Dr. Tuggy’s response

I posted a critique of Dr. Dale Tuggy’s Trilemma a couple of weeks ago.

He offered a charitable analysis, and when I have time, I hope to respond.  Check it out here.

Or you can listen through Youtube:

The Cartesian Ontological Argument

D1. God is the x such that for all attributes Y, if Y is a perfection, Y belongs to x.
P1. Necessarily existing is a perfection
P2. For all x, if it is not the case that x exists, possibly it is not the case that x exists.
C. God exists.

Let,

E!x ≝ x exists
P(Y)≝ Y is a perfection

g ≝ (ɿx)(∀Y)(P(Y)⊃ Yx)

1. P(☐E!) (premise)
2. (∀x)[~E!x ⊃ ♢~E!x] (premise)
3. ~E!g (IP)
4. (∃x){[(∀Y)(P(Y) ⊃ Yx) ∧ (∀y)[(∀Y)(P(Y) ⊃ Yy) ⊃ (y = x)]] ∧ ~E!x} (3 theory of descriptions)
5. [(∀Y)(P(Y)⊃ Yμ) ∧ (∀y)[(∀Y)(P(Y)⊃ Yy) ⊃ (y = μ)]] ∧ ~E!μ (4 EI)
6. ~E!μ ⊃ ♢~E!μ (2 UI)
7. ~E!μ (5 Simp)
8. ♢~E!μ (6,7 MP)
9. ~☐E!μ (8 MN)
10. (∀Y)(P(Y) ⊃ Yμ) ∧ (∀y)[(∀Y)(P(Y) ⊃ Yy) ⊃ (y = μ)] (5 Simp)
11. (∀Y)(P(Y) ⊃ Yμ) (10 Simp)
12. P(☐E!) ⊃ ☐E!μ (11 UI)
13. ☐E!μ (1,12 MP)
14. ☐E!μ ∧ ~☐E!μ (9,13 Conj)
15. E!g (3-14 IP)

In the definition, I am just setting down what I take g to mean… all I mean by g is that it is the something that, for any attribute, if that attribute is a perfection, then it has that perfect attribute. So God is the being that has all perfections (as I define God).  You might say that there is no definite description of a perfect being, i.e. there could be multiple perfect beings.  However, I would argue that there cannot be two omnipotent beings, since a simple reductio would rule out this possibility.  That is, if there are two omnipotent beings, then any power the one has would be limited by whether or not the other being wills to bring about a contradictory state of affairs.  Since they cannot both bring about contradictory states of affairs, they cannot both be omnipotent.  So there cannot be two beings that have all perfections, given that omnipotence is a perfection that implies uniqueness. 

P1 say necessary existence is a perfection because a perfection is any attribute that is of a simple kind that is positively complete. Omniscience is a perfection of because it is an attribute of the simple kind (knowledge) that is positively complete. Whatever has omniscience lacks nothing with respect to knowledge. So we recognize omniscience as a kind of perfection regarding knowledge. So necessary existence is an attribute regarding the simple kind “modes of existence” that is positively complete. Whatever exists necessarily exists in all possible situations, so it does not lack positive existence given any other state of affairs.

P2 is axiomatically true given that if something is necessarily true (system M of modal logic), then it is true. Assume P2 is false: ~(~E!x ⊃ ♢~E!x), this is logically equivalent to saying ~E!x ∧ ☐E!x (x does not exist and necessarily x exists). Given system M, ☐E!x implies E!x, so P2 cannot be false. In order to object to P2, you would have to say that some necessary truths are not actually true, which I think is a rather absurd position to take.

Tuggy’s Trilemma


Dale Tuggy offers the following trilemma over at his excellent Trinities blog/podcast:

1. Jesus died.

2. Jesus was fully divine.

3. No fully divine being has ever died.

Tuggy explains that one cannot hold to all three, so at least one must go.  But which one? As a unitarian, he thinks the Biblical data requires the affirmation of 1 and 3, and so rejects 2.

