Consider this: In the ancient world, murder and theft were prohibited. However, slavery was ubiquitous and considered normal. AFAIK, nobody thought of it as immoral, though probably some called for kind treatment of slaves.

So when did people start talking of the very institution of slavery as immoral and demanding its abolition? And how did they justify that? Obviously, since they had to convince others of their point of view, they couldn't just say "We hold this truth to be self-evident".

I know that the Church prohibited slavery in the early centuries of its existence (but then allowed owning non-Christian slaves).

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    This actually is a really good question. The holy books of most world religons acknowledge slavery's existance without saying a thing bad about it. I've even heard it argued that, in a world where the alternative was often genocide, slavery was actually a more moral option (thankfully we mostly don't live in such a world anymore).
    – T.E.D.
    Commented Nov 1, 2012 at 21:05
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    Yes, and holy books also say that slaves have certain rights.
    – Lev
    Commented Nov 2, 2012 at 15:09
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    Some holy books (e.g. Bible) have supported slavery. Commented Nov 5, 2012 at 11:14
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    It agreed to slavery with limitations. For example, slaves had to be released after a certain amount of time. Slavery during the times in which the Books of the Law were written was quite different from antebellum slavery.
    – Luke_0
    Commented Nov 5, 2012 at 12:51
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    @Luke - In the interest of thoroughness, it should be mentioned that only Israelite males were to be released on the Sabbath year - purchased foreigners and women were exempt. It is, however, debatable about whether the OT supports slavery; I personally get the feeling that slavery was a social/economic institution, not a religious/moral one (especially given that it seems to mostly be dealing with debt-relief). Commented Nov 5, 2012 at 21:00

8 Answers 8


As @Luke states, there seems to have been a tipping point in the 19th century; I'd have dated it a few years earlier, and I'd have located it in England; Britain started out as a major participant in the slave trade (more slaves went to British possessions in the Caribbean than to the US colonies).

I've edited in a few comments with credit to the original authors with the intent of preserving them from the beasts that roam SE and consume comments like bon-bons.

The redoubtable P. Geerkens draws our attention to 1772:

Somerset v Stewart, 1772, where the judgement says, in part: It [the state of slavery] is so odious, that nothing can be suffered to support it, but positive [ie statute] law. Whatever inconveniences, therefore, may follow from the decision, I cannot say this case is allowed or approved by the law of England; and therefore the black must be discharged.

Sometime between 1780's and 1830's there was a major shift in perception and values. I would point to the Quaker AntiSlavery committees and William Wilberforce as representatives of that shift.

The British campaign to abolish the slave trade is generally considered to have begun in the 1780s with the establishment of the Quakers' antislavery committees, and their presentation to Parliament of the first slave trade petition in 1783.[53][54] The same year, Wilberforce, while dining with his old Cambridge friend Gerard Edwards,[55] met Rev. James Ramsay, a ship's surgeon who had become a clergyman on the island of St Christopher (later St Kitts) in the Leeward Islands, and a medical supervisor of the plantations there. What Ramsay had witnessed of the conditions endured by the slaves, both at sea and on the plantations, horrified him. Returning to England after fifteen years, he accepted the living of Teston, Kent in 1781, and there met Sir Charles Middleton, Lady Middleton, Thomas Clarkson, Hannah More and others, a group that later became known as the Testonites.[56] Interested in promoting Christianity and moral improvement in Britain and overseas, they were appalled by Ramsay's reports of the depraved lifestyles of slave owners, the cruel treatment meted out to the enslaved, and the lack of Christian instruction provided to the slaves.[57] With their encouragement and help, Ramsay spent three years writing An essay on the treatment and conversion of African slaves in the British sugar colonies, which was highly critical of slavery in the West Indies. The book, published in 1784, was to have an important impact in raising public awareness and interest, and it excited the ire of West Indian planters who in the coming years attacked both Ramsay and his ideas in a series of pro-slavery tracts. Wikipedia summary of William Wilberforce

Mr. Quinsey cites 1793

As I understand it, in 1793 Ontario was the first place in the British Empire to ban slavery (albeit grandfathered). See Lt Gov John Simcoe's 1793 "Act to prevent the further introduction of slaves and to limit the term of contract for servitude within this province".

The question is far larger; books could and have been written on the subject, but I hope this pointer is useful in setting up further research.

Update: Valladolid debate is an earlier event that some cite as the beginning of anti- slavery; I discovered it through the In Our Time podcast, although as the podcast relates, this is not an unqualified attack on slavery - reality is somewhat more complex.

