Ask HN: Is there a way to quantify opinions into a tangible tree/graph?

Yes! There is a great way to do this called ACH (Analysis of Competing Hypothesis). It's a wonderful way to clarify your thoughts about a complex issue. It is used within the CIA.

http://competinghypotheses.org/docs/ACH,_Step_By_Step

There are many ways to do it.

You could load documents containing facts, opinions or other information into a database and then add another "table" that links one thing to another so we can say that "opinion B is a response to opinion A" or that any sort of relationship exists between them.

I think this even more interesting when we apply it to a set of documents that have business, engineering or science value.

In addition to ACH (mentioned by tboyd47), there is argument mapping.

https://www.rationaleonline.com/docs/en/tutorials#h9qc66

See rationale for software:

https://www.reasoninglab.com/