What does happen according to the scientific method is a problem is encountered and a solution is conjectured, and there is no method for this part of problem-solving. — tom

That was indeed Popper's view, but not Peirce's. The latter suggested - long before Popper wrote anything - that the logical form of abduction looks something like this:

• The surprising fact, C, is observed.
• But if A were true, then C would be a matter of course.
• Hence there is reason to suspect that A is true.

Indeed, this is deductively invalid - reasoning from consequent to antecedent, which is why Peirce also called it retroduction and acknowledged that its outcome is merely plausible at best. However, it furnishes the components of a perfectly valid deductive syllogism in which the conclusion is the surprising fact (C), the minor premiss is the credible conjecture (A), and the major premiss is the reason why C follows necessarily from A. In other words, A explains C in light of other known information, so a well-prepared mind is absolutely essential to the generation of viable hypotheses.

Of course, a plausible explanation does not yet count as a scientific hypothesis. The next step is deductively explicating the conjecture to determine whether it has any necessary consequences that can be experienced, preferably under controlled conditions; this is where Peirce's "pragmatic maxim" comes into play. The third and final step is then inductively evaluating whether the predicted outcomes actually occur, by conducting appropriate experiments. Like Popper much later, Peirce acknowledged that the hypothesis is never confirmed with certainty, only corroborated or falsified. Nevertheless, the logical form of induction is such that if the hypothesis is false, this will eventually come to light - induction is by no means infallible, but it is self-correcting over the long run.

This is the point of view I was coming from as a critic of "terminological" disputes or "differences that make no difference." — R-13

Peirce evidently believed that the realism vs. nominalism debate was very consequential, because he waged that battle quite vigorously over the course of almost his entire philosophical career. He contended that nominalism has an inherent tendency to "block the way of inquiry" in various ways, and thus violate what he considered to be "the first rule of logic." I again highly recommend Peirce and the Threat of Nominalism by Paul Forster if you are interested in exploring this further.

Both abduction and induction are ... certainly not part of the scientific method as expounded by Popper. — tom

The Popper who wrote Conjectures and Refutations? Conjectures result from what Peirce called abduction (or retroduction), and refutations (or corroborations) result from what Peirce called induction.

The histories of quantum mechanics and relativity for example bear no traces of tales of abduction or induction ... — tom

Do you really want to claim that quantum mechanics and relativity did not begin as plausible conjectures to explain surprising phenomena (abduction), which had predictable experiential consequences (deduction) that were subsequently evaluated through rigorous experimental testing (induction)?

We act on beliefs, and nothing manifests genuine belief as convincingly as action that involves risk. — R-13

Right - Peirce once described pragmatism as "scarce more than a corollary" of Alexander Bain's definition of a belief as "that upon which a man is prepared to act."

I roughly believe that the human being is "essentially" an engineer and that thinking is usefully conceived of in terms of engineering. — R-13

I would probably not go quite that far. However, I do think that Peirce's characterization of inquiry as the struggle prompted by doubt, which has the fixation of belief as its goal, is analogous to ingenuity as the struggle prompted by uncertainty, which has the fixation of decision as its goal.

How do you circumvent "the problem of abduction" - i.e. that it's just another name for induction, which never happens in reality, because it can't. — tom

Abduction is not another name for induction, and induction can and does happen in reality. The scientific method employs both of them routinely. It seems like you may not be familiar at all with what Peirce meant by these terms.

Nominalism can be falsified: simply show evidence for a real universal. — Terrapin Station

What would you count as evidence for a real universal?

On the other hand, is realism is falsifiable?

The importance of this practical wisdom, though, is one of the things that thinking about thinking can clarify. — R-13

I fully agree with this, and my own primary philosophical interest is "thinking about thinking." For example, I have been working for a while on adapting Peirce's "logic of inquiry" in science to identify a "logic of ingenuity" in my profession of engineering. Furthermore, I see it as being applicable to other types of decision-making, including ethical deliberation. That being the case, I hope eventually to integrate it with my virtue-based approach to engineering ethics.

Would you say that you are not terribly interested in philosophy as the pursuit of wisdom? — R-13

No, I would not say that at all; but I am not only interested in philosophy as the pursuit of wisdom.

I'd describe it as thinking about thinking in the pursuit of the good life and the improvement of one's character. — R-13

I see this as primarily a matter of cultivating practical wisdom (phronesis) - i.e., good judgment in the form of good habits of feeling (esthetics), action (ethics), and thought (logic) - rather than just intellectual wisdom (sophia). Instincts, sentiments, common sense, tradition, etc. are all better guides than philosophy for that pursuit, especially since we often have to make decisions without taking the time to work out a comprehensive theory.