I am going to respond to this Trilemma by adopting a “Two Natures” view as expressed by the doctrine of the hypostatic union.  So, I believe the Second Person of the Holy Trinity is a Divine hypostasis that has two natures.  Those natures are not mixed or confused.

Proposition 1:  Did Jesus die?

I accept that Jesus Christ died.  This is affirmed throughout scripture.  1 Peter 3:18 tells us that he was “put to death in the flesh”, in Matthew 27:50 John 19:30 it is said that Jesus “gave up the ghost.”  The death of Christ is a mystery of the Catholic faith, repeated at every Mass in both thr litergy and in the Nicene Creed.

So, I am inclined to accept (1).  I will note, however, that the plain reading of scripture suggests that death involves the flesh and separation or loss of the soul or spirit.  So, I would understand death as the separation of the soul from the body.  Tuggy defines death as the loss of all or most living functions and does not limit life-functions to biological or natural life functions.  The question might then be raised if, on the two-natures view, an individual hypostasis is dead if the life-functions of one of his natures are still fully operational even if the life-functions of the other nature become severally restricted.  It seems to me that when orthodox Christians claim that Jesus died, they mean that the human substance that he assumed at the incarnation was destroyed by the separation of Christ’s human soul from his human body, but that he also has a divine nature in which he is consubstantial with the Father and Holy Spirit.  That divine substance is essentially immortal.

So, would Tuggy say that I deny Proposition 1?  I don’t know, but I think there is a literal sense in which Jesus died.

Proposition 2: Was Jesus fully divine?

Here, I think we need to tease out different ways of understanding “fully”.  In one sense, a thing can be fully of a nature if that is the only nature it has.  For example, I am fully human and this implies that I am not anything non-human.  In this sense, it could not be said that Jesus is fully divine.  Jesus is divine, but on the two natures view, we must reject the implication that he is not anything non-divine.  He is human, and a human nature, even if assumed by a divine person, does not become a divine nature (lest we confuse the natures).

There is a sense in which I would say Jesus is fully divine though.  I would say that something is fully some nature if it lacks nothing essentially had by things of that nature.  So, again, I am fully human in this sense too, since I do not lack any of the essential attributes of a human.  We might imagine some monster, like the Minotaur, who is half-man and half-bull.  Such a creature may have some of the essential attributes of a human, and some of the attributes of a bull, but really could not be said to be fully human or fully bull.  That is not Christ’s situation, however.  He is not a monstrosity, but has a complete human nature and a complete divine nature.  So according to his human nature, he has a human body, human organs, a human mind, a human will, and so forth.  According to his divine nature, as I said above, Christ is of the very same substance as the Father and the Holy Spirit, and so according to that divine nature, shares in the Divine Essence and lacks nothing essential to the True God.  In this sense Jesus is fully divine.  That is, he is a hypostasis that has a divine nature identical to the divine ousia.  Would Tuggy agree with me that I can affirm Proposition 2, in some sense?  I am not sure.

Proposition  3:  Can a fully divine being die?

Again, there is a sense in which I affirm 3 and a sense in which it could be said that I deny 3.  As Aristotle tells, “being” is said in many ways.  In fact, he thought the primary sense of “being” is “ousia” (see Meta IV.2).  Another sense of “being” could be some individual x, which is how I understand the function of “hypostasis” or “supposite” in these debates.  The Father, Son, and Holy Spirit are persons insofar as they are rational individuals.  We could say that the Father is a rational being.  In fact, the Father is essentially rational insofar as he cannot fail to have an intellect and will.  However, he is not essentially rational insofar as he is an individual x, but insofar as his substance is essentially rational.  Substances have essential attributes, and individual have essential attributes only with reference to their substances.  They do not have essential attributes qua hypostasis or because they are an individual x.

So, I would say that essential immortality belongs to the divine substance (ousia).  Divine Persons, or Divine Hypostases are essentially immortal only in reference to their substantial nature.  It makes no sense to say that a Divine Person is essentially immortal because of the essential nature of being a hypostasis.

