Are there any remarkable economists who have envisioned alternative economic system to the ones previously tried? I'm looking for realistic economic system models and their authors.
George saw his system as different than either Capitalism or Communism, as both of those systems equated Land with Capital and called for either the private ownership of both, or the communal ownership of both. Georgism calls for the private ownership of Capital but public ownership (of a sort) for Land.
Distributism is one such alternative, promoted in the early 20th century by Hilaire Belloc (Economics for Helen: A Brief Outline of Real Economy) and G. K. Chesterton (Utopia of Usurers). As John Médaille describes it:
Its key tenet is that ownership of the means of production should be as widespread as possible rather than being concentrated in the hands of a few owners (Capitalism) or in the hands of state bureaucrats (Socialism).
In a chapter entitled "Capitalism & Socialism" (p. 159) of Ethics and the National Economy, Heinrich Pesch, S.J., founder of "Solidarism," writes:
Capitalists are usurers in the broadest sense of the word. We understand usury in the same sense as Franz Schaub does, as any contractual expropriation of what is clearly surplus value. So, in our time, we use the word capitalism to mean a social system where usury operates with more or less complete freedom. The concept, capitalism, signifies a quest for gain that is totally uninhibited. Capitalism, therefore, means economic dominion by capitalists…
And pp. 85-6:
Usury is not exclusively a monetary phenomenon having to do with money-lending. A disparity between what is offered and what is given in return, resulting in excessive gain, can arise anywhere in the exchange process, and especially in business transactions.
Usury in a business transaction is the contractual appropriation of obvious surplus value in the process of buying and selling. The damage is done by the contract itself where performance and remuneration are juxtaposed. …
As E. Michael Jones, Ph.D., editor of Culture Wars Magazine and author of Barren Metal: A History of Capitalism as the Conflict Between Labor and Usury, writes:
Communism has failed, and now that Capitalism has shown us in the intervening years that it is even more ruthless than the communists imagined, we need an alternative to both Marx and the Manchester School. Heinrich Pesch is that alternative, and Rupert Ederer [the translator] is his prophet.
In my opinion there are two alternatives which are rather complementary.
Participatory Economics or PARECON by Michael Albert and Robin Hahnel : http://www.zcommunications.org/znet/topics/parecon, and the Reciprocity by Dominique Temple and Mireille Chabal (although these two are not economists) http://dominique.temple.free.fr/ and http://mireille.chabal.free.fr/
PARECON is a proposition of norms and institutions that would allow for a society to work, however it doesn't contain an alternative to utilitarianism which is really the main characteristic of capitalism. Reciprocity is the opposite: it is an alternative to utilitarianism but it doesn't propose any specific norm or institution alternative to exchange markets.
Myself I'm working on formalizing reciprocity as an economic system, although I'm not a remarkable economist, you can have a look at some of my articles describing how a systemic alternative based on reciprocity is possible http://independent.academia.edu/AyarPortugal