We have sets of facts and assumptions. Then we have logical deduction. Why is there so much back and forth debate on certain topics?

Shouldn't all scientists come up with the same conclusions, given the same facts and assumptions?

And if there's a disagreement... shouldn't it be very easy to pin down the source of disagreement? ie: a different assumption... or a different data point etc.

I mean give the same facts and assumptions, using logical deduction there's only one conclusion.

I'm confused by the back and forth debate in certain scientific fields... not so much in math or physics... maybe more in social sciences, but biology also, when it seems to me that if each participant in the debate simply lists the assumptions and data... then it should be very simple to pin down the source of a disagreement.

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    Logical deduction is of limited use in science, like it is in any practical/empirical context, there is no deducing theory from observations, as Quine put it. The hypothetical side of the "hypothetico-deductive method" is far more influential in shaping science than the deductive part. Generation and selection of hypotheses is heavily underdetermined by evidence, and turns, even ideally, on epistemic values, coherence, parsimony, inification, elegance, etc. Judgments of what is "best" on those vary across scientists.
    – Conifold
    Commented Feb 22, 2021 at 6:27
  • @Conifold, sure but my point is that the source of the disagreement should be transparent. Is it a conflict of epistemic values? Is it a conflict of which data or theories each scientist is using. As an example maybe take this: en.wikipedia.org/wiki/The_Black_Hole_War I really don't understand how there can be any kind of "debate" like this. Perhaps there are conflicting epistemic values between the two scientists. Both should realize that at some point and the debate should end. There seems to me to be an obfuscation of the simplicity of disagreement because of language. Commented Feb 23, 2021 at 0:07
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    Wikipedia transparently describes it as an epistemic value disagreement "between scientists favoring an emphasis on the principles of relativity against those in favor of quantum mechanics". What is more "elegant", "unifying", "parsimonious", etc., to keep conservation of information in quantum gravity, as Susskind prefers, or to drop it, as Hawking prefers. The task of each side is to present consequences of their choice and elicit epistemic intuitions in a way that favors judgment for their preference. Deduction is a part of it, but so is analogy, illustrative metaphors, shared heuristics...
    – Conifold
    Commented Feb 23, 2021 at 0:40

3 Answers 3


What are types of science are you talking about?

Let's reconstruct your premise:

  • We have sets of facts and assumptions

What are facts in social sciences?

Are people relatively independent?

From the sociological point of view the answer is 'no'. At the same time, psychology (and especially economics) will disagree.

What facts for one field are nothing for another. Therefore, further assumptions also differ.

  • Then we have logical deduction

Yes, we have. Yet, the previous steps of logical deduction were different (different assumptions, theories, facts, etc.)

  • And if there's a disagreement... shouldn't it be very easy to pin down the source of disagreement?

It's quite easy to do it when you can step back from the debate. In this case, you'll say that the methods or theories differ. However, when you are a scientist, only your method and your field seems exclusively true and fruitful. Thus, we have so many debates, especially multidisciplinary ones.


I'll just give an answer from a logical point of view, I'm not a scientist.

All sciences are founded on math and logic, usually in the form of axiomatic, deductive systems. But these systems tend to be economically designed in terms of the number of axioms. Therefore, (I remind you I'm not a scientist) these "assumptions" you mention give a lot of freedom to scientists, in terms of interpreting a fact within a given system.

I'm sure these scientists don't argue about the logic, it would be just stupid (I mean if they both accept the same logic, which they usually do), so don't worry about the "logic" part :)

It's most often about, eg.: which theory to apply, when to apply it, how to interpret the facts within a given system (you'd be surprised about the non-preciceness of some deductive systems).

But I think the answer you'd be satisfied with will come from a real scientist.

  • Sure, but the things you mentioned... which theory to apply, when to apply it... those can be "logicized" too. Not absolutely, but to a great degree. My issue is that the "source" of disagreement should be pretty transparent. There's a lot of "essay" writing and discussion back and forth. Feels to me like this masks the ability to pinpoint the source of disagreement. Commented Feb 21, 2021 at 17:01
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    "Logicized" - well, you'd be surprised what these disagreements come down to sometimes.. I can only be guessing here, but what follows. Imagine a class of natural sciences, where each science is a class of theorems. The latter classes are not excluding each other, the are often overlapping. What I'm trying to say is that the disagreements most often concern contradicting theorems... Commented Feb 21, 2021 at 17:11

Put as simply as possible (the tl/dr version):

  • Scientists see events and effects
  • Scientists debate causation

In most cases, no one actually 'sees' causation. We see outcomes: we drop a stone and see it fall to the Earth; we roll a cueball into the eight ball and see the eight ball start to move. We assume that there are natural, regular, systematic forces lying behind what we see — 'gravity' in the first case, and 'momentum' in the second — and we can even describe those causal forces mathematically, allowing us to use them with ever-greater precision. But no one 'sees' gravity, and no one 'sees' momentum. We only see their effects within events that that happen in the world.

The scientific process boils down to this: we see some perceptible event happen, and then we struggle to find a theory (a model, an understanding...) about what caused that event to happen. You make one theory, I make another, and then we debate it. Scientific debates are resolved when we find or create new observable events that act as 'litmus tests': events that only make sense in your theory or in mine, so that if we do (or do not) see them, it enhances (or reduces) the credibility of one of the theories. We can see this right now in astrophysics. careful measurement shows that galaxies spin at a rate inconsistent with the amount of mass they have. That is the observed event, the effect that we need to find the cause for. First people assumed that there was dark matter (lots of mass that cannot for one reason or another be detected, but accounts for the unexplained observation). Then some theorists suggested that maybe gravity isn't as uniform a force as we think, and that the unexpected spin rates can be accounted for by variations in gravity's effects over cosmic distances. And so there's an ongoing debate, with some scientists trying to find ways to see or describe dark matter, while others try to model systematic variable gravity that would explain what we see without the invocation of dark matter.

The thing we always have to acknowledge as scientists (particularly when confronting some of the crazier theories we might meet in the real world) is that theories have an i=unfortunate tendency (using the old horse metaphor) to 'get the bit in their teeth'. A theory is a belief, like any other belief: something we want to be true because it makes our world more likable, accessible, or understandable. But we need to subject our beliefs to those evidentiary litmus tests. in other words:

  • There's no sense having a theory unless we first have an event we want to understand
  • We cannot choose to ignore events that work against what we want to believe
  • We cannot hang onto events that do not occur (no matter how convinced we are that they could/should/would occur) just because they would support our beliefs

But within those evidentiary constraints, there is a lot of room for reasonable argument and debate, because we never really experience causation itself.

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