I think you understand the problem, so maybe you know what the solution is. First let me try and convince you that you understand the problem:
If one defines truth in this instrumentalist/operationalist fashion, then 'yes', physics is as close to truth as one can express since physics is closest to a instrumentalist and/or operationalist means by which to demonstrate one's model as meeting this criteria. For example, if I say that 'truth' is being able to perform an experiment where I can demonstrate what I mean by velocity, then it only takes an experiment in any situation to demonstrate that a phenomena in question has velocity.
Wonderful! That's the kind of thing I'm talking about, only just keep in mind I'm using physics as an example. I think physics is just a small part of the solution, but there's a lot more. There must be.
The problem with operationalism and instrumentalism is that they are weak arguments for defining truth. In the case of both of these views, there is the whole problem of verification within the context of a theory. That is, you need to accept the background theory before the experiments which you are using to define 'as true' make any sense
I don't have a problem with that, except that it is beside the point I'm trying to make. I don't want to define "truth", let alone discover what is "true", I'll leave that for the people who enjoy dealing with those issues. What I'm trying to show is that there is "something", some criteria, method, whatever, which allows us to get things done. You object to calling that something truth, that's fine with me, let's call it "whatevergetsthingsdone"
Do you agree that "whatevergetsthingsdone" exist? Do you also agree that it's perfectly possible, totally within our means, to discover a lot of "whatevergetsthingsdone"? Do you also agree that any attempt to discover that which is not "whatevergetsthingsdone" will not result in getting things done, which means it's probably a waste of time?
What I'm trying to understand here is, why do people spend time with things that are not "whatevergetsthingsdone"? What's the point? If they do it for fun, I can understand it, but that is not what it seems. It does seem that they believe that things which are not "whatevergetsthingsdone" matter, and with that I can't possibly agree.
Am I making myself clear?