題目 1 · AO1 Knowledge and Understanding Essay
25 分Examine the ontological argument for the existence of God, with reference to the contributions of Anselm and Descartes. [25]
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解題
The ontological argument is unique among the classical arguments for God's existence in being an entirely a priori, deductive argument: rather than reasoning from observed features of the world (as the cosmological and teleological arguments do), it attempts to derive God's existence directly from the very definition or concept of God.
The argument originates with Anselm of Canterbury in his Proslogion (1078). Anselm begins from a definition of God as 'that than which nothing greater can be conceived' — the greatest possible being conceivable. He then argues that even someone who denies God's existence (the 'fool' of Psalm 14) must have this concept of God in their mind, since they understand what is being denied. Anselm then argues that a being which exists both in the mind and in reality is greater than a being which exists in the mind alone; therefore, if 'that than which nothing greater can be conceived' existed only in the mind, one could conceive of a greater being — one that also existed in reality — which is a contradiction, since nothing greater than 'that than which nothing greater can be conceived' can, by definition, be conceived. It follows, for Anselm, that God must exist in reality and not merely as an idea. In Proslogion 3, Anselm develops a second, related form of the argument, arguing that a being whose non-existence is inconceivable (a being with necessary existence) is greater than a being that merely happens to exist (contingent existence); since God is the greatest conceivable being, God's existence must be necessary rather than contingent, meaning God cannot fail to exist. Anselm anticipated objections to his argument, notably from the monk Gaunilo, who proposed the parallel case of a 'Lost Island' — the greatest conceivable island — arguing that Anselm's logic would absurdly prove such an island must exist; Anselm responded that the argument works uniquely for God as the greatest conceivable being in every category, not for a greatest conceivable member of a finite, limited category such as islands.
Descartes reformulated the argument in his Fifth Meditation (1641), using different but related reasoning. Descartes argued that certain concepts have properties that necessarily belong to them by definition — a valid triangle, for example, necessarily has interior angles summing to two right angles, and one cannot coherently conceive of a triangle lacking this property while still calling it a triangle. Descartes argued that existence functions similarly as a necessary predicate of the concept of God: since God is defined as a supremely perfect being, and existence is itself a perfection (it is greater to exist than not to exist), a supremely perfect being cannot lack the perfection of existence without ceasing to be supremely perfect. To conceive of God as not existing would therefore be as incoherent, for Descartes, as conceiving of a triangle whose angles do not sum to two right angles, or a mountain without a valley.
Both Anselm and Descartes therefore share the core strategy of treating existence (or necessary existence) as logically inseparable from the very concept of a supremely perfect or greatest conceivable being, making the argument formally deductive: if the definition of God is accepted, God's existence appears to follow with logical necessity, independent of any empirical observation of the world.
The argument originates with Anselm of Canterbury in his Proslogion (1078). Anselm begins from a definition of God as 'that than which nothing greater can be conceived' — the greatest possible being conceivable. He then argues that even someone who denies God's existence (the 'fool' of Psalm 14) must have this concept of God in their mind, since they understand what is being denied. Anselm then argues that a being which exists both in the mind and in reality is greater than a being which exists in the mind alone; therefore, if 'that than which nothing greater can be conceived' existed only in the mind, one could conceive of a greater being — one that also existed in reality — which is a contradiction, since nothing greater than 'that than which nothing greater can be conceived' can, by definition, be conceived. It follows, for Anselm, that God must exist in reality and not merely as an idea. In Proslogion 3, Anselm develops a second, related form of the argument, arguing that a being whose non-existence is inconceivable (a being with necessary existence) is greater than a being that merely happens to exist (contingent existence); since God is the greatest conceivable being, God's existence must be necessary rather than contingent, meaning God cannot fail to exist. Anselm anticipated objections to his argument, notably from the monk Gaunilo, who proposed the parallel case of a 'Lost Island' — the greatest conceivable island — arguing that Anselm's logic would absurdly prove such an island must exist; Anselm responded that the argument works uniquely for God as the greatest conceivable being in every category, not for a greatest conceivable member of a finite, limited category such as islands.
Descartes reformulated the argument in his Fifth Meditation (1641), using different but related reasoning. Descartes argued that certain concepts have properties that necessarily belong to them by definition — a valid triangle, for example, necessarily has interior angles summing to two right angles, and one cannot coherently conceive of a triangle lacking this property while still calling it a triangle. Descartes argued that existence functions similarly as a necessary predicate of the concept of God: since God is defined as a supremely perfect being, and existence is itself a perfection (it is greater to exist than not to exist), a supremely perfect being cannot lack the perfection of existence without ceasing to be supremely perfect. To conceive of God as not existing would therefore be as incoherent, for Descartes, as conceiving of a triangle whose angles do not sum to two right angles, or a mountain without a valley.
Both Anselm and Descartes therefore share the core strategy of treating existence (or necessary existence) as logically inseparable from the very concept of a supremely perfect or greatest conceivable being, making the argument formally deductive: if the definition of God is accepted, God's existence appears to follow with logical necessity, independent of any empirical observation of the world.
評分準則
Band-of-response marking (25 marks). Band 1 (1–4): Basic, fragmentary knowledge of the ontological argument; little or no reference to Anselm or Descartes; weak written communication. Band 2 (5–8): Limited knowledge, perhaps naming Anselm and/or Descartes but with little accurate detail of the argument's structure; adequate written communication. Band 3 (9–12): Reasonable, generally accurate account of the ontological argument with some reference to both Anselm and Descartes, though development may be uneven; adequate use of specialist vocabulary. Band 4 (13–16): Good, accurate knowledge of both Anselm's and Descartes' formulations, with clear explanation of the a priori, deductive character of the argument and some reference to objections such as Gaunilo's; clear organisation. Band 5 (17–20 base range; extended to 25 for exceptional responses): Comprehensive, precise and well-organised knowledge of both formulations of the argument, using accurate technical vocabulary (a priori, necessary existence, contingent existence) and demonstrating sophisticated understanding of the logical structure and its reformulations. Max 25 marks.