Ah. <light-bulb emoji> You are trying to make the point that colour is a property of an object out there in the world, and not a consequence of looking at that object with human eyes. With that I must disagree.

I think @jkg20's point is that whilst you might disagree with it, neither you nor Steve Klinko have given an argument that he/she is wrong about this. We might be able to get an argument on the basis of @jkg20's reply to my last question about whether he thinks there is representation going on in the case of veridical vision, but we'll have to wait and see. Just saying that it is wrong and that physics proves it won't cut the mustard because as far as I understand it, @jkg20's position is that modern physics is contaminated by conceptual confusion about what colour is and so proves nothing.

But when you observe that something is red, you are talking about the frequency of electromagnetic radiation.

This seems wrong for all sorts of reasons. First, just from the ordinary language perspective there are plenty of people who talk about things being red who have not the faintest idea of what electromagnetic radiation is, so in the ordinary sense of "talking about something" they are certainly not talking about electromagnetic radiation. Also, prior to the century or so of science that culminated in Maxwell's equations, nobody had the faintest idea that electromagnetic radiation even existed, so it cannot be sensibly supposed that everyone was talking about electromagnetic radiation when they made observations about red things in the 16th century (for instance) You might want to say that what makes an observational statement like "the snooker ball is red" true involves and always did involve some story about electromagnetic radiation, but that is an entirely different claim from claiming that the person making the statement is talking about electromagnetic radiation. The difference to be sensitive to here is that between the meaning of a statement and the facts that make the statement true. Consider from the Steve Klinko perspective (with which you seem to be in sympathy) the following two statements:
1) I saw a red snooker ball
2) I dreamt about a red snooker ball
For Klinko and yourself "red" has more or less the same meaning in both statements. So, if you are claiming that in (1) the meaning of the term "red" unpacks in to some kind of talk about electromagnetic radiation, then it must also do so in (2). But in (1) that unpacking is (presumably) justified on the basis that electromagnetic radiation plays a causal role in making the statement true. So, either you have to deny that in (2) what is being talked about is electromagnetic radiation, and in which case you undermine your position that "red" in 1 and 2 have the same meaning, or you have to stick to your guns and say that electromagnetic radiation plays a causal role in making (2) true, but that is just empirically false. You cannot eat your cake and have it too.

I heartily agree. IQ tests provide an excellent means of ascertaining how good people are at taking IQ tests, that we can say for sure. People in the IQ business then go on and try to make statistical correlations between people's results on IQ tests and various other things. In most cases those correlations are both contestable and contested and always remain open to interpretation. Those who draw anything other than very tentative conclusions from the statistical data are usually manifesting some kind of bias.

But does case (3) involve a representation of a red snooker ball as well? If so, what's the vehicle for the representation in that case, is it the same kind of vehicle as for (1) and (2)?

I think Dummett became a Roman Catholic in the end, so that he ends up with a theistic anti-realism isn't a big surprise to some extent. As for the hardcore idealist line, denying that perception has an explanatory structure seems to be going against the grain of the principle of sufficient reason, and that principle is probably what drives them to idealism in the first place.

He at least had God keeping things in the quad when nobody was around

Yes, with God in the picture, Berkeley's idealism becomes a kind of realism, at least insofar as bivalence can hold of propositions that human beings could not even in principle come to know the truth of. It has the merit, then, of allowing for a reality independent of what you or I or our pets might think about it.

The only truly godless idealism that I'm familiar with tends to talk about permanent possibilities of perception being what underlies claims to the effect that unperceived/unknown facts/object etc exist. That just pushes the question back to what grounds those possibilities, of course.

Since the Red we experience with all 3 of these things is the same or at least similar, it is completely sensible to think that there has to be something common in the production of all three.

You are kind of missing jkg20's point I think. You seem to imply that in all three cases that there is an instance of redness that we are aware of. That might be the case for (3), but is it for (2) and (1)? What are you going to say to someone like jkg20 who denies (or at least appears to be denying) that any instance of redness is involved in cases of (1) and (2), and that it is only in case (3) that we have a genuine instance of redness, and it is the redness of the snooker ball?

Does that mean there's (1) no such thing as a proposition whose truth is unknown? Or just propositions where (2) we don't know how figure out whether they're true or false?

