It is often said that constructive empiricism is anti-realist, and theories are not about the unobservable objects.

1. The first point we may need the settle is the problem of the existence of the unobserved, and the unobservable. An electron is invisible, mostly a mathematical construction (Schlick, an old idea), and we see only "macroscopic phenomena" in QM.

2. Is the QM convincing? If we're not interested the purely theoretical, mathematical objects, what are we interested in?

What exists, if the unobserved and the unobservable does not matter, but I want to believe in the actually unobserved and actually unobservable electron? (And _not_ only macroscopic, sensual data.)

The Quine-Duhem thesis counts (I think), and we can't emiminate the purely theoretical parts (not even Hartry Field, I think).

So, if the QM is empirically adequate, then I can believe in it [semantically, literally] , but I don't care about it's purely mathematical objects (e.g. Hilbert speces), and the QM is underdetermined.

What does it mean "semantical", if the Q-D thesis is relevant, and anyway, I don't care about the theoretical [unobservable] truths?

What remains then? Pure structure? Van Fraassen doesn't like it. What is reality then, what can we say about the structure of ontology?

The van Fraassen-Ladyman debate (2000, 2004) is a good introduction to this topic.

I consider the constructive empiricist position contradictory in these problems, but I know some answers from the protagonists and I'm open for arguments.

Contradiction gets nowehere, so I don't see any conclusion to your question.

(sorry if there are misprints if there are any:)

My view of constructive empiricism is, etymologically, that we are able to build a coherent view of the world from the data we gather. The problem with this is that the data can be interpreted in variable ways by equally empirically adequate theories. The view of substance is meant, at least traditionally, to point at what is past mere empirical adequacy to what science cannot ultimately falsify, simply because any point at which coherence is reached also allows for the epistemic possibility that more can be said. This just means that the concept of substance will forever be an undetermined idea, because to determine it entails begging the question of what it is not, and if what it is not is contradictory, then that does not ensure its nonexistence, just its nonexistence within the system that deemed the negation contradictory to begin with, which is not tantamount to necessity outside that system at all.

"the concept of substance will forever be an undetermined idea"

It depends on the philosophy we are in. Van Fraassen, Rosen and others know about this objection.

See this:

"One reason the constructive empiricist would be well-advised not to embrace the Argument from Underdetermination, then, is that it goes against a voluntarist position in epistemology. (This point is clearly made by Van Dyck 2007, 19–22, and agreed to by van Fraassen 2007, 347.) By the voluntarist’s reckoning, going beyond the evidence to the extent that one chooses to believe in the truth of a theory, both in its observable and unobservable aspects, could very well be rational.

The relatively permissive epistemological view of a constructive empiricist who is also an epistemic voluntarist helps explain why such a constructive empiricist would be prudent not to take constructive empiricism to be a normative theory concerning the deliverances of science. Mistakenly understood in that normative way, constructive empiricism would imply that belief in a theory’s empirical adequacy is the only rational candidate for the belief involved in a theory’s acceptance. Such a constraint on the rationality of opinion is clearly at odds with any epistemic voluntarism the constructive empiricist might embrace.

Gideon Rosen (1994, 160–161) gives another reason that the constructive empiricist ought not accept underdetermination arguments as grounds for constructive empiricism. Consider the following two hypotheses:

As Rosen notes, one’s current evidence does not tell in favor of either hypothesis over the other. So by an underdetermination-style argument, one is not justified in believing either hypothesis. But belief in (A) is the belief the constructive empiricist contends is involved in theory acceptance. (For more on how one might take Rosen’s argument as an argument against constructive empiricism, see Section 3.4 below.)"

https://plato.stanford.edu/entries/constructive-empiricism/

Balazs Inotai

"By the voluntarist’s reckoning, going beyond the evidence to the extent that one chooses to believe in the truth of a theory, both in its observable and unobservable aspects, could very well be rational"

That could very well be the case, but my contention is not in terms of its actual rationality, but on whether one could be able to tell for sure that such an approach is rational. It seems to me that doing away with Underdetermination is simply to let go of one normative constraint in favor of another and have the latter be definitional of what constitutes a rational approach.

The point of science is to construct theories that contain observable entities but it searches for unobservable entities. What we cannot observe is the basis of a semantical theory about science, I think, and can help to determine a way into truths through abduction. It is more common to believe that induction is the best method for science, but if we are going to construct words that explain meaning, it seems that abduction provides the most reasonable way into definitions and relations. Theory acceptance is based on logic, which is not part of a substance, and this is the reason for my question. I think that rationality is a separate thing from logic, and we can see logic being used in other species, just not as complex as humans. A pure structure is dependent on the knowledge that the hypothesis will prove the relations of ideas according to certainty, rather than possibility. This means that the evidence contains a nature of truth that is part of conception and reality.

If you get rid of a constraint in favor for another, you may have good reasons.

Within a philosophical theory you may have proposal to support the new definition.

Rosen, van Fraassen tried it. If Underdetermination is irrelevant, van Fraassen has to explain this within the framework, and he (and others) did it.