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    As I understand it, in 1793 Ontario was the first place in the British Empire to ban slavery (albeit grandfathered). See Lt Gov John Simcoe's 1793 "Act to prevent the further introduction of slaves and to limit the term of contract for servitude within this province". Commented Nov 8, 2012 at 6:07
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    Nobody has mentioned Somerset v Stewart, 1772, where the judgement says, in part: It [the state of slavery] is so odious, that nothing can be suffered to support it, but positive [ie statute] law. Whatever inconveniences, therefore, may follow from the decision, I cannot say this case is allowed or approved by the law of England; and therefore the black must be discharged. Commented Jul 3, 2017 at 16:28
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    @JosephQuinsey Pennsylvania abolished slavery in 1780. It was technically part of the British Empire until 1783. So that predates Ontario.
    – C Monsour
    Commented Feb 24, 2020 at 20:40
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    @CMonsour whether Pennsylvania was part of the British empire was in dispute between 1776 and 1783. The legislators who enacted the 1780 law certainly did not see themselves as part of the British empire, as is immediately evident from the first section of the act. Furthermore, it is an act for the "gradual" abolition of slavery; if Wikipedia is to be believed, slavery was not entirely abolished in Pennsylvania until 1847.
    – phoog
    Commented Feb 21 at 13:25

It is incorrect to perceive that there was a single concept of slavery in ancient world. The Latin word for slave, "servus" at the same time meant a servant.

The concept of slavery differed very much between ancient societies and also differed in time. Sometimes a slave would be considered a member of the family to the extent that a formal kinly relationship such as formal adoption would be required for having a slave while in other societies the concept of slavery rose from the captured enemies or even possibly, rebels. Still in others one could become a slave for failing to pay a debt and could earn freedom back upon paying the sum or serving a certain term.

The societies differed much in the social status of "slaves" and their rights and the very word for slave could only barely be translated from one language to another without loosing a part of the meaning.

We currently apply the same term "slave" to penal farm convicts, prisoners of war, debtors forced to work to repay debts, dependent peasants, minor clan members and so on, who all had different legal status.

The situation is quite similar to how we apply the term "king" to various ancient titles that had little in common (rex, basilios, vanax, archon, archagestes, despotes, hegemon, tyrannos etc). There was little in common between elected and not heriditary Roman rex responsive to the senate and a Egyptian pharaon yet we call the both "kings". If a Roman of the time appeared in modern day he would possibly call the president "rex" and the penal farm prisoners "public slaves".

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    +1. I tried to research this question in British and European medieval history, and kept stumbling over issues of terminology. (eg: Were serfs "slaves"?)
    – T.E.D.
    Commented Nov 5, 2012 at 16:26
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    @Lev classically by Marx the difference is in that the slaves unlike the serfs cannot possess property. But when referring to the ancient world there are numerous examples of "slaves" possessing property and even becoming richer than their masters.
    – Anixx
    Commented Nov 5, 2012 at 22:47
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    From some little I have heard about Roman culture surrounding slavery, I think it is even possible that Roman would view much of our labor force as being a type slavery. They seem to have a very different way of arranging their labor. A contractually obligated employee is really not all that far away from much of the slavery the Romans performed.
    – Jonathon
    Commented Aug 17, 2015 at 1:57
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    @JonathonWisnoski Sorry, but this is utterly wrong! Your employer cannot flog you, brand you, maim you, starve you, or sell you! You receive payment for your services, and can leave if you wish. Where is the similarity?
    – TheHonRose
    Commented Oct 31, 2015 at 5:17
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    FWIW, a thrall in Norse society was considered property, but not without (rather limited but existing) protection by the law. They were also considered part of the household, which a worker-for-hire was not. They could be freed, or even buy their freedom. +1 for pointing out that "slave" did not equal "slave" across cultures.
    – DevSolar
    Commented Jul 3, 2017 at 14:37

Nobody so far has pointed out the obvious:

The first people to believe that slavery was evil and wrong were probably discontented slaves (as opposed to contented slaves).

I would guess that nobody was as likely to notice and disapprove of his boss's unjust treatment of him as a slave would be.

In ancient Rome the First Servile War was in Sicily from 135 to 132 BC and involved about 70,000 to 200,000 rebel slaves. The Second Servile War in Sicily lasted from 104 to 100 BC. The Third Servile War was on the mainland of Italy from 73 to 71 BC and involved 120,000 slaves led by Spartacus. These rebel slaves were mostly interested in gaining their own freedom and the freedom of their friends and families. But it is quite possible they sometimes expressed the opinion that all slavery was wrong, and that other people heard of that opinion.

