Showing posts with label Categories. Show all posts
Showing posts with label Categories. Show all posts

Tuesday, January 26, 2010

Henry of Ghent on real relationships

According to Henry, all real relationships are ultimately based on the absolute features, parts, or constituents of the things that are related. For instance, the fact that Peter is taller than Paul is based on the fact that Peter and Paul have certain heights, and the fact that the chairs in my kitchen are similar in color is based on the fact that they are all white. The same goes for any relationship: there is always some absolute basis for it.

Nevertheless, Henry does not believe that a real relationship consists simply in some x and y having the right sorts of absolute features, parts, or constituents, for if that were the case, then the only connection between x and y would be something we draw in our minds. But as Henry sees it, real relationships are real, so there must be some sort of genuine ‘relatedness’ that exists outside the mind.

However, Henry does not think this relatedness can be a distinct thing in its own right. After all, if it were a distinct thing, then it would have to be related to its basis by some further relatedness, and if that relatedness were also a distinct thing, it too would have to be related by yet another relatedness, and so on ad infinitum. But that is absurd, so Henry concludes that the relatedness we are seeking cannot be a distinct thing in its own right.

Instead, says Henry, it is just a special ‘way of being’ for the absolute basis in question. In particular, it is a way of being which ‘looks outwards at’ (respicit), and so points towards, something else. And this outward-looking characteristic (respectus) transforms, as it were, the absolute basis into a ‘pointing thing’. Hence, on Henry’s view, some x is really related to some y because it really has something in it that points towards y.

Tuesday, July 14, 2009

One argument of Scotus against Henry of Ghent (translation)

From the Lectura

‘According to the Philosopher in Physics 5, a change belongs to the same species as its end-point, just as [the act of] whitewashing [a log] belongs to the species of whiteness, not the species of “white-log”, which is only one “thing” incidentally’.

[Scotus, Lect. 1.5.2.un., n. 72 (Vat. 16: 437.2-4): ‘quia secundum Philosophum V Physicorum [224b6-8] mutatio est eadem specie cum termino, ut dealbatio cum albedine, et non cum ligno albo, quod est unum per acccidens’.]

From the Ordinatio

‘A production is placed in a genus or a species from its formal end-point, as is clear from the Philosopher in Physics V [224a26-30]. For instance, a change in quality is placed in the genus of quality, for here there is a [qualitative] form which is the formal end-point of the change in quality. Therefore, if the formal end-point of some such production were a relation, that production would be placed in the genus of relation, and it would not be a generation’.

[Scotus, Ord. 1.5.2.un., n. 69 (Vat. 4: 49.8-13): ‘productio ponitur in genere vel specie ex suo termino formali, sicut patet per Philosophum V Physicorum, — sicut alteratio ponitur in genere qualitatis, qua ibi est forma quae est formalis terminus alterationis; ergo si formalis terminus huiusmodi productionis esset relatio, ista productio poneretur in genere relationis et non esset generatio’.]


From the Reportatio

‘Change and every per se production is placed per se in the genus of the end-point to which [the change or production is directed], and [it is placed] precisely in the genus of the formal end-point, according to Physics V, where examples are given from each [kind of] per se motion or change, namely generation, alteration [i.e., change in quality], and growth [i.e., change in size]. If, then, the formal end-point of the Son’s production were a relation [i.e., the Son’s unique property of sonship] rather than the [divine] essence, then the Son’s production would not be a generation, but more a change in relationship’.

[Scotus, Rep. 1.5.2.un., n. 63 (Wolter, 275): ‘mutatio et omnis per se productio ponitur per se in genere termini ad quem et praecipue in genere termini formalis, V Physicorum, ubi exemplificatur de omnibus per se motu et mutatione, scilicet generatione et alteratione et augmentatione. Si igitur formalis terminus productionis Filii non est essentia sed relatio, tunc productio Filii non esset generatio, sed magis adaliquatio erit’.]

Thursday, February 12, 2009

Aquinas on what kinds of correlatives distinguish the Son and Spirit

It's been some time since I've posted, as I've been busy writing a paper on Arius and Athanasius. That's pretty much done now, so I can jump back into what I've been posting about for the last couple of months, namely one of Aquinas's argument from the Summa Contra Gentiles on the filioque. This argument is fairly complicated, so I've been posting on it for some time now.

