The purposiveness of nature is not a product of design, but of necessity. The Universe needs perceiving, living organisms in order to exist. It needs sapiens creatures capable of perceiving and understanding it in order for its existence to be comprehensible. The underlying fabric of everything is necessity.
Existence was born out of a need intuited by the infinite lack of the void, and the presence of need in that metaphysical equation points toward a universal purposive meaning.
In evolutionary science, need, through adaptation, determines or explains evolutionary processes – and it can also explain the process out of the inanimate universe into worlds with life. If we can admit that the first amphibian didn’t develop its lungs in a purely accidental fashion, then why should we assume that life on earth had to have been formed in a purely accidental way?
But this need is a great problem for science, because it leads to an idea of the deterministic universe, which allows room for the idea of God, which opens the door to religions, which leads to a lot of very unscientific hogwash and the negation of science.
Yet, must determinism be rejected because of this. What is God? The fact that the Universe has an a priori element in its creation doesn’t oblige us to admit the validity of scripture. Not at all. To suggest that the Universe is deterministic and that the origin of its necessary existence is necessity itself, does not have to be an invitation to pray. There may be a deistic element in saying the Universe was born from need, but, historically, deism has always be associated with atheism by religions and should not be problematic for science.
How is necessity understood by science? To what extent can science be understood by understanding necessity? Can we say that all necessity exists like oxygen exists, or like the platypus exists, waiting to be discovered through observation and analysis? Can we therefore imagine a science of necessity dedicated to the uncovering of authentic needs?
Or perhaps these questions are irrelevant: scientific validity is already subject to necessity and possibility. All causes contain a certain amount of accident, and because the accidental is buried in cause, indetermination must also be embedded in results. But is it valid to ask what the necessity is behind a cancer? Or what is the necessity involved in a hurricane? Surely it is: for only through understanding its necessity can we possibly understand why things exist.
Everything exists for a reason that includes both necessity and possibility. It is there because it could be and because it had to be given the circumstances.
This should not be confused with fatalism. If what has to be is not desirable then, if we understand that it has to come about given the current conditions, we can go about taking steps to change those conditions and avoid the otherwise imminent outcome. This is pure common sense. But in order to avoid what is inevitable we have to firstly understand what is inevitable.