Hylomorphism in brief
Longtime
readers of this blog or of my books will be familiar with the
Aristotelian-Thomistic conception of physical substances as composites of form
and matter, where (to a first approximation) matter is the stuff out of which such
a substance is made and form is what organizes that stuff in a way that allows
it to manifest its characteristic properties and powers. More precisely, it is substantial form that does so.
And the soul is a substantial form of the kind that gives a physical
substance the distinctive properties and powers of a living thing.
Matter, on
Aquinas’s account, is what makes it possible for there to be more than one instance
of any species of physical substance (using “species” here in the traditional
broad metaphysical sense, not the narrower biological sense). Different lumps of iron all have the same
basic nature, as do different oak trees and different poodles. But if they have the same nature, how can
they be different substances? The answer
is that there are different bits of matter which have all taken on the same
nature. Matter is in this way the “principle
of individuation” of physical substances.
When the
matter of a purely physical substance loses its substantial form, that
particular substance goes out of existence altogether. For example, when you chop down an oak tree
and burn it in the fireplace, that particular oak tree is gone. The matter out of which it is made persists,
but it has taken on an entirely different form, the form of ash. The substantial form of an oak tree is no
longer present in it (even though there are, of course, other oak trees, and they have such a substantial form).
Now, Aquinas
thinks of angels as substances that are purely intellectual in nature, and thus
(since he takes the intellect to be incorporeal) to be immaterial
substances. Because they are immaterial,
there is no way to individuate one member of an angelic species from
another. There can still be different
species of angel, but each will have exactly one member. Hence there are as many angelic species as
there are angels.
The human
intellect, like angelic intellects, is incorporeal. How, then, can there be more than one member
of the human species? The answer, for Aquinas,
is that while human beings are not purely corporeal substances (unlike iron,
oak trees, and poodles) neither are they purely
incorporeal substances (as angels are).
A human being is a unique sort of substance that has both corporeal
properties and powers (such as eating, walking, seeing, and hearing) and
incorporeal ones (thinking and willing).
Because
human beings are partly corporeal, they can be individuated from one another as
different members of the same species.
But because they are partly incorporeal, they do not go out of existence
altogether at death. They carry on as incomplete
substances after death, reduced to just their intellectual (and thus
incorporeal) operations. Because every
substance has a form, and human beings continue on as incomplete substances, a
human being’s form continues on after death.
And since the soul just is the substantial form of a human being, that means
that the soul carries on after death. It
no longer manifests the corporeal
powers that it would normally give human beings (since, absent the body, there’s
no matter for it to inform). But the incorporeal powers can still
manifest.
Vallicella’s objection
Bill begins
his criticism of this view by saying that Aristotelian-Thomistic hylomorphism holds
that “substances of the same kind have the same substantial form.” In the case of human beings, he continues, “since
these substances of the human kind have the same form, it is not their form
that makes them numerically different… It is the matter of their respective bodies that makes
numerically different human beings numerically different.”
But in that
case, Bill argues, when the matter of some particular human being goes at
death, there is nothing left to individuate him. Hence there can be nothing of him, in particular, that carries
on. Bill writes:
After death a human person ceases to exist as the particular
person that he or she is. But that is to
say that the particular person, Socrates say, ceases to exist, full stop. What survives is at best a form which is
common to all persons. That form,
however, cannot be you or me. Thus the
particularity, individuality, haecceity, ipseity of persons, which is essential
to persons, is lost at death and does not survive post mortem.
Bill appears
to think that if the Aristotelian-Thomistic view were applied consistently, it
would have to say of human beings what it says of iron, oak trees, and
poodles. Just as the particular
individual oak tree that you burn in the fireplace is altogether gone (even
though there are other oak trees that carry on), so too, after death, is the
particular individual human being altogether gone (even though there are other
human beings who carry on).
But there
are two problems with Bill’s argument.
The first is that it rests on a mistaken conception of substantial
form. The second is that it neglects the
crucial difference the Thomist says exists between human beings and every other
corporeal substance, which is that human beings have incorporeal intellectual
powers.
Let’s
consider these points in order. When
Bill says that, for hylomorphism, “substances of the same kind have the same
substantial form,” he speaks ambiguously.
That could mean that, while each individual physical substance has its
own substantial form, with physical substances of the same species their
substantial forms are of the same kind.