Can  the Divine Ousia die?  No, it is essentially immortal.  Can a divine hypostasis die when referencing their divine nature?  No.  Can a divine hypostasis assume a moral nature and die with respect to that nature.  Yes, and Thomas Aquinas agrees that each of the divine hypostases could have assumed a moral nature (I mention this not to appeal to his authority, but as a marker to show that I am not far off the reservation of orthodoxy).

Conclusion: So, there is a sense in which I affirm all three propositions.  I really affirm that Jesus died a human death, which is the separation of the human soul from the human body in which most of the living functions of the human substance ceased.  I really affirm that Jesus is a fully divine hypostasis insofar as he has a nature that lacks none of the essential divine attributes.  I really affirm that the fully divine ousia is essentially immortal.  I think these are ways to affirm what orthodox Christians mean when they say such things, though they may not be what Tuggy means.  So he might say that I reject all three propositions, even if I think I affirm them after making the distinctions I have made.  But then we would just be quibbling, and I could grant that I reject one or more of the propositions as Tuggy defines them and still safely be in orthodoxy.  Nonetheless, I see no contradiction in accepting the three propositions given my qualifications.

Ontological Argument Improved Again

Let, 

E!x ≝ x exists in re
Ix ≝ x exists in intellectu
Gx ≝ x admits of more greatness
G<Px,~Px> ≝ x having P is greater than x not having P
Gxy ≝ x is greater than y
©… ≝ it is conceivable that…

g ≝ (ɿx)(~©Gx ∧ ~©(∃y)Gyx)

1. (∀x)[(Ix ∧ ~E!x) ⊃ ©E!x] (premise)
2. (∀x)G<E!x, (~E!x ∧ Ix)> (premise)
3. (∀x){[[~E!x ∧ G<E!x, (~E!x ∧ Ix)>] ∧ ©E!x] ⊃ ©Gx}(premise)
4. Ig (premise)
5. ~E!g (IP)
6. Ig ∧ ~E!g (4,5 Conj)
7. (Ig ∧ ~E!g) ⊃ ©E!g (1 UI)
8. ©E!g (6,7 MP)
9. G<E!g, (~E!g ∧ Ig)> (2 UI)
10. ~E!g ∧ G<E!g, (~E!g ∧ Ig)> (8,9 Conj)
11. [~E!g ∧ G<E!g, (~E!g ∧ Ig)>] ∧ ©E!g (5,10 Conj)
12. [[~E!g ∧ G<E!g, (~E!g ∧ Ig)>] ∧ ©E!g] ⊃ ©Gg (3 UI)
13. ©Gg (11,12 MP)
14. (∃x){{[~©Gx ∧ ~©(∃y)Gyx] ∧ (∀z){[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = x)]}} ∧ ©Gx} (13 theory of descriptions)
15. {[~©Gμ ∧ ~©(∃y)Gyμ] ∧ (∀z){[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = μ)]}} ∧ ©Gμ (14 EI)
16. {(∀z){[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = μ)]} ∧ [~©Gμ ∧ ~©(∃y)Gyμ]} ∧ ©Gμ (15 Comm)
17. {(∀z){[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = μ)]} ∧ [~©(∃y)Gyμ ∧ ~©Gμ]} ∧ ©Gμ (16 Comm)
18. {(∀z){[[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = μ)]} ∧ ~©(∃y)Gyμ] ∧ ~©Gμ} ∧ ©Gμ (17 Assoc)
19. (∀z){[[~©Gz ∧ ~©(∃y)Gyz] ⊃ (z = μ)]} ∧ ~©(∃y)Gyμ] ∧ {~©Gμ ∧ ©Gμ} (18 Assoc)
20. ~©Gμ ∧ ©Gμ (19 Simp
21. E!g (5-20 IP)

A Possible Interpretation of Proslogion 2

One of my struggles in trying to understand Proslogion 2 is how Anselm gets to the actual existence of God rather than what he arrives at in Proslogion 3, namely the inconceivability of God’s non-existence.  I’ve also struggled with the notion of using a two-place predicate like “greater than”, since Anselm tells us that if God exists in the mind alone, a greater could be conceived, i.e. to think of God as existing in reality.  Here, we are saying that we could conceive of one and the same concept in greater ways rather than conducting a comparison of the God concept to other items in the world.  The following interpretation approximates what Anselm seems to be arguing, and I would say that it is a sound argument for God’s existence.

