Mind and Body Page 1 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 Subject: Philosophy,	History	of	Western	Philosophy	(PostClassical),	Philosophy	of	Mind Online	Publication	Date: Jun 2015 DOI: 10.1093/oxfordhb/9780199744725.013.28 Mind	and	Body Adam	Harmer The	Oxford	Handbook	of	Leibniz	(Forthcoming) Edited	by	Maria	Rosa	Antognazza Oxford	Handbooks	Online Abstract	and	Keywords This	chapter	discusses	Gottfried	Wilhelm	Leibniz's	philosophical	reflections	on	mind	and	body.	It	first	considers Leibniz's	distinction	between	substance	and	aggregate,	referring	to	the	former	as	a	being	that	must	have	true	unity (what	he	calls	unum	per	se)	and	to	the	latter	as	simply	a	collection	of	other	beings.	It	then	describes	Leibniz's extension	of	the	term	"substance"	to	monads	and	other	things	such	as	animals	and	living	beings.	It	also	examines Leibniz's	views	about	the	union	of	mind	and	body,	whether	mind	and	body	interact,	and	how	interaction	is	related to	union.	More	specifically,	it	asks	whether	mind	and	body	together	constitute	an	unum	per	se	and	analyzes Leibniz's	account	of	the	per	se	unity	of	mind-body	composites.	In	addition,	the	chapter	explores	the	problem	of soul-body	union	as	opposed	to	mind-body	union	and	concludes	by	discussing	Leibniz's	explanation	of	soul-body interaction	using	a	system	of	pre-established	harmony. Keywords:	Leibniz,	mind,	body,	substance,	aggregate,	unum	per	se,	mind-body	union,	soul-body	union,	soul,	pre-established	harmony Introduction Leibniz	systematically	distinguishes	between	substances	and	aggregates.	A	substance	is	a	being	that	must	have true	unity	(Leibniz	calls	it	an	unum	per	se),	whereas	an	aggregate	is	merely	a	collection	of	other	beings	and	not itself	a	single	thing	or	a	substance.	An	aggregate	has	merely	accidental	unity,	which,	in	Leibniz's	view,	originates in	some	mind	perceiving	the	collection	together	(Leibniz	calls	it	an	unum	per	accidens).	Leibniz	illustrates	this distinction	by	contrasting,	for	example,	herds	and	armies	(aggregates)	with	sheep	and	soldiers	(substances). Characterizing	substance	as	unum	per	se	fits	rather	nicely	with	the	account	we	find	in	Leibniz's	Monadology (1714);	that	is,	that	the	world	is	constituted	by	the	harmonious	perceptions	and	appetites	of	infinitely	many	simple, active,	mind-like	substances-what	he	calls	monads.	A	monad,	insofar	as	it	is	simple,	is	not	at	risk	of	failing	to	meet Leibniz's	strict	criteria	of	substantial	unity. Yet	for	many	years	prior	to	the	Monadology,	and	even	in	the	Monadology	itself,	Leibniz	appears	willing	to	extend the	term	"substance"	to	things	other	than	monads:	animals	and,	more	broadly,	living	beings	are	characterized	as substances.	But	living	beings	are	not	simple	substances;	they	are	composites	of	a	soul	(or	dominant	monad)	and an	organic	body,	a	body	that	is	itself	constituted	by	a	mass	of	infinitely	many	other	substances.	Given	that	a substance	must	be	an	unum	per	se,	can	Leibniz	establish	that	living	beings	are	substances?	Or	should	he conclude	that	the	only	substances	are	simple,	mind-like	monads? One	way	to	approach	these	questions	is	to	consider	Leibniz's	views	about	the	union	of	mind	and	body.	The	central questions	I	address	in	this	chapter	are: 1.	Do	the	mind	and	body	interact?	How	is	interaction	related	to	union? Mind and Body Page 2 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 2.	Do	mind	and	body	together	constitute	an	unum	per	se?	If	so,	what	is	Leibniz's	account	of	the	per	se	unity of	mind-body	composites? A	few	points	of	clarification	are	required	concerning	how	we	should	understand	the	character	of	these	questions for	Leibniz.	For	some	philosophers	(Descartes,	for	instance),	the	human	being	is	the	only	mind-body	composite.	For Leibniz,	however,	the	problem	of	mind-body	union	is	not	restricted	to	human	beings	but	has	a	broader	application. Soul,	for	Leibniz,	is	a	genus	with	various	species	falling	under	it:	rational	souls-minds-and	nonrational	souls- what	Leibniz	sometimes	calls	"forms."	For	this	reason,	I	will	characterize	the	central	question	as	one	of	soul-body union,	rather	than	mind-body	union.	Furthermore,	in	Leibniz's	view,	the	soul	and	body	are	not	really	distinct substances	in	their	own	right	(as	they	are	for	Descartes	and	other	dualists).	The	human	body,	on	Leibniz's	view,	is not	a	material	substance	at	all,	but	a	collection	or	aggregate	of	substances-what	Leibniz	often	calls	"second matter."	(There	are	also	difficult	questions	about	the	nature	of	the	substances	that	make	up	these	aggregates-are they	composites	themselves	or	are	they	mind-like	simple	substances?-that	I	will	ignore	at	present.)	Leibniz's account	of	the	soul	differs	from	the	Cartesian	one,	too.	In	some	texts,	Leibniz	characterizes	the	soul	as	a substance	in	its	own	right,	whereas	at	other	times	he	more	guardedly	describes	the	soul	as	only	the	form	of	a substance. With	all	of	this	in	mind,	Leibniz's	answers	to	our	posed	questions	can	be	outlined	as	follows,	leaving	the	details aside	to	be	developed	later.	Leibniz	denies	that	soul	and	body	genuinely	interact,	but	he	does	not	deny	the appearance	of	interaction.	He	proposes	the	system	of	pre-established	harmony	to	explain	the	apparent	interaction of	soul	and	body. However,	I	will	argue	that	pre-established	harmony	is	not	an	explanation	of	the	unity	of	soulbody	composites,	although	it	does	account	for	union	in	another	sense. Despite	this	fact,	there	are	texts	in	which Leibniz	seems	to	claim	that	soul	and	body	together	constitute	an	unum	per	se. Nevertheless,	I	will	provide	reason to	think	that	Leibniz	does	not	provide	an	account	of	soul-body	unity.	I	will	suggest	that	if	there	are	any	prospects	in Leibniz	for	providing	such	an	account,	they	do	not	rely	on	any	relation	(such	as	pre-established	harmony) between	the	soul	and	the	body	but,	instead,	on	certain	structural	features	of	soul-body	composites. Soul-Body	Interaction Pre-established	harmony	is	Leibniz's	alternative	to	the	extant	seventeenth-century	accounts	of	soul-body interaction.	In	the	New	System,	after	discussing	the	shortcomings	of	Descartes's	and	Malebranche's	treatments	of the	problem,	Leibniz	writes,	"I	was	led,	little	by	little,	to	a	view	that	surprised	me,	but	which	seems	inevitable,	and which,	in	fact,	has	very	great	advantages	and	rather	considerable	beauty." He	goes	on	to	elaborate	his	view: [W]e	must	say	that	God	originally	created	the	soul	(and	any	other	real	unity)	in	such	a	way	that	everything must	arise	for	it	from	its	own	depths,	through	a	perfect	spontaneity	relative	to	itself,	and	yet	with	a	perfect conformity	relative	to	external	things. Although	there	is,	strictly	speaking,	no	causal	interaction	between	soul	and	body,	pre-established	harmony	stands in	for	an	account	of	interaction,	since,	as	Leibniz	continues, [t]here	will	be	a	perfect	agreement	among	all	these	substances,	producing	the	same	effect	that	would	be noticed	if	they	communicated	through	the	transmission	of	species	or	qualities,	as	the	common philosophers	imagine	they	do. Although	not	a	causal	relation,	pre-established	harmony	is	nonetheless	a	relation	between	soul	and	body,	one	that explains	the	appearance	of	their	interaction. In	these	passages,	we	find	two	main	features	of	pre-established	harmony: Spontaneity:	Everything	that	happens	to	a	soul	arises	from	its	own	depths.	