Not quite sure what you are getting at here. Anti-realism does allow for there to be sensible questions that we do not know the answer to - at least, it ought to, otherwise it runs not just counter to common sense but to any sense whatsoever. So, to use your example: Is there life on Mars? Now, we could turn this into the form: Is it true that there is life on Mars? Here we seem to have a proposition
P) There is life on Mars
the truth of which we do not know, yet which makes sense. How does an anti-realist account for this fact? I guess the response will be that it has meaning because we at least have some idea (perhaps many) of what would count as providing evidence for accepting it to be true.

In any case, you are correct to indicate that common sense is mired in realism. Berkeley tried to deny that his idealism ran counter to common sense, but was way off target if you ask me.

Maybe a fourth case needs to be added that might (and let me emphasise the might) push one to look for a common factor:
4) Visually mistaking a red snooker ball for a yellow snooker ball (e.g. because of light conditions, or perhaps an unusually virulent attack of jaundice).

In a case like that there is some pressure to think both that there is actually something that is yellow but that it is not the snooker ball, and in that case what is it that is yellow?

Why did you shot the sherif?

I was aiming for the deputy but the sheriff got in the way.

Well, if you don't want to answer my questions, answer @jkg20's question then:

Let me ask you a question: when I recognise intelligent behaviour, what are the intentional conscious activities I engage in to determine the extent, dimensions or quantity of intelligence? I certainly do not administer any kind of written IQ test.

tell me about someone able to recognize wich letter is wich without engaging into the intentional activity of reading the letters. — Tomseltje

Well, I don't know about you, but I don't intentionally read letters one by one when I read, I read whole words. I may have started reading by intentionally going letter by letter, but I gave that up a long time ago and I suspect you did too.

I don't think "truth consists in justification" is the same as a deflationary account, although it's been a while since I've thought about these issues so I might be wrong. As far as I remember deflationary accounts just point to the fact that there is no distinction between asserting a statement and asserting that a statement is true, and then claim that this is all there is to say about truth. An anti-realist theory of truth as justification would seem to be offering rather more to say about what truth is than a deflationist would be comfortable with (a realist theory of truth as correspondence would also be offering rather more than a deflationist would be comfortable with as well).

I'm not sure being an anti-realist about truth is to be skeptical - at least, I'd need to see the argument. As far as I'm aware anti-realism about truth boils down to the idea that the truth of a statement consists in its justification (where what counts as justification will vary from domain to domain). I might be wrong about that, and I might be wrong about it not entailing skepticism, but you'd need to help me see the error of my ways if so.

Incidently, if one is an anti-realist about truth in general, wouldn't that entail anti-realism for all domains about which true statements can be made?

Isn't it more along the lines that whilst both the anti-realist and realist can accept that weather reports/general facts about tree stability in the face of high winds etc can justify the claim that the tree fell over during the night, for the anti-realist the truth of that claim actually consists in those justifications whilst for the realist, those justifications allow one to infer the existence of a state of affairs that makes the claim true regardless of those justifications?

Depending on the system of rules of inference you have at hand, it could be as simple as
1) ∀x.∀y.p(x,y) Premise
1 2) ∀y.p(a,y) 1, Universal Elimination
1 3) p(a,b) 2, Universal Elimination
1 4) ∀x.p(a,x) 3, Universal Introduction
1 5) ∀y.∀x.p(y,x), 4, Universal Introduction
6) ∀x.∀y.p(x,y) -> ∀y.∀x.p(y,x) 1,5 Conditional Introduction

I wouldn't bother with Tomseltje, or Flux23 for that matter - they just avoid the issue. Flux23 got the hump and stormed off with a parting "do you know who I am?" defence of his position, which is always a good sign that a person is on the ropes argumentatively. Tomseltje never seems to respond to direct questions.

@Srap Tasmaner<br /> There's something niggling at me that makes me want to say that the difference between an actual state of affairs and a possible state of affairs is significant to understanding W here, but I'm having difficulty putting my finger on what might be the difference between our positions here. I'll have a rethink and see if I can be more precise - but you may be right that there is nothing significant here.<br /> <br /> @Sam26" I think it is pretty clear that whatever "objects" are for W, they definitely are not the medium-sized dry goods we're familiar with in our everyday lives. Perhaps my use of "object" = "object of perception" gave you the impression that I was in danger of making that kind of link, but really I'm not. I am still tempted by the idea of linking W's logical space to the idea of the visual field, and so tying objects to smallest identifiable elements of the visual field, but (1) that's a long way from confusing objects with everyday macroscopic or microscopic things and (2) I'm not wedded to that idea. I appreciate that the Tractatus has very little to say explicitly about perception (5.5423 is about the only exception that I noticed during my skim read) and perhaps W thought that one of the problems with previous philosophy is that philosophers were trying to say things about perception that could not really be said (interestingly, 5.5423 has a diagram).