D1. God is defined as that which cannot be conceived to admit of more greatness.
P1. For all x, if x exists in intelletu and not in re, then it can be conceived that x exists in intellectu and not in re.
P2. For all x, if it can be conceived that x exists in intellectu and not in re, then it can be conceived that x exists in intellectu and in re.
P3. For all x, if it can be conceived that x exists in intellectu and not in re and it can be conceived that x exists in intellectu and in re, then it is conceivable that x admits of more greatness.
P4. God exists in intellectu.
C. Therefore, God exists in re.

Let,

E!x ≝ x exists in re
Ix ≝ x exists in intellectu
Gx ≝ x admits of more greatness
©… ≝ it is conceivable that…

g ≝ (ɿx)~©Gx

1. (∀x)[(Ix ∧ ~E!x) ⊃ ©(Ix ∧~E!x)] (premise)
2. (∀x)[©(Ix ∧ ~E!x) ⊃ ©(Ix ∧ E!x)] (premise)
3. (∀x){[©(Ix ∧ ~E!x) ∧ ©(Ix ∧ E!x)] ⊃ ©Gx} (premise)
4. Ig (premise)
5. ~E!g (IP)
6. Ig ∧ ~E!g (4,5 Conj)
7. (Ig ∧ ~E!g) ⊃ ©(Ig ∧~E!g) (1 UI)
8. ©(Ig ∧~E!g) (6,7 MP)
9. ©(Ig ∧ ~E!g) ⊃ ©(Ig ∧ E!g) (2 UI)
10. ©(Ig ∧ E!g) (8,9 MP)
11. ©(Ig ∧~E!g) ∧ ©(Ig ∧ E!g) (8,10 Conj)
12. ©(Ig ∧ ~E!g) ∧ ©(Ig ∧ E!g)] ⊃ ©Gg (3 UI)
13. ©Gg (11,12 MP)
14. (∃x){{~©Gx ∧ (∀y)[~©Gy ⊃ (y = x)]} ∧ ©Gx} (13 theory of descriptions)
15. {~©Gμ ∧ (∀y)[~©Gy ⊃ (y = μ)]} ∧ ©Gμ (14 EI)
16. {(∀y)[~©Gy ⊃ (y = μ)] ∧ ~©Gμ} ∧ ©Gμ (15 Comm)
17. (∀y)[~©Gy ⊃ (y = μ)] ∧ {~©Gμ ∧ ©Gμ} (16 Assoc)
18. ~©Gμ ∧ ©Gμ (17 Simp)
19. E!g (5-18 IP)

QED

[Edit: My friend, Matt, thinks my argument may be susceptible to parody.  Here is my response]

Generally, I think parodies fail because such supposed objects, like islands of which none greater can be conceived, do not really exist in the intellect for the very same reason round squares are not abstract objects in the mind.  The phrase is nonesense, and so does not pick out any object of the understanding.

Islands just are the sorts of things that admit of degrees of greatness, so are other objects used in parody. For example, islands are present in a specified location that is surrounded by water, but it is unclear how big an island should be when considering its greatness.  It certainly cannot be omnipresent and be an island.  How many trees, island beauties, or sandy beaches ought there to be on the island which cannot be conceivably greater?  

My argument can motivate this response by proving that the greatest conceivable island is not an object that exists in the intellect.  This is because specifying that there is an island than which none greater can be conceived leads to the conclusion that God is an island, and that seems like a good reductio of the idea such a concept can be conceived.