That	is,	for	any	state,	x,	of	a soul,	s,	the	causal	ancestry	of	x	contains	only	states	of	s. Conformity:	The	states	of	soul	and	body	agree	with	each	other.	That	is,	for	any	state	of	the	soul,	y,	there	is a	corresponding	state	of	its	body,	y*,	such	that	y	and	y*	agree	with	one	another,	though	they	have	no causal	connection. 1 2 3 4 5 6 Mind and Body Page 3 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 Taken	together,	spontaneity	and	conformity	explain	the	appearance	of	interaction	between	soul	and	body.	Leibniz sometimes	says	that	the	soul	and	body	each	follow	their	own	laws	(the	soul	the	laws	of	final	causes,	the	body	the laws	of	efficient	causes	or	mechanical	laws),	yet	they	agree	perfectly	with	one	another. That	is,	a	soul	really	does cause	its	own	states,	but	it	does	not	cause	the	states	of	any	body.	(One	thing	to	note	about	these	passages	is	that at	no	time	is	causal	efficacy	attributed	to	a	body.	A	body,	for	Leibniz,	is	an	aggregate	of	substances,	and	any causal	efficacy	it	appears	to	have	is	ultimately	explained	by	the	forms	of	the	substances	in	the	aggregate.	I	will	not develop	this	any	further	here,	though.) It	is	also	worth	noting	that	pre-established	harmony	has	both	a	specific	and	a	general	application.	The	specific application	of	pre-established	harmony	explains	the	appearance	of	interaction	between	soul	and	body.	The general	application	explains	the	appearance	of	interaction	between	any	two	(or	more)	substances.	One	way	to express	this	aspect	of	Leibniz's	view	is	to	say	that	he	denies	intersubstantial	causation-causation	between substances-but	accepts	intrasubstantial	causation-causation	within	a	substance.	Neither	do	minds,	strictly speaking,	interact	with	bodies,	nor	do	bodies,	strictly	speaking,	interact	with	each	other.	As	such,	my	soul	and body	not	only	conform	or	agree	with	each	other,	they	agree	with	all	other	created	substances	as	well.	Thus,	the notion	of	harmony	has	various	senses	for	Leibniz,	including	soul-body	harmony,	intersubstantial	harmony, harmony	between	types	of	explanations	(i.e.,	mechanical	and	final-causal),	and	so	on. At	this	point,	we	might	wonder:	how	does	pre-established	harmony	relate	to	soul-body	union?	I	will	take	up	this question	at	more	length	in	the	following	section.	For	now,	let	us	consider	the	following,	slightly	more	modest question:	how	does	pre-established	harmony	even	explain	the	connection	between	a	particular	soul	and	body such	that	they	jointly	make	up	one	animal?	Given	that	the	soul	and	body	do	not,	strictly	speaking,	interact,	and furthermore	that	each	substance	harmonizes	with	every	other	substance,	not	only	the	substances	contained	in	its body,	how	can	Leibniz	explain	the	privileged	connection	between	the	soul	and	body	of	an	individual	animal? Leibniz's	account	is	that	souls	perceive	their	own	bodies	more	distinctly	than	they	perceive	anything	else	in	the world. Thus,	I	perceive	my	hands,	legs,	and	feet	more	distinctly	than	I	perceive	the	chair	I	am	sitting	on	or	the table	in	front	of	me.	This	may	sound	somewhat	surprising.	As	Antoine	Arnauld	plausibly	objects,	it	seems	odd	to claim	that	I	perceive,	for	example,	the	motions	of	lymph	in	my	lymphatic	vessels	more	distinctly	than	I	perceive	the motions	of	Saturn,	since	the	motions	of	lymph	in	my	lymphatic	vessels	are	effectively	inscrutable	to	me. Leibniz's response	to	Arnauld's	question	is	somewhat	puzzling:	he	claims	that	I	perceive	my	body	more	distinctly	than,	for example,	the	motions	of	Saturn	because	my	body	provides	my	soul	with	a	particular	perspective	on	the	world. That	is,	as	Leibniz	has	written	earlier	in	the	correspondence	with	Arnauld,	a	particular	mind	"is	an	expression	of	the phenomena	of	all	other	bodies	in	accordance	with	the	relationship	to	its	own." In	effect,	my	body	is	the	lens through	which	my	soul	sees	the	rest	of	the	world.	To	make	this	slightly	more	palatable,	it	must	be	kept	in	mind	that, for	Leibniz,	the	entire	physical	world	is	interconnected	such	that,	at	any	given	time,	my	body	expresses	the	entire universe. This	provides	some	basis	for	the	view	that	I	can	perceive	the	universe	beyond	my	body	simply	by perceiving	my	body.	Ultimately,	then,	the	distinctness	of	the	perceptual	relation	explains	why	my	body	is	my	body despite	the	fact	that	my	soul	and	body	do	not	strictly	interact	and	that	my	soul	conforms	with	the	entire	universe. Pre-established	Harmony	and	Soul-Body	Unity Although	pre-established	harmony	explains	the	apparent	interaction	of	soul	and	body,	I	will	argue	that	it	does	not explain	how	soul	and	body	together	constitute	an	unum	per	se,	although	it	does	explain	union	in	another	sense. Before	we	can	address	this	issue,	however,	we	must	consider	whether	and	to	what	extent	Leibniz	is	committed	to the	unity	of	soul-body	composites	in	the	first	place. There	is	an	ongoing	controversy	in	the	literature	concerning	Leibniz's	commitment	to	corporeal	substances.	Daniel Garber	has	suggested	that	Leibniz's	basic	ontological	commitments	change	dramatically	between	what	he	calls	the "Middle	Years"	(roughly	1680–1700)	and	the	"Mature	Period"	(roughly	1700–16). (There	is	also	controversy about	where	to	draw	the	dividing	lines	between	the	different	periods	of	Leibniz's	thought,	although	nothing	I	say here	turns	on	the	particular	dates	I	have	chosen.)	Garber's	contention	is	that,	in	the	Middle	Years,	Leibniz	is committed	to	bona	fide	corporeal	substances,	composites	of	soul	and	body	that	have	true,	substantial	unity,	and that	these	corporeal	substances	are	the	basic	constituents	of	reality.	Later	on,	this	commitment	disappears	and	the fundamental	constituents	of	reality	come	to	be	simple,	partless,	active	substances,	which	Leibniz	calls	"monads." However,	others,	Robert	Adams	and	Robert	Sleigh	to	cite	two	canonical	sources,	argue	that	Leibniz's	commitment 7 8 9 10 11 12 13 14 Mind and Body Page 4 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 to	simple	substances	is	already	implicit	in	his	views	during	the	so-called	Middle	Years. That	the	commitment	to simple	substances	comes	to	take	center	stage	does	not,	therefore,	betray	a	radical	change	of	mind	on	Leibniz's part,	but	instead	is	just	the	natural	development	of	his	implicit	commitments	or	maybe	just	an	original	commitment being	made	explicit.	