In a climate where the richest collectors – Charles Saatchi, Roman Abramovich – are as celebrated as the artists they buy, we tend to forget that in the history of arts patronage, entrepreneurs-turned-connoisseurs are a young development. The world's greatest museums – the Louvre, Hermitage, Prado – began as lavish civilisation-is-power statements by monarchs and emperors; private individuals did not emerge as significant museum patrons before the 19th century. Until a generation ago, those wanting to leave their mark in bricks and mortar usually did so in a room of their own – albeit a very grand one – in a state museum: the Duveen Galleries at Tate Britain, the Abby Aldrich Rockefeller Gallery at New York's Museum of Modern Art, the National Gallery's Sainsbury Wing. But in the past 15 years, that has changed: worldwide, collectors seek immortality in glass and steel, through a museum of their own, designed by an architect of their choosing.

These are not latter-day Henry Tates or Pavel Tretyakovs. Although they gave their names to museums, Tate and Moscow's Tretyakov were democratic visionaries who paid for buildings and donated core collections to kick-start evolving national, state-run institutions. Museum builders of the 1990s and 2000s, by contrast, are products of late capitalism, dedicated to more personal projects, with an individualistic flavour. They represent the legacy of Thatcher-Reagan mantras of choice, private philanthropy, me-generation celebrity.

Many of the new establishments are extravagantly specialist – Ronald Lauder's 2001 Neue Galerie in Manhattan, dedicated to German and Austrian art; Wal-Mart heiress Alice Walton's Crystal Bridges Museum of American Art, planned for Arkansas in 2010. And in recently capitalist nations, the symbolism of the private museum is heavy. Dasha Zhukova's museum of contemporary art, the Garage, launched in Moscow last month, trumpets the power of the new Russian billionaires. Guy and Miriam Ullens' contemporary art museum in Beijing, opened earlier this year, showcases the social and aesthetic transformation of a nation.

 Together, these and scores more bring diversity and flatten old geographical hierarchies. In Istanbul, collector Sakip Sabanci's museum, founded in 2002, is the first ever to show western modernism – currently, Salvador Dali – in Turkey. Thanks to Dominique de Menil, the greatest collection of paintings by Cy Twombly, who lives in Italy, is on permanent show in Houston, Texas, in a gallery designed in 1995 by Renzo Piano. In 1996 the late collector and dealer Heinz Berggruen launched his Museum Berggruen in Berlin, giving Germany its only Picasso collection. This week, Charles Saatchi's new gallery opened in London with a show of recently acquired Chinese work.

Is all for the best in the best of all possible worlds? Certainly, more private museums mean more art on display for more people to see. Today's collectors are reluctant to bequeath to established museums, where space shortages mean works may go straight into storerooms and stay there. By contrast, a dedicated museum maintains the integrity of a collection, keeping together outstanding groups of works, assembled with personal flair, in buildings designed to enhance them. Renzo Piano's light, limpid 1997 construction for Ernst Beyeler's cherry-picked modernist paintings in Basel is the shining European example. For contemporary work, private collectors have particular advantages: free of state bureaucracy, they can respond quickly to the fast pace, and show work in ways that are too radical for traditional museums – in the confiscated-goods warehouse of a former drug enforcement agency in Miami, for example, that since 1996 has housed the Rubell Family Collection, ranging from sensationalist Chinese photography by Zhang Huan to Jeff Koons' vacuum cleaners.

What's not to like? Only that, whether they are stylishly successful or tediously tacky, today's rush of private museums is destabilising the art landscape. That they challenge the economics of taste may waft fresh air into art-history's ivory tower, but the speed with which new money shapes scholarly endeavour is daunting – witness the recent splash of monographs and retrospectives of Gustav Klimt, reckoned a minor Austrian symbolist until Lauder paid a record $135m in 2006 to install “Adele Bloch Bauer I” as “our Mona Lisa” in his Neue Galerie. Private museums speed up, too, 21st-century crises of shrinking art resources and growing demand. Will Asher B Durand's iconic American painting “Kindred Spirits”, for example, bought for $35m by Alice Walton from under the noses of the Metropolitan Museum and the National Gallery, who had banded together to try to keep it in a public gallery, speak to more people in Bentonville, Arkansas, or in New York and Washington? If you strengthen holdings in the regions, you inevitably dilute centres of excellence. But to tell art's histories, public museums need a concentration of important work; diminishing that is to the detriment of scholars and serious art lovers everywhere.