So, if we grant the parody, I could prove that island can be predicated of God, or a being than which a greater cannot be conceived. But since islands are essentially contingent and admit of degrees of greatness, island cannot be a predicate of God, who is the being than which none greater can be conceived. So, we must reject the assumption that a greatest conceivable island exists in intellectu and we can base it on the somewhat reasonable premise that God is not an island. I would argue as follows:

Let,

Lx ≝ x is an island

i ≝ (ɿx)(~©Gx ∧ Lx)

20. ~Lg (premise)
21. (∃x){{~©Gx ∧ (∀y)[~©Gy ⊃ (y = x)]} ∧ E!x} (19 theory of descriptions)
22. Ii (IP)
23. (∃x){{(~©Gx ∧ Lx) ∧ (∀y)[(~©Gy ∧ Ly) ⊃ (y = x)]} ∧ Ix} (22 theory of descriptions)
24. {~©Gμ ∧ (∀y)[~©Gy ⊃ (y = μ)]} ∧ E!μ (21 EI)
25. {(~©Gν ∧ Lν) ∧ (∀y)[(~©Gy ∧ Ly) ⊃ (y = ν)]} ∧ Iν (23 ΕΙ)
26. ~©Gμ ∧ (∀y)[~©Gy ⊃ (y = μ)] (24 Simp)
27. (∀y)[~©Gy ⊃ (y = μ)] (26 Simp)
28. (~©Gν ∧ Lν) ∧ (∀y)[(~©Gy ∧ Ly) ⊃ (y = ν)] (25 Simp)
29. ~©Gν ∧ Lν (28 Simp)
30. ~©Gν (29 Simp)
31. ~©Gν ⊃ (ν = μ) (27 UI)
32. ν = μ (30,31 MP)
33. ~©Gμ ∧ Lμ (29,32 ID)
34. (~©Gμ ∧ Lμ) ∧ (∀y)[~©Gy ⊃ (y = μ)] (27,33 Conj)
35. ~©Gμ ∧ {Lμ ∧ (∀y)[~©Gy ⊃ (y = μ)]} (34 Assoc)
36. ~©Gμ ∧ {(∀y)[~©Gy ⊃ (y = μ)] ∧ Lμ} (35 Comm)
37. {~©Gμ ∧ {(∀y)[~©Gy ⊃ (y = μ)]} ∧ Lμ (36 Assoc)
38. (∃x){{~©Gx ∧ {(∀y)[~©Gy ⊃ (y = x)]} ∧ Lx} (37 EG)
39. Lg (38 theory of descriptions)
40. ~Lg ∧ Lg
41. ~Ii (22-40 IP)

So as long as you can provide the premise that God is not an island, not a pizza, etc. the proof works to show that such objects really are not in the intellect.

Absolute and Relative Identity

I have seen some argue that any relative identity claim can be reduce to an absolute identity claim in the following manner:

1) x and y are the same F  ≝ is an Fis an F, and x = y.

However, I don’t think this works.  Part of the motivation for relative identity is that there may be circumstances like:

2) x and y are the same F, but x and y are not the same G.

But (1) and (2) are not compatible, since we would have to affirm and deny absolute identity between x and y.  So the relative identity theorist should reject (1) given his commitment to (2).

Relative identity is not just absolute identity, plus the idea that x and y fall under the same sortal.  Moreover, this would be to suggest that relative identity is derivative, and absolute identity is the more primitive notion.  I would argue that is it the other way around.  So I would define absolute identity in terms of relative identity in the following manner:

4) x = y ≝ for any sortal, S, if x is an S or y is an S, then x and are the same S.

In other words, the absolute identity between x and y is derived from the fact that for any sortal which belongs to either x or y, it is the case that x and y count as the same S.  I say “either x is an S, or y is an S” as opposed to “both x is an S and y is an S” to avoid situations where x can be counted as an S and some y cannot, but they are the same S for any sortal underwhich both can be counted.  For there to be absolute identity, it must be the case that all sortals that belong to x must also belong to y.  I believe (4) captures this.

So to say x and y are absolutely identical is to say that for any sortal underwhich x or y can be counted, x and y are the same sortal.

 

A More Iconic Trio?

Merry Christmas!  Happy New Year!  Here is a meme for you!

An Argument Against Subjective Morality

P1. If morality is relative to the subject, then morality is a domain that is a  matter of personal opinion.

