Fatalism, Indeterminacy, and Power

Here's an interesting argument I came up with:

Many people (i.e., many (but not all) growing block theorists and presentists) don't believe in a real, concrete and determinate future because they think it leads to fatalism and hence a lack of freedom on our part. Here are some assumed (incompatibilist) assumptions:

Freedom Implies Power (FIP): If I am free to make it the case that p then I have the power to make it the case that p and I have the power not to make it the case that p.

and

Power Implies Possibility (PIP): If I have the power to make it the case that p then possibly (I make it the case that p).

These seem to be fairly straightforward incompatibilist beliefs - incompatibilists will accept them, even if others do not. Here's another principle:

Power Produces Determinacy (PPD): I have the power to make it the case that p iff I have the power to make it the case that determinately p.

This is pretty straightforward - it makes no sense to say that someone has the power to bring something about if they do not also have the power to make it determinately the case (and vice versa). So far none of this gives us fatalism when conjoined to a determinate, real future. But then, some no-future folks will also hold to the following controversial principle:

Fatalistic Principle (FP): If it is the case that determinately p then necessarily p.

FP in conjunction with FIP and PIP entails the relevant belief in no determinate future:

Openness Principle (OP): If I am free to make it the case that p then it is not the case that determinately p.

And so these folks will take it that there are instances where I am free to do something and hence where my doing it in the future is indeterminate. And, of course, I am not only free to do certain things, but I am determinately so (since really robust freedom requires us to be determinately free, not merely for it to be indeterminate whether we are so):

Determinate Freedom (DF): I am determinately free to make it the case that p.

From OP and DF, we can reasonably infer,

Determinate Indeterminacy (DI): It is determinate that it is not the case that determinately p.

Now here's where my real argument starts to get going: From DI and FP, we get:

Necessary Indeterminacy (NI): It is not possible that determinately p.

From NI and PIP, we get:

Power Failure for Determinacy (PFD): It is not the case that I have the power to make it the case that determinately p.

And now we finally get to use PPD which I mentioned earlier. From PFD and PPD we get:

General Power Failure (GPF): It is not the case that I have the power to make it the case that p.

So from GPF and FIP we get:

Unfree (U): I am not free to make it the case that p.

And so we have a contradiction, which means at least one major assumption must be false. The only real substantive premises that might be candidates for rejection, I would contend, are FIP, PIP, FP, or DF. Since FIP and PIP just follow from incompatibilism and DF is just a way of saying that we are free, we can put things this way: What this argument shows is that either incompatibilism is false, the Fatalistic Principle is false, or we have no free will. Contra the no-future folks who hold to all three of these, we must choose one of these options. In my opinion, a rejection of the Fatalistic Principle is the obvious choice.