Although science often despises the philosophical approach, we must underline both that science appeared due to philosophy and still exists because of the philosophical appetite of man. And this philosophical appetite that moved Socrates was what we could call the valuing approach.
It asks: why is it better for something to be rather than not to be? (Who cannot notice Hamlet’s dilemma here?) Or, why is it better for something to be as it is and not otherwise? This is not simply curiosity, as it might seem at first sight. This is the expression of the impulse to understand the world.
Modern science was rooted in this impulse. While burdened with the need to solve practical questions, contemporary science sometimes seems to have forgotten this purely unpractical want. However, cosmologists thinking of the universe’s beginning and ending are a breed of scientists in whom we still see that pure curiosity about how the world functions as a whole.
Now, science, in all its steps, beyond explaining why things are what and how they are, also endeavors to show what is their highest good. It is an essential part of every science to elaborate models of its object.
However, these models are nothing else than the ideal way of being of that object, their concept. These models are similar and function similarly to pure geometrical forms as compared with the eternally imperfect things that display the corresponding geometrical form concretely.
When you try to understand something – anything – you build a concept in which you try to put together an ideal schema of how things work. What you do is to explain that if that phenomenon exists, and especially can continue to exist, it is because it has that suggested structure. Implicitly, you state that if that structure was lacking or different, the concrete thing would collapse into itself: your ideal concept allows it to exist.
Thus, it is better for a class of things to partake in that concept than in another because otherwise, they would cease to exist. Thus, your concept inevitably has a value component. This is what Leibniz meant with his theory of the best of all possible worlds.
This is also immediately evident in the competition of two theories concerning the same phenomenon, for example, the modern competition between the Newtonian theory of light and its Goethean challenger. The winner is the better one, either because of its simplicity or because it manages to explain a wider pool of facts.
Coming back to the example of how biologists explain the occurrence of pain, we can say that they simply use this valuing way of thinking when they claim that the organism managed to survive due to that triggering effect of pain. So the pain had value for them, enabling them to continue to exist. Thus we cannot separate the theory of adaptation from its valuing (utilitarian) background.
Now, after all this detour, we can set our inquiry to a deeper level and ask: why is there any pain, or why does pain have value in the universe? Why does the universe need pain? Or, why is pain better existing than not existing?
Pain is a general phenomenon on Earth, and, both because of its prevalence on Earth and because we do not yet know of any other form of life than earthly life, we dare assume that pain is a general phenomenon in the universe.
If you are to try to understand pain as such an element, you need to create a scheme of the universe in which this pain must play a specific role. From this point of view, the schemes of the universe as they appear in recent cosmological theories are utterly incomplete because they ignore pain. (Of course, there are very many other aspects that that cosmological schemes ignore too.)
But, on the other hand, could we ever have an adequate theory of the universe? Of course, not. The universe is infinite (at least compared to our minuscule being and capacity for understanding). As finite beings, we will never be able to encompass the infinity of the universe.
Therefore, we will never have a scientific explanation of pain because the pain will never be able to be explained as deriving from a scientific theory that can be tested (as is necessary for any science).
We have two options: either we give up any attempt at a scientific theory of pain (in the sense mentioned above), or we try to explain it by proceeding differently. In other words, we will create a metaphysical theory of the universe (horribile dictu, for convinced scientists).
Of course, one could be criticized for such an attempt. However, a real metaphysical theory of the universe does not seek to explain only pain. Metaphysics always aimed to be an overall explanation of everything there was, of all that was known at a certain moment. It offered a scheme in which the results of science (be it physics, biology, geology, and so forth) and then art, morality, or culture in general, had to be derived with the same rational legitimacy.
Indeed, metaphysics nowadays seems a discipline of the past because it is humanly impossible to cover all the knowledge that science has recently assembled.
The metaphysical scheme, as any other scientific scheme, consists of a rule to put together a formal diversity. That formal diversity can thereafter be incorporated into any concrete things whatever. The scheme reuniting a formal diversity is like a pure triangle that you can never see in reality as such but only as incorporated in things more or less resembling a triangle.
However, who can dare imagine a scheme that afterwards can be identified in all things as well as in all scientific objects? If you have a purely causal view of the universe, you will be forced to ignore art, beauty, culture, the Good, and morality. On the other hand, if you base your metaphysical scheme on the latter, more ‘humanistic’ aspects, you will be unable to verify it through such measurements as science requires.