That would be a correct characterization of the Aristotelian-Thomistic
position, but unfortunately it does not seem to be what Bill means. He seems to mean instead that there is one
substantial form shared by all human beings in common – not one kind of substantial form, but one substantial form.
But that is
not what Aristotelian-Thomistic hylomorphism says, and it is not true. There are, it seems to me, two ways to read
Bill’s claim. On one reading, the
substantial form of human beings is a kind of Platonic Form, and different
human bodies are all human because they participate in that same one Form. The problem with this is that it isn’t an Aristotelian conception of form at all,
but a Platonic conception. A substantial
form, for the Aristotelian, isn’t an abstract Platonic object in which a thing
participates. Rather, it is a concrete
principle intrinsic to a substance that grounds its characteristic properties
and powers.
The other
way to read Bill’s characterization of hylomorphism is as holding that human
beings share one substantial form in the sense that they are all part of one
big substance – humanity considered as something like a single organism, with
different individual human beings as analogous to body parts that that organism
gains or loses as people are conceived or die.
But this is obviously not Aristotle’s or Aquinas’s view. They take human beings to be substances, not parts of a substance. And as
substances, each must have his own substantial form.
I think it’s
the first of these interpretations (what I’m characterizing as the Platonic
one), rather than the second, that Bill has in mind. But, again, it is a mistaken
interpretation. It just isn’t the case
that you, me, and Socrates all share the same one substantial form in the sense
Bill’s argument requires. Rather, you
have your own substantial form (and thus soul), I have mine, and Socrates has
his.
The same
thing is true of an oak tree. This oak
tree has its own individual substantial form, that oak tree has its own individual
substantial form, and so on. The reason
none of them continue after death is that everything an oak tree has or does –
and thus every property or power its substantial form gives it – depends on
matter. Hence when the matter goes,
there’s nothing left for the form to inform, nothing left for it to be the form
of.
This brings
us to the second crucial point, which is that a human being, unlike an oak
tree, has properties and powers that do not
depend on matter – namely, the intellectual properties and powers. Hence, a human being is not an entirely
corporeal substance, but a partly incorporeal one. This incorporeal part carries on after the
body dies, so that there is in this
case (unlike the case of the oak tree) something for the form to continue to be
the form of.
And that is
the sense in which the soul carries on beyond the death of the body. Yes, the soul is the form of the body,
because it is the form of a substance that it partially bodily in nature.
But unlike an oak or a poodle, a human being is not entirely bodily in nature, so that there is (as it were) still work
for the human soul to do even after the body is gone.
Why does
this not make the human soul after death like an angel, the unique member of
its own distinct species? The answer is
that the soul was once conjoined to its body and always retains its orientation
to that particular body. An angel
without a body is no less an angel for that.
It is complete in its incorporeal
mode of existence. By contrast, a human
being without a body (that is to say, a disembodied soul) is less of a human
being insofar as it is an incomplete
human being. Incorporeality is normal
for an angel, but not for a human being.
This orientation toward matter, which persists even in the absence of
matter, suffices to individuate human souls.
Of course, Bill
may raise further objections, to some or all of what I’ve said here. The point, though, is to indicate why I think
the particular objection he raises in his post fails. (Longtime readers might remember that this
issue is in fact a matter of longstanding dispute between Bill and me. I’ve linked to some earlier posts on the
subject below.)
I want to
add in closing that I have been reading Bill’s recent book Life’s Path with pleasure and profit, and advise you to do the
same. Bill is among the rare
contemporary philosophers who live up to the traditional ideal of producing both
solid technical academic philosophical work (as in his superb earlier book A Paradigm
Theory of Existence) and insightful moral, political, and other practical
reflections accessible to a more popular audience (as in the more recent
book). Read and learn.
Related
posts:
Vallicella
on hylemorphic dualism
I'm probably misunderstanding. But it seems to me that this passage....
ReplyDelete"The same thing is true of an oak tree. This oak tree has its own individual substantial form, that oak tree has its own individual substantial form, and so on. The reason none of them continue after death is that everything an oak tree has or does – and thus every property or power its substantial form gives it – depends on matter. Hence when the matter goes, there’s nothing left for the form to inform, nothing left for it to be the form of."
kind of obviates the need for matter as a principle of individuation. If each oak tree has its own (distinct) substantial form, then in fact, it did not need matter to individuate it. Each oak tree is its own species, like each angel.
No? What am I missing?