Up to this point, Aquinas has argued that spirits can only be distinguished as opposites, and the only kinds of opposite features that can distinguish the Son and Spirit are correlative opposites (like 'double' and 'half', or 'father' and 'son'). But then Aquinas wonders which kind of correlative opposites distinguish the Son and Spirit. In the last post, I explained that Aquinas says there are two basic kinds of correlatives: sameness-correlatives and action-correlatives. Sameness-correlatives are 'being the same as' (or 'being different from') with respect to substance (i.e., identity and distinction relations), quantity (equality and inequality relations), or quality (similarity and dissimilarity relations). Action-correlatives obtain between things that do an action and things that have that action done to them. Okay, so that's where we got to last time. Let's move on.

Given these two kinds of correlatives, which kind applies to the Son and Spirit? Aquinas says the first kind (sameness-correlatives) doesn't apply. Long before Aquinas’s day, Augustine established that the Father, Son, and Spirit must all be the same in substance, quantity, and quality. That is, they are all the same substance (they are all the very same God), they are all equal in magnitude or greatness, and they are all qualitatively similar (all have the same divine attributes).

Aquinas accepts this Augustinian rule, and so the divine persons can’t be different in any of those ways. Consequently, they can’t be opposites in any of those ways either. If two things are the same, they’re not opposites. Cicero and Tully are not opposite substances because they’re the same substance; two 10kg blocks are not opposite in weight because they have the same weight; and two white objects are not opposite in color because they’re the same color. So the divine persons are not opposites with respect to sameness-correlatives.

That leaves the second kind of correlatives, i.e., those based on action. But here, Aquinas makes an odd statement:

When it comes to correlatives based on action or passion, one of the pair of correlatives is in a subject that’s unequal in power [to that of the other’s subject]. The only exception are correlatives based on origination, for there nothing is designated as the ‘lesser’. Rather, in cases of origination, we find something that produces another which is similar and equal to it in nature and power.

Aquinas seems to be saying that most of the time, when one thing acts on another, one of them has more power than the other. But there’s a special case where this doesn’t happen, and that’s called ‘origination’. In cases of origination, one thing produces another, and the producer and the product are the same kinds of things (similar in ‘nature’, as Aquinas puts it), and they have the same degree of power.

What I don’t get about this is the claim that an action always involves one thing that has more power than another. What about when living organisms beget offspring? In those cases, Aquinas is happy to say that the producer and the product are the same kinds of things, and so they would also be equal in power. Humans are humans, and they have the exact some innate powers, irrespective of whether they’re fathers or sons.

Perhaps Aquinas is thinking about the raw materials that a producer uses to make a product. Raw materials don’t have any of the powers they have once they’re fashioned into a product (raw steel isn’t drive-able, but a car is), and so of course the producer has more power than the raw materials it uses to make a product. Or maybe Aquinas is thinking of offspring that need to develop their powers. Human zygotes don’t initially have the same powers as their parents. They have to develop those powers.

More generally, perhaps Aquinas is thinking that every action involves an agent and a patient, where the agent has active powers (powers to do something), and the patient has passive powers (powers to have something done to it). Thus, for every standard case of action down here on earth, the agent is more powerful than the patient.

But if that’s right, then Aquinas thinks ‘origination’ is a very specific kind of production that occurs only in the Trinity. Natural generation here on earth would not count as ‘origination’. Only in the Trinity is the producer and the product totally equal in power, for that’s the only instance of production that doesn’t involve any ‘moment’ when the patient (an underdeveloped product or the raw materials) has less power than the producer.

There might be something else going on here too. In most cases of production, producers cause their products to come to exist. That is, products depend on their producers for their existence. One would think that this applies in the Trinity too. If the Father produces the Son, then surely the Son depends on the Father for his existence.

However, the Son is supposed to have aseity -- and part of what it means to have aseity is not to depend on anything for existence. How then, can the Son both have aseity and be produced? This is a difficult issue, and I don’t intend to go into it here. The point is just that Aquinas might be thinking that products normally don’t have aseity, but in the divine case, the products (the Son and Spirit) do have aseity, and so he uses a special word -- ‘origination’ -- to talk about that special kind of divine production.

Still, that seems a stretch. Aquinas makes no mention of aseity or existential dependence here. Instead, he talks about the producer and the product being the same in kind and power. So I would think my former comments about power are closer to the mark.

