ビットコインという電子マネーをご存知だろうか。ビットコインとは、ネット上で取引される「仮想通貨」の一つである。

ビットコインの構想は、2008年に生まれた「中本哲史」という日本人の論文に基いて作られた電子マネーだが、この中本氏という人物が実在しているかは明らかになっていない。

ビットコインは銀行などを介さないので決済手数料が非常に安く、ピアツーピア(P2P。接続されたコンピューターが専用のサーバーを介さないで直接コミュニケーションがとれるネットワーク形態)で取引でき、獲得したビットコインはデジタルウォレットに貯蓄することができる。ただし、通常取引されるドルや円といった通貨と違って政府や中央銀行、現物資産などの裏付けがない。

ビットコインの特徴は、こうした政府や中央銀行の統制を受けず、「mining software」(採掘ソフト)を使って、ビットコインを自ら「掘り当てる」ことができる点にある。ビットコインを採掘する人が少なければ、短い時間で掘り当てることが可能だが、競争相手が多くなると採掘に時間がかかるように作られている。

【ビットコイン「採掘」の仕組み】

What is Bitcoin Mining? from Antram Technologies on Vimeo.

また、金や銀といった鉱物と同じように、ビットコインにも採掘できる「埋蔵量」が限定されており、2100万枚までと設定されている。すでにドルやユーロなどの通貨がビットコインへの両替に対応できるようになっている。

ギリシャやキプロスなどでヨーロッパが金融危機に陥る中、ビットコインは規制を受けない世界的な通貨という評判が高まり、11月27日にビットコインを取り扱う東京の取引所「Mt.GOX」(マウントゴックス)で、1ビットコインが1000ドルの大台に乗った。

しかし、ビットコインは非常に匿名性が高いため、マネーロンダリング(資金洗浄)や不法ドラッグ取引で使用される問題が懸念されている。また、投機が加熱してバブルが起きているという指摘もある。

ハフィントンポストUK版では、外国為替取引企業「ワールド・ファースト」のチーフエコノミスト、ジェレミー・クック氏がビットコインへの警鐘を鳴らすブログを11月29日に投稿した
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IT企業に勤めているジェームズ・ハウエルは今週、血眼になってウェールズのゴミ埋立地を捜索している。彼は400万ポンド(6億7000万円)以上の価値があるビットコインを収めていたハードディスクを捨ててしまったのだ。今週起きた金融バブルについての報道と投機熱が加熱した、まさに熱狂に包まれた1週間だった。

ビットコインほど、報道で話題となった金融資産は今までなかった。ビットコインのあらゆる資産がこの12カ月で価格が80倍も上昇したことがメディアで注目され始めている。そして結果として、ビットコインはすぐに利益を得たい人たちの注目の的となっている。

ビットコインにまつわるすごい話題をお伝えしよう。今年の初めに1ビットコインあたり13ドル(約1300円)の価値だったのだが、今週、1000ドル(約10万円)の大台を越えた。経済に大変革を起こす通貨になると言っている人もいる。これをそのまま受け取ると非現実的な話になるが。

ビットコインは通貨ではない。2008年のリーマン・ショックが起きた時、世界は奈落の底に突き落とされ、世界の外国為替市場はかつてないほど不安定になり、日々急激な変動にさらされた。ビットコインは現在のように急上昇することもあれば、先週のように1日で価格が半減することもあるが、リーマン・ショックの時とは比べ物にならない。ここで言いたいのは、「通貨」とは、以下のような特質を持つものでなければならない、ということだ。

1 貨幣などの交換手段がある
2 会計単位がある
3 価値の保存ができる

ビットコインには、2と3が欠けているのだ。

私があなたに700ポンド(約12万円)貸すとすると、仮定の話として、あなたに1ビットコイン渡せばいいことになる。最近の市場の動きに忠実に従えば、翌日には最大で20%ビットコインの価格が上昇するから、840ポンド(14万円)で返すことになる。20%も価格が上昇すれば、元本以上の資産を引き受けなければならなくなるし、その逆もしかりだ。商取引でビットコインを使ってしまったら、少しずつ利益を拡大していくことを待ちきれないために生じる機会費用(ある行動を選択することで失われる利益、他の選択肢をとっていた場合に得られていたと思われる利益)があることを忘れてしまうことになる。