That is not what we mean by "realism" in this thread. We are talking about whether universals are real, not whether anything is real. You might want to take a look at the links from @Wayfarer to understand the debate.

I was claiming that there is no way to demonstrate that nominalism is true or false. — m-theory

Do you think that there is some way to demonstrate that realism is true or false?

Pierce and the Threat of Nominalism — Wayfarer

I read this book (the link is to a review of it) over the long holiday weekend and found it very illuminating. Thanks again for bringing it to my attention.

Some version of nominalism may be true — aletheist

How would you propose this could be demonstrated? — m-theory

Are you claiming that only propositions that can be demonstrated may be true? If so, how would you propose this could be demonstrated?

In any case, again, you will have to ask a nominalist.

We employ the words "exist" and "real" without worry in ordinary life. — R-13

What does "ordinary life" have to do with philosophy? I say that only slightly tongue-in-cheek. "Ordinary life" is a matter of employing habits based largely on instincts and sentiments, rather than philosophical or even scientific theories.

Again, I used "brute fact" in it is usual philosophical sense. — apokrisis

I had in mind this notion from Peirce: "A compulsion is 'Brute' whose immediate efficacy nowise consists in conformity to rule or reason." However, I broadly agree that our experience of reality, not just existence, includes encountering resistance.

Nominalism cannot be falsified, it cannot be true or false. — m-theory

A tautology (e.g., "all nominalists are nominalists") cannot be falsified, and yet is trivially true - in fact, necessarily true. Therefore, it is not the case that something that cannot be falsified cannot be true or false. Some version of nominalism may be true, in which case realism is false; or some version of realism may be true, in which case nominalism is false; and this binary obviously does not exhaust the possibilities.

Why should nominalism be taken seriously? — m-theory

You will have to ask a nominalist. Paging @Terrapin Station ...

Would you agree that many metaphysical debates are debates about how to best name the shared experiences that the discussion takes for granted as a condition of its possibility? — R-13

No, because characterizing the subject matter of metaphysical debates as merely how to name things sounds like presupposing nominalism.

I lean toward realism myself, but the usefulness of our models is not sufficient by itself to demonstrate that realism is true and nominalism is false.

The only prediction it had was wrong, as soon as we were able to observe it was useless. — m-theory

How have we observed that the earth is not at the center of the universe? Heliocentrism ultimately prevailed because it facilitated better predictions of things like when the sun would rise and set, and the locations of the stars and planets in the sky, without all of the ad hoc adjustments that geocentrism required.

I think it is more accurate to say realists claim the consistency in nature is real, and hence using models with universal laws produces useful results. — m-theory

That is clearly how you prefer to frame the issue. However, nominalists do not dispute that "using models with universal laws produces useful results"; what they dispute is that those laws are real apart from how we use them.

The prediction of geocentricism was that the earth was at the center of the universe, not that the sun rises and sets. — m-theory

No, the model of geocentrism was that the earth was at the center of the universe. Its usefulness was that it facilitated accurate (enough) predictions of certain phenomena, including when the sun would rise and set each day, and the locations of the stars and planets in the sky. It was when these predictions increasingly failed, requiring more and more ad hoc adjustments to the model, that it became imperative to come up with a different model.

To this day Newtonian mechanics is still taught in the classroom because it remains useful.
Newtonian mechanics still produces reliable predictions. — m-theory

Yes - under certain conditions, and therefore for certain purposes, that model is accurate enough.

If nature was inconsistent and had no universal principles why should our models be useful, and why should we be able to improve upon them? — m-theory

Right - and, returning to the thread topic, the consistency of nature calls for an explanation. Realists believe that the laws of nature are real and genuinely govern actual events, including those that will occur in the future.

That the sun rises and sets was an observation not a prediction. — m-theory

I referred to when the sun rises and sets - i.e., the time of each event - which varies each day. That was a prediction, and it was quite accurate under geocentrism. Likewise for the locations of the stars and planets in the sky - again, with various ad hoc adjustments over time.

Newtonian mechanics is not what I would call inconsistent with reality.
That would make it as useless as geocentricism. — m-theory

Newtonian mechanics will give you incorrect answers for certain scenarios; therefore, it is (to that extent) inconsistent with reality, and thus useless for solving those kinds of problems. It is not entirely useless, though, because it is consistent enough with reality for many other scenarios. Again, whether a particular model is an adequate representation of reality depends on the purpose in for which it is being used.

Or as George Box famously put it, "All models are wrong, but some are useful."