In any case, Aquinas concludes from this that ‘origination’ is the only action that applies to the Son and Spirit, and so the only kinds of correlatives that can apply here are those based on origination. And presumably, these correlatives are the features of ‘being the producer of’ and ‘being the product of’ for an instance of origination. Finally, then, Aquinas has identified the opposite features in question. These are the features that distinguish the Son and Spirit.

Friday, January 16, 2009

Aquinas on different kinds of correlatives

Aquinas says that the Son and Spirit are opposites, but we can ask: what kinds of opposites are they? In the last post, I explained why Aquinas thinks that of Aristotle's four kinds of opposites, the Son and Spirit are only opposites in the way that correlatives are opposites. However, there are different kinds of correlatives, so Aquinas needs to say something about the different kinds of correlatives.

To that end, Aquinas says that correlatives come in two kinds: those based on ‘quantity’, and those based on ‘action’. (Note that Aquinas surely has book 5 of Aristotle's Metaphysics in mind here.) Let’s look at each in turn.

(a) Quantity. The term ‘quantity’ is a little misleading in this context, and Aquinas's comments ehre can be a little obscure. Here's the stuff to keep in mind. Instead of ‘quantity’, it would probably be more helpful to talk about ‘sameness’ and ‘difference’. Let me explain.

Whenever two things are the same in some way, they are said to be ‘one’ in that way. For example, Socrates and Plato are the same kinds of things: they are both humans. Thus, we can say that they are ‘one in kind’. In this sense, sameness is based on situations where two things are ‘one’ in some way.

But when two things are different in some way, they are said to be ‘many’ in that way. Socrates and Felix the cat, for example, are different kinds of things. One is a human, and the other is a cat. Thus, we can say that they are ‘many in kind’ (in the sense that there are many (more than one) kinds of things there). In this sense, difference is based on situations where two things are ‘many’ in some way.

Now, talking about ‘one’ and ‘many’ makes it sound as if we’re talking about quantities — either one or many — and so Aquinas (following Aristotle) classes this kind of sameness and difference under the broad heading of ‘quantity’. But really, he is thinking of two things being the same (being ‘one’) or different (being ‘many’) in some way.

Aquinas next points out that there are only three ways that something can be ‘one’ or ‘many’ (same or different).

(i) First, two things can be the same or different with respect to substance. This is what the medievals (and us too) call identity and distinction. That is, when some x and y are they very same thing, they are identical, but when they are two things, then they’re distinct. For example, Cicero and Tully are identical, for ‘Cicero’ and ‘Tully’ are just two names for one and the same person. But Cicero and Plato are distinct, because Cicero and Plato are two separate persons.

(ii) Second, two things can be the same or different with respect to quantity. This is what the medievals (and us too) call equality and inequality. Note that here Aquinas is talking about ‘quantity’ in the strict sense (as in, the second of Aristotle’s categories). When two things are the same size/weight/some other quantity, then they are equal with respect to quantity, but otherwise they’re unequal. For example, two 10kg blocks are equal in weight, but a 10kg block and a 5kg block are unequal in weight.

(iii) Third, two things can be the same or different with respect to quality. This is what the medievals (and us too) call similarity and dissimilarity. When two things are the same in color, temperature, or some other quality, then they are similar with respect to quality, but otherwise they’re dissimilar with respect to quality. For example, the white table in my kitchen and the white walls in my living room are similar in color, but black cows and red cows are dissimilar in color.

At this particular point in his text then, when Aquinas talks about correlatives that are founded on ‘quantity’, he is talking about two things being ‘one’ or ‘many’ (same or different) in one of these three ways. Aquinas does not always talk about ‘quantity’ correlatives like this. More frequently, he talks about ‘quantity’ in the stricter sense, in which case he is talking about equality and inequality (type (ii) above). Here, I’ll just say ‘sameness-correlatives’ when I mean the broader kind based on ‘one’ and ‘many’, and I’ll reserve the word ‘quantity’ for the strict sense that pertains to equality and inequality.

(b) Action. The second kind of correlative is based on action. These sorts of correlatives occur between two things where one acts in some way on the other. In these cases, one thing x acts on another thing y, and a specific relationship occurs between the two that is based on that action.