There are useful strategies to abandon Underdetermination otherwise. The No Miracle argument works, or a kind of "ontological equivalence" relation on the empirically equivalent theories also acceptable under natural but not trivial conditions. (Quine's ontological relativity helps us, I think.)

It also works if we believe in a "true" theory (but getting to know that it is the "true" theory for sure is out of our capabilities) because Underdetermination is epistemical. (Limits of epistemology, existing ontological structure.)

It also works if there is no "limit theory" (GUT or something), but science has stronger and stronger predictional power.

Thomas Kader's question is about the limits of philosophy within constructive empiricism which is a popular contemporary philosophy of science.

To answer that, we should understand what kind of entities (abstract and concrete, mathematical-ontological and empirical), are existing under the CE basic assumptions.

It seems to be difficult to answer.

If CE claims that the ontology or some parts of ontology are inconceivable or non-existent, that would be a limit of philosophy. (Our knowledge about the world.)

Is this the case? That's an important question.

Thomas, around induction anti-realism or skepticism is an issue.

It is based in similarity.

If you don't observe (and make proper experiments) on the dark side of the Moon now, and nobody does things like that, is General Relativity "true" there?

I think supporting the new definition means finding how the analytic word is a representation of a concept that is purely semantic. Most of the subjects that science questions indeed have to do with what microscopic entities have the reasonable theoretical foundations to explain why something exists. But, the results of induction are entirely based on perceptual systems that interfere with the concrete entities that solidify the meaning of inference. An inference is a limit in itself that suggests, with the correct knowledge of method, it will appear again in other conditions. But, I critique induction because of Hume. There is nothing in our experience that makes us cognizant of future ideas unless it through self-correction. In my opinion, the parts of ontology are logical processes that are determined by reason. The relativity of a concept is a separate case from the limit of a proposition. If we can show why this is true, we have more ways to show what similarities there are between science and metaphysics.

Balazs Inotai The issue of having good reasons for favoring one constraint over another seems to me to be intimately connected to the explication of the coherent semantics of the system within which such reasons are intelligible. I'm just trying to mull over the possible meta-reasons that would influence reasonability in choosing one system over another - i.e. considerations regarding simplicity and the like. The Quine-Carnap debate would be instructive in this case.

In terms of CE, I agree with Thomas Kader concerning the finding of what entities are fundamental to the logical system at play, because to suppose otherwise would mean that one's desired entities would attain extra-system existence/characteristics, thereby escaping any form of system-based defining.

I would like to recommend to you the book "An Outline of Philosophy" by Bertrand Russell. From my perspective, in it you will find the best account of what substance is. The book is written using analytic philosophy.

Thomas Kader "Theory acceptance is based on logic, which is not part of a substance, and this is the reason for my question. I think that rationality is a separate thing from logic, and we can see logic being used in other species, just not as complex as humans."

Do you think only human beings can be rational?

Huge complexity of the brain allows consciousness? What is consciousness? (Rough definition needed if you think so.)

A fly is, perhaps, a Turing Machine. Are we Turing Machines? (But much more complex?)

What is your viewpoint in the philosophy of mind? Are you a monist? Does it matter?

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Iñaki Xavier Larrauri Pertierra "seems to me to be intimately connected to the explication of the coherent semantics of the system within which such reasons are intelligible. I'm just trying to mull over the possible meta-reasons that would influence reasonability in choosing one system over another - i.e. considerations regarding simplicity and the like."

There are no "meta-reasons", you are always in a system, and it may be a meta-system.

Quine and Carnap had a common vocabulary, terms they understood in the same way. The neopositivist and traditional terms (analytic and synthetic truths for example) gave the possibility of arguing for a meta-theory between Carnap's philosophy and the Two Dogmas.

But if you're a continental philosopher (now or in 1953) this debate is senseless and irrelevant.

I mean to say that rational thinking is caused by time, which impresses ideas on us about how science should guide us in the right direction because of ethics. Logic evolves in other species in different ways than us since we have intensions. A fly is a Turing machine, while a human has consciousness, an attribute that makes us different from a Turing machine. I think substance monism supports a self-corrective thesis because it observes behavior as a fundamental tenet for reality. That is the biological side of metaphysics. In terms of meta-reasons, I think we should look for ways to explain that analytic predicates cause synthetic ideas about truth.

Thomas Kader All right, but yours is a specific standpoint, I mean, you have a philosophy, and you want to seek principles within this philosophy.

So, a fly is a TM, we are not, because we are conscious.

I assume, but you must know that many philosophers disagree and it is a crucial point to discuss your tenets.

(Ethics may not be metaphysical, it can be a product of our TM-like causal system-evolution or agent-evolution, you can be an emotivist and so on.)

What is your opinion about Quine's position in the Two Dogmas where he states that there is no fixed demarcation line between analytic and synthetic truths?

What do you think about Carnap who considered logic analytic (besides his tolerance)?

(Don't talk about Kripke and neo-Kantian issues now in this question, but it's your choice.)

The reason why I ask it, because these are well-known answers in analytic philosophy.

I'm open to discuss anything (and find answers within your chosen principles), but before that I have to know your reflection to the popular and strong claims in the literature.