The Oak tree's individual, material form is what gets destroyed. It is a purely material construct that gets materially destroyed. Whether it is distinct does not change that. While it exists as a material thing, that matter is all that individuates it: but not as another species. It still has Oak DNA material, like any other oak. Humans and Angels cannot be materially destroyed. A human soul that was a black male when it had a body will still have the mind and identity of that particular black male forever. When he rises again at Judgement Day, he gets the same kind of black male body he had before because that's his unique physical form.
DeleteI could be wrong, but I think Prof. Feser means something like this: “Each oak tree instantiates the same substantial form, but that form exists in numerically distinct instances only because of matter.” That is, there’s the form as a kind (shared by all oak trees), and the form as it exists in *this* individual by informing *this* matter.
DeleteSo when he says “this oak tree has its own individual substantial form,” he’s referring to the form as instantiated in a particular parcel of matter—not a different kind of form, but a distinct occurrence of the same form. On this reading, matter is not bypassed but precisely what individuates.
Thank you, Wesley. But in that case, I don't see how he successfully rebuts Vallicella's argument.
Delete"Orientation toward matter” is an intentional or relational property, not an individuating property in the Thomistic sense (which depends on actual matter). Saying that a relation to potential matter individuates an immaterial form is to derive individuation from a non-existent correlate. This is analogous to saying:
ReplyDelete“All numbered tickets are individuated by the people who hold them.”
“Even when no one holds the ticket, its orientation toward holders individuates it.”
That doesn’t follow logically. It assumes what it needs to prove: that individuation can be preserved by a mere relational potential.
It's more like,
Delete"Everybody signs their ticket. Everyone has a name whether they hold a ticket or not. Tickets are only meant for people who can sign them. Animals need not apply. (sorry animals)."
Re: Thomas Kelly's comment,
DeleteProf. Feser can correct me if I’m wrong, but I take “orientation” here to be teleological—not a merely relational property, but an intrinsic directedness toward informing a particular body. That ordering persists even when the body is absent, because the soul remains the form of this human being, not just an instance of human nature.
If one allows Natural Kinds e.g. Oak, Humanity, as distinct from Properties I find it puzzling that Matter should be the individuating principle. The trope/instance of the natural kind “Man” in Plato and Aristotle is not the same—just as the redness of one rose is not the same as that of another—rather they are instances of the same universal “Man.” This if I recall correctly was close to E.J. Lowe’s view.
ReplyDeleteThis does not hinder the subsistence part of course since the kind instance “Man” is partly immaterial it will partly survive bodily destruction—but being the instance of a universal rather than the universal itself we will not end up with Averröes’ Monopsychism.
(Prime Matter relative to Form might still be needed for other good reasons e.g. explaining substantial change)
Ed I've raised a similar objection to the Thomistic account but with a different diagnoses of the underlying issue (see here: https://open.substack.com/pub/mashshai/p/a-problem-for-thomistic-psychology?r=4on5dv&utm_campaign=post&utm_medium=web&showWelcomeOnShare=false)
ReplyDeleteAlso, another, related objection here: https://open.substack.com/pub/mashshai/p/the-metaphysics-of-the-rational-soul?r=4on5dv&utm_campaign=post&utm_medium=web&showWelcomeOnShare=false
both from an Avicennian point of view.
@Sinawi,
DeleteYou raised interesting questions, but Ed is very, very busy to take on such large topics, especially when he already wrote two books on that matter (i.e. Scholastic Metaphysics, and, the new gem, albeit indirectly adressing those topics, Immortal Souls).
If its alright, I think I can give a glimpse of what he would say regarding "A problem for Thomistic Psychology" (https://mashshai.substack.com/p/a-problem-for-thomistic-psychology?triedRedirect=true), but take what I'm saying here as a grain of salt, since I'm not qualified or intelligent as Ed to make a robust defense of these matters.
So, in the post you said, "A body, the author agrees, is a composite of (substantial) form and prime matter. Now, consider the s. form itself. What sort of relation does it have to the prime matter? Specifically, does it inhere in the prime matter? If so, then s. form, by their criteria, is not a substance but rather an attribute i.e., of prime matter, where the prime matter serves as the ‘subject’ of said attribute."
