Transcendental Dialectic
The Ideal of Pure Reason

Section I. On an Ideal as Such
“Ideas are further removed from objective reality than are categories” (A568)
Appearances cannot be found to represent ideas in concreto
Ideas contain completeness which no empirical cognition can reach
“But what I call an ideal seems to be still further removed from objective reality” (A568)
An ideal is not just in concreto, but in individuo
Determinable or determined by the idea alone
Idea / Ideal example (A569)
Virtue and human wisdom are ideas
The wise person, or the human being who exists only in thoughts and completely agrees with the idea of wisdom, is an ideal
“… the aim that reason has with its ideal is through determination according to a priori rules.” (A571)
Reason thinks an object to be determinable according to principles
Conditions for determination not in experience, the concept is transcendent

Section II. On the Transcendental Ideal “The proposition that every existing thing is thoroughly determined means not only that of each pair of given predicates opposed to reach other, but also that of all possible [pairs of] predicates one always belongs to the thing.” (A573)
In order to cognize a thing completely, one must cognize everything possible
The sum of all possibility
Determination through the sum of all possibilities
“No one can think a negation determinately without using as a basis the opposed affirmation” (A575)
“All true negations are then nothing but limits ­– which they could not be called if the unlimited (the total) did not lie at the basis” (A575)
Negative concepts are just limitations of positive concepts
The presentation of a being through all possible positive concepts is an idea of total reality
A being in possession of this total reality presents the concept of ens realissimun, the concept of a thing in itself or an ideal being
The ideal is a based on all possibility, thus can only be one such ideal
“Logical determination of a concept by reason rests on a disjunctive syllogism” (A576)
Major Premise: a logical division (either-or)
Minor Premise: limits the sphere to a part
Conclusion: determines the concept through this part
Reason does not presuppose the existence of a being corresponding to the above ideal, but only the idea of said being
“Hence the object of reason’s ideal, an object which is to be found only in reason, is also the original being (ens originarium); and insofar as everything, as conditioned, is subject to it, it is called the being of all beings (ens entium) (A578)
The concept of God taken in the transcendental sense
The ideal of pure reason

Section III. On Speculative Reason’s Bases of Proof for Inferring the Existence of a Supreme Being
“If something – whatever it may be – exists, then we must grant also that something or other exists necessarily” (A584)
Reason searches for a concept that fits with absolute necessity
A being containing the sum of all possibilities is the most suited for this
“For since it itself possesses all conditions for all that is possible, it does not itself require – nor is even capable of [depending on] – any condition, and consequently satisfies at least in one point the concept of unconditioned necessity.” (A586)

Limited beings may also be compatible with absolute necessity
Hypothetical Syllogism problem: “I cannot say that when a certain condition is not there, then the conditioned also is not there”
From [P > Q; ~P], it does not follow necessarily that [~Q]
Hence, argument for existence of God through unconditioned necessity as an unlimited being does not work
Three remaining possible ways to prove the existence of God by means of reason:
Physicotheological: concerned with determinate experience then ascends from it in accordance to laws of causality to the supreme cause outside the world
Cosmological: begins from experience of existence in general
Ontological: takes from all experience and argues a priori from concepts to the existence of a supreme cause