Postdiction vs. Prediction

Same for biologists. So my point is that your taking issue with my use of “prediction” has no real professional basis.

I don’t understand what you are trying to say here…

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I’m using the term in the same way as astronomers do.

Okay, so when you say:

Do you say that prediction includes

things like that?

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Is that what you are claiming they did? I don’t get that impression from the paper.

I sure don’t see that in biomedical science:
postdict* - PubMed - NCBI 153
predict* - PubMed - NCBI 1,555,929

What point are you trying to make here?

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Yes. The EHT fits for things like the mass of the black hole, the parameter describing deviations from general relativity, etc in the manner like this:

Show me where they describe it that way in the paper.

My point is that every scientist see their own work as prediction, so this data you are presenting perfectly matches this self-perception. We often deride others as making postdictions. The reality is more subtle. post and pre are relative pronouns, and there several valid ways picking the event to which we are defining these terms.

There is a problem with post-diction if and only in cases where it is a sign of epistemological circularity. Sometimes chronological prediction prevents circularity, but not always, and this is not the only way of guarding against circularity.

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Look at appendix B in their paper VI: https://iopscience.iop.org/article/10.3847/2041-8213/ab1141/pdf
for the models and free parameters in the model. The model is fitted to obtain the observed values of the parameters. The free parameters are directly related to e.g. the mass of the black hole.

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There’s not one model. You are grasping at straws.

“In this appendix we describe the GC models used in Section 5 to fit the M87 data.”

It looks to me as if the models were all in place before the measurements came.

You’ve made a very sweeping claim:

You claimed the entirety.

Are you really claiming that these >200 authors were wrong at every one of the multiple points in this paper at which they refer to predictions?

Yes, the models were all in place before the measurements came, but these models say nothing of the mass of the black hole. These models have free parameters that relate to the mass of the black hole, that are then fitted to the observed image to do exactly this:

I don’t know how to explain this anymore to you.

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Maybe a split is needed?

They make different predictions about the mass, and the images point to one or more models that have a better fit.

You could explain how a series of papers that discuss predictions dozens of times and never mention postdictions are in fact, entirely about postdictions.

Or, you might consider the first rule of holes (pun intended)…

No, the models do not make predictions of the mass. The masses in these models are completely free parameters.

As I kept explaining, postdiction is not in the vocabulary of most astronomers, at least when we write papers. However, their methodology is this:

Which to me is clearly postdiction.

And it is precisely what they did, and called it a prediction…

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That’s nice, but it is clearly prediction to me and the >200 authors of the paper.

Like I said, maybe you should set them right. How would you propose to do that? Why argue with me if you’re not going to argue with them?

So you think that:

Is prediction?

The different Ms, at least one dating from 2013, make different predictions, do they not?

Why are you arguing with me and not with them? According to you, the whole series of papers is nothing but postdictions, correct?

Which different Ms are you talking about? The gas dynamics and stellar dynamics results? Those are different observations, not predictions.

But let me ask again:

Well you didn’t know if I did or didn’t argue with them. Even if I didn’t, it will be because prediction/postdiction distinction is not important for the crux of the paper, the observation of the image of a black hole.

Not the entire series of papers; I said Papers V and VI.

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