P2. All domains that are matters of personal opinion, are domains where facts and evidence cannot determine correct belief.

P3.  All domains where facts and evidence cannot determine correct belief are domains that lack propositions for which it is worth dying before giving assent under coercion.

P4.  Morality is a domain with propositions for which it is worth dying before giving assent under coercion.

C. Morality is not relative to the subject.

P1 and P2 are not too objectionable.  That is just what we mean when we say that morality is subjective.  I think that if you are going to object to the argument, you will object to P3 or P4.

A Remix of Anselm’s Conceptual Ontological Argument

st-20anselm20weninger

D1. God is defined as the x such that there is not something, y, where y is conceivably greater than x.
P1. For all x, if x is conceivable, then there is something, y, such that either y is identical to x and y exists or there is something, z, such that z is identical to x, z does not exist, and y is conceivably greater than z.
P2. There is some x such that x is conceivable and it is not the case that there is some y such that y is conceivably greater than x.
P3. For all x and y, either x is conceivably greater than y or y is conceivably greater than x, or if it is not the case that either x is conceivably greater than y or that y is conceivably greater than x, there is some z such that z is the mereological sum of x and y, and either z is conceivably greater than x or z is conceivably greater than y.
C. God exists.1

E!x ≝ x exists
Cx ≝ x is conceivable
Gxy ≝ x is conceivably greater than y
σ<x,y> ≝ the mereological sum of x and y
g ≝ (ɿx)~(∃y)Gyx

