Scientific method is fundamentally concerned with repeatable events. The phenomena that science captures most easily may be described using the following formula: once conditions A have been established, if B is done, then C happens.
This kind of science is a science of reactions, of the reactive. But what about a science of the active? Is such a science possible?
To phrase what I have in mind in a different way, suppose that there are events in our universe that are not reproducible or repeatable. They would not be the consequence of some stimulus or trigger. But neither would they be the act of some imaginary god. They might simply be part of the same underlying, mysterious generator that is responsible for what we call scientific laws (patterns of reproducibility). (So far we have inferred some of the properties of this generator, but we are very far from apprehending it or understanding its totality and boundaries. Intellectual humility is crucial.) Would science be able to record and theorise about such events? Certainly not. Modern scientific method is firmly aimed at eliminating irreproducible results.
To put it in still another way, we are able to verify determinism in those cases where it holds up, but we are always unable to verify the absence of cases (in the past or in the future) where the deterministic rules break down.
This is a quandary, since it does seem that the world contains phenomena that are difficult to reproduce. The belief that the world can ultimately be reduced to a set of deterministic rules is not at all uncontroversial (and perhaps many physicists have given it up already). Particularly in biology, we constantly struggle to understand phenomena in terms of such rules. However, we can perhaps see biology residing at the boundary between the reactive/deterministic and the active/irreproducible. Gradual determinism? –