@Srap Tasmaner

It seems clear that any predicate will have such a smallest unit of applicability, and then the smallest unit of difference in the world we can imagine is such a predicate applying or not applying to one such a unit.

I think @Posty McPostface touches on what I'm about to say in his last post. Do we need to be careful about introducing talk about predicates when expounding W's arguments in this part of the Tractatus? 2.0231 says that we do not get material properties until we already have configurations of objects, and predicates are generally used to signify material properties. Unlike Frege who had a basic ontology of concept and object, and a corresponding predicate/name distinction, W in the Tractatus seems to be burrowing down deeper and has only objects and names. Of course, these are issues we'll be digging into in more depth when we start dealing with W's theory of symbolism. I get, though, that you are just giving an analogy of how one might argue for some kind of foundationalism, but we might need to come back to W's argument for foundationalism once we've dealt a little more with his ideas about depiction (somewhere he gives the metaphor of depiction involving putting out feelers, and there needs to be something that feelers can grab hold of - if everything they grab hold of dissipates when grabbed, then they never end up touching reality).

@Posty McPostface The link to the Jeff Speaks lecture notes was useful, thanks.

I'm travelling for the next few days - I'll have the Tractatus with me and will have some time to be on the internet, but it might be intermittent.

Under relational logic there will be some relations that are are reflexive and some that are not. In this case, q is a reflexive relation. Think of the relation "as tall as". I am as tall as myself, so "as tall as" is reflexive since it holds between me and myself. It also holds between me and anyone else as tall as me. However, "smaller than" is not a relation that holds between me and myself, even though it holds between me and anyone smaller than me.

Does that help, or am I missing your point?

Thought, language and world meet at the crossroad of perception, at least that seems to be a reasonable idea, and obviously would have occured to W, and his use of perceptual concepts at 2.0131 and 2.0251 cannot be accidental. Having said that, I'm still going to retract my earlier emphasis on the perceptual in the light of @Srap Tasmaner's earlier remarks, and I am not going to insist that "object" = "object of perception" or sense data, or whatever : although I reserve the right to retract that retraction as we move on. As I suspected from the beginning, the Tractatus seems to be peculiar (perhaps unique) insofar as to understand any part of it, you have to understand all of it, and I'm expecting a good deal of toing-and-froing in my opinions.

@Srap Tasmaner

Anyway, I think states of affairs are more or less by definition possibilities, and a fact is such a possibility obtaining. Thus the world (i.e., the actual world) is fully determined by which possibilities happen to obtain.

I can see that - there is as you indicate a lot of emphasis on modality in the opening sections dealing with states of affairs and objects, including what seems to be an almost impossible constraint on knowledge of objects requiring knowledge of all the possibilities for that object. However, on the other hand doesn't at least some of what is going on in these opening propositions suggest a distinction between actual and possible states of affairs? For instance, one thing we can be sure of is that in these sections, there is no such thing as a merely possible object: objects just are and they make up the substance of the world. States of affairs are combinations of these objects, so it looks like at least some states of affairs must be actual and not just possible.

Another thing that makes me doubt that states of affairs are just possibilities is that, possibilities - whatever they are - certainly seem to be real for W (although of course not actual) and so they exist, and at proposition 2 we have a fact described as the existence of states of affairs. If states of affairs are just possibilities, then 2 would seem to imply that facts are just possibilities too, whereas facts - like objects - seem to be always in the realm of the actual for W (don't they? he does talk about negative facts, of course, so perhaps talk about possible facts also makes sense for him). Anyway, this specific point may be a translational issue - perhaps (2) should better be read along the lines "a fact is the obtaining of states of affairs".

You can imagine a collection of things, but even if you imagined a collection of everything, you would not be imagining a world.

(

1) A collection of things;
(2) A collection of things arranged into states of affairs;

This distinction I do have a problem with, at least at the moment as an interpretation of W - given 2.012 and 2.0121 . I may not be understanding you clearly, but I take it that the idea is that the difference between (1) and (2) is that the latter has the requisite form. However, arguably whatever form a collection of objects has is derived from and only from those objects, so any collection of objects has form at least in some sense. So the issue would then be to find some non-accidental way of distinguishing between types of forms such that on the one hand we have states of affairs, and on the other just some other kind of collection of objects. Perhaps there'll be some answers to this when we move on to W's theory of representation.

