John Stuart Mill. Fealsamh Sasanach, eacnamaí polaitíochta agus státseirbhíseach ab ea John Stuart Mill (20 Bealtaine 1806 – 8 Bealtaine 1873).  Bhí sé ar cheann de na smaointeoirí is mó tionchar i stair an liobrálachais, ghlac sé páirt go forleathan i ndíospóireachtí faoi theoiric shóisialta, theoiric pholaitiúil agus gheilleagar polaitiúil. Tugadh "the most influential English-speaking philosopher of the nineteenth century" air, Thacaigh an tuiscint a bhí aige ar an gcoincheap saoirse le saoirse bain an duine aonair i gcoinne smachta gan teorainn an stáit agus ag na rialacháin shóisialta.
Thacaigh Mill leis an bhfóntachas, teoiric eiticiúil a bhí forbartha ag a réamhtheachtaí Jeremy Bentham, agus a chuidigh go mór le teoiric an mhodha eolaíoch.
Ina bhall den Pháirtí Liobrálach, ba é ,freisin,  an chéad Fheisire Parlaiminte a rinneadh glaoch ar iarratas ar vóta a thabhairt do mhná.
Beathaisnéis.
Rugadh John Stuart Mill ag 13 Sráid Rodney i Pentonville limistéar Londan, an mac ba shine de chuid James Mill,  fealsamh Albanach, staraí agus eacnamaí, agus Harriet Burrow. Chuir a athair  oideachas air, le comhairle agus chúnamh ó Jeremy Bentham agus Francis Place. Tugadh tógáil thar a bheith dian dó, agus d'aon ghnó cosnaíodh é ar chaidreamh le páistí ar a aois féin, seachas a chuid siblíní. Deisceabal dílis de chuid Bentham ab a athair agus tacadóir an chomhcheangaltachais, agus bhí sé mar aidhm fhollasach aige saoi intleachtúil a chruthú a bheadh in ann cúis an fhóntachais a leanúint agus a chur i bhfeidhm tar éis a bháis féin agus báis Bentham.
Saoirse.
Is éard an tuairim a bhí  ag John Stuart Mil ar 'saoirse', a bhí faoi thionchar Joseph Priestley agus Josiah Warren, na gur chóir go mbeadh cead a chinn ag an duine atá saor a rogha rud a dhéanamh ach amháin nach dtarlófaí díobháil ar bith do dhaoine eile. Tá daoine aonair réasúnach go leor chun cinntí a dhéanamh faoi a n-aimhleas. Ba chóir don rialtas a ladar a chur isteach nuair atá sé i gcomhair na sochaí a chosaint. Mhínigh Mill:The sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection. That the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not sufficient warrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinion of others, to do so would be wise, or even right...The only part of the conduct of anyone, for which he is amenable to society, is that which concerns others. In the part which merely concerns him, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereig .
Saoirse cainte.
Abhcóide suntasach ab ea Mill i gcomhair saoirse cainte, bhí Mill i gcoinne na cinsireachta. Deir sé:I choose, by preference the cases which are least favourable to me – In which the argument opposing freedom of opinion, both on truth and that of utility, is considered the strongest. Let the opinions impugned be the belief of God and in a future state, or any of the commonly received doctrines of morality... But I must be permitted to observe that it is not the feeling sure of a doctrine (be it what it may) which I call an assumption of infallibility. It is the undertaking to decide that question for others, without allowing them to hear what can be said on the contrary side. And I denounce and reprobate this pretension not the less if it is put forth on the side of my most solemn convictions. However, positive anyone's persuasion may be, not only of the faculty but of the pernicious consequences, but (to adopt expressions which I altogether condemn) the immorality and impiety of opinion. – yet if, in pursuance of that private judgement, though backed by the public judgement of his country or contemporaries, he prevents the opinion from being heard in its defence, he assumes infallibility. And so far from the assumption being less objectionable or less dangerous because the opinion is called immoral or impious, this is the case of all others in which it is most fatal..Muileann breac-chuntas ar na buntáistí a bhaineann le 'ag cuardach le haghaidh agus fionnachtain na fírinne' mar bhealach chun eolas breise. D ' áitigh sé go fiú má tuairim go bhfuil sé bréagach, an fhírinne is féidir a thuiscint níos fearr trí refuting an earráid. Agus mar chuid is mó tá tuairimí nach fíor go hiomlán ná go hiomlán bréagach, pointí sé amach go bhfuil ag ligean saor in aisce léiriú ar chumas an mhaistíní ar iomaíocht tuairimí mar bhealach a chaomhnú go páirteach fhírinne sna tuairimí éagsúla. Buartha faoi mionlaigh tuairimí a bheith faoi chois, Muileann chomh maith leis sin d 'áitigh tacú le saoirse cainte ar fhorais pholaitiúla, á rá go bhfuil sé ina chomhpháirt ríthábhachtach do ionadaí rialtas a bhfuil d' fhonn a chumasú díospóireacht ar bheartas poiblí. Muileann chomh maith leis sin deaslabhartha d ' áitigh go bhfuil saoirse cainte ceadaíonn le haghaidh fás pearsanta agus féin-réadú. Dúirt sé go bhfuil saoirse cainte a bhí ríthábhachtach ar a mbealach chun a fhorbairt a chuid buanna agus a bhaint amach an duine cumas agus cruthaitheacht. Sé arís agus arís eile a dúirt go bhfuil éalárnacht a bhí níos fearr a aonfhoirmeacht agus marbhántacht.