ビットコインを支持する議論の大半を占めるのは、マネーサプライ(通貨供給量)が厳しくコントロールされているからインフレが生じない、というものだ。しかし、その代わりに巨大なデフレを自ら招くことになる。

資金供給は引き締められ、その結果ビットコインの価格だけが上昇するということになりかねない。そして、それらは貯蓄へと回されることになるだろう。端的に言えば、このような「貴重な」資産をビザを買ったりビールを買ったりするようなどうでもいいことに使っておけば、資産は維持できるし、価格が上昇するのをただ見守っていればいい(訳注・2010年5月、当時1ビットコインが1セント以下のレートだったとき、Laszlo Hanyeczという名前のプログラマーが2枚のピザを1万ビットコインで購入した。現在だと1000万ドル[約10億2000万円]以上となる)。

ビットコインに手を出すくらいなら、私はイギリス通貨のように本当に商取引が可能な通貨体制の下でインフレも受け入れる。実際に商取引をしている人達も同じようにするだろう。「ビットコインはこちらで受け付けています」という広告は結局のところマーケティングの手段でしかないし、それ以上のものではない。

もちろん、ダイナミックな資金供給をもたらし、価格の上昇が期待できる分、ビットコインを保有している人は今の生活が潤うだろう。BBCの番組「ニュースナイト」でも「秘密の通貨」にまつわる賛否を議論したが、私はビットコイン支持者に取り囲まれた。彼らはビットコインに投資した人が利益をあげていることを羨ましく思っているだけだ。彼らは自分たちの意見を述べていたが、私はそれでも懐疑的だ。なぜならビットコインのバブルが持続するとは思えないという懸念が拭えないからだ。

経済史を通じて、バブル的な熱狂はこれまでも研究されてきた。だから私はビットコインは単に最新のバブルでしかないと信じて疑わない。「本質的価値」という考え方がここでは鍵となる。ビットコインの信奉者は、お金は不換紙幣であり、中央銀行や政府がどこかわからない場所で作っているものだという。彼らは、お金はだからこそ裏付けがないし、価値もないと言う。それはまったくの間違いだ。お金には民主主義の手段を通じた中央銀行と政府の裏付けがあるし、もっと言えば、その国の人々の裏付けがある。

通貨は政府や中央銀行の恣意的判断で作られるもの、つまり不換紙幣状態だという主張は明らかにビットコイン信奉者の誤った考えだ。ビットコインこそが不換紙幣の中の不換紙幣だ。市場で価値があるものと判断されているあらゆるもののなかで、もっとも裏付けがないものだ。

少なくとも、金や銀は産業や商業で使われている。しかしビットコインは金融の世界にある、燃え盛る炎の中にあるチョコレートのようなものだ。ビットコインは完全に主観的なものだ。ポンド、ドル、円、そしてその他のあらゆる合法的な通貨には客観性がある。実際に持っている財布にどちらを入れておけばいいか、私はよく知っている。

___________________________________

※仮想通貨「ビットコイン」は通貨に改革をもたらす電子マネーなのか、それとも単なるバブルなのか、みなさんのご意見をお寄せください。

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  • World's First Bitcoin ATM Debuts In Vancouver, Canada

    VANCOUVER, BC - OCTOBER 29: The world's first bitcoin ATM at Waves Coffee House on October 29, 2013 in Vancouver, British Columbia, Canada. The ATM, named Robocoin, allows users to buy or sell the digital currency known as bitcoins. Once only used for black market sales on the internet, bitcoins are starting to be accepted at a growing number of businesses. (Photo by David Ryder/Getty Images)

