Here I have to break in and ask: how does one know that a specific trait is beneficial to the environment?


This part seems to be oke


Nothing intrinsically "wrong" with this part, but it is interesting none the less, since if you ask me, this part of your definition goes beond wat NS is, strictly speaking, and goes on to discuss the result.
There is however something else going on here, first you speak of "beneficial to the environment" (and I asked what that is), and here you say that the result is that it is beneficial to survival and even an increased survival rate for a population.

Now you make it a bit more complicated by importing the notion of a gene pool (a concept I think I understand), but something would be wrong here, if the book I'm reading is to be believed.

For you go from "beneficial to the enivronment" to "living longer/reproducing more often/contributing to the gene pool" (doesn't really matter how you label the 2nd step), to "increased survival rate".

Now first I asked you to define what you meant by "beneficial to the environment". Do you have a definition or perhaps an example?
Now, again: how would you know it is beneficial?
By the result, right? That is: if it helps to "increase the survival rate".
But if "increase of the survival rate" is the way to determine whether something is "beneficial to the environment", then the two are equal. By definition.

Hence we have a tautology.
A tautology is true (by definition), but it is not scientific in the sense that it can be tested.



I hope my repetition/application of what I think is his argument made sense to you