So, what's your argument against modal realism? — mosesquine

I disagree that whatever is thinkable necessarily can exist. — Agustino

In other words, the mere fact that we can think about unicorns does not (by itself) entail that unicorns can exist in some world other than our own, let alone that they do exist in such a world.

How was geocentricism useful, it did not provide accurate predictions? — m-theory

It provided very accurate predictions, especially as various ad hoc adjustments were incorporated over the centuries. For example, the sun rose and set right when the predictions said that it would.

And Newtonian mechanics is still useful, there are simply more accurate models. — m-theory

In other words, you now acknowledge that a model can be useful despite being inconsistent with some aspects of reality, as long as the modeler does not consider those aspects to be significant given the purpose of the model.

To say that a possible, or potential thing (non-actual thing) is real, is self-contradictory. "Real", by definition refers to the actual thing, as indicating its difference from the possible, or non-actual thing. — Metaphysician Undercover

No; you are ignoring the distinction between "real" and "actual," and instead treating them as synonyms. Realism regarding universals/generals is the view that the real is a broader category than the actual, such that possibilities and regularities (for example) are just as real as actualities. You are simply asserting nominalism - the opposing view that the real and the actual are one and the same. You cannot refute realism by simply insisting on a nominalist definition of "real."

Unless we can establish as a fact, that ideals are what is real, or at least some sort of relationship between ideals and reality, there is no basis for your claim that models must be "of something real", if they are useful. — Metaphysician Undercover

The model itself is ideal, but that which it is intended to represent is real. In particular, a mathematical model - i.e., a diagram - embodies the real relations among the parts of its object; and again, the modeler selects those parts and their relations as those that are significant, given the purpose of the model.

What the irrational nature of pi demonstrates is that a circle cannot have both a circumference and a diameter, in any absolute, or "ideal" sense. These two are incompatible, the diameter and the circumference, as the ratio between them cannot be resolved, in any absolute sense. — Metaphysician Undercover

Huh? The ideal sense is the only sense in which a circle can have both a circumference and a diameter in the exact ratio of pi. The two lengths are not "incompatible," whatever that means; they are incommensurable, which simply means - as I said before - that their ratio cannot be precisely measured as a rational number, not that it is somehow "unreal." The same goes for the ratio between the diagonal and side length of a square. It is not by accident that what we call "real numbers" include not only all rational numbers, but also all irrational numbers.

Even an infinite number of non-dimensional points could not produce a dimensional line, we must assume something in between the non-dimensional points, line segments. — Metaphysician Undercover

I agree with this, since it is the very definition of a true continuum. No multitude of actual points - not even the infinite total of all real numbers - comprises a line; instead, a line contains potential points exceeding all multitude. Every part of a continuum is itself a continuum, not an individual; every part of a line is itself a line, not a point. The dispute between realists and nominalists may also be framed as the question of whether there are any real continua of this sort; realists say yes, nominalists say no.

So the circumference is incompatible with the diameter, one is two dimensional, the other is one dimensional. — Metaphysician Undercover

This, however, is nonsense; if it were true, then the perimeter of a (two-dimensional) square would be "incompatible" with its (one-dimensional) side length, while the (one-dimensional) diagonal length of a square would be "compatible" with its (one-dimensional) side length. On the contrary, the perimeter and side length of a square are commensurable, but its diagonal and side length are incommensurable.

My point - in response to mtheory largely - was that they are as much a brute fact of existence as the material particulars which they govern. — apokrisis

I think that Peirce would disagree. He categorized all brute facts of existence under 2ns, but all generals under 1ns (qualities) and especially 3ns (regularities).

I would reserve the term 'existence' for 'phenomena' - broadly speaking, any object which can be known by science. — Wayfarer

The problem with this is that science does not just study "objects," it also studies laws - and in Peirce's terminology, laws are real (3ns) but do not exist (2ns).

Peirce says “Existence [. . .] is a special mode of reality, which, whatever other characteristics it possesses, has that of being absolutely determinate" - from here. — Wayfarer

He continues, "Reality, in its turn, is a special mode of being, the characteristic of which is that things that are real are whatever they really are, independently of any assertion about them." He also writes elsewhere that existence is a "mode of being of that which reacts with other things," that "existence means reaction with the environment," and "I myself always use exist in its strict philosophical sense of 'react with the other like things in the environment.'"

My point is there is no way to account for why our models are useful if those models are not of something real. — m-theory

And my point is simply that the usefulness of our models does not, by itself, guarantee that they are of something real. Geocentrism was a useful model for many centuries. Phlogiston and ether were useful models for a while. Newtonian physics is still a useful model today, even though we know that it is not strictly correct.