A	third	option	worth	noting,	which	has	been	highlighted	by	some	of	the	recent	literature	on	this topic,	is	that,	even	during	the	Mature	Period,	Leibniz	uses	the	language	of	corporeal	(or	sometimes	composite) substance. This	suggests	that	the	shift	between	corporeal	substances	and	monads	may	not	be	primarily	a developmental	shift.	Perhaps	a	better	way	to	understand	what	is	going	on	is	to	think	of	Leibniz	as	wrestling	with different	conceptions	of	substance	throughout	his	entire	career.	I	do	not	aim	to	settle	this	issue	here,	but	merely	to keep	it	in	view	while	considering	Leibniz's	engagement	with	the	question	of	soul-body	unity. This	dispute	has	clear	implications	for	the	topic	of	soul-body	unity	because,	if	Leibniz	was	always	a	monadologist,	it is	possible	that	he	never	took	seriously	the	view	that	soul	and	body	together	make	up	an	unum	per	se.	If	this	is correct,	any	search	for	Leibniz's	account	of	soul-body	unity	will	be	in	vain.	I	cannot	definitively	rule	this	option	out. Nevertheless,	it	is	undeniable	that	there	are	texts	in	which	Leibniz	at	least	seems	to	characterize	soul-body composites,	the	human	being	in	particular,	as	per	se	unities. For	this	reason,	it	seems	worthwhile	to	look	for	an account. A	good	place	to	start	the	search	is	with	pre-established	harmony	itself.	A	prima	facie	reason	to	think	preestablished	harmony	is	a	good	candidate	is	that	Leibniz	often	presents	pre-established	harmony	as	an	account	of soul-body	union.	One	example	is	in	Leibniz's	New	System,	published	in	1695,	the	full	title	of	which	is	New	System of	the	Nature	of	Substances	and	their	Communication,	and	of	the	Union	which	Exists	between	the	Soul	and	the Body	(1695). The	account	of	union	we	find	there	is	pre-established	harmony.	Some	commentators	have suggested,	on	this	basis,	that	pre-established	harmony	should	be	read	as	an	account	of	the	unity	of	soul-body composites.	Daniel	Garber,	for	instance,	writes	that	"since	the	result	of	a	union	is	a	unity,	and	a	genuine	unity	is, for	Leibniz,	a	substance,	this	suggests	that	the	hypothesis	of	concomitance	[i.e.,	pre-established	harmony]	is supposed	to	account	for	the	fact	that	mind	and	body	together	constitute	a	substance." However,	there	are reasons	to	resist	this	interpretation	of	Leibniz's	view. In	an	exchange	with	the	Jesuit	Father	Tournemine	between	1704	and	1708,	Leibniz	denies	both	that	preestablished	harmony	provides	an	account	of	soul-body	unity	and	that	he	ever	intended	it	to	do	so.	Tournemine	had voiced	concern	that,	although	Leibniz	often	claims	that	pre-established	harmony	fares	better	than	the	Cartesians (by	which	Leibniz	means	the	occasionalists)	as	an	account	of	soul-body	union,	it	does	no	better	at	explaining	their unity. Here	is	Leibniz's	reply: I	have	to	admit	that	I	would	be	greatly	mistaken	if	I	objected	against	the	Cartesians	that	the	agreement which,	according	to	them,	God	maintains	immediately	between	the	soul	and	the	body,	does	not	create	a genuine	unity,	because	most	certainly	my	pre-established	harmony	could	not	do	it	any	better.	My	aim	was to	explain	naturally	what	they	explain	by	perpetual	miracles,	and	in	doing	so	I	attempted	only	to	give	an explanation	of	the	phenomena,	that	is	to	say,	of	the	relation	we	perceive	between	the	soul	and	the	body. But	since	this	metaphysical	union,	which	is	added	on	to	that,	is	not	a	phenomenon,	and	as	we	have	not even	been	given	an	intelligible	notion	of	it,	I	have	not	taken	it	upon	myself	to	look	for	an	explanation	of	it. In	this	passage,	Leibniz	claims	that	the	goal	of	pre-established	harmony	is	(and	was)	to	explain	"the	relation	we perceive	between	the	soul	and	the	body,"	by	which	he	means	their	apparent	interaction.	He	distinguishes	this	goal from	a	different	more	ambitious	one:	to	explain	the	"metaphysical	union"	between	soul	and	body.	In	a	letter	to Burcher	de	Volder,	which	Leibniz	wrote	after	reading	Tournemine's	objection	but	before	publishing	his	reply, Leibniz	characterizes	the	hope	for	an	account	of	metaphysical	union	as	"utopian." In	this	passage,	Leibniz	even appears	dubious	that	the	notion	of	metaphysical	union	has	been	given	an	intelligible	characterization. If	we	turn	back	to	the	New	System,	it	is	possible	to	see	merely	the	aim	that	Leibniz	suggests:	an	account	of interaction.	There,	Leibniz	characterizes	pre-established	harmony	as	a	"mutual	relationship,	arranged	in	advance in	each	substance	in	the	universe,	which	produces	what	we	call	their	communication,	and	which	alone	constitutes the	union	of	soul	and	body." This	brief	formulation	of	his	view,	read	in	light	of	his	remark	to	Tournemine,	can	be seen	as	further	indication	that	by	"union"	Leibniz	means	"communication"	(i.e.,	the	deflationary	sense	of "interaction"	developed	earlier	in	this	chapter)	and	nothing	more.	If	we	turn	to	the	Monadology,	we	find	Leibniz using	"union"	and	"conformity"	almost	interchangeably:	"these	principles	[i.e.,	the	principles	of	pre-established 14 15 16 17 18 19 20 21 22 Mind and Body Page 5 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 harmony]	have	given	me	a	way	of	naturally	explaining	the	union,	or	rather	the	conformity	of	the	soul	and	the organic	body." If	pre-established	harmony	was	always	intended	to	account	only	for	interaction,	there	is	good	reason	to	resist	the claim	that	pre-established	harmony	explains	the	unity	of	soul-body	composites.	Interaction	and	unity	are importantly	different.	Two	things	can	interact	without	thereby	constituting	a	unity. When	the	sense	of	"union" involved	in	pre-established	harmony	is	understood	as	"interaction,"	the	plausibility	of	inferring	genuine	unity	from union,	as	Garber	does,	quickly	disappears. Soul-Body	Unity Despite	this,	it	is	certainly	possible	that	Leibniz	is	being	disingenuous	in	his	reply	to	Tournemine.	Perhaps	he	has changed	his	view	but	is	attempting	to	save	face	by	denying	that	he	ever	had	"utopian"	hopes	for	pre-established harmony.	Perhaps	Tournemine's	remarks	prompted	Leibniz	to	consider	more	deeply	something	he	had	been	taking for	granted. Furthermore,	if	we	look	at	some	texts	from	Leibniz's	Middle	Years,	it	seems	that	Leibniz	does,	at	least during	this	period,	believe	that	soul	and	body	together	make	up	an	unum	per	se.	How	can	this	be	reconciled	with Leibniz's	claim	that	anything	beyond	"the	phenomena"	is	a	utopian	dream,	one	that	he	never	set	about	attempting to	realize? There	are	various	passages	from	Leibniz's	correspondence	with	Arnauld,	in	which	Leibniz	attributes	true	unity	to the	composite	of	soul	and	body.	