Aquinas gives ‘mover’ and ‘moved’ as an example. When one thing moves another, there is a reciprocal relationship there: one thing does the moving, and the other gets moved. The mover/moved relationship is based on the mover’s activity that causes the movement.

Aquinas also gives ‘master’ and ‘slave’ as an example. The idea is that a master/slave relationship is based on the activity of governing and being governed: the master governs the slave, and the slave is governed by the master. Another example Aquinas gives is ‘father’ and ‘son’, for the father/son relationship is based on the father’s reproductive activity that brought the son into being: the father does the producing, and the son is produced.

Wednesday, December 24, 2008

Aristotle on Opposites 4: Contradictories

In the Categories 10, Aristotle describes four different kinds of opposites. I talked about the first three of those in the last three posts. As for the fourth, Aristotle says that contradictories are opposites.

Contradictories are pairs of statements, one of which is an affirmative sentence of the form 'x is F' (as in, 'Socrates is sitting'), and the other of which is a negative sentence of the form 'x is not F' (as in, 'Socrates is not sitting'). Negative sentences can also be expressed as 'it is not the case that x is F' (as in, 'it is not the case that Socrates is sitting').

(I use the word 'sentence' here instead of 'proposition' because I don't know if Aristotle believes in propositions -- i.e., eternal, abstract statement-like entities that somehow describe the world or worlds. I'd also be happy to use the word 'statement' too.)

Right off the bat, it's clear that contradictions belong to a separate class of opposites than the other three (namely: correlatives, contraries, and possession/deprivation). Contradictions are sentences, but the rest apply to some feature of things. Correlatives are relational features, contraries are non-relational features, and possession/deprivation apply to natural features, but none of these are sentences.

Further, Aristotle points out that if we do try to express the other kinds of opposites with language, we express them with predicates, not full sentences. 'Double', 'hot', and 'having sight' are predicates, and predicates don't contradict anything. Only sentences can be contradictory. ('Hot' doesn't contradict anything, but 'that thing is hot' contradicts 'that thing is not hot'.)

But can't we formulate contradictory sentences about any of the other kinds of opposites? Take sight and blindness. Can't we say 'Socrates is blind' and 'Socrates can see', and aren't those contradictory sentences?

According to Aristotle, the crucial characteristic of contradictions of this: it's always the case that one of them is true, and the other is false. We can, of course, form contradictory sentences from the other kinds of opposites, but it's not always the case that one is true and the other is false.

There are cases, for example, where both 'Socrates can see' and 'Socrates is blind' are false. When Socrates is a zygote, he can't see yet, so he neither has sight nor is blind. Similarly, if Socrates doesn't exist, there is no Socrates to be blind or to see. The same holds for correlatives and contraries too.

But with genuine contradictions, one is always true and the other is false. For example, 'Socrates is sitting' and 'Socrates is not sitting' are contradictons, and one is always true and the other is always false, no matter what. If Socrates exists, then one will be true and the other false (depending on whether Socrates is sitting or standing). Likewise, if Socrates doesn't exist, then 'Socrates is not sitting' (or better: 'it is not the case that Socrates is sitting') is true. There simply is no Socrates, so it's not the case that he's sitting.

(Thus, for contradictions, we can identify this general rule: if the subject of the contradictory sentences does not exist, the negative sentence is true; if the subject does exist, then one or the other is true.)

The key here is that contradictions always involve a negative statement, and the negative statement is always true when the subject doesn't exist. The other kinds of opposites can't be reduced to mere negative sentences. On the contrary, they all amount to some positive state of affairs.

For example, 'double' and 'half' are positive states of affairs: something is double, and something is half. 'Hot' and 'cold' are too, for something is hot and/or something is cold. 'Sight' and 'blindness' are also positive states of affairs: either something can see, or something is there, but it can't see. (As I said in the last post, being deprived of something is not the same as simply not having it.)

Friday, December 19, 2008

Aristotle on Opposites 2: Contraries

Last time, I talked about the first kind of 'opposites' that Aristotle talks about in the Categories 10, namely 'correlatives'. Correlatives are relational features that are reciprocal, like 'double' and 'half' (each refers to the other).

The second kind of 'opposites' are what Aristotle calls 'contraries'. These are what we typically think of when someone says, 'give me an example of a pair of opposites'. 'Hot' and 'cold', 'good' and 'bad', 'black' and 'white', 'healthy' and 'sick', things like that.

