In the philosophy of science, the pessimistic induction, also known as the pessimistic meta-induction, is an argument which seeks to rebut scientific realism, particularly the scientific realist's notion of epistemic optimism.
== Overview ==
Scientific realists argue that we have good reasons to believe that our presently successful scientific theories are true or approximately true. The pessimistic meta-induction undermines the realist's warrant for his epistemic optimism (the view that science tends to succeed in revealing what the world is like and that there are good reasons to take theories...
3:07 AM
My personal opinion is that it's a bit problematic talking about things as such levels of abstraction. The argument that past scientific theories failed therefore present ones are bad, in particular, is unconvincing to me in general; it seems like a negated form of confirmation bias
Specifically what I mean is something like this... a scientific theory from a historical perspective can generally be viewed in this light in two categories... either the theory has been overturned or it is still standing. Obviously you can pick the theories that have been overturned and, with hindsight, judge them as bad; but you can always do that, even if the ones that are standing are good
3 hours later…
6:06 AM
@H Walters: Sure, my reading of physics history is that its rarely as clearly cut as this. I was just reading a little about the early history of vector analysis and I foud it fascinating. It began with Liebniz, he recognised its importance but wasn't actually able to come up with anything significant. But the general idea aroused such significant interest that a prize was offered and Grassmann won it. And its from him, really, that most of our notions of linear algebra are derived from.
3 hours later…
8:38 AM
Yeah sorry for the no response. But yeah, that's what the pessimistic induction is. Since asking that question I've kind of formed more of an opinion on it. Being that it is a bad argument.
When people discuss the pessimistic induction they usually cite theories like 'Aristotelian physics', 'the phlogiston theory of heat' and the 'caloric theory of heat'.
The difference between those theories and the theories we have today is that they were never good theories because they were never used to make predictions. They were always used to explain phenomena after the fact. Which is fine and kind of supports the theory but anyone can come up with ad hoc explanations of phenomena. The real challenge for a theory is to make predictions. Pretty much from Galileo onwards, science started to mature and prediction was taken seriously.
Surprise surprise, most of the scientific theories from when we started caring about prediction still work today and have not been 'altered' to fit the data.
Kepler's laws, for example (a very very early example of theoretical astrophysics) which were used to make predictions about the working of the solar system are still used today.
It's actually trivial to show that Kepler's law can be derived from Newtonian mechanics and Newtonian gravity. So Kepler's law was retained. And now that we have general relativity (GR), we know Newtonian physics is by no means the most fundamental physics but it emerges from GR by way of mathematical approximation. Therefore, Kepler's law emerges from GR by way of mathematical approximation. It's a good approximation too.
A scientist released his three laws in 1610's and they are still considered very good and useful approximations now. This looks like a case for (as you put it) the 'optimistic induction'.
I agree that the pessimistic induction looks like a bad reading of history and confirmation bias all over. Science is not equal to all study of the natural world. What Aristotle did (although you have to appreciate that Aristotle painted a very consistent picture of the world some of which had decent reasoning) is not any kind of mature science. It shouldn't be included when we consider the theories of today.
3 hours later…
11:28 AM
@JoeLee-Doktor: I think the point is about accuracy. Sure, you can still use, say, Bohr's model of atoms today for some applications. But it is not exactly right. In the same sense, we are not even clear about what the fundamental entities are. Most use quarks or strings to describe stuff, but it may turn out that there is nothing but force distributions in the end and that the four fundamental forces turn out to be one and the same
The main point being: Scientists should bear in mind that they are doing models, i.e. particular conceptual grasps trying to represent reality. They do in some sense not exactly describe ontic reality as it is (scientific realism), but rather how to make sense of it. They deliver a hermeneutics for the outcomes of their experiments. And hermeneutics are subject to historical development.
12:12 PM
I understand and agree with what you're saying as regards to realism on unobservable entities.
However (and I'll point you to this article by Steven Weinberg: http://www.physics.utah.edu/~detar/phys4910/readings/fundamentals/weinberg.html
In it he criticises Kuhn's reading of the history of physics and physical theories.