By the way, the proposal about how to present subsequent post formatting as we move on to other sections seems to be a good one to me.

Should we move on, or do people think there is more to milk out of these first few propositions?

There's a lot in your main post, and it's late where I am so I'll be replying tomorrow, although I think you might be right that I have overworked the colour angle - space time and colour are forms of objects, but at least the translation I have does not add a definite article. I'll reread the section tomorrow in light of what you say and have another stab at it.
@Posty McPostface On the terminological points, we should think of "atomic fact" and "state of affairs" as synonyms. Atomic facts are combinations of objects/things. So we have a threefold ontology of facts, atomic facts and objects/things. The relationship of facts to atomic facts is pretty much that the former are just collections of the latter, with atomic facts being things that can exist with absolute independence. The relationship of atomic facts to objects seems to be more complicated, since it is not just one of whole to its parts insofar as the parts (objects) cannot have an existence independent from the whole (atomic facts) whereas typically a part-whole relationship does allow for independent existence of the parts (buildings and bricks for instance). However, at this point I need to have a think about ST's post and a reread of the sections of the Tractatus before saying anything else.

Here we go then - some reflections and remarks on propositions 1 to 2.062.
A point about terminology first of all - the translation I have uses "facts" as the translation for "tatsachen", and these I just take to be facts of the common-or-garden kind - e.g. the fact that Theresa May is Prime Minister of the United Kingdom and Northern Ireland, that tap water is mostly hydrogen dioxide. The translation I have uses "state of affairs" to indicate the fundamental truth-evaluable consituents of facts (as per proposition 2). I'll stick with "state of affairs" in this post, but am happy to adopt a different terminology if appropriate. Lastly, "objects" are the things the combinations of which constitute states of affairs (2.01)

My overall impression is that W is attempting to present us with a mix of rationalism and empiricism. Why? Well, on the rationalism side, taking 2.012, 2.0121 and 1.13 together there seems to be a particularly strong form of the principle of sufficient reason in play, and there is also a form of foundationalism evident in 2.0.2 - 2.0211. Everything that actually exists seems to depend on everything that might possibly exist (2.013) and the modal world is one that outstrips any of our perceptual capacities. Yet when I come to know an object (and I presume that W believes we can know objects) my knowledge encompasses all its possibilities (2.0123) and so has to outstrip what is available from perception. So much for the rationalism, what about the empiricism? Well that for me comes down to what these things called objects, the combinations of which make for states of affairs, actually are supposed to be. I take it that it is no coincidence that at 2.0131 we have W talking about specks in the visual field, and then going on at 2.0251 to say that space, time and colour are forms of objects. My initial inclination - which I admit may be naive - is to suppose that these objects can thus be thought of as elements of the visual field, which would make these objects, which are a basic ontological element of his system, objects of perception, so if we do come to know them it must be on the basis of perception. Of course, there is the somewhat cryptic remark at 2.0232: In a manner of speaking , objects are colourless. But note the hedge with which that begins. I think here that W is saying that objects are colourless in the sense that although a specific object participating in a state of affairs must have some colour - since the state of affairs itself is (on my understanding) the state of affairs that an element of the visual field has a certain specific colour - nevertheless that object could have any other colour - it could have been a constituent of many different possible states of affairs. But, even here there is an element of rationalism in play, since objects do not exist independently of possible states of affairs (2.0122), and the entirety of possible states of affairs is written into the very essence of the object (2.012, 2.0141).
So, I suppose this at least raises the question of where W stands in relation to rationalism and empiricism - is he trying to offer an alternative way of melding/surpassing them than Kant proposed? After all for W space and time are on the surface at least forms of objects, not forms of perception of objects as in Kant. However, having said that, by adding colour into the forms of objects, W seems to be tying the notion of an object and an object of perception so closely together that making a distinction between them is not easy, and so in stating what the forms of objects are he would also be giving us the forms of perception.
A few related side questions which occured to me but to which I have no response:
Why have colour as a form of objects and not shape? Is the latter supposed to be subsumed under the form of space?
Is a world entirely without colour unimaginable? In 2.0131 we have not just vision but also hearing and touch being gestured to, yet it is colour that wins the prize at 2.0251, not pitch or hardness.

One point I am having a little difficulty understanding concerns 2.05 - 2.063. If the totality of existing states of affairs determines the non-existent states of affairs, why can we not infer the non-existence of some states of affairs given the existence of other states of affairs (2.062)? Is the determination talked about in 2.05 not logical determination?