Consider	the	following: Supposing	that	there	is	a	soul	or	substantial	form	in	beasts	or	other	corporeal	substances,	one	must reason	with	respect	to	them	on	this	point	as	we	all	reason	with	respect	to	man,	who	is	an	entity	endowed with	a	true	unity	that	his	soul	gives	to	him,	not	withstanding	the	fact	that	the	mass	of	his	body	is	divided into	organs,	vessels,	humors,	spirits,	and	that	the	parts	are	undoubtedly	full	of	an	infinite	number	of	other corporeal	substances	endowed	with	their	own	forms. There	are	two	aspects	of	this	passage	that	I	would	like	to	highlight,	although	I	will	focus	on	the	first	for	now: 1.	Leibniz	claims	that	the	soul	gives	true	unity	to	the	human	being.	This	suggests	that	a	soul-body composite,	in	this	case	a	human	being,	can	be	an	unum	per	se. 2.	Leibniz's	phrasing	is	rather	tentative:	we	must	reason	with	respect	to	animals	as	we	all	reason	with respect	to	man.	It	is	unclear,	therefore,	how	strong	Leibniz's	commitment	really	is	here. In	another	letter	to	Arnauld,	Leibniz	writes: [I]t	is	the	animated	substance	to	which	the	matter	belongs	that	is	truly	one	being,	and	the	matter	taken	as a	mass	in	itself	is	only	a	pure	phenomenon	or	well-founded	appearance,	as	also	are	space	and	time. In	this	passage,	true	unity	is	attributed	to	"the	animated	substance."	Although	it	may	be	possible	to	understand "the	animated	substance"	as	indicating	the	soul,	I	think	there	is	good	reason	to	think	that	Leibniz	means	to	indicate the	soul-body	composite.	Leibniz's	correspondence	with	Arnauld	is	full	of	language	suggestive	of	a	roughly hylomorphic	conception	of	substance.	This	is	displayed	by	Leibniz	when	he	says,	"[a]s	our	body	is	the	matter,	and the	soul	is	the	form	of	our	substance,	it	is	the	same	with	other	bodily	substances." So	it	is	natural	to	read	"the animated	substance"	as	referring	to	the	soul-body	composite. What	are	we	to	make	of	Leibniz's	claim	to	Tournemine	that	he	never	intended	to	explain	the	"metaphysical	union" of	soul	and	body	in	light	of	these	attributions	(and	others	like	them)	of	true	unity	to	the	soul-body	composite?	Some commentators	have	identified	the	exchange	with	Tournemine	as	a	turning	point	for	Leibniz's	theory	of	substance, after	which	he	realized	that	he	was	no	longer	entitled	to	maintain	the	true	unity	of	soul-body	composites. However,	I	think	it	is	more	likely	that	Leibniz	is	being	straightforward	with	Tournemine;	that	is,	that	Leibniz	never intended	pre-established	harmony	to	account	for	the	unity	of	soul-body	composites.	As	I	see	it,	there	are	two	ways to	maintain	this	view.	The	first	is	to	find	a	basis	for	downplaying	the	importance	of	the	passages	written	to	Arnauld (and	others	like	them).	The	second	(which	I	favor,	as	will	become	clear)	is	to	consider	that	if	Leibniz	did	in	fact	think that	soul-body	composites	were	true	unities,	he	might	have	thought	so,	not	in	virtue	of	some	relation	(such	as	preestablished	harmony)	between	the	soul	and	the	body,	but	for	other	reasons.	I	will	briefly	consider	the	first	option 23 24 25 26 27 28 29 30 Mind and Body Page 6 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 before	turning,	in	the	following	section,	to	the	second. That	all	of	the	texts	just	considered	are	written	to	Arnauld	provides	some	reason	to	wonder:	does	Leibniz	equally attribute	true	unity	to	soul-body	composites	outside	of	the	Arnauld	correspondence?	Could	Leibniz's	friendliness toward	a	roughly	hylomorphic	theory	of	substance	be	explained	away	as	a	nod	to	Catholic	orthodoxy,	one	which wouldn't	ruffle	the	feathers	of	the	Catholic	Arnauld? It	is	not	altogether	clear	why	Catholic	Orthodoxy	would require	a	commitment	to	corporeal	substances	with	true	unity,	and	none	of	the	discussions	of	this	possibility	has provided	a	compelling	explanation. So,	although	it	is	possible	that	Leibniz's	willingness	to	use	the	language	of	corporeal	substances	is	ultimately	a concession	to	the	Catholics,	more	evidence	is	needed. One	reason,	internal	to	the	texts	themselves	and	on	the	basis	of	which	we	might	suspect	that	the	commitment	to corporeal	substances	is	not	very	strong	is	that,	as	noted	earlier,	Leibniz's	phrasing	in	some	of	the	passages considered	is	rather	cautious:	one	must	reason	with	respect	to	animals	as	we	all	reason	with	respect	to	man. Perhaps	Leibniz	is	simply	noting	a	way	in	which	"we	all	reason"	rather	than	expressing	a	genuine	commitment. Still,	there	might	be	other,	deeper	theological	commitments	driving	Leibniz's	commitment	to	corporeal	substances, although	not	Catholic	ones.	In	particular,	Leibniz's	account	of	the	Incarnation	appears	to	be	modeled	after	the union	between	soul	and	body	and	furthermore	to	require	a	proper	substantial	union	between	different substances. The	Incarnation	is	a	mystery	that	Leibniz,	as	a	Lutheran,	would	be	motivated	to	accommodate.	It	is not	only	Catholic	Orthodoxy,	then,	that	might	push	Leibniz	to	account	for	soul-body	unity,	but	also	theological commitments	much	closer	to	home. True	Unity Despite	the	evidence	that	Leibniz	is	willing	to	characterize	soul-body	composites	as	true	unities,	I	do	not	think	that pre-established	harmony	explains	the	unity	of	soul-body	composites	or	that	Leibniz	ever	thought	so.	Instead,	I suggest	that	the	more	likely	candidate	for	an	account	of	unity	is	the	structure	of	soul-body	composites.	Although	I do	not	think	that	Leibniz	ever	argues	for	the	per	se	unity	of	soul-body	composites	on	this	basis,	I	do	think	that	it provides	a	way	of	understanding	his	stated	commitment	to	this	unity. At	least	as	early	as	1685,	Leibniz	expressed	the	view	that	true	unity	involves	having	no	parts.	In	the	following passage,	Leibniz	characterized	the	difference	between	substances	and	aggregates	in	terms	of	having	and	not having	parts,	respectively: But	actually	no	entity	that	is	really	one	is	composed	of	a	plurality	of	parts,	and	every	substance	is indivisible,	and	those	things	that	have	parts	are	not	entities,	but	merely	phenomena. This	passage	was	written	near	the	beginning	of	Leibniz's	correspondence	with	Arnauld.	It	very	strongly	indicates that,	at	this	time,	Leibniz	believed	that	having	no	parts	is	at	least	a	necessary	condition	of	being	a	true	unity.	Of course,	more	needs	to	be	said	about	what	it	means	to	have	or	not	have	parts.	I	consider	this	further	later.	For	now, the	passage	provides	some	insight	into	why	and	in	what	sense	Leibniz	would	be	willing	to	attribute	true	unity	to	a soul-body	composite. If	we	take	another	look	at	the	quoted	passages,	the	ones	in	which	Leibniz	attributes	true	unity	to	soul-body composites,	we	find	that	none	of	them	offers	a	positive	account	of	the	unity	of	composites.	Rather,	each	states	that composite	substances	(e.g.,	human	beings)	are	true	unities	despite	the	fact	that	the	bodies	of	such	composites have	parts. Consider	once	more:	"man...	is	an	entity	endowed	with	a	true	unity	that	his	soul	gives	to	him,	not withstanding	the	fact	that	the	mass	of	his	body	is	divided	into	organs,	vessels,	humors,	spirits." In	my	view,	Leibniz's	attributions	of	true	unity	to	soul-body	composites	are,	therefore,	not	based	on	pre-established harmony	but	instead	rely	on	the	structure	of	composites.	