Faith and rationality are two modes of belief that exist in varying degrees of conflict or compatibility. Rationality is belief based on reason or evidence. Faith is belief in inspiration, revelation, or authority. The word faith generally refers to a belief that is held with lack of, in spite of or against reason and evidence.

Although the words faith and belief are sometimes erroneously conflated and used as synonyms, faith properly refers to a particular type (or subset) of belief, as defined above.

Broadly speaking, there are two categories of views regarding the relationship between faith and rationality:

1. Rationalism holds that truth should be determined by reason and factual analysis, rather than faith, dogma, tradition or religious teaching.
2. Fideism holds that faith is necessary, and that beliefs may be held without evidence or reason, or even in conflict with evidence and reason.

The Catholic Church also has taught that faith and reason can and must work together, in the Papal encyclical letter issued by Pope John Paul II, Fides et Ratio ("[On] Faith and Reason").

Adjective

irrational (comparative more irrational, superlative most irrational)

1. Not rational; unfounded or nonsensical.

   an irrational decision

2. (mathematics, arithmetic, not comparable) Of a real number, that cannot be written as the ratio of two integers.

   The number π is irrational.

• irrational number

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• Science: Science in Society: Science and Religion (74)
• Society: Religion and Spirituality (95,091)
• Society: Religion and Spirituality: Religious Studies (133)

• The Lublin School of Philosophy
  vaxxine.com
  Known also as Lublin Thomism and Christian Existentialism. Site contains basic information and articles.
• Stanford Encyclopedia of Philosophy: Descartes' Ontological Argument
  plato.stanford.edu
  Discussion of René Descartes' ontological proof of the existence of God. By Lawrence Nolan.
• Analytic Philosophy of Religion
  philofreligion.homestead.com
  Resources in the analytic philosophical tradition, including religious epistemology, theistic arguments, medieval philosophy, and teaching resources and discussion groups.
• Wikipedia: Gödel's Ontological Proof - Article on 20th-century logician Kurt Gödel's formulation of this argument for God's existence.