventually able to shed even those deeply rooted imprints and begin to think for ourselves and to decide for ourselves what is good and bad on a personal level. It is not our responsibility to decide what is good or bad for others. But as a society, when enough like minded (imprinted) folks live amongst each other you end up not being able to buy porn within 500 feet of a church.
Just sayin.

I think this is likely a lot more simple than you realize. If we don't have an idea of what is good, then we have no idea of what to strive for.