At	least	two	questions	arise	at	this	point: 1.	How	can	Leibniz	maintain	that	a	soul-body	composite	such	as	a	human	being	has	no	parts?	Is	it	not	plain that	we	have	parts:	cells,	limbs,	organs,	and	so	on? 2.	Why	are	soul	and	body	themselves	not	considered	parts	of	the	composite	substance?	Even	if	we	can 31 32 33 34 35 36 Mind and Body Page 7 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 establish-in	light	of	question	1-that	the	complexity	of	the	body	of	a	substance	does	not	entail	that	the substance	has	parts,	shouldn't	we	still	conclude	that	a	substance	is	composed	of	(at	least)	two	parts:	a	body and	a	soul? The	problem	indicated	by	question	1	can	be	addressed	by	distinguishing	the	body	of	a	substance	from	the substance	itself.	In	this	way,	Leibniz	can	maintain	that	the	body	of	a	substance	has	parts,	although	the	substance itself	has	no	parts.	The	body	of	a	substance	is	still	an	aggregate	for	Leibniz,	even	though	it	is	the	body	of	a substance.	There	are	various	passages	in	which	Leibniz	clearly	distinguishes	the	substance	from	its	body,	one	of which	we	have	seen	earlier.	In	these	passages,	Leibniz	attributes	unity	to	the	substance	but	not	to	the	body.	He makes	analogous	claims	about	the	persistence	of	substances.	Consider	the	following	passage	from	the	New Essays: So	we	must	acknowledge	that	organic	bodies	as	well	as	others	remain	"the	same"	only	in	appearance,	and not	strictly	speaking....	[A]s	for	substantial	beings,	quae	uno	spiritu	continentur	as	one	of	the	ancient jurists	says,	meaning	that	a	certain	indivisible	spirit	animates	them:	one	can	rightly	say	that	they	remain perfectly	"the	same	individual"	in	virtue	of	this	soul	or	spirit	which	makes	the	I	in	substances	which	think. "Organic	bodies"	is	Leibniz's	term	for	the	bodies	of	substances.	This	passage	claims	that	the	body	of	a	substance does	not	persist,	although	the	substance	itself	does.	In	light	of	the	distinction	between	the	substance	and	the	body of	the	substance,	we	can	say	that	the	things	mentioned	earlier-cells,	limbs,	organs-may	be	parts	of	the	body	of the	substance,	but	they	are	not	parts	of	the	substance	itself. Leibniz	faces	more	difficulty	in	attempting	to	respond	to	question	2.	Why	are	the	soul	and	body	not	parts	of	the composite	substance?	There	is	a	preliminary	response	open	to	Leibniz	in	light	of	how	he	defines	"part,"	but	it	faces certain	difficulties,	as	we	will	see.	A	part	is,	for	Leibniz,	a	homogeneous	requisite. Soul	and	body	might	fail	to	be parts	of	the	substance,	on	this	definition,	because	they	are	not	homogeneous,	they	are	not	the	same	kind	of	thing as	each	other	or	as	the	substance	they	jointly	constitute. As	Leibniz	writes	to	De	Volder,	"substantial	unities	are	not	parts,	but	the	foundations	of	phenomena." To	keep track	of	this,	I	will	call	soul	and	body	constituents	of	composite	substances	(not	parts).	We	can	then	distinguish	two types	of	composition:	part-wise	composition	versus	constituent-wise	composition.	As	we	have	seen	in	the	earlier quoted	texts,	Leibniz	is	clear	that	part-wise	composition	is	incompatible	with	per	se	unity.	However,	the	presence	of constituents	could	still	be	compatible	with	per	se	unity.	If	so,	this	would	allow	Leibniz	to	maintain	the	per	se	unity	of the	soul-body	composite	despite	the	presence	of	a	plurality	of	constituents:	so	long	as	the	constituents	are	not parts,	per	se	unity	can	be	maintained. This	line	of	response	is	complicated,	however,	by	the	fact	that	Leibniz	does	not	give	a	straightforwardly hylomorphic	account	of	substance.	Unlike	Aristotle,	for	Leibniz,	soul	and	body	are	not	strictly	heterogeneous because	a	body	is	ultimately	resolvable	into	a	collection	of	soul-like	monads.	So,	the	soul	is	a	monad,	and	the	body is	a	collection	of	monads.	In	what	sense,	then,	do	the	soul	and	body	fail	to	be	homogeneous?	This	line	of	reasoning pushes	toward	the	conclusion	that	composite	substances	do,	in	fact,	have	parts	and	thus	can	be	nothing	more than	mere	aggregates. Nonetheless,	there	may	be	some	room	for	Leibniz	to	resist	this	conclusion.	Despite	the	apparent	homogeneity	of the	soul	and	body	on	the	monadological	analysis,	Leibniz	is	explicit	that	monads	are	not	parts.	One	way	to	make sense	of	this	is	to	move	away	from	relying	on	homogeneity	to	characterize	parts	and	rely	instead	on	the	fact	that, for	Leibniz,	parts	are	always	essential	to	the	wholes	they	compose.	This	gives	a	more	robust	way	to	distinguish between	the	parts	of	an	aggregate	and	the	constituents	of	a	substance.	As	Leibniz	writes,	"what	constitutes	the essence	of	an	entity	through	aggregation	is	only	a	state	of	being	of	its	constituent	entities." Unlike	a	substance, a	change	to	the	parts	of	an	aggregate	entails	a	change	to	the	identity	of	the	aggregate.	If,	for	example,	the MacLean	herd	is	made	up	of	three	sheep,	Angus,	Barclay,	and	Calum,	and	Calum	leaves	the	herd	and	is	replaced by	Dugald,	then	the	MacLean	herd	is	not,	strictly	speaking,	the	same	herd	anymore.	Calum	himself,	by	contrast, continues	to	be	the	same	sheep	even	if	he	grows,	gets	shorn,	or	has	his	hooves	trimmed.	On	this	characterization, monads	will	fail	to	be	parts	because	the	removal	of	any	given	monad	does	not	affect	the	identity	of	the	composite. As	Leibniz	writes	in	the	Monadology,	"all	bodies	are	in	a	perpetual	state	of	flux,	like	rivers,	and	parts	are	constantly coming	into	them	and	going	out." Substances,	however,	"remain	perfectly	'the	same	individual.'" This	provides a	way,	which	does	not	rely	merely	on	a	terminological	distinction,	to	maintain	that	soul-body	composites,	even 37 38 39 40 41 42 Mind and Body Page 8 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 when	understood	as	collections	of	monads,	do	not	have	parts. But	even	if	Leibniz	thinks	of	soul-body	composites	along	the	lines	I	have	suggested,	as	constituent-wise composites	rather	than	part-wise	composites,	this	does	not	fully	answer	the	question	of	soul-body	unity.	At	best, understanding	the	soul	and	body	as	constituents	rather	than	parts	of	composites	meets	one	necessary	condition	of substantial	unity;	namely,	not	having	parts.	But	it	seems	that	some	account	of	the	unity	of	the	constituents-of	soul and	body-is	still	needed.	Even	granting	that	soul	and	body	are	constituents	in	the	sense	just	elaborated,	how could	it	be	that	a	soul-body	composite	is	not	a	composition	in	any	problematic	sense? Here,	we	might	consider	two	different	ways	to	think	about	the	structure	of	composite	substance,	formulated	in terms	of	"form"	and	"matter": 1.	Actual-Constituent	View:	Form	and	matter	are	entities	in	their	own	right,	so	related	as	to	compose	a	unified composite	substance. 