Here in Categories 10, Aristotle says two things about contraries.

(1) Contraries are not relational and reciprocal. They do not each relate to the other in the way that 'double' and 'half' do. If something's 'double', then there must be something else that's 'half'. A 10kg block couldn't be 'double' if it were the only thing in the universe, for there'd be nothing it could be the double of. But if something's hot, then there's no guarantee that something else will be cold. A candle could exist all by itself, and it'd still be hot. Hell, even if one thing is hotter than another, the cooler of the two still needn't be cold.

Of course, contraries like 'hot' can stand in various relationships -- this bit of heat might be double the temperature of that one -- but the contraries themselves are not relational features like correlatives are. Contraries are, I reckon, non-relational features.

(2) Contraries are divided into two broad groups.

(a) In the first group belong all that are necessary and binary. A pair of contraries is necessary if the appropriate sorts of things always have one or the other (but not both), and never neither. (I say 'the appropriate sorts of things' because contraries don't belong to just any old thing. Only certain kinds of things can have certain kinds of contraries. Animals can be healthy or sick, but stones cannot.) A pair of contraries are binary if those two contraries are the only options, and there's nothing in between.

For example, health and sickness are necessary and binary in this sense. Every animal must be either healthy or sick, but never neither, and it can't be somewhere in between. (Of course, we might say that an animal is 'in between' in the sense that it's partly healthy and partly sick, but that applies to different parts of the animal, not the same part.) Similarly, 'odd' and 'even' are necessary and binary for whole numbers (except zero). Every whole number (apart from zero) must be either odd or even, and it can't be somewhere in between.

(b) In the second group belong all contraries that are neither necessary nor binary. White and blackness, for example, are not necessary, nor are they binary. Animals can be white, black, or anywhere in between.

Aristotle speaks as if the division between (a) and (b) is exhaustive. All necessary contraries are binary, and all unnecessary contraries are not binary. There are no necessary contraries that are not binary, and there are no unnecessary contraries that are binary.

That's all Aristotle says in Categories 10. It doesn't give us a whole lot to go on. I still wonder what it is, exactly, that makes two things contrary? Elsewhere, Aristotle says that contraries are what are 'the most distant in the same genus' (Categories 6, 6a15-18). That is, if we take any particular kind of feature that comes in a variety of degrees, the two ends of the spectrum are the contraries. For example, color comes in different shades ranging from black to white, but since black and white sit at the ends of the color spectrum, black and white are the contraries for color.

But that won't do; not quite. Aristotle thinks some contraries are binary; for them, there's nothing in between, so there's no spectrum. Consequently, we can't talk about a 'spectrum', or a 'variety of degrees', or anything like that. Instead, we need to talk about contraries as the two most different features that belong to the same kind. So even if there were no colors except for black and white, black and white would still be contraries because they're the most different of any two colors. And that would work for any feature-kind, no matter how many different features belonged to that kind.

However, this would mean that every two-membered feature-kind is a contrary. Would Aristotle accept that? I don't know. But more importantly, this would mean that all two-membered feature-kinds are necessary, for those kinds would be binary, and all binary contraries are necessary. Conversely, any more-than-two-membered feature-kinds would be unnecessary. I'm not sure whether Aristotle would accept this implication. Maybe he would. I don't know.

Before I finish, there are two little problems to bring up.

(i) A short while later in the Categories (see 12b37-13a2), Aristotle says that some contraries are essential constituents for certain kinds of things. For example, whiteness is an essential constituent of snow, because snow is always white. Doesn't this mean that whiteness is necessary for snow? If so, it should follow that whiteness belongs to a pair of binary contraries (for Aristotle has said that all necessary contraries are binary). But that's obviously false. There are other colors besides white and black. On the one hand, then, Aristotle says that all necessary pairs are binary, but on the other hand, he says some necessary pairs are not. Which is it?

(ii) Aristotle also says a little later (see 13a31-37) that contraries are variable: something can switch from one contrary to the other (a pot can become hot, then cold, then hot again). He makes this point in order to distinguish contraries from the third kind of opposites: namely, possessing a natural ability, and being deprived of that ability. Possession and deprivation, says Aristotle, are permanent (once blind, a man doesn't regain his sight), and since contraries are variable, they're not the same as possession/deprivation. Now, if some contraries are necessary constituents for certain things (as whiteness is for snow), then surely those are 'permanent'. Again, then, it seems that Aristotle is saying that contraries are 'variable', and that they're 'permanent'. Which is it?