The Zanji Rebellion in southern Iraq from 869 to 883 was one of the biggest and bloodiest revolts against the the Abbasid Caliphate and the rebels included black slaves and free men. It is certainly possible that some of the slaves involved expressed the opinion that all slavery was wrong.

And there have been many other revolts of slaves who mostly sought their own personal freedom, but may have sometimes said that all slavery was wrong.

The Institutes of Emperor Justinian (ruled 527 to 565) say:

. . the law of nations is common to the whole human race; for nations have settled certain things for themselves as occasion and the necessities of human life required. For instance, wars arose, and then followed captivity and slavery, which are contrary to the law of nature; for by the law of nature all men from the beginning were born free.


Slavery is an institution of the law of nations, against nature, subjecting one man to the dominion of another.

And these can be interpreted as anti slavery opinions. Certainly many 19th century southern Americans expressed opinions far more favorable to slavery.

An early American protest against slavery was the Germantown (Pennsylvania) petition in 1688 by four German Quakers and Mennonites.

Slavery has been abolished by many Chinese governments for various reasons, the first time by the Qin Dynasty of 221 to 205 BC.

The Sachsenspiegel lawbook of about 1220 condemned slavery as a violation of God's likeness in man.

King Louis X of France decreed in 1315 that "France means freedom" and any slave entering France was to be freed.

And so on. There are many possible anti-slavery expressions throughout history, making a definite history of opposition to slavery difficult to wwrite.

  • You are right, of course, there have been anti-slavery movements since antiquity. Even before the Servile Wars, Helots rose against Spartans, etc. And Plato has something about the immorality of holding Greek slaves (although not so much barbarian slaves). However, those movements were short-lived. The way I read the intent of the question is when the notion that slavery was immoral took root and persisted. Sort of like Norse versus Columbus regarding the first Europeans in America: the former may be the first to arrive, but the latter arrived for good.
    – Michael
    Commented Feb 12 at 16:36
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    All evidence is that ancient slaves did not object to slavery, but to being themselves held as slaves. Witness that there are no recorded instances of freedmen having any objection to holding slaves except among philosophers.
    – Mary
    Commented Feb 17 at 3:56

As Mark C. Wallace very correctly points out, the British antislavery movement of the 18th and 19th centuries was the first serious anti-slavery movement that managed to roll back slavery. However, no discussion of anti-slavery can be complete without a mention of the good friar Las Casas.

  • I wonder why the downvote... Commented Dec 26, 2012 at 2:28
  • +1 Your answer enlightened me on this friar, though some of his actions have proved controversial.
    – user8309
    Commented Jan 11, 2015 at 21:47

Sublimis Deus a Papal encyclical promulgated by Pope Paul III in 1537 condemns slavery and declares it null. Native population of South America is declared to be rational beings with soul.


Wikipedia states:

Slave ownership was widely accepted by the majority of early Jewish societies, but the Essenes were a small, ascetic sect that reportedly renounced slavery,[16] although some scholars question whether the Essenes actually renounced slavery.[17][18]

The sources for those references is Hezser, Catherine, "Jewish slavery in antiquity", Oxford University Press, 2005

Please note that due to economic considerations, non-slavery society was not a very viable proposition in ancient times.


Let's not forget that you could sell yourself into slavery (and keep the money of course, maybe a fee to slave traders if you needed them).

This was a COMMON practice in Roman times. Specially educated Greeks, whose homeland had been devastated by never ending conflicts, would usually sell themselves into slavery to Roman masters, where though they became property, and could be sold, they got wages and food and shelter and could teach and form families, a much preferable outcome than starving or dying in a war in Greece.

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    Sources would improve this answer.
    – MCW
    Commented Jun 5, 2018 at 16:06
  • I hadn't known about that but I know that some people sold themselves into slavery to pay debts.
    – Lev
    Commented Jun 7, 2018 at 6:46

Pigmy peoples in Central Africa never accepted slavery. They were taken as slaves, but they did not take anybody as slaves.

The same for tribes of New Guinea. They ate foreigners or accepted them as members of the tribe, but slavery was unknown to them.

Also, I haven't read any information about the Australian Aboriginals using slavery.

If we count them, there always were societies not accepting slavery.

We in Europe don't look well in that context.

What is interesting, there exists a precise answer to the question "What country was the first to forbid slavery". -> Haiti, 1804.

  • 1
    Not my DV but this would really be interesting with some backup/links, so that we don't have to do the research from scratch :)
    – OldPadawan
    Commented Feb 17 at 10:53

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