So, as it stands at the moment, given my understanding of the propositions 1 to 2.063, I'm going to be under the impression that the space of possible states of affairs is to be thought of as the visual field. If that is a fundamental error, it would be good to find out before I go any further!

@Wayfarer@jkg20:up: I'm going to stay over here in the dunce's corner, now that two more able people are here to stand in my stead. I am hoping that tom's current parading of the Deutsche principle as some kind of panacea for philosophical issues about the mind, will go the same way as his earlier parading of the Free Will Theorem (i.e. into the dustbin of irrelevance).

No.

And tom is one of his altar boys.

The Deutsch Principle applies to all of Reality, even humans.

Wrong, the Deutsche principle applies explicitly to two things and two things only, finitely realizable physical systems and universal model computing machines, neither of which in isolation nor in conjunction can be claimed to constitute all of reality without further argument. But I've had enough now, I'll go and join @Noble Dust in the dunce's corner.

What has Godel got to do with any of this?

Take it up with Akl and co. - the paper I linked to draws a parallel between Godel's work on completeness and consistency in arithmetic and the impossibility of acheiving a universal computer. I have not read Rosen, but given what @StreetlightX says, it seems he (Rosen) also thinks there is an implication of that work on the Turing-Church thesis. Curious that Deutsche did not make any reference to Rosen's work.

Right, they are abstractions obeying abstract rules, not real physical systems obeying the laws of physics.

Physical systems that obey the laws of physics may be emulated on certain other physical systems that possess the physical property of computational universality.

You don't seem to understand that in the Deutsche principle which you presume to be relevant to this thread, the universal model computing machine he is referring to is an abstract model, he is not using the term to refer to actual nuts and bolts and silcon-chipped physical machines. Computational universality is a mathematical construct. Deutsche's principle is about the extent of what that construct can be used to model. Read the paper you linked to, his brief discussion of what a UMCM is makes it clear that it is an abstract model.

Babbage's Analytic Engine is a universal computer, as are PCs. These are all finite state machines. Ignoring the fact that Turing machines do not exist, they are not finite state machines. — tom

You display here even more confusion about the abstract notion of a machine, on the one hand, and its physical implementations, on the other. If by "universal computer" you mean to evoke the same concept that Deutsche is using when he talks about universal model computing machines, your statement is false, since UMCMs (like Turing machines) have infinite memory, something which no actual physical implementation of any abstract machine actually has. Furthermore, a finite state machine is a mathematical construct just like a Turing machine, in a sense it is a conceptual restriction on a Turing machine, just as Deutche's UMCM is a conceptual extension of a Turing machine.

The real point here, anyway, and one which you seem to be overlooking by getting bogged down in nitpicking about technicalities - presumably the aim being to catch me in an outrageous error - is whether the Deutsche principle applies to human beings andthat question turns on the philosophical question whether human beings are finitely realizable physical systems, about which the Deutsche principle has nothing to contribute.

Playing it by ear to begin with anyway - there's so much secondary literature. I'll have a shot at expressing my understanding/problems without recourse to it for the moment - it'll probably end up being a little bit naive, but it might serve a purpose anyway.

Hi - yep, sorry, apart from a few off the cuff contributions to other threads, I've been a little bogged down with other stuff. I'll put my thoughts on propositions 1 up to 2.1 together today and will post them later today, for better or for worse.

@tom

What has the Turing machine got to do with any of this, or Godel for that matter? What laws of physics do Turing machines obey?

To the first question, I suggest you read the papers referred to - and note that the remark was about Turing machines and their extensions (Deutsche's universal model computing machine is an extension of a Turing machine).
To the second question, is it a trick one? Turing machines (and their extensions) are abstract constructs, as such the notion of obeying a law of physics does not apply to them. If you are talking about actual physical machines that attempt to implement the operations of a Turing machine, then I suppose contraptions like that must obey all the same laws of physics that any physical contraption obeys. Why? What's your point?

Point taken. In fact when I admitted that the Deutsche principle applies to physical systems, I should have more accurately stated that it applies only to finitely realizable physical systems.