2.	Dual-Aspect	View:	Form	and	matter	are	not	entities	in	their	own	right,	but	aspects	of	a	single	thing,	which we	can	consider	separately	(but	which	cannot	exist	separately). Each	of	these	views	is	represented	within	the	scholastic-Aristotelian	tradition	to	some	degree,	and	Leibniz	would have	been	familiar	with	them	both. The	Dual-Aspect	view	more	nearly	aligns	with	Aristotle	himself,	although Aquinas	also	held	something	like	this	view,	with	the	caveat	that	the	human	soul	(being	immortal)	can	in	some	way subsist	without	any	matter.	The	Actual-Constituent	view	appears	to	have	been	held	by,	for	example,	William Ockham	and	Duns	Scotus. Leibniz's	own	texts	fall	on	both	sides	of	this	divide. Which	of	these	two	conceptions	of	substance	one	favors	has	important	consequences	for	whether	and	in	what sense	the	"composition"	of	soul	and	body	is	compatible	with	true	unity.	On	the	Dual-Aspect	view,	one	need	not explain	how	the	composition	of	form	and	matter	results	in	a	being	with	true	unity	because	form	and	matter	are	not things	in	their	own	right.	On	this	view,	soul	and	body	need	not	be	even	constituents,	but	instead	something	like aspects	of	the	individual	being.	As	such,	no	account	of	how	they	come	together	to	form	a	true	unity	would	be needed.	On	the	Actual-Constituent	view,	on	the	other	hand,	some	account	does	appear	to	be	needed	as	to	how these	two	(or	more)	distinct	entities	can	compose	a	being	with	true	unity.	Some	would	deny	that	such	an	account can	be	given	at	all.	Aquinas,	for	example,	denies	that	more	than	one	actual	constituent	can	combine	to	form	a being	with	true	unity. Because	the	Dual-Aspect	view	seems	much	more	congenial	to	the	possibility	of	accounting	for	the	per	se	unity	of	a composite	substance,	it	would	be	nice	if	there	was	evidence	that	this	is	how	Leibniz	understands	the	structure	of composite	substance.	But,	as	I	mentioned,	the	evidence	is	at	best	divided.	Some	commentators	have	picked	up	on the	evidence	inclining	toward	the	Dual-Aspect	view	and	proposed	that	Leibniz	held	something	like	Aquinas's view. There	are,	however,	at	least	two	reasons	to	resist	attributing	the	Dual-Aspect	view	to	Leibniz.	First,	even during	the	Middle	Years,	Leibniz	characterizes	bodies	as	aggregates	of	substances. This	suggests	that	the Actual-Constituent	view	is	a	better	fit,	insofar	as	substances	are	beings	in	their	own	right.	Second,	even	by	the earliest	years	of	his	Mature	Period,	the	Dual-Aspect	view	seems	to	fit	more	neatly	as	a	characterization	of	monads than	of	composite	substances.	Consider	the	following	well-known	passage	from	a	1703	letter	to	De	Volder: I	therefore	distinguish:	(1)	the	primitive	entelechy,	i.e.,	the	soul;	(2)	matter,	namely,	primary	matter,	i.e., primitive	passive	power;	(3)	the	monad	completed	by	these	two	things;	(4)	the	mass,	i.e.,	the	secondary matter,	i.e.,	the	organic	machine,	for	which	innumerable	subordinate	monads	come	together;	and	(5)	the animal,	i.e.,	the	corporeal	substance,	which	the	monad	dominating	in	the	machine	makes	one. In	this	passage,	Leibniz	claims	that	the	primitive	entelechy	(i.e.,	the	form)	combines	with	the	primitive	passive power	(i.e.,	the	matter)	to	complete,	not	the	composite	substance	as	we	might	expect,	but	the	simple	substance (i.e.,	the	monad).	The	dominant	monad	is	then	distinct	from	and	joined	to	its	body,	which	is	itself	a	mass	of subordinate	monads. Given	this	characterization,	it	seems	difficult	to	see	how	Leibniz	could	understand	composite	substance	along	the lines	of	the	Dual-Aspect	view.	The	composite	substance	is	fairly	clearly	characterized	as	a	collection	of	monads- that	is,	as	independent	beings-that	bear	certain	relations	to	one	another	(the	relevant	relation	here	being domination).	Consequently,	it	seems	that	he	must	think	about	composites	along	the	lines	of	the	Actual-Constituent 43 44 45 46 47 48 Mind and Body Page 9 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 view.	But,	given	Leibniz's	exacting	standards	of	substantial	unity,	this	seems	to	preclude	an	account	of	the	per	se unity	of	composite	substance-Leibniz	appears	to	be	of	the	same	mind	as	Aquinas	on	this	point.	(But	note	also	that even	in	this	passage	Leibniz	claims	that	the	machine	is	"one.") Despite	the	difficulty	Leibniz	faces	in	accounting	for	the	per	se	unity	of	composites	on	the	Actual-Constituent	view, all	hope	may	not	be	lost.	Paul	Lodge	(2014)	has	recently	suggested	that	the	relation	of	monadic	domination- articulated	in	(5)	of	the	passage	to	De	Volder	just	quoted-might	ground	the	substantial	unity	of	soul-body composites. On	Lodge's	account,	domination	might	be	sufficient	to	ground	per	se	unity	because	it	provides	an internal	principle	of	unity	for	the	collection	of	monads	that	make	up	the	composite. That	this	relation	is	internal marks	a	clear	difference	between	soul-body	composites	and	aggregates.	Aggregates,	such	as	flocks	of	sheep	or armies,	have	an	external	principle	of	unity:	some	mind	grouping	the	parts	of	the	aggregate	on	the	basis	of	relations that	hold	between	them.	For	example,	I	think	of	the	sheep	Angus,	Barclay,	Calum,	and	Dugald	as	the	MacLean	herd because	they	are	standing	near	one	another	in	the	same	meadow.	Unlike	this	example,	the	relation	grounding	the unity	of	a	composite	(i.e.,	domination)	is	internal	to	the	collection.	Furthermore,	on	Lodge's	account,	domination does	not	rely	on	the	perception	or	grouping	by	some	finite	mind	(as	with	the	herd	of	sheep)	but	only	on	facts, represented	by	the	divine	mind,	about	the	relations	between	the	relevant	monads.	Thus,	the	domination	relation,	on Lodge's	account,	does	not	yield	an	aggregate	in	the	way	that	my	mental	grouping	of	the	four	sheep	does.	For	this reason,	Lodge	characterizes	domination	as	a	"non-aggregate	relation." As	Lodge	himself	notes,	this	approach	faces	some	textual	obstacles.	For	example,	Leibniz	writes	to	Des	Bosses that	"composite	substance	does	not	formally	consist	in	monads	and	their	subordination." Although	not	an	explicit denial	that	the	domination	relation	can	ground	the	unity	of	composites,	this	text	tends	in	that	direction. Nevertheless,	as	I	see	it,	Lodge's	(2013)	approach	has	two	significant	virtues.	First,	it	reckons	with	the	places	in which	Leibniz	characterizes	soul-body	composites	as	having	per	se	unity.	We	have	seen	some	such	texts	from Leibniz's	correspondence	with	Arnauld	in	the	1680s;	there	are	others	stretching	well	into	Leibniz's	mature philosophy. Any	approach	that	abandons	the	per	se	unity	of	composites	is	forced	to	explain	these	texts	away somehow.	Second,	it	aligns	the	question	of	unity	with	the	question	of	what	sense	of	"composite"	is	at	stake. Aggregates,	such	as	bodies,	are	clearly	composites	in	a	certain	sense.	