1. (∀x){Cx ⊃ (∃y){[(y = x) ∧ E!y] ∨ (∃z)[(z = x) ∧ (~E!z ∧ Gyz)]}} (premise)
2. (∃x)(Cx ∧ ~(∃y)Gyx) (premise)
3. (∀x)(∀y){[Gxy ∨ Gyx] ∨ {~(Gxy ∨ Gyx) ⊃ (∃z)[(z = σ<x,y>) ∧ (Gzx ∨ Gzy)]}} (premise)
4. Cμ ∧ ~(∃y)Gyμ (2 EI)
5. ~(∃y)Gyμ (4 Simp)
6. (∃z)[~(∃z1)Gz1z ∧ ~(z = μ)] (IP)
7. ~(∃z1)Gz1ν ∧ ~(ν = μ) (6 EI)
8. (∀y){[Gνy ∨ Gyν] ∨ {~(Gνy ∨ Gyν) ⊃ (∃z)[(z = σ<ν,y>) ∧ (Gzν ∨ Gzy)]}} (3 UI)
9. [Gνμ ∨ Gμν] ∨ {~(Gνμ ∨ Gμν) ⊃ (∃z)[(z = σ<ν,μ>) ∧ (Gzν ∨ Gzμ)]} (8 UI)
10. (∀y)~Gyμ (5 QN)
11. ~Gνμ (10 UI)
12. ~(∃z1)Gz1ν (7 Simp)
13. (∀z1)~Gz1ν (12 QN)
14. ~Gμν (13 UI)
15. Gνμ ∨ [Gμν ∨ {~(Gνμ ∨ Gμν) ⊃ (∃z)[(z = σ<ν,μ>) ∧ (Gzν ∨ Gzμ)]}] (9 Assoc)
16. Gμν ∨ {~(Gνμ ∨ Gμν) ⊃ (∃z)[(z = σ<ν,μ>) ∧ (Gzν ∨ Gzμ)]} (11,15 DS)
17. ~(Gνμ ∨ Gμν) ⊃ (∃z)[(z = σ<ν,μ>) ∧ (Gzν ∨ Gzμ)] (14,16 DS)
18. ~Gνμ ∧ ~Gμν (11,14 Conj)
19. ~(Gνμ ∨ Gμν) (18 DeM)
20. (∃z)[(z = σ<ν,μ>) ∧ (Gzν ∨ Gzμ)] (17,19 MP)
21. (ζ = σ<ν,μ>) ∧ (Gζν ∨ Gζμ) (20 EI)
22. Gζν ∨ Gζμ (21 Simp)
23. ~Gζμ (10 UI)
24. Gζν (22,23 DS)
25. ~Gζν (13 UI)
26. Gζν ∧ ~Gζν (24,25 Conj)
24. ~(∃z)[~(∃z1)Gz1z ∧ ~(z = μ)] (6-23 IP)
25. (∀z)~[~(∃z1)Gz1z ∧ ~(z = μ)] (24 QN)
26. (∀z)[~~(∃z1)Gz1z ∨ ~~(z = μ)] (25 DeM)
27. (∀z)[~(∃z1)Gz1z ⊃ ~~(z = μ)] (26 Impl)
28. (∀z)[~(∃z1)Gz1z ⊃ (z = μ)] (27 DN)
29. {Cμ ∧ ~(∃y)Gyμ} ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = μ)] (4,28 Conj)
30. Cμ ∧ {~(∃y)Gyμ ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = μ)]} (29 Assoc)
31. {~(∃y)Gyμ ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = μ)]} ∧ Cμ (30 Comm)
32. (∃x){~(∃y)Gyx ∧ (∀z)[~(∃z1)Gz1z ⊃ (z =x)]} ∧ Cx} (31 EG)
33. Cg (32 theory of descriptions)
34. Cg ⊃ (∃y){[(y = g) ∧ E!y] ∨ (∃z)[(z = g) ∧ (~E!z ∧ Gyz)]} (1 UI)
35. (∃y){[(y = g) ∧ E!y] ∨ (∃z)[(z = g) ∧ (~E!z ∧ Gyz)]} (33,34 MP)
36. [(ξ = g) ∧ E!ξ] ∨ (∃z)[(z = g) ∧ (~E!z ∧ Gξz)] (35 EI)
37. (∃z)[(z = g) ∧ (~E!z ∧ Gξz)] (IP)
38. (ν = g) ∧ (~E!ν ∧ Gξν) (37 EI)
39. ~E!ν ∧ Gξν (38 Simp)
40. Gξν (39 Simp)
41. (ν = g) (38 Simp)
42. Gξg (40,41 ID)
43. (∃x){~(∃y)Gyx ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = x)]} ∧ Gξx} (42 theory of descriptions)
44. {~(∃y)Gyζ ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = ζ)]} ∧ Gξζ (43 EI)
45. ~(∃y)Gyζ ∧ (∀z)[~(∃z1)Gz1z ⊃ (z = ζ)](44 Simp)
46. ~(∃y)Gyζ (45 Simp)
47. (∀y)~Gyζ (46 QN)
48. ~Gξζ (47 UI)
49. Gξζ (44 Simp)
50. Gξζ ∧ ~Gξζ (48,49 Conj)
51. ~(∃z)[(z = g) ∧ (~E!z ∧ Gξz)] (37-50 IP)
52. (ξ = g) ∧ E!ξ (36,51 DS)
53. (ξ = g) (52 Simp)
54. E!ξ (52 Simp)
55. E!g (53,54 ID)

QED

1 Some aspects of this argument are influenced by Oppenheimer & Zalta (1991), i.e. the existential quantifier carries no existential import and is analogous to Anselm’s existence in intellectu whereas E! is a predicate that indicates existence in re. One weakness of Oppenheimer & Zalta’s argument is that it depends on a non-logical axiom regarding Gxy such that it is connected. In other words, either Gxy or Gyx or (x = y). This requires all individuals to stand in a greater than relationship. It is plausible, though, that two non-identical individuals could share equal greatness. I am able to derive the uniqueness of the being than which none greater can be conceived by appealing to the notion that the merelogical composite of two equally great individuals is at least greater than one of its proper parts, which I take to be a modest premise. The interesting thing about my formulation is the first premise, which distinguishes in intellectu from in re existence, and captures Anselm’s claim that a greater could be conceived than a being that exists in the understanding alone without begging the question that this greater thing actually exists—it is merely conceptually greater.  See P.E Oppenheimer & E.N. Zalta. (1991). “On the Logic of the Ontological Argument.” In Philosophical Perspectives. Vol. 5. 509-529.

Calvin’s basket is full

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