Suppose you are a scientist. You aren’t a solipsist, an anti-realist. You believe your senses convey you meaningful messages about the outside world. The outside world exists!
Why do you believe in the outside world?
For one thing, as a practical matter, no one actually believes the outside world doesn’t exist. At least, they don’t if we take disbelieving in the outside world to mean being disposed to act as if the outside world doesn’t exist. It is easy to imagine that such people would starve, or walk in front of busses, or at least be locked in asylums so they didn’t do such things.
As a scientist, however, you have a name, and a representation, for the thing that guarantees that the outside world is meaningful: Natural Law. Natural law guarantees that the your senses’ signals make sense. They are not random noise, or the cunning manipulations of the devil. Indeed, this seems to be a more fundamental definition for what Natural Law is than the common hazy picture of natural laws as constraints, which at its root stems from the religious vision of God imposing law on lawless material. What trait of material, after all, would be left if Natural Law were removed?
To restate this reflection as a definition, Natural Law is the entity that makes true the judgement that sensory perceptions of the outside world can have meaning. I also note in passing that every judgement that isn’t a tautology must have some entity (or entities) that make it true. Otherwise, what would we mean by saying it is not a tautology? I will call Natural Law the guarantor of the meaningfulness of perception. Now let us turn to God.
I define God as the guarantor of the meaningfulness of individual human existence.
God is the entity that makes true the judgement that the existence of individuals — yourself included, is meaningful.
As a practical matter, pretty much everyone believes human action is meaningful. At least, the act as if they believe it. You as a scientist, would you not find it hard to muster all the organized effort to do science if you didn’t believe this? However, as we noted above, since this meaningfulness is not a matter of logic, there must be an entity or entities which make the statement true.
A number of objections spring to mind. Why just one entity? Couldn’t God and Natural Law be identical? Doesn’t this definition abuse the term “God”?
Addressing these questions in reverse order, it seems to me that most people who do believe in God (or Gods) would be happy to affirm that He/She/It/They do (does) in fact guarantee the meaning of individual human existence. They would mostly ascribe additional attributes to God, the aggregate of which, ascribed by different believers, might well be mutually contradictory. However, that doesn’t mean that this argument isn’t relevant to their beliefs: if God is a figment of their imagination, then what attributes pertain or are essential is also a subjective matter. However, if God is a real entity, then clearly it is possible to be mistaken about an attribute while still having in mind the same entity.
As a scientist, you might be tempted to identify God and Natural Law. I would say that, without further argument, we can’t rule out the possibility that Natural Law could be an aspect of the same entity, I don’t see how Natural Law as described by the scientific method, could guarantee the meaningfulness of individual existence. That is because the scientific method discovers principles that are necessarily general, as experiments to uncover them have to be repeatable. How could they guarantee the meaningfulness of individuals?
As a practical matter, we also don’t believe that Natural Law guarantees the meaningfulness of individual existence the same way that it guarantees the meaningfulness of the external world. For instance, no one would accept as valid a murderer’s defense that they weren’t responsible for the crime — it was the laws of physics that did it. The meaningfulness of human existence clearly involves purposeful action, for which in turn individuals are responsible. In attempting to describe an individual, Natural Law can at most describe something like an equivalence relation on a phase space, whose occurrence may roughly correspond to (the space-time extension of) an individual. Are we prepared to hold such a timeless, abstract entity responsible for anything?
Could Natural Law be an aspect of the same entity that guarantees the meaningfulness of human existence? Why do I speak of “an entity” — perhaps it is many different entities? Perhaps it’s ourselves, or our society? Interesting questions! But to answer them, you have to engage in theology. You have already admitted the existence of God (or Gods).