I always assumed that Logical Positivism and reductionism went hand in hand, and that refutations of LP automatically made the case for reductionism weaker.

My reasoning was: if only empirically verifiable statements are considered meaningful, then all meaningful statements can be reduced to physical measurements of some sort or another, and that somehow implied the reduction of all sciences to physics.

I realize that there are serious gaps in that reasoning.

So my questions:

  1. Can someone be both a logical positivist and anti-redictionist?
  2. What would be the implications for logical positivism of empirically verifiable, but non reducible statements/theories?
  • 1
    This is odd, reductionists hold that everything reduces to some materialist ontology, positivists are skeptical of such ontologies, and hold that they are fictions organizing sense data. So positivists are neither pro nor anti reductionists, they reject the presupposition that makes the distinction even meaningful. In fact, logical positivists became famous for classifying metaphysical problems like that as pseudo-problems caused by linguistic confusion.
    – Conifold
    Nov 24 '15 at 20:57
  • @Conifold how is reductionism a metaphysical position? There's nothing metaphysical about reducing chemistry to quantum mechanics or thermodynamics to statistical mechanics. Nov 24 '15 at 21:20
  • Whether chemistry reduces to quantum mechanics or thermodynamics to statistical mechanics, or more generally one theory to another, are mathematical questions, not philosophical ones. They make sense to a positivist, but will be answered by technical developments. The philosophical questions are whether all spiritual, psychological, biological, chemical, etc., processes are at the root physical/material ones, no Geist, no elan vital, no ontological emergence. It is these that are positivistically meaningless since all of the above are just different ways of talking about sense data.
    – Conifold
    Nov 24 '15 at 22:07

Logical Positivism assigns meaningfulness to thoughts based on their empirical verifiability. Reductionism is typically phrased as the declaration that everything is matter, bound by natural laws. The two can be thought of orthogonally.

Logicial Positivism can recognize that a thought could be meaningless, and still be a thought. Attempting to prove or disprove the existence of a "mind" from reductionist would be meaningless, because there is no empirical process to test it. Of course, it would also declare any lines of reasoning dependent on a "mind" to be meaningless as well.

Reductionism states that everything is matter, or governed by natural laws. It does not state that this must be empirically testable. A reductionist point of view can accept an existence proof "the known laws of nature permit the illusion of mind, so even if we have no empirical way to verify that it is an illusion, we can assume it as such."

Thus, Logical Positivism may not accept non-constructive existence proofs, while reductionism may not result in fully empirically verifiable results. Their shared body is that of the empirically verifiable results of science, which is vast.


Logical positivists are reductionists, but there are different forms of reductionism.

Ontological reductionism says that everything reduces to a physical base, epistemuc reductionism days that higher level theories are reducible to physical theories, but the version entertained by logical positivists is semantic reductionism: a reduction of meaning to a basic observation vocabulary.

Observation does not strictly mean physical measurement, and reduction to measurements does not mean reduction to physics (quite the converse actually: reduction of physics). Early logical positivists were actually phenomenalists, attempting to reduce everything to sense data. Only later they accepted that a physicalist vocabulary could be the right reduction base, but by this they meant ordinary objects that everyone accepts, not unobservable physical entities such as electrons.

Logical positivists have always been suspicious about unobservable entities. These are precisely the entities that they thought were reducible to observations, which is kind of the converse of what we usually think reductionism is (but it's only a different form of reductionism).

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