Oh, come on. You are playing semantics by conflating "actual" to mean both direct and indirect measurements. The latter differentiation is common and people colloquially use actual synonymous with direct as opposed to indirect.
When you take indirect measurements, whether they correspond to the same measurements if it were to be measured directly depends (not on math as you erroneously say) but on the computation/formula used to arrive at the direct measurement. In some cases, the formula is exact (V = IR, for example, where you can measure any two directly to get the third indirectly) which is where you seem to be stuck at or it is an approximation from a model because the direct measurement is often impractical to do but the indirect measurement may be good enough for the purpose. But the latter requires separate validation that it is indeed a good representation of the direct measurements if it were possible. This is not an issue of math but the accuracy and precision of modeling that enables indirect measurement to imply a value for direct measurement. Climate change, astronomy. acoustics, quantum mechanics, all involve inexact models to infer a value that cannot be directly measured.
There is no problem in doing so as long as people don't assume the model is necessarily exact and are open to the idea of models being wrong or requiring refinement as one gathers evidence. That is the way most of science works. Not by bringing in metaphysical concepts of what is "actual" to obfuscate the issue.
No, I am not playing with semantics at all. Not in the least. Nor am I "stuck", nor did I "erroneously" say something referring to math instead of to the use of formulae, or whatever it is exactly that you mean there. You clearly have made the assumption that your understanding of this stuff is perfect and that I am just being silly. I implore you to be less hasty with your assumptions and conclusions.
One of the fundamental difficulties with dialogs of this nature, concerning philosophy-science, is that most people simply don't have any appreciation for the degree of linguistic precision that is needed with dialogs of this nature, in order for them to be truly meaningful.
It is necessary to abide a high degree of linguistic precision, such that ambiguity is fully avoided. The importance of this cannot be overstated.
You have provided a clarification of what you (or maybe someone else, it doesn't matter) meant by "actual". This was good. You assert (strongly in
bold) that people colloquially use "actual" synonymous with "direct" as distinct from "indirect". Okay, but it matters nought whether this is or isn't a colloquial practice.
To make clearer what is meant by "actually" in this context, you now talk about "indirect measurements" vs. "direct measurements". I am expected to know precisely how you define the two, such that I would know with absolutely certainty which measurements you would deem "direct" and which measurements you would deem "indirect". I am afraid that I fall short of this expectation. I think I might have a fuzzy idea what you might mean by this, but we would both be fools were we to permit this dialog to go further without first making entirely certain that what you mean is entirely clear to both of us.
It is absolutely essential for you to state the necessary and sufficient conditions by which some particular measurement would be deemed an "actual" measurement.
Once you have made it entirely clear what the distinction is, between a direct measurement and an indirect measurement, the next step is to inquire into whether the measurement of torque taken on some class of dynamometer meets the necessary and sufficient conditions such that it would be deemed a "direct" measurement. You are most likely thinking at this point that the distinction between a direct and an indirect measurement is self-evident and that it is silly for me to ask you to define this distinction. But as soon as you start to think about this question seriously, you will mostly likely change your mind. Or at least I hope that you will.
I want to suggest a few questions that you may find relevant, as you ponder the question of how to define the distinction between direct and indirect measurements. How exactly is the measure of torque obtained? Does it involve taking a measure of force and multiplying it by a predetermined distance? If so, how is the measure of force obtained? Does it involve a strain gauge? If so, is force inferred from a reading of voltage? If so, is the voltage measured by way of comparison to calibrated voltage sources and using calibrated resistors? What is involved in the calibration of the calibrated voltage sources? Are they calibrated by way of comparison with other voltage sources, or how exactly?
If you want the easy way out, all you need to say is something along the lines of, "A direct measurement is a measurement that is directly taken."
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