But	perhaps,	as	Lodge	suggests,	not	all composites	are	aggregates.	Or,	put	in	the	terms	I	have	elaborated	earlier:	not	all	composites	have	parts.	If	correct, Lodge's	account	would	provide	just	what	Leibniz,	on	my	account,	needs:	a	way,	independent	of	pre-established harmony,	to	account	for	the	unity	of	the	actual	constituents	of	a	composite	substance. One	problem	faced	by	any	account	given,	on	Leibniz's	behalf,	of	the	unity	of	soul-body	composites	is	that,	in	his late	correspondence	with	the	Jesuit	Bartholomew	Des	Bosses,	Leibniz	appears	to	admit	that	something	more	is needed	to	explain	the	unity	of	composite	substance.	On	one	interpretation	of	this	correspondence,	the	lack	of	an account	of	the	per	se	unity	of	composite	substance	is	what	prompts	Leibniz	to	consider	the	introduction	of	a	bond -vinculum (which	later	becomes	the	substantial	bond;	the	vinculum	substantiale )-invoked	to	account	for transubstantiation	within	the	theory	of	monads.	The	status	of	the	substantial	bond	within	Leibniz	philosophy	is	the subject	of	ongoing	dispute,	and	I	cannot	engage	the	issue	fully	here.	Still,	one	way	to	read	the	introduction	of substantial	bonds	is	to	see	it	as	Leibniz's	own	tacit	admission	that	the	Actual-Constituent	view	creates	difficulty	for the	claim	that	soul	and	body	constitute	a	composite	with	per	se	unity.	This	would	square	with	some	of	the	concerns I	raised	earlier	about	Leibniz's	prospects	for	accounting	for	the	unity	of	anything	with	more	than	one	constituent. Conclusion One	virtue	of	the	approach	I	have	developed	is	that	it	allows	us	to	take	Leibniz's	remarks	to	Tournemine	at	face value.	It	also	allows	us	to	take	seriously	Leibniz's	stated	commitment	to	the	per	se	unity	of	composite	substance,	at least	in	the	Middle	Years	and	perhaps	beyond.	On	my	interpretation,	although	Leibniz	may	have	held	that	soul-body composites	have	per	se	unity,	he	did	not	hold	that	pre-established	harmony	was	the	explanation	of	their	unity. However,	my	suggestions	do	not	provide	a	complete	account	of	the	unity	of	composite	substance. Whether	or	not	Leibniz	can	ultimately	give	an	account	of	the	per	se	unity	of	composites,	one	important consequence	of	my	view	is	that	the	way	in	which	Leibniz	understands	unity	in	the	early	to	middle	period	prefigures very	closely	the	way	in	which	he	understands	simplicity	later	on-"simple,	that	is,	without	parts." This	result	has a	direct	bearing	on	the	status	of	composites	in	any	period	of	Leibniz's	thought.	What	follows,	in	my	view,	is	that 49 50 51 52 53 54 55 56 57 Mind and Body Page 10 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 composites,	understood	in	the	specific	sense	of	part-wise	composites,	were	never	part	of	Leibniz's	fundamental ontology.	Substances	are	always	noncomposite,	in	this	sense,	for	Leibniz.	Perhaps	Leibniz's	transition	to	a monadological	metaphysics	is	ultimately	motivated	by	his	inability	to	account	for	the	unity	of	anything	composite (i.e.,	anything	with	more	than	one	part,	constituent,	element,	ingredient,	etc.).	Or	perhaps	the	transition	need	not abandon	the	unity	of	soul-body	composites	after	all.	A	great	deal	hinges	on	what	sense	of	"composite"	is	at	stake. Relative	to	what	has	been	achieved	here,	however,	any	conclusions	on	these	matters	must	remain	speculative. Acknowledgments I	am	grateful	to	Marleen	Rozemond,	Christian	Barth,	Maria	Rosa	Antognazza,	Paul	Lodge,	and	the	participants	of	the Toronto-Berlin-Groningen	Workshop	on	Medieval	and	Early	Modern	Philosophy	and	the	History	of	Modern	Group	at the	University	of	Toronto	for	comments	on	previous	versions	of	this	chapter. A Leibniz,	G.	W.	Sämtliche	Schriften	und	Briefe.	Edited	by	the	Academy	of	Sciences	of	Berlin.	Series	I‒VIII. Darmstadt/Leipzig/Berlin,	1923.	Cited	by	series,	volume,	and	page.	"N."	followed	by	an	Arabic	numeral	indicates the	number	assigned	to	the	text	by	the	editors. AG Leibniz,	G.	W.	Philosophical	Essays.	Edited	and	translated	by	R.	Ariew	and	D.	Garber,	Indianapolis:	Hackett, 1989. GP Leibniz,	G.	W.	Die	Philosophischen	Schriften.	Edited	by	C.	I.	Gerhardt.	7	vols.	Berlin:	Weidmannsche Buchhandlung,	1875‒1890.	Reprint,	Hildesheim:	Olms,	1960‒1961.	Cited	by	volume	and	page. LA The	Leibniz-Arnauld	Correspondence.	Edited	and	translated	by	H.	T.	Mason.	Manchester:	Manchester	University Press,	1967;	New	York:	Garland,	1985. Lodge The	Leibniz-De	Volder	Correspondence.	With	Selections	from	the	Correspondence	Between	Leibniz	and Johann	Bernoulli.	Translated,	Edited,	and	with	an	Introduction	by	Paul	Lodge.	New	Haven	London:	Yale University	Press,	2013. NE Leibniz,	G.	W.	New	Essays	on	Human	Understanding.	Edited	and	translated	by	Peter	Remnant	and	Jonathan Bennett.	Cambridge:	Cambridge	University	Press,	1981. WFN Leibniz's	New	System	and	Associated	Contemporary	Texts.	Translated	and	edited	by	R.	S.	Woolhouse	and Richard	Francks.	Oxford:	Clarendon	Press,	1997. WFP Leibniz,	G.	W.	Philosophical	Texts.	Edited	and	translated	by	R.	S.	Woolhouse	and	Richard	Franks.	Oxford: Oxford	University	Press,	1998. References Adams,	Marilyn	McCord.	1987.	William	Ockham.	2	Vols.	New	York:	Oxford	University	Press. Adams,	Robert	M.	1994.	Leibniz:	Determinist,	Theist,	Idealist.	Oxford:	Oxford	University	Press. Antognazza,	Maria	Rosa.	2014.	"Leibniz's	theory	of	substance	and	his	metaphysics	of	the	Incarnation,"	in	Paul Lodge	and	T.	W.	C.	Stoneham	(eds.),	Locke	and	Leibniz	on	Substance	and	Identity.	Abingdon/New	York: Routledge. Arthur,	Richard	T.	W.,	and	Peter	Lopston.	2006.	"Leibniz's	body	realism:	Two	interpretations."	The	Leibniz	Review 16:	1–42. Garber,	Daniel.	1985.	"Leibniz	and	the	foundations	of	physics:	The	Middle	Years,"	in	K.	Okruhlik	and	J.	Brown (eds.),	The	Natural	Philosophy	of	Leibniz.	Dordrecht:	Kluwer	Academic	Publishers,	pp.	27–130. Mind and Body Page 11 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 Garber,	Daniel.	2009.	Body,	Substance,	Monad.	Oxford:	Oxford	University	Press. Lodge,	Paul	(ed.	and	trans.).	2013.	The	Leibniz-De	Volder	Correspondence.	New	Haven:	Yale	University	Press. Lodge,	Paul.	2014.	"Corporeal	substances	as	monadic	composites	in	Leibniz's	later	philosophy,"	in	A.	Nita	(ed.), Leibniz's	Metaphysics	and	Adoption	of	Substantial	Forms.	Springer. McDonough,	Jeff.	2013.	"Leibniz's	conciliatory	account	of	substance."	Philosopher's	Imprint	13(6):	1–23. Rozemond,	Marleen.	1997.	"Leibniz	on	the	union	of	body	and	soul."	Archiv	für	Geschichte	der	Philosophie	79: 150–78. Rutherford,	Donald.	1995.	Leibniz	and	the	Rational	Order	of	Nature.	New	York:	Cambridge	University	Press. Sleigh,	Robert	C.	Jr.	1990.	Leibniz	and	Arnauld:	A	Commentary	on	Their	Correspondence.	New	Haven:	Yale University	Press. Notes: ( )	Pre-established	harmony	is	also	called	the	hypothesis	of	concomitance.	