Gravity is conditional to mass. Is that what you mean? I'm still not quite understanding you.
Maybe I'm not explaining it clearly. In order to verify the truth of the proposition that "gravity exists", various conditions must be met. That's to say, the truth of the proposition depends on those conditions being met. Or put more simply, the truth is conditional.
Let's take a less abstract look at the problem. Suppose I want to verify the proposition that "gravity exists". How would I do that?
Well, I might begin by making a prediction: "If gravity exists, then my pen will fall towards the center of the earth, until it reaches an obstruction, when I release it, rather than it will float around the room." (The prediction is logically derived from my operational definition of "gravity", which I have not stated here.)
Next, I test my prediction by holding my pen up and releasing it. I observe that it falls in the general direction of the center of the earth until it hits my floor. So, I am now confident that the proposition "gravity exists" has been collaborated in at least one way. Let's say I now proceed to perform a number of other experiments, all of which either support the notion that gravity exists or falsify some competing explanation for gravity. And after weeks and weeks of such experiments, I am prepared to say with great confidence that the overwhelming weight of evidence very strongly suggests gravity exists.
Now, please note that the means whereby the proposition "gravity exists" is tested are conditional. They are all circumstantial, contingent. There is no means used to test the notion that "gravity exists" that is independent of circumstances, conditions, and contingencies. For instance, holding my pen up and releasing it involves a set of circumstances. I might generalize this and other similar observations by saying that the truth or falsity of the proposition, "gravity exists", depends on various sets of circumstances, and that therefore the truth or falsity of the proposition is circumstantial, conditional, or contingent -- whatever you wish to call it.
Why must I say the proposition is circumstantial? Because I have no means -- none! -- of determining the absolute truth or falsity of the proposition. To illustrate, I have no means of knowing, with absolute certainty, whether gravity will exist tomorrow. I might conclude, based on all my experiments, that it is highly likely to exist tomorrow, but I cannot conclude that it is absolutely certain to exist tomorrow. On the other hand, if I were able to determine the absolute certainty of the proposition, "gravity exists", I would presumably be able to determine whether gravity exists independent of the conditions of past, present, or future.
OK. That's the best explanation I can come up with at the moment. I'm not sure it's all that clear, but I hope it is sufficient.