And if the new museums are not up to scratch? There is no polite way to say this: many private collections are far inferior to those in public institutions. They collapse standards and offer a vainglorious travesty of a cultural experience to a paying public. We all have our bêtes noires; one of mine is Fran?ois Pinault's disappointing art-as-fashion-emporium at Venice's Palazzo Grassi, launched in 2006 (another Pinault museum is planned for Venice in 2009).

Cautious national galleries stringently buy and accept as gifts only “museum quality” works. Private collectors, answerable to no one, buying on whim, not necessarily knowledgeable, often don't. Berggruen and Beyeler – each a dealer who was, as Berggruen wrote, “his own best client” – and the de Menils are exceptional. In the long run, though, it doesn't matter. Collectors have fun doing what they like and time will separate the best from the rest and ensure their survival. Meanwhile, we can all enjoy the new Darwinian museum jungle.

在最为富有的收藏家——查尔斯•萨奇(Charles Saatchi)、罗曼•阿布拉莫维奇(Roman Abramovich)——被视为是他们购买艺术家的环境下，我们往往会忘记，在艺术品捐赠史上，企业家转变为鉴赏家是一个新的进展。全球最伟大的博物馆——卢浮宫(Louvre)、Hermitage、普拉多博物馆(Prado)——都是由君主和皇帝发出的“富足文明就是权力”的言论开始的； 19世纪以后，个人才成为重要的博物馆捐赠者。一个世纪以前，那些希望自己名留史册的人通常会在公立博物馆的一间属于自己的展室中——尽管面积很大——实现这一理想：泰特英国美术馆(Tate Britain)的杜威恩画廊( Duveen Galleries)、纽约现代艺术博物馆(Museum of Modern Art)的艾比•奥尔德里奇•洛克菲勒美术馆(Abby Aldrich Rockefeller Gallery)、国家美术馆(National Gallery)的塞恩斯伯里展室(Sainsbury Wing)。但过去15年，情况发生了变化：全球收藏者希望由自己选定的建筑师设计属于自己的博物馆，从而让自己名留史册。

他们并非亨利•塔特(Henry Tate)或帕维尔•特列季亚科夫斯(Pavel Tretyakovs)的现代版。尽管二人的名字都留在了博物馆，但他们都是崇尚民主的理想家，他们出资兴建了博物馆，并捐赠了核心藏品，以推动国家公立博物馆的发展。相比之下，上世纪90年代和20世纪初的博物馆建造者们都是后资本主义的产物，这些博物馆致力于更为个人化的项目，都带有个人特色。它们代表着撒切尔(Thatcher)-里根(Reagan)时代关于选择、私人慈善以及以自我为中心一代的名人箴言的遗产。

 其中许多新建博物馆都是挥霍无度的专家——罗纳德•洛德(Ronald Lauder)2001年建于曼哈顿的Neue Galerie博物馆，专门展示德国和奥地利艺术品；沃尔玛(Wal-Mart)女继承人艾丽斯•沃尔顿(Alice Walton)的水晶桥美国艺术品博物馆(Crystal Bridges Museum of American Art)，计划在美国阿肯色州兴建，于2010年开放。在最近的资本主义国家，私人博物馆有着巨大的象征意义。达莎•茹科娃(Dasha Zhukova)的当代艺术品博物馆Garage于上月在莫斯科开放，彰显出俄罗斯新一代亿万富翁的实力。盖伊•乌伦斯(Guy Ullens)和米里亚姆•乌伦斯(Miriam Ullens)夫妇在北京的当代艺术品博物馆于今年早些时候向公众开放，显示了一国的社会和审美变革。

