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Fibonacci (Leonardo Pisano) (1170-1250)

Italian mathematician. After travelling in North Africa, Fibonacci wrote Liber Abaci (1202), introducing the use of Arabic numerals for the decimal system into European arithmetic. His Liber quadratorum (Book of Square Numbers) (1225) introduced the "Fibonacci series" of natural numbers: 0, 1, 1, 2, 3 ,5 ,8, 13, . . . ., each element of which is the sum of the preceding two.

Recommended Reading: Morris Kline, Mathematical Thought from Ancient to Modern Times (Oxford, 1990) and Paul Chika Emekwulu, Fibonacci Numbers For Research Mathematicians & AI Applications (Novelty, 2000).

Also see MMT, EB, and WSB.

Fichte, Johann Gottlieb (1762-1814)

German philosopher. In Versuch einer Kritik aller Offenbarung (Critique of all Revelation) (1792) Fichte turned the critical philosophy of Kant into full-fledged idealism by emphasizing the metaphysical reality of the noumenal self as well as its moral autonomy. His amplification of this theme in Grundlage der gesamten Wissenschaftslehre (Foundations of the Science of Knowledge) (1794-95) and Darstellung der Wissenschaftslehre (Outlines of the Doctrine of Knowledge) (1810) greatly influenced Schelling and Hegel. Die Bestimmung des Menschen (The Vocation of Man) (1800) is Fichte's effort to defend himself against the charge of atheism. Fichte encouraged the development of German nationalism in opposition to Napoleonic threats in Der geschlossene Handelsstaat (The Closed Commercial State) (1800) and Reden an die deutsche Nation (Speeches to the German Nation) (1808).

Recommended Reading: Fichtes Werke, ed. by Immanuel H. Fichte (de Gruyter, 1971); George J. Seidel, Fichte's Wissenschaftslehre of 1794: A Commentary on Part I (Purdue, 1993); Gunter Zoller, Fichte's Transcendental Philosophy: The Original Duplicity of Intelligence and Will (Cambridge, 1998); and Frederick Neuhouser, Fichte's Theory of Subjectivity (Cambridge, 1990).

Also see EB, IEP, SEP, William Smith, ELC, and Alfred Weber.

Ficino, Marsillio (1433-1499)

Italian philosopher whose translations into Latin made the works of Plato and Plotinus accessible during the Renaissance. Despite his fascination with myth and magic, Ficino endorsed a synthesis of neoplatonic thought with the doctrines of Christianity.

Recommended Reading: Marsilio Ficino, Commentary on Plato's Symposium on Love (Spring, 2000); Marsilio Ficino, Three Books on Life, ed. by Carol V. Kaske, John R. Clark (Medieval & Renaissance, 1989); Renaissance Philosophy of Man, ed. by Ernst Cassirer, Paul Oskar Kristeller, and John H. Randall (Chicago, 1956).

Also see SEP, EB, and ELC.


Belief that religious doctrines rest exclusively on faith {Lat. fides}, instead of on reason. In various forms, fideism was maintained by philosophers as diverse as Pascal, Bayle, and Kierkegaard.

Recommended Reading: Delbert J. Hanson, Fideism and Hume's Philosophy: Knowledge, Religion and Metaphysics (Peter Lang, 1993) and Terence Penelhum, God and Skepticism: A Study in Skepticism and Fideism (Reidel, 1983).

Also see SEP, David E. White, EB, ISM, and CE.


A systematic way of indicating the position of the middle term in a categorical syllogism.

Filmer, Robert (1588-1653)

English political philosopher. Filmer's posthumously-published defense of a divinely-ordained hereditary monarchy in Patriarcha, or the Natural Power of Kings (1680) was attacked at length in the first of Locke's Two Treatises of Civil Government.

Also see EB.

final cause

The ultimate purpose, end, or goal of a thing; one of Aristotle's four causes. Explanations of how a thing is that rely on reference to its end {Gk. τελος [télos]} are often called "teleological;" their use fell into disfavor during the Renaissance.

Recommended Reading: Aristotle, Physics, tr. by Robin Waterfield and David Bostock (Oxford, 1999).

five ways

The attempts to prove the existence of god included in Thomas Aquinas's Summa Theologica I, 2, 3. They include three versions of the cosmological argument, an argument from moral perfection, and the teleological argument.

Recommended Reading: Thomas Aquinas, Selected Philosophical Writings, tr. by Timothy McDermott (Oxford, 1998); Basic Writings of Saint Thomas Aquinas: God and the Order of Creation, ed. by Anton Charles Pegis (Hackett, 1997); and Anthony Kenny, The Five Ways: Saint Thomas Aquinas' Proofs of God's Existence (Routledge, 1991).