Prionsabal na díobhála.
Bunaíodh an creideamh go gcuirfeadh an tsaoirse cainte  an tsochaí chun cinn  leis an mhuinín go raibh an pobal in ann cíoradh go beacht. Má tá aon argóint mícheart nó díobhálach, 
measfaidh an phobail í a bheith mícheart nó díobhálach, agus ansin ní féidir na hargóintí a bheith marthanach agus curfear as an áireamh iad. D' áitigh Mill go fiú aon argóintí a úsáidtear le haghaidh dúnmharaithe nó éirí amach i gcoinne an rialtais, níor chóir iad a bheith curtha faoi chois ó thaobh na polaitíochta de nó géarleanúint a dhéanamh ar go sóisialta. Dar leis, má tá gá i ndáiríre le héirí" "amach, ba chóir do dhaoine dul chun ceannairce; má tá dúnmharú go fírinneach cuí, ba chóir dó a bheith ceadaithe. Seo é prionsabal na díobhála. 
"That the only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others".&lt;br&gt;
Coilíneachas.
D'áitigh Mill, fostaí  san Chomhlacht  Briotanach na hIndia Thoir ó 1823 go dtí 1858, ", maidir le tacaíocht a thabhairt don mhéid a thug sé 'forlámhaí dea-mhéiniúil'  (Béarla:'benevolent despotism') air, maidir leis na coilíneachtaí. . D'áitigh Mill an méid seo a leanas; "To suppose that the same international customs, and the same rules of international morality, can obtain between one civilized nation and another, and between civilized nations and barbarians, is a grave error...To characterize any conduct whatever towards a barbarous people as a violation of the law of nations, only shows that he who so speaks has never considered the subject. "
Slábhaíocht.
Sa bhliain 1850, sheol Mill litir gan ainm (a tháinig chun cinn faoin teideal "The Negro Question"), i gcoinne na litreach gan ainm ó Thomas Carlyle chuig Fraser's Magazine for Town and Country,  inar áitigh Carlyle le haghaidh sclábhaíochta. Thacaigh Mill le cealú na sclábhaíochta sna Stáit Aontaithe.
In aiste Mhill ón bhliain 1869, "The Subjection of Women", léirigh sé go raibh sé in aghaidh na sclábhaíochta:
This absolutely extreme case of the law of force, condemned by those who can tolerate almost every other form of arbitrary power, and which, of all others, presents features the most revolting to the feeling of all who look at it from an impartial position, was the law of civilized and Christian England within the memory of persons now living: and in one half of Angle-Saxon America three or four years ago, not only did slavery exist, but the slave trade, and the breeding of slaves expressly for it, was a general practice between slave states. Yet not only was there a greater strength of sentiment against it, but, in England at least, a less amount either of feeling or of interest in favour of it, than of any other of the customary abuses of force: for its motive was the love of gain, unmixed and undisguised: and those who profited by it were a very small numerical fraction of the country, while the natural feeling of all who were not personally interested in it, was unmitigated abhorrence.