See,	e.g.,	A	II	ii	53. ( )	Some	interpreters	suggest	Leibniz	changed	his	mind	on	this	issue.	See,	e.g.,	Daniel	Garber,	Leibniz:	Body, Substance,	Monad	(New	York:	Oxford	University	Press,	2009),	p.	80;	and	Donald	Rutherford,	Leibniz	and	the Rational	Order	of	Nature	(New	York:	Cambridge	University	Press,	1995),	chapter	10. ( )	The	texts	in	which	Leibniz	seems	to	characterize	soul-body	composites	as	per	se	unities	are	often	difficult	to interpret.	First	of	all,	Leibniz	rarely	uses	the	phrase	"unum	per	se"	explicitly,	using,	for	example,	"Ens	vere	unum," "veritablement	un	estre,"	or	"unité	veritable"	instead.	(I	should	note	that	I	am	treating	all	such	phrases	as effectively	equivalent,	although	there	might	be	some	reason	to	resist	this.)	Second,	it	is	often	not	altogether	clear what	the	unity	is	being	attributed	to;	i.e.,	is	it	being	attributed	the	soul-body	composite	or	simply	the	soul?	For	a representative	selection,	which	is	by	no	means	complete,	see,	e.g.,	A	VI	iv	627,	A	VI	iv	1506-1508.,	A	VI	iv	1583,	A II	ii	249,	GP	IV	395,	GP	IV	459,	GP	IV	572. ( )	GP	IV	484;	AG	143. ( )	GP	IV	484;	AG	143. ( )	GP	IV	484;	AG	143. ( )	GP	VI	620;	AG	223. ( )	A	II	ii	116;	GP	II	74. ( )	A	II	ii	221;	GP	II	105–106. ( )	A	II	ii	240;	GP	II	113. ( )	A	II	ii	82;	GP	II	58;	LA	65. ( )	GP	VI	618. ( )	See	Daniel	Garber,	"Leibniz	and	the	foundations	of	physics:	The	Middle	Years,"	in	The	Natural	Philosophy	of Leibniz,	edited	by	K.	Okruhlik	and	J.	R.	Brown	(Dordrecht:	Kluwer	Academic	Publishers,	1985),	pp.	27–130;	and Garber,	Leibniz,	p.	382. ( )	See	Robert	C.	Sleigh	Jr.,	Leibniz	and	Arnauld:	A	Commentary	on	Their	Correspondence	(New	Haven:	Yale University	Press,	1990);	and	Robert	M.	Adams,	Leibniz:	Determinist,	Theist,	Idealist	(New	York:	Oxford	University Press,	1994). ( )	See,	e.g.,	Jeff	McDonough,	"Leibniz's	conciliatory	account	of	substance,"	in	Philosopher's	Imprint	13/6	(2013), 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Mind and Body Page 12 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 pp.	1–23;	Look-Rutherford,	Introduction;	and	Richard	T.	W.	Arthur	and	Peter	Lopston,	"Leibniz's	body	realism:	Two interpretations,"	in	The	Leibniz	Review	16	(2006),	pp.	1–42. ( )	For	discussion	of	some	early	texts	(late	1660s)	in	which	Leibniz	explicitly	upholds	the	unity	of	soul-body composites,	see	Maria	Rosa	Antognazza,	"Leibniz's	theory	of	substance	and	his	metaphysics	of	the	Incarnation," in	Locke	and	Leibniz	on	Substance	and	Identity,	edited	by	Paul	Lodge	and	T.	W.	C.	Stoneham	(Abingdon/New	York: Routledge,	2014).	The	text	Antognazza	discusses	in	some	detail	is	"De	Incarnation	Dei."	See	A	VI.1,	532. ( )	GP	IV	477–87. ( )	Garber,	Leibniz,	p.	80. ( )	For	Tournemine's	criticism,	see	René-Joseph	de	Tournemine,	"Conjectures	sur	l'Union	de	l'Ame	et	du	Corps," Journal	de	Trevoux,	ou	Memoires	pour	servir	a	l'histoire	des	sciences	et	des	arts,	vol.	III	(May	1703),	869;	WFN 251. ( )	GP	VI	595;	WFN	250. ( )	GP	II	281;	Lodge,	p.	481. ( )	GP	IV	484–85;	WFN	18. ( )	GP	V	620;	AG	223. ( )	For	further	development	of	this	view,	see	Rozemond	"Body	and	Soul,"	pp.	152–156. ( )	For	development	of	this	view,	see	Rutherford,	Rational	Order,	pp.	273–276. ( )	This	question	treats	the	question	of	"metaphysical	union"	as	equivalent	to	the	unity	of	soul-body	composites. There	is	some	reason	to	worry	about	this	identification,	although	I	cannot	fully	engage	this	issue	here. ( )	A	II	ii	250–51,	n.	77;	GP	II	120;	LA	154;	emphasis	added. ( )	A	II	ii	249;	GP	II	118;	WFP	131;	emphasis	added. ( )	A	II	ii	250,	n.	77;	GP	II	119;	LA	153. ( )	See	Rutherford	Rational	Order,	pp.	273–276. ( )	For	this	suggestion,	see	R.	Adams,	Leibniz,	p.	307;	see	also	Rutherford,	Rational	Order,	p.	268. ( )	One	possibility	derives	from	the	decree	by	the	Fifth	Lateran	Council	(1512)	that	the	soul	is	to	be	considered	the substantial	form	of	the	body.	For	discussion,	including	reasons	to	think	this	does	not	explain	why	the	per	se	unity	of corporeal	substance	is	a	Catholic	commitment,	see	Rozemond	"Body	and	Soul,"	pp.	176–177. ( )	For	a	very	helpful	discussion	of	Leibniz's	account	of	the	Incarnation	in	relation	to	his	philosophy,	see Antognazza,	"Incarnation."	However,	and	as	Antognazza	also	notes,	it	is	not	clear	whether	the	type	of	union required	by	the	Incarnation	is	the	same	as	the	substantial	unity	required	by	composite	substances. ( )	A	VI	iv	627;	Arthur,	pp.	272–273. ( )	For	development	of	the	view	that	Leibniz	presumes	rather	than	argues	for	the	unity	of	the	composite,	see Robert	C.	Sleigh,	Leibniz	and	Arnauld,	p.	107. ( )	A	II	ii	251;	GP	II	120;	LA	154. ( )	NE	231. ( )	A	II	ii	251,	n.	77;	GP	II	120;	LA	153.	See	also	GM	VII	18–19;	L	667–668	for	a	similar	characterization	with different	terminology. ( )	GP	II	268;	Lodge	463. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Mind and Body Page 13 of 13 PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2014. All Rights Reserved. Under the terms of the l icence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Handbooks Online for personal use (for details see Privacy Policy). Subscriber: OUP-Reference Gratis Access; date: 17 June 2015 ( )	GP	II	96–97;	LA	121. ( )	GP	VI	619;	WFP	278. ( )	NE	231. ( )	For	the	development	and	discussion	of	a	similar	distinction,	see	Look-Rutherford	xliii. ( )	For	further	discussion,	see	Marilyn	Adams,	William	Ockham	(New	York:	Oxford	University	Press,	1987),	pp. 633–670. ( )	For	discussion,	see	M.	Adams,	Ockham,	pp.	637–638. ( )	For	development	of	this	view,	see	R.	Adams,	Leibniz,	pp.	269–274. ( )	See,	e.g.,	GP	IV	491;	WFP	185. ( )	GP	II	252;	Lodge,	p.	438. ( )	Paul	Lodge,	"Corporeal	Substances	as	Monadic	Composites	in	Leibniz's	Later	Philosophy,"	in	Leibniz's Metaphysics	and	Adoption	of	Substantial	Forms,	edited	by	A.	Nita	(Springer,	2014). ( )	Lodge,	"Monadic	Composites." ( )	Lodge,	"Monadic	Composites." ( )	Look-Rutherford	371;	quoted	in	Lodge,	"Monadic	Composites." ( )	Here	is	one	from	1702:	"This	substance	[i.e.,	a	corporeal	substance]	of	course,	is	one	per	se,	and	not	a	mere aggregate	of	many	substances,	for	there	is	a	great	difference	between	an	animal,	for	example,	and	a	flock."	GP	IV 395;	AG	252 ( )	Despite	my	sympathies	with	Lodge's	approach,	I	am	hesitant	to	accept	that	domination	grounds	the	per	se unity	of	monadic	composites.	I	see	some	difficulty	in	differentiating	domination	from	a	special	case	of	relations	of harmony,	which	I	argued	earlier	in	this	chapter	would	not	be	sufficient	for	per	se	unity. ( )	Look-Rutherford	23.	For	discussion,	see	Look-Rutherford	lv,	lviii–lix. ( )	Look-Rutherford	227.	For	discussion,	see	Look-Rutherford	lxii–lxxii. ( )	GP	VI	607;	AG	213. Adam	Harmer Adam	Harmer,	Department	of	Philosophy,	University	of	California,	Riverside 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56