Persecuted by Franco's regime, his mother (born in the Madrid Royal Palace in 1911) was not allowed to return to the Spanish capital city until 1952.

In Madrid Peña was taught Greek and Indoeuropean linguistics by the renowned Spanish philologist Francisco Rodríguez Adrados and ethics by J.L.

In 1974 Peña was awarded his philosophy degree (licenciatura) from the PUCE (the Ecuadorian Pontifical University in Quito), with a thesis on Anselm of Canterbury's Ontological argument for the existence of God, his adviser being Julio C. Terán, S.J., who taught him hermeneutics.

He then spent four years in Liège, Belgium, (1975–1979) where, under Paul Gochet's supervision, he wrote his dissertation on a system of contradictorial (paraconsistent) logic.

He spent six months in Canberra as a visiting scholar (1992–1993), under the guidance of the late Richard Sylvan, and was a colleague of Philip Pettit at the philosophy department of the Australian National University.

Rather than regarding sentences and states of affairs in a static way, as logical atomists have done, ontophantics looks upon them dynamically, as transitions or processes.

Ontophantics contains a holistic theory of knowledge influenced by Gonseth and Quine, considering the cleavage between analytic and synthetic judgments a matter of degree.

This epistemological holism is a sort of empirical coherentism, for which the task of human knowledge is to set up theories, to confront them with experience taken as a whole and to gradually modify them.

The choice among alternative logical systems has to be made in accordance with plausible criteria, one of which is fitness with the best explanation of available evidence, thus resorting to an optimization postulate, which in turn gets circularly warranted by its epistemological fruitness.

His approach to fuzziness deviates from Zadeh's mainstream orthodoxy in rejecting alethic maximalism and so embracing the principle of excluded middle, regarding all intermediaries as degrees of both truth and falseness, being and non-being (Plato's influence is discernable here).

(2) All transitions are either aggregations or disaggregations (processes of sedimentation or erosion) since cumulation, gathering, is reality's most prominent feature (ontophantics had already conceived of all entities as sets, but now the principle of togetherness is made the mainstay of the philosophical system).

At that time, he essentially clung to von Wright's standard approach, departing from it only by introducing degrees and admitting normative contradictions or antinomies.

The underlying mistake, according to Peña, is a wrong metaphysical assumption which denies the existence of deontic states of affairs connected by implications.

It is only by studying normative reasoning as it really happens in legal practice that sanitized sets of axioms and inference rules can be devised and then subject to the acid test of applicability.

Peña admits that a pluralistic axiology faces a serious difficulty, namely that it provides no clear guidance for action, unless there is an objective all-things-considered perspective.

As against all who claim that progress is a vapid concept and that there is no continuous improvement along history, Peña's philosophy of history argues that progress is the necessary outcome of our cultural rationality—weak and partial though it is—thanks to which any human society will tend to ameliorate its welfare by blending the scattered wisdom of its members into a combined collective purposive intelligence, thus increasing, little by little, its social accumulation of material and intellectual assets, establishing more workable, reliable and socially acceptable laws and making distribution practices more consonant with the public interest.

The law of human progress is not to be assimilated to grand schemes postulating a predetermined succession of ages, such as those of the Stoics, Vico, Hegel, A. Comte and K. Marx.

There is also a common destination, owing to our shared Planet and a converging tendency, which needs no mysterious invisible hand but results from objective constraints.

Peña does not deny the existence of historic breaks caused by social involutions and disasters (wars, foreign subjugations, natural catastrophes) but thinks that every human society finds its way to restart the ascending march.

Peña's legal philosophy is a natural-law theory deriving from Aquinas's conception of law as an ordinance of reason for the common good.

As against social-covenant views, Peña regards human beings as naturally social, antecedently banded together into a community under an established authority, whose duty is to pursue the public interest.

One of the main claims this social philosophy advances is the rejection of the dichotomy between State and civil society, a contrived duality which he blames as the root of serious misconceptions.

This doctrine borrows a number of ideas from the traditions of the British Fabian Society, French solidarism and German chair-socialism as well as the Spanish school of Krausist philosophers and lawyers who inspired the II Republic (1931–1939), whose Constitution he takes as a paradigm.

He contends that the State's patronage and intervention can alone bring a sense of directedness and unity of purpose, failing which the only practicable way is mercantile competition, with its dreary, ruthless consequences.

Peña views regional blocks as splits of the human family bringing about enmities and conflicts of interest rather than a fraternal union, which he champions on the ground of both prudential and axiological considerations.