However (and I'll point you to this article by Steven Weinberg: http://www.physics.utah.edu/~detar/phys4910/readings/fundamentals/weinberg.html
In it he criticises Kuhn's reading of the history of physics and physical theories.
He also makes the distinction between the 'hard' parts of a theory and the 'soft' parts. The soft parts are the entities that are supposed to be moving around in the unobservable parts of nature. The hard parts are the equations which do the actual predictive work and those 'hard' parts must be absorbed by future theories if those future theories are to remain empirically successful.
I don't actually know how empirically successful Bohr's equations for describing his model of the atom were but, for the sake of argument, let's say that those equations had some level of empirical success. Whether or not we want to say that the world is made up of tiny little balls which have these standing electron waves inside of them, the equations which describe the behaviour of those entities are successfully describing reality.
So they have captured some structural truth about it. This was Weinberg's argument and it seems (knowingly or not) he has adopted Worrall's structural realist view of the development of physics where unobservable entities are concerned.
But that was my point when I said that theories of physics are retained as mathematical approximations in newer theories. Sure, the interpretive or hermeneutic element (as you put it) is liable to change, the structural element isn't. At least not in the same way.
That's something physicists know, too. Physicists created a view of the fundamentals of reality that includes 'particles' as building blocks. Now they interpret particles and everything else as perturbations of 'fields' (which are a much more abstract mathematical entity) and, as Weinberg points out in that article, physicists know that their understanding may develop further to a point where 'fields' no longer give us a good picture.
Oh also, he does bring up the pessimistic induction directly. But I thought his criticism of Kuhn's paradigm shifts was more relevant.
I'm not really sure how a structural realist view of science applies to other fields since most of my knowledge of science is in physics. Though, there aren't many other fields which posit so many unobservable entities as physics.
I also haven't really made my mind up on what we should take to be 'observable' and 'unobservable' entities. If the effects of particles are being detected in colliders which seem to correlate strongly with the equations, it certainly seems like there's good reason to believe that they exist. Or something very similar to them. I'm still doing reading, really.
Also @PhilipKlöcking although I agree with you that it's more about accuracy, many people use the pessimistic induction and Kuhn's paradigm shifts as a reason to believe that there really is nothing that we're learning about nature from science as an enterprise. I don't think there's anything wrong with saying that it's a work in progress and we shouldn't take the entities too literally. But I think there's plenty wrong with saying that we've learned nothing since Aristotle's day.
1:07 PM
@JoeLee-Doktor: I see your points and I guess we are in agreement for a lot of things here, e.g. that there are structural relations described that do not lose their meaningfulness when described with different means or as being of different nature. Here, Kuhn's paradigm shift has its shortcomings since they still are phenomena to be accounted for.
1:56 PM
Yeah, I think scientists should communicate the idea that the entities that scientific theories posit are constructions which we cannot know about in a literal sense but only in an indirect sense (though observing their effects and understanding their mathematical structure). I think it's more likely that the public and non-scientists take these ideas for granted more than scientists themselves. Good scientists, at least.
@JoeLee-Doktor: I think you will find more neurologists that state "thoughts are neurological signals in the brain" and physicists that state "colours are electromagnetic radiation with a certain wavelength" than you expect. The thing is: No physical theory can by itself define where "red" ends or "orange" begins. And no neurologist will ever be able to show logic as a structure of proteins.
A good introduction for that is "Philosophy and the Scientific Image of Man" by Wilfried Sellars. I think that those realism debates - at least in philosophy - are more pointedly objected by the mentioning of qualia as it shows that there is no such thing as "objective phenomenon" that is any "more real" than qualia.
2:12 PM
There is no coherent structural argument available that is able to justify internal or external realism, see Tim Button's interpretation of Putnam in The Limits of Realism. This is rather technical at times, but written in a nice style and showing how insistence on objective entities (or any epistemological access to them) is incoherent/meaningless
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