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  • Sydney Pub To Accept Bitcoin Virtual Currency

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  • Sydney Pub To Accept Bitcoin Virtual Currency

    SYDNEY, AUSTRALIA - SEPTEMBER 19: In this photo illustration, a terminal to accept payments using bitcoins is displayed on the bar at the Old Fitzroy pub on September 19, 2013 in Sydney, Australia. The Old Fitzroy pub in Sydney's eastern suburbs will accept the digital currency, Bitcoin, as of Next Sunday. Using a smartphone and a QR code scanning application customers will be able to purchase beer and menu items at the bar. The Old Fitzroy is the first Australian pub to accept Bitcoin payment. (Photo by Cameron Spencer/Getty Images)

  • Sydney Pub To Accept Bitcoin Virtual Currency

    SYDNEY, AUSTRALIA - SEPTEMBER 19: In this photo illustration, a terminal to accept payments using bitcoins is displayed on the bar at the Old Fitzroy pub on September 19, 2013 in Sydney, Australia. The Old Fitzroy pub in Sydney's eastern suburbs will accept the digital currency, Bitcoin, as of Next Sunday. Using a smartphone and a QR code scanning application customers will be able to purchase beer and menu items at the bar. The Old Fitzroy is the first Australian pub to accept Bitcoin payment. (Photo by Cameron Spencer/Getty Images)

  • Sydney Pub To Accept Bitcoin Virtual Currency

    SYDNEY, AUSTRALIA - SEPTEMBER 19: In this photo illustration, a customer pays for drinks at the Old Fitzroy Pub using bitcoins on September 19, 2013 in Sydney, Australia. The Old Fitzroy pub in Sydney's eastern suburbs will accept the digital currency, Bitcoin, as of Next Sunday. Using a smartphone and a QR code scanning application customers will be able to purchase beer and menu items at the bar. The Old Fitzroy is the first Australian pub to accept Bitcoin payment. (Photo by Cameron Spencer/Getty Images)

  • Sydney Pub To Accept Bitcoin Virtual Currency

    SYDNEY, AUSTRALIA - SEPTEMBER 19: A sign displaying Bitcoins accepted is seen on the front door of the Old Fitzroy Pub on September 19, 2013 in Sydney, Australia. The Old Fitzroy pub in Sydney's eastern suburbs will accept the digital currency, Bitcoin, as of Next Sunday. Using a smartphone and a QR code scanning application customers will be able to purchase beer and menu items at the bar. The Old Fitzroy is the first Australian pub to accept Bitcoin payment. (Photo by Cameron Spencer/Getty Images)

  • Sydney Pub To Accept Bitcoin Virtual Currency

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  • Utah Software Engineer Mints Physical Bitcoins

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  • Utah Software Engineer Mints Physical Bitcoins

    SALT LAKE CITY, UT - APRIL 26: Software engineer Mike Caldwell applies holograms to Bitcoins he is minting in his shop on April 26, 2013 in Sandy, Utah. Bitcoin is an experimental digital currency used over the Internet that is gaining in popularity worldwide. (Photo by George Frey/Getty Images)

  • Utah Software Engineer Mints Physical Bitcoins

    SALT LAKE CITY, UT - APRIL 26: Software engineer Mike Caldwell holds physical Bitcoins he minted in his shop on April 26, 2013 in Sandy, Utah. Bitcoin is an experimental digital currency used over the Internet that is gaining in popularity worldwide. (Photo by George Frey/Getty Images)

  • Utah Software Engineer Mints Physical Bitcoins

    SALT LAKE CITY, UT - APRIL 26: Software engineer Mike Caldwell shows the front (R) and back, hologram side, (L) of a physical Bitcoin he minted in his shop on April 26, 2013 in Sandy, Utah. Bitcoin is an experimental digital currency used over the Internet that is gaining in popularity worldwide. (Photo by George Frey/Getty Images)