You are nota selective realist-dialetheist*

No eres un realista selectivo dialetheísta

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In her (2019), Martínez-Ordaz puts forward an argument whose conclusion pretends to be a dilemma for selective realists:

1. 1. The Pessimistic Meta-Induction methodology (henceforth, pmi methodology) is usually understood as the possibility of testing philosophical theses against the history (of science or of philosophy, etc.).
2. 2. The standard characterization of selective realism includes the non-miracles argument motivation, the selectivity character, the PMI-motivations regarding both truth and falsehood, as well as the use of a methodology inspired by the pmi.
3. 3. Because of their pmi motivation and methodology, as per 1 and 2, selective realists gave up the possibility of saying anything definitive about falsehoods. So they have prevented pmi-type of counterexamples about falsities in science.
4. 4. It seems that selective realists might not be allowed to forbid dialetheias to be linked to the partial truth. In general terms, by 3, the selective realist cannot prohibit a priori anything in science. Thus they cannot say that specific statements, such as contradictions, are necessarily false.
5. 5. If selective realists cannot reject the possible (partial) truth of a statement, they must accept the possibility of its (partial) truth.
6. 6. But philosophers tend to agree on contradictions being at least not true, and so it seems counterintuitive that selective realists should allow for dialetheias in the realist realm. Also, even dialetheists do not seem to demand that contradictions, if true, are the link between the scientific theories and the partial truth. In particular, they do not argue in favor of dialetheias to be preserved under theory change, either.

D. Therefore, either minimalist selective realism cannot explain why and how to forbid dialetheias in science, or the general characterization of selective realism is mistaken because it leaves room for possibilities that no selective realist would ever endorse.

Actually, Martínez-Ordaz seems to favor the second horn of the dilemma, suggesting that realist dialetheists also need to endorse “certain logical constrains that allow us to explain the success of science in the most metaphysically simple way available” because, furthermore, “maybe all scientific realist do so and (...) that fact should be incorporated to the general characterization of selective realism.” (Martínez-Ordaz 2019 114)

But her argument for the dilemma is flawed in several respects. First of all, the Pessimistic Meta-Induction does not have the required scope. The argument “A selective realist holds the pmi. Thus, they cannot say that specific statements, such as contradictions, are necessarily false.” is a non-sequitur and 3 and 4 in the argument above turn out to be overstatements. At most, the PMI shows that whatever one thinks at a certain moment of a given contingent truth or falsehood, might be wrong. The argument does not cover limit cases of truths or falsehoods, like the necessary truths and falsehoods of logic or mathematics. That is why I say that ‘the selective realist cannot prohibit a priori anything in science’ is an overstatement: what one gets from the PMI methodology is at most that a selective realist cannot rule out a priori any contingent statement in science.

Something beyond the PMI is needed to start making a case for the contrary, and thus to start making a case for selective realism-dialetheism, especially of an unconscious kind. The PMI can be strengthened with general fallibilist arguments that also extend to the realm of logic and mathematics; for example, Quinean revisability arguments (see Quine 1951/1971) and their more recent incarnations in anti-exceptionalism about logic (see for example Hjortland 2017). Nonetheles, these arguments typically depend on the continuity between the empirical and the formal sciences. A sort of pessimistic meta-induction in logic not assuming the continuity between the empirical and the formal sciences is discussed in Mortensen (1989) and Estrada-González (2015). The problem is that without continuity or any good story on how fallibilism in the formal might directly affect the empirical, it is difficult to use those arguments for Martínez-Ordaz’s purposes.

Let me illustrate how even granting the truth of dialetheism is not enough for the kind of conclusion Martínez-Ordaz wants to draw. The most elaborated realist dialetheist view to date is very explicit on its scope (cf. Priest 2006: Ch. 8): true contradictions or dialetheias are very unlikely and they occur only in few places. Evidence for their unlikeness abound, but a principled argument would go as follows: “If dialetheias are common, quasi-valid arguments² are wrong quite frequently. But it is not the case that quasi-valid arguments are wrong quite frequently. Hence, dialetheias are not common.” Also, for the dialetheist there are true contradictions, but they are found only in some special circumstances. The are true contradictions at the conceptual level (like the Liar sentence, the claim of the existence of a Russell set, etc.) and some of an empirical nature (like sentences about the instant of change, for example), but not beyond those few cases.

Finally, in the light of all the above, the dilemma presented by Martínez-Ordaz is far from devastating for the selective realist. Let us grant that the selective realist cannot “forbid” dialetheias in science, whether for PMI or for general fallibilist reasons. The important thing here is that they do not need to do that. Martínez-Ordaz thinks that the selective realist must explain why no selective realist ever have endorsed the possibility of dialetheias. But now it should be clear why it has been so: true contradictions are very rare, and in the empirical realm are even rarer and are well-located, and they have produced no change in our best empirical theories. Without any good arguments for the contrary, their likelihood is negligible.

Martínez-Ordaz might be right in that the selective realist needs general constraints that allow them to explain, in the most metaphysically simple way available, the success of science –and that maybe all scientific realists need to incorporate such general constraints. But I do not see why they should be logical (of the kind, “all contradictions are false”, for example) nor why it should be explicitly added to the characterization of selective realism. They are rather of a methodological kind concerning rational acceptance and rational rejection, and these seem not peculiar to selective realism, but common to virtually any theoretical enterprise.

Therefore, even if it is possible that you are a selective-realist dialetheist, just as much it is possible that you are a frog, I would save words and say plainly that you are not such a selective realist, just as I would save some words and plainly say that you are not a frog, instead of saying that to the best of our current knowledge et cetera, et cetera, you are not a frog.

The writing of this piece was supported by the PAPIIT project IN403719 “Intensionality all the way down: a new plan for logical relevance”.

https://revistas.unbosque.edu.co/index.php/rcfc/article/view/2748/2699 (pdf)