Hmm - I'm not going to speak for jkg20, but neither statement (1) nor (2) has any "on the surface" implications about visual images or internal conscious phenomena, whatever they might be. The explicit quantification is over instances of visible properties ("the redness of the snooker ball") and psychological subjects ("I"), the difference between 1 and 2 (if there is one) comes down to a difference of connection between these two things. Sure, if you already come at the two statements with a pre-existing philosophy of perception, you might reinterpret the statements as talking about visual images and so on, but then what's to recommend that kind of philosophy of perception? The traditional arguments for indirect realism (and you seem to be hinting at some kind of indirect realism) - i.e. the arguments from illusion and hallucination - tend to be given shortish shrift these days, mostly on the grounds that they try to arrive at metaphysical conclusions on the bases of epistemological premises.

The claim made is not that computable functions cannot be computed, that would be a contradiction in terms. The claim is that there are computable functions that cannot be computed by specific types of computing machine (i.e. Turing machines and their extensions). Read the work of S.G. Akl if you are really interested in specific examples.

I think you are missing @jkg20's point. Note the use of the personal pronoun in both the statements.

@tomThe Deutsche principle applies to physical systems. Physical systems are part of reality, sure, but whether or not human beings are just physical systems is precisely the issue in question and so whether or not the Deutsche principle applies to them is a question the Deutsche principle is not going to be able to answer.

I'm not sure why you think the first remark is funny - I didn't find anything particularly amusing about this paper

The earliest known design of a universal computer is Babbage's Analytic Engine.

Whatever Babbage's Analytic Engine was, that it was the realization of a universal computer is what the computer scientists I am talking about deny. Specifically they deny (in fact they claim to be able to prove) that there are computable functions that cannot be computed on any machine capable only of a finite number of operations.

It is proved that current known laws of physics obey the Deutsch Principle. It is conjectured that all future laws must also.

That says nothing to the question whether the principle applies to human beings.

"Every finitely realizable physical system can be perfectly simulated by a universal model computing machine operating by finite means"
That's what Deutsche takes to be his physical version of the (unproven/unprovable) Church-Turing thesis.
There are a handful of scientists who believe that a universal computer cannot be realized, but that is a technical argument in computer science. The issue here seems to be more the following question: are human beings finitely realizable physical systems? If they are not, then the Deutsche principle is entirely irrelevant. Of course, the Deutsche principle itself does not provide the means to answer that question, and was not intended to.

@FLUX23

Oh by the way, I am a scientist and I do measurement every weekdays. I have a PhD in chemistry and I skipped a year in doing so. Thank you very much.

Why are you parading your credentials? Does having a PhD in chemistry - or indeed any subject - provide immunity from conceptual confusion?

@Tomseltje

You sound alot like someone acknowledging that he/she can move his/her arm, but denies the chemical reactions taking place within your muscle tissue.

Exactly what I have I said that entails skepticism about the science of human physiology? Plenty of what I have said manifests skepticism about what the IQ industry is messed up in, but nothing I have said undermines the work of physiologists.

I'm using the terms"measure" "measurement" and so on in exactly the way they are used in science and daily life. Scientists measure things all the time, for instance. Certainly there are philosophical issues around what measurement actually is, but they arise on the basis that it is always an intentional activity. You seem to be using "measure" in the sense of "differentially react to", thus stripping it of the intentional aspect, which is not common practice at all - it is a special and technical sense of "measure" that you have helped yourself to and that I am not even sure any scientist uses, you have singularly failed to provide me with a reference to such a definition, but perhaps there is one. My knee reacts differentially to being struck, but my knee doesn't measure anything when it does so.
My skepticism about intelligence being something that comes in amounts and is measurable was under attack because I was supposed to have been forced to accept that I am measuring intelligence when I recognise intelligent behaviour. If by "measure" you mean just "differentially react to" then, because simply in recognising intelligent behaviour I differentially react to intelligent behavior, the idea that I "measure " intelligence in that sense is tautologically empty and says absolutely nothing to the point that intelligence is a thing that comes in amounts and can be measured in the way scientists measure things.

I'm not convinced it is just terminology. The point is scepticism about there being a thing called intelligence that comes in amounts and can be measured, in the ordinary sense of measurement that goes on when people take themselves to be measuring IQ. When I doubt this, I am told that it must be a measurable thing because we can recognise intelligent behaviour. I claim that recognition and measurement are entirely distinct things and recognising something need not involve measuring anything - in that same perfectly ordinary sense of measurement, and also - as if it were any different - in the sense defined by Tomseltj. Then I am told there is a special technical sense of measurement, but no one seems able to tell me what that is, nor why it needs to be going on when I recognise intelligent behaviour. If all you mean is that there must be brain activity going on when I recognise intelligent behaviour, sure, maybe that's right, but that does not entail that what that activity is is measuring something called intelligence.