The models we live by are more or less reality-for-us until they break down. — R-13

Right, and the "breaking down" is what happens when reality confronts us with its independence from our thoughts about it. We maintain our current beliefs until such anomalies create the irritation of genuine doubt, which compels us to undertake inquiry in an effort to reestablish the equilibrium of stable beliefs.

So I think that it is only when a model is useful toward a particular type of goal, or end, that we can establish a relationship between the model and reality. — Metaphysician Undercover

Right - we create our models with some goal or end in mind, and that is what guides us in ascertaining which parts of reality and which relations among them are significant, such that we then include them in the model and leave out everything else.

But what the irrational nature of pi demonstrates is that there is no such thing as the aggregate of possible points equidistant from a single point. — Metaphysician Undercover

Again, if "thing" refers only to an actual individual, then that statement is true; but if "thing" can also refer to a continuum, then it is false - there is such a "thing" as a potential (not actual) aggregate of possible (not actual) points that are in the same plane and equidistant from any other single point. This is a real relation, not an existing object. The irrational nature of pi simply means that we cannot precisely measure the ratio of a circle's circumference to its diameter; it has no bearing on whether that ratio is real.

Yes, I know; you seem to have misunderstood my comment. I was asking @apokrisis to confirm that the reason why universals or generals are real is not because they themselves are brute or objective facts of nature, but because they govern the brute or objective facts of nature.

So if the criteria for being real is that we are encountering some brute or objective fact of nature, then universals or generals are real as limits on being. — apokrisis

To clarify - universals or generals are not real because they themselves are brute or objective facts of nature, but because they govern the brute or objective facts of nature. Right?

Action - being symmetry breaking - has to have a real symmetry that it breaks. — apokrisis

Is this related to the notion that the actualization of any possibility necessarily rules out others?

There is no such thing as a real circle ... — Metaphysician Undercover

Getting back to the question posed by the thread title, it depends on what we mean by "thing" and "real." If "thing" refers only to an individual and "real" is equivalent to "actual," then that statement is true and no one (except maybe a Platonist) regards universals as "real things." However, if "thing" can also refer to a continuum - a quality or regularity - and "real" encompasses whatever has its characters regardless of whether anyone ever thinks so, then that statement is false. In this sense, any potential aggregate of possible points that are all in the same plane and equidistant from any other single point is a real circle.

If our models were not of something real then it seems to me that they should not produce useful results. — m-theory

That which is real does not necessarily turn out to be useful, and that which is useful does not necessarily turn out to be real; hence the notion of "useful fictions." What I think we can say instead is that if our models do not represent something real, then eventually they will produce results that are in conflict with our experience.

It's funny, because I consider Beethoven superior to Mozart. — Noble Dust

Blasphemy! :-O I do often wonder how Mozart's music might have evolved, had he lived beyond the age of 35. Presumably he would have interacted further with Beethoven, of whom he supposedly said, "He will make a great noise in the world."

I'd say that it's what they're taken to represent, and add "just in case someone is using correspondence theory." — Terrapin Station

Fair enough, given your views.

Representation is a way of thinking about things. Representation is not a feature of non-mental existents. — Terrapin Station

It depends on exactly what we mean by "representation"; but again, I understand that this is your view.

,

Can we say that facts are the objects of true propositions - i.e., that which they represent? I guess this gets tricky on the view that truth is a subjective judgment. What other word can we substitute for true? Correct? Accurate?

In other words, that the difference amounts to seeing the conceptual abstractions as having the same qualities that they have as conceptual abstractions, only we're saying that they're not a mental phenomenon but some sort of phenomenon that obtains independently of people. — Terrapin Station

What would it mean to affirm that conceptual abstractions are not mental phenomena? I was under the impression that the whole debate between realists and nominalists is precisely over whether that which a universal signifies is real (independent of people) vs. strictly conceptual/mental.

I have clearly been wasting my time. Cheers.

You changed the statement. We agree that "there are no truths" is self-refuting. The statement was, "If there were no minds, then there would be no truths." Here the consequent, "there would be no truths," is NOT self-refuting. Consider this statement:

If there were no truths, then there would be no truths.

This is necessarily true - if P, then P - and thus obviously not self-contradictory.

But this part in particular is self refuting in my view
"There are no truths". — m-theory

That would indeed be self-refuting ... but it is not what I said. My statement did not assert anything about what actually is the case, but rather about what would be the case under a certain condition - IF there were no minds, THEN there would be no truths. There is simply no way to construe this as self-contradictory.

Seriously? This statement:

If there were no minds in our actual world, then there would be no truths in our actual world.

NOT self-contradictory, right?