Also see R. J. Kilcullen and EB.

force, appeal to (argumentum ad baculum)

The informal fallacy of securing agreement by threatening adverse consequences in case of disagreement.

Example: "Anyone who believes that the government has exceeded its proper authority under the constitution will be subjected to severe harassment by the provincial police. Therefore, the government has not exceeded its authority."

Recommended Reading: Douglas Walton, Scare Tactics: Arguments That Appeal to Fear and Threats (Kluwer, 2000).

Also see FF and GLF.

formal cause

Structural features or attributes of a thing; one of the four causes.

Recommended Reading: Aristotle, Physics, tr. by Robin Waterfield and David Bostock (Oxford, 1999).

formal fallacy

Invalid arguments that may appear convincing at first glance because they closely resemble legitimate patterns of reasoning. Commonly occurring formal fallacies include:

four terms (quaeternio terminorum),
undistributed middle,
illicit major,
illicit minor,
exclusive premises,
affirmative conclusion from negative premises,
affirming the consequent,
denying the antecedent,
converting the conditional,
negating the antecedent and the consequent, and
affirming the alternative.

Also see FF.

Forms, Platonic {Gk. ειδη [eide]}

The pure objects of mathematical and dialectical knowledge. In the vigorous realism of Plato's middle dialogues, necessary truths are taken to involve knowledge of eternal, unchanging Forms (or Ideas). Particular things in the realm of appearance are beautiful, or equal, or good only insofar as they participate in the universal Forms of Beauty, Equality, or the Good. The doctrine of Forms was attacked in Plato's own Parmenides and by Aristotle.

Recommended Reading: The Dialogues of Plato, ed. by Eric Segal (Bantam, 1986); Gail Fine, On Ideas: Aristotle's Criticism of Plato's Theory of Forms (Clarendon, 1995); and John Malcolm, Plato on the Self-Predication of Forms: Early and Middle Dialogues (Clarendon, 1991).

Also see EB, Rose Cherubin and D. K. House.

Foucault, Michel (1926-1984)

French philosopher. As he explained in Folie et déraison (Madness and Civilization) (1961), Les Mots et les choses (The Order of Things) (1966), and L'Archéologie du savoir (The Archaeology of Knowledge) (1969), Foucault used historical investigations as a method of exposing how the structure of contemporary thought is shaped by conventional social institutions and practices, including especially the forceful marginalization of deviant behavior by discursive rationality. Surveiller et Punir (Discipline and Punish) (1975) and the unfinished Histoire de la sexualité (History of Sexuality: Introduction, Care of the Self, and The Use of Pleasure ) (1976, 1984) focus on the use of social power to circumscribe and control subjective human experience. Genuine freedom, Foucault maintained, can be achieved only through detachment from what is expected of us as "normal."

Recommended Reading: The Foucault Reader, ed. by Paul Rabinow (Random House, 1984); Michel Foucault, The Birth of the Clinic: An Archaeology of Medical Perception (Vintage, 1994); Michel Foucault, Fearless Speech, ed. by Joseph Pearson (Semiotext(e), 2001); James Miller, The Passion of Michel Foucault (Harvard, 2000); Barry Smart, Michel Foucault (Routledge, 1993); Béatrice Han, Foucault's Critical Project, tr. by Edward Pile (Stanford, 2002); The Cambridge Companion to Foucault, ed. by Gary Gutting (Cambridge, 1994); Hubert L. Dreyfus, Michel Foucault: Beyond Structuralism and Hermeneutics (Chicago, 1983); Feminist Interpretations of Michel Foucault, ed. by Susan J. Hekman (Penn. State, 1996); Arnold Davidson, The Emergence of Sexuality: Historical Epistemology and the Formation of Concepts (Harvard, 2002); and Gary Gutting, Michel Foucault's Archaeology of Scientific Reason (Cambridge, 1989).

Also see Ben Attias, SEP, EB, Jeffrey Hearn, Frank Pignatelli, ELC, and Andy Blunden.

Foucher, Simon (1644-1696)

French philosopher who offered trenchant criticisms of Cartesianism, Malebranche, and Leibniz. The skeptical arguments of Foucher's Dissertation sur la recherche de la vérité (On the Search for Truth) (1673) influenced the rejection of the primary / secondary quality distinction by Bayle and Berkeley.

Recommended Reading: Richard A. Watson and Marjorie Grene, Malebranche's First and Last Critics: Simon Foucher and Dortous De Mairan (Southern Illinois, 1995).


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Last modified 26 December 2011.
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