上述收藏家以及更多其他人带来了多样性，并打破了旧式的地理格局。在伊斯坦布尔，收藏家萨基普•萨班哲(Sakip Sabanci)的博物馆建于2002年，是土耳其迄今第一家展现西方现代主义作品的博物馆——目前展出的是萨尔瓦多•达利(Salvador Dali)的作品。由于多米尼克•德梅尼(Dominique de Menil)，现居意大利的塞•托姆布雷(Cy Twombly)最伟大的绘画作品得以在伦佐•皮亚诺(Renzo Piano)设计的美术馆的得克萨斯休斯敦作品展上进行永久展示，该美术馆建于1995年。1996年，已故的收藏家、交易商亨氏•伯格鲁恩(Heinz Berggruen)在柏林推出了自己的伯格鲁恩博物馆(Museum Berggruen)。最近，查尔斯•萨奇的新美术馆在伦敦开放，展示了他最近购买的中国艺术品。

这对于世界来说是件好事吗？当然，更多的私人博物馆意味着展出的艺术品更多，有更多的人会去参观。如今的收藏家不愿将藏品捐赠给知名博物馆，在那里，展区短缺意味着有些作品可能会被直接搬入储藏室并在那里栖身。相比之下，专业博物馆借助个人鉴赏能力，保持了藏品的完整性，并将优秀作品汇聚在旨在提升其价值的博物馆中。1997年，伦佐•皮亚诺为恩斯特•拜勒(Ernst Beyeler)精选的现代主义画作建造了一座明亮宁静的博物馆，这就是一个很好的欧洲例子。对于当代艺术品而言，私人收藏家拥有特殊优势：他们摆脱了政府官僚主义的束缚，能够迅速对快速发展做出回应，同时能够以对传统博物馆而言过于激进的方式展示作品，例如在迈阿密的前稽毒署的一个没收商品的储藏室进行展示，自1996年以来，这里一直是卢贝尔家族珍藏馆(Rubell Family Collection)的展区，展示的作品从中国的张桓那精湛的摄影作品到杰夫•库恩斯(Jeff Koons)的真空吸尘器。

不喜欢吗？不管私人博物馆是成功流行还是枯燥俗气，如今私人博物馆的热潮正在解构艺术品市场。它们对品味经济学的挑战可能会为艺术历史的象牙塔带来一股清新空气，但新资金改变这种学术性活动的速度十分惊人。看看最近古斯塔夫•克里姆特(Gustav Klimt)的论集和过去的作品吧，他被称为奥地利二流象征主义者，直到Lauder于2006年以1.35亿美元天价买下克里姆特的作品《Adele Bloch Bauer I》，并令其成为Neue Galerie的“我们的蒙娜•丽莎”(our Mona Lisa)。此外，私人博物馆还加速了21世纪艺术品资源不断下降和需求不断上升的危机。例如，阿什尔•杜兰(Asher B Durand)标志性的美国画作《Kindred Spirits》将与阿肯色州本顿维尔或纽约和华盛顿的更多人交流吗？这幅画由艾丽斯•沃尔顿在纽约大都会博物馆(Metropolitan Museum)和国家美术馆的眼皮底下以3500万美元购得，这两家博物馆曾试图联合起来让这幅作品留在公立博物馆。如果你扩大该地区的藏品，你不可避免的会削弱这些优秀作品收藏中心。但为了讲述艺术品历史，公立博物馆需要集中重要作品；削弱这一点将损害各地学者和严肃艺术品爱好者的利益。

设想如果这些新一代博物馆状况不好，我们会毫不客气地说：“许多私人藏品质量远比公立博物馆差。”它们破坏了标准，并给付费公众带来了对文化体验的虚荣模仿。我们都有自己的黑名单；弗朗克斯•皮诺特(Fran?ois Pinault)在威尼斯格拉西宫(Palazzo Grassi)兴建的令人失望的博物馆建于2006年，那里就像是一个服装百货商店，皮诺特的另一座博物馆计划于2009年在威尼斯开放。

行事谨慎的国立美术馆严格购买和接受那些“符合博物馆质量要求”的作品。那些不对任何人负责的私人收藏家通常不会如此，他们购买作品可能是一时兴起，他们的见识也并不一定广。伯格鲁恩和拜勒——都是交易商，就像伯格鲁恩所写的，他们都是“自己最好的客户”——德梅尼则是个例外。不过，长期而言，这并不重要。收藏家在做自己喜欢的事情中得到了乐趣，而时间将辨别出最优秀的作品，并确保它们生存下去。同时，我们都能享受一个新的达尔文博物馆丛林。