I think that most of the problems you raised could be disarmed if we rectify what was said here. I mean, the problem is that this is not the Aristotelian-Thomistic (AT, for now on) view. Substantial Form does not inhere in Prime Matter, since Prime Matter is not a subject in this sense. We would be in trouble if Prime Matter was indeed the subject of Substantial Form, since, as you aptly said, Substantial Form would be an attribute (or quality) of Prime Matter.
Now, the correct view is that, even though we may say comonly that the Substance is a composite of Substantial Form and Prime Matter, the reality is that this analysis is holistic i.e. the Substance is not reducible to Substantial Form and Prime Matter, but it is a UNITY of these both principles (and these principles are only intelligible when we see the Substance as a whole). So, it is not correct to attribute to AT metaphysics the views you raised.
Prime Matter does not have any kind of actuallity on its own -- it only begins to exist IN ACT when it is united with Substantial Form. So, the analysis is not that Prime Matter is a subject of Substantial Form. Its a mistake to think that Prime Matter already exists in Act, as it is something 'just already there' to receive Substantial Form as a kind of accidentality.
Really hope that helps!
May God bless you!
@Vini, thanks for the response! You said:
Delete"Now, the correct view is that, even though we may say comonly that the Substance is a composite of Substantial Form and Prime Matter, the reality is that this analysis is holistic i.e. the Substance is not reducible to Substantial Form and Prime Matter, but it is a UNITY of these both principles (and these principles are only intelligible when we see the Substance as a whole)."
this doesn't address the question though, which was: what sort of relation does s. form have to the p. matter? is it one of inherence? if yes, there's a problem (as you see). if no, then, given that (as Ed says in the book) "Substances, in general, just are the sorts of things which exist in themselves rather than inhering in anything else", s. form would be a substance.
Sinawi,
DeleteThe substantial form has a couple different relations to prime matter:
(1) making prime matter determinate, and
(2) being (or having been) individuated and delimited by prime matter
The error here is in treating principles of a substance (form/matter) as if they themselves are either substances or accidents. But the form/matter distinction is more fundamental (and hence general) than the substance/accident distinction, meaning what is true of substances and accidents might not be true of form and matter.
So while we would say substances exist in themselves and accidents exist in another, we wouldn't say that substantial forms either exist in themselves or in another, precisely because substantial forms are neither proper substances nor accidents. They are more fundamental. Thus the dilemma you are setting up is a false one.
@Sinawi
DeleteHi again!
Oh, I see where you're getting at.
When Ed says, "Substances, in general, just are the sorts of things which exist in themselves rather than inhering in anything else," he is contrasting Substances with Accidents (qualities). He is not simply pointing out the general mode of existence of Substances; he is contrasting it strictly with Accidents (which inhere in a Substance, that's why he says in the end that they "exist in themselves rather than inhering in anything else").
And now, to the important part. Substantial Form cannot be a Substance in any sense, since a principle of Substances (heuristically, you can think that Substantial Form is "said of" a Substance, since it only exists "in" that Substance, instead of a third realm of Platonica). As I said in the earlier reply, Substantial Form unites with Prime Matter to constitute a Substance, but these metaphysical parts (Substantial Form and Prime Matter) are only intelligible and could only exist because they are "said of" Substances. It is through Substances that we know that they must be real components of reality, and it's also through Substances that we know they don't have any reality apart from that Substance (as opposed to what a Platonist would say).
And, we must be careful, because if we think by just analyzing crudely what Ed said in the quote "Substances, in general, just are the sorts of things which exist in themselves rather than inhering in anything else," isolated from the rest of the framework he's working with, the trouble arises -- this problem only arises if we misrepresents what he is actually saying. To put it differently -- and kinda rhetorically --, what guarantees us that Substantial Forms exist in themselves when they are, in fact, only knowable through actual Substances? Substantial Form is an inner organizing principle of a Substance, not something that could exist apart from it, so it could never fill the criteria of something that exists in itself.
I hope that this is clearer now.
ccmnxc, thanks for the response. you said:
Delete"The error here is in treating principles of a substance (form/matter) as if they themselves are either substances or accidents. But the form/matter distinction is more fundamental"
i don't think i'm treating s. form as if it were a substance. rather, i'm inferring that it is a substance based on a line of reasoning.
"...we wouldn't say that substantial forms either exist in themselves or in another, precisely because substantial forms are neither proper substances nor accidents. They are more fundamental."
but why should that distinction/question be inapplicable to/asked of s. forms themselves? to say "because substantial forms are neither proper substances nor accidents" is just question-begging, since that distinction is precisely the means to determine whether something is a substance or not in the first place (depending on how it is answered).