Tuesday, December 16, 2008

Aristotle on Opposites: Correlatives

What are opposites? Any of us could give plenty of examples. 'Hot' and 'cold', 'good' and 'bad', and so forth. But what is it that makes these pairs of features opposites? And what is it that makes 'hot' the opposite only of 'cold' rather than, say, 'bad'?

Explaining a theory of opposites is no easy task, but Aristotle takes a shot at it in the Categories 10. There he says there are four kinds of opposites:
(a) correlatives (e.g., 'double' vs. 'half'),
(b) contraries (e.g., 'hot' vs. 'cold'),
(c) possession/deprivation (e.g., 'sight' vs. 'blindness'), and
(d) contradiction (e.g., 'Socrates is sitting' vs. 'Socrates is not sitting').
What about the first of these – what, exactly, are correlatives? Aristotle says the following:
'Pairs of opposites which fall under the category of relation are explained by reference of the one to the other, the reference being indicated by the preposition "of" or by some other preposition. Thus, "double" is a relative term, for that which is double is explained as the double of something'.
[11b22-33, emphasis mine, and I added the quotes around 'double'.]
Here's what I gather from this: every correlative is a relational feature. A relational feature relates one thing to another. How do we know when a feature relates one thing to another?

Well, Aristotle thinks it goes something like this. If we take some feature and try to explain what that feature is, we can only do so if we make reference to something else. For example, if I tried to explain to you what 'double' is, I'd have to talk about how something that's 'double' is twice as much as another thing. I couldn't really explain what 'double' is without also talking about what it's the double of.

In modern logic speak, we might say that relational features can only be expressed by two-place predicates. A two-place predicate is one that requires filling in two blanks to make sense. For example, the predicate 'is the double of' only makes sense if I fill in both of the following blanks: '_____ is the double of _____'.

I couldn't say '10kg is the double of...' and just drop off. You'd think I was either asking you to fill in the blank (as if I went around giving you pop math quizzes all day), or you'd think I got lost in thought and stopped mid-sentence (which I do). But you wouldn't think I uttered a complete sentence. A two-place predicate needs both blanks filled in.

(There are three-place, four-place, and n-place predicates too. A three-place predicate would be something like '_____ is half way in between _____ and _____'. I've got to fill in three blanks there, so it's a three-place predicate. But I think Aristotle believes that correlatives are best expressed by two-place predicates, so we can ignore all these n-place thing-a-ma-jigs for now.)

In any case, my point is that a relational feature is explained with reference to something else (it's explained with a two-place predicate), and every correlative is like this. Thus, 'double' is a relational feature because you have to explain it as the double of another thing. Likewise, 'half' is a relational feature because you have to explain it as the half of another thing. The same goes for other correlatives like 'parent' and 'offspring', 'taller' and 'shorter', and so on.

Another thing I gather from the quotation above is this: correlatives are reciprocal. That is, each one refers to the other: for any pair of correlatives R and R*, if x is related to y by R, then y is related to x by R*. Every correlative is like that. If x is the double of y, then y is half of x. If x is the parent of y, then y is the offspring of x. If x is taller than y, then y is shorter than x.

So that's correlatives. A pair of features are correlatives iff (i) each of the pair is a relational feature, and (ii) each of the pair are reciprocal. As Aristotle sees it, correlatives are one kind of opposites. 'Double' is the opposite of 'half'. 'Parent' is the opposite of 'offspring'. 'Taller' is the opposite of 'short'.

One last thing. We should be careful not to confuse the correlatives themselves with the things they correlate. Suppose I have a 10kg block and a 5kg block. Obviously, the first is double the second in weight, and the second is half the first in weight. But what are the actual 'opposites' here? The blocks? The weights?

It seems to me that the genuine opposites are the relationships the blocks have to each other (namely, the relationships of being double and half). The blocks (and their respective weights?) are 'opposites' only in virtue of their double/half relationships.

(Strictly speaking, perhaps the blocks are opposites in virtue of the double/half relationship, and the weights are the foundation/basis for that relationship. But still, aren't 10kg and 5kg opposites?)