Matter cannot be a principle of individuation, because it's already matter, an individual thing. Or am I missing something?
ReplyDeleteYou are missing that matter, as Aristotelian-Thomists conceive of it, is definitely *not* an individual thing.
Delete@Richard,
DeleteYou said, "Matter cannot be a principle of individuation, because it's already matter, an individual thing. Or am I missing something?"
Thats not the Aristotelian-Thomistic (AT, for now on) view on the 'matter' (no pun inteded). Matter is not "an individual thing" that exists by itself or already exists by itself, its an internal principle of something -- and it only exists when united with Form.
Let's begin by the basics. For AT, a Substance (me, you, a tree), is composed by Substantial Form (the inner principle that make something be what it is) and Prime Matter (the pure pontecy to become something or take on Form). Prime Matter does not exist by itself, as if it is something 'already there' waiting for it to be united with another thing that is already there -- it only exists ACTUALLY because it is united with a Substantial Form that gives it the full reality, an ACTUAL reality, instead of the mere POTENTIAL reality that it exists.
So, Matter is a principle of individuation because it is Matter of this something rather than that other something. It is the Matter (which is informed by this Substantial Form) that gives it the actual reality I'm talking about. So, since this Matter is what is being informed by this Substantial Form, it is what is responsible for individuating such thing.
The key here is to understand the Act/Potency distinction in AT metaphysics. The error of thinking that Matter is something 'already there', is to treat it as a kind of Act or Actuallity, when it is, in fact, mere a Potentiallity to take on Form (which is a kind of Act).
Oh, and btw, I recommend you to read Ed's Scholastic Metaphysics. Its an incredible book, and it will explain everything I am talking about here, but 100x better. To be precise, Chapter 1, and, 3 is where Ed addresses these topics (i.e. Chapter 1 he explain the distinction of Act and Potency, and on Chapter 3 he explains how these principles apply to Form and Matter as a composite that makes the Substances that we see everyday).
Hope that helps!
(Off-topic: your profile picture is adorable! You have such a nice baby! I hope someday to make one little angel like that too!)
Dear Dr.Feser, I’d like to know what you think regarding the phenomenon of terminal lucidity because I think that, but its nature, is a strong evidence against materialism and riductionism, and a strong evidence pointing at the existence of a soul, because in many of those cases the brain of these people was so heavily damaged that they could have not retrieved their personalities and their memories IF consciousness was a mere result of physical and material processes. I’d really like to know your position on this subject. Greetings from Italy
ReplyDeleteMassimiliano
Buongiormo,
DeleteThe professor doesn't reply as often as he used to. But since you are from Italy, he may make an exception. Ciao.
Can anyone point me to William Vallicella's blog? I think the link on the right hand side of this page is old and no longer working.
ReplyDeleteHi Kyle, here's Bill's new blog address (which is different from the Substack referred to in the post above): https://maverickphilosopher.blog/
DeleteI have a question about matter being the principle of individuation: if form explains what a thing has in common with other things sharing the same nature, then for matter to distinguish a thing from other members of the same species, doesn’t there already have to be some distinguishing features in the underlying matter? But this seems to imply that there are forms already present in the underlying matter. What otherwise could account for these distinguishing features in the underlying matter?
ReplyDeleteHi Ian, if I am correct, in AT when you read "matter," you should think of "prime matter," meaning pure potentiality and therefore something absolutely indistinct. Therefore, matter itself does not exist, or rather, it is not in act unless there is a form that distinguishes it.
DeleteIan,
DeleteMight be better to say that matter as such has a distinguishing function rather than a distinguishing feature. This is to say, matter plays such-and-such a role with respect to form in a given substance.
Part of the issue at play here is that there really never is an instance of formless matter, and so to that extent your intuition is correct. It is what we call "designate matter," in particular, which does the individuating, and designate matter is always bound by location. To that extent, then, there is already some formal feature of the matter which does the individuating.
But this is where we get back to functions or roles. What individuates an accidental form? The substance in which it inheres. What individuates a substantial form? Prime matter, but prime matter which is specified according to some location (and hence 'designate matter'). The substance is in potency to the accidental forms, and the matter is in potency to the substantial form. In both cases, the role these things play is of individuator, even though substance and matter are not the same thing. Rather, they perform the same function or role with respect to different things.
Happy to elaborate further if that would be helpful.
@Ian, hi again!
DeleteYou said, "[...] if form explains what a thing has in common with other things sharing the same nature, then for matter to distinguish a thing from other members of the same species, doesn’t there already have to be some distinguishing features in the underlying matter? But this seems to imply that there are forms already present in the underlying matter [...]"
But that misses the point and also conflates the fundamental difference between those two (i.e., Form and Matter).
First, we need to be clear of a very important distinction: Matter (as opposed to Prime Matter) is the kind of stuff that is already informed by a Form -- it already has a kind of ACTUAL reality that is united with a Form.
Now, what underlies change, like when one individual Substance (e.g., a tree) goes out of existence (e.g., goes to the wood chipper and then to the fireplace), is Prime Matter -- which is the principle of reality that has the capacity and the potential reality to take any Form. In the case of the tree, the Form of that Substance is gone, and also the Matter of that said tree, but the Prime Matter has taken on various forms (e.g., burnt powder and ashes).
So, when you said, "But this seems to imply that there are forms already present in the underlying matter," you are not thinking of Prime Matter; you are thinking of Matter (which, as I said, already has a Form informing it). So, there is no incoherence right here, just a misunderstanding of what these principles mean. Again, Matter is something that already has a Form, which is why it can individuate this individual from that other one (that's why you think there is some Form already informing it, because it really has!).
Hope that makes it crystal-clear!
Hi, Theophilius,
DeleteBut if matter is something absolutely indistinct (and that's also my understanding of prime matter) and requires form to distinguish it, then how can it act as the principle of individuation?
Another question:
ReplyDeleteIt just isn’t the case that you, me, and Socrates all share the same one substantial form in the sense Bill’s argument requires. Rather, you have your own substantial form (and thus soul), I have mine, and Socrates has his.
How do the different substantial forms that Socrates has, and that you have, and that I have relate to the form of human being that I form a concept of when I abstract from the particulars of any individual human being? Doesn't the form that is in the individual have to be the same that I form a concept of for it genuinely to count as knowledge? But in that case, how can my substantial form differ from yours and Socrates?
Hi @Ian,
DeleteI think you are conflating how we know these things (epistemology) with their nature or what they are in extramental reality.
1 - In the mind, there is no difference between my, your, or Socrates' Substantial Form when you abstract the rest of the attributes and all. The Substantial Form, as I said in earlier comments, is an inner organizing principle of a Substance, and when we think about it, it is just like a Universal (philosophically speaking), since our concept of Substantial Form (e.g., in the case of the human being, we have a Substantial Form of Rational Animality) covers every member from the especies that has that specific Substantial Form when we 'peel of' the rest of the Accidents (qualities).
2 - In reality, my Substantial Form is united with my Matter, and your Substantial Form is united with your Matter -- that's how we are individuated.
So, even though in the mind we have the same Substantial Form, as a concept, in reality, my Substantial Form is numerically distinct from yours, and it is united with my Matter, which is also distinct from yours.
Hope that helps.
God bless!
Introduction: I am a Platonist.
ReplyDeleteFrom my perspective, the uniqueness of the person is entirely identified with the soul, which participates in the idea of human being. It follows that my personality is entirely whole even if it is no longer conjoined with the body (for now, let's leave aside the "how" this conjugation is conceived by the various types of Platonism). Can I say the same thing for the Aristotelian-Thomistic conception? Can I say, according to the latter, that incomplete being is nevertheless what identifies me as a person? I'm inclined to say no, because from my perspective, the person is unique and therefore, as such, is not composite and therefore cannot be something incomplete. Question to Ed: would it be acceptable to consider the human soul incomplete in the sense that in the absence of matter it cannot realize its essential power?
If it takes over 500 pages to "prove" the immortal existence of the human soul, something is wrong.
ReplyDeleteAs they say on Twitter, tell me you haven’t actually read the book without telling me you haven’t actually read the book.
DeleteThe book does not devote 500 pages to proving the soul’s immortality. Only the second to last chapter is devoted to that topic. Some of the preceding material sets the stage for that, but much of it does not and is instead devoted to other aspects of human nature (since, as the subtitle indicates, the book is about human nature more generally, not just immortality).
Then again, why the length of an argument would somehow cast doubt on its cogency, I have no idea.
But I realize your comment was not a serious one anyway, but just a bit of sophomoric snark.