Socratic/Platonic reasoning is inductive, meaning that it is ultimately based on clear perceptions of what is admirable and not admirable in clear concrete cases. "Counterexamples" appeal to negative perceptions of things clearly not admirable, to uncover and remove imperfections in general concepts of virtue. It is also possible to use positive perceptions, cases of things clearly admirable, and then generalize from these positive perceptions to more perfect generalizations defining the essence of some kind of excellence.
Plato's idea of the positive relation between imperfect concrete reality and perfect Platonic Forms is best represented in the image of a mental "ladder" in Plato's Symposium. It formed the basis for a later Christian tradition concerning the possibility of knowing God, known as the doctrine of "Analogy." For example, God's love is thought to be completely perfect, unlike the imperfect love we are familiar with in human life. But the imperfect love easily accessible to human understanding is analogous to God's perfect love, and so we can come to understand God's perfect qualities by using imperfect human examples as starting points, then imagining what these qualities would be at their most perfect. This is a way of climbing a mental ladder from imperfect concrete reality to perfect transcendent reality. This is connected also to Plato's idea of "participation": a person cannot hope to completely embody Perfect Courage, but to cultivate a kind of courage that approximates or "participates in" the perfect Platonic Form of Courage.
I will call this the "The Principle of Analogy and Participation," or "Plato's Ladder." It is the Fourth Principle of Socratic/Platonic reasoning, described in the earlier Four Principles essay.
Here is the Symposium passage describing "Plato's Ladder":
[To learn about beauty, one should] start when young by pursuing beautiful bodies. First... he will love one beautiful body... then he must realize that the beauty attached to one body is kin to [the beauty] attached to another body, so if it is necessary to pursue beauty in Form, it is great folly not to regard as one the Beauty found in all bodies. Realizing this he must make himself a lover of all beautiful bodies...
After this he must realize that the beauty in souls is of much more value than the beauty in the body, [so that] if there is a soul with a little bloom [of beauty] beginning in it, he will love and care for it...
Contemplating [many specific] beautiful things rightly and in due order... he will suddenly have revealed to him something wonderful...
This [the Form of Beauty] is something always-being, not coming into being and perishing, not increasing and decreasing... It is not partly beautiful and partly shameful, nor now [beautiful] now-not [beautiful], nor in some respects beautiful and in some respects shameful... Nor will the beautiful appear to him as a face, or hands, nor any other part of the body... nor something existing in something else... but always being something single-formed having its own being with itself in itself... All other beautiful things participate in this, in such a manner that, while these other things come into being and perish, this thing becomes neither greater nor lesser...
Beginning from those beautiful things, always ascending upward for the sake of The Beautiful, like someone using the steps of a ladder, from one to two, and from two to all beautiful bodies, and from beautiful bodies to beautiful institutions, and from institutions to beautiful learnings, and from beautiful learnings... to that learning which is none other than the learning concerning The Beautiful...
What would you think if it happened to someone to see The Beautiful, exact, pure, unmixed... [What if] he were able to see unique Divine Beauty? Does it seem to you a trifling life for a man to lead, looking ‘over there,' contemplating it the way it should be [contemplated]?...
Seeing The Beautiful through what is visible, [he will] bring forth not images of virtue [aręte], since he is in touch not with images [of virtue] but with true [virtue]... When he has brought forth and reared true virtue he is destined to become God-pleasing.
(Note that whereas the English word "beauty" has strong associations with visual beauty, the Greek word Plato uses is kalos, which also has a broader meaning of "fine," "noble," or "refined." This is why Plato can refer to "beautiful laws and institutions," and also regard "beauty" (to kalon) as a personal "virtue" (arētē). ML)
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Applied to Nibbana: If Nibbana is a hard-to-understand transcendent Good, it is the perfection of
some kind of goodness we should be able to grasp in more familiar and
easy-to-understand concepts, serving for us as more accessible analogies to
Nibbana.
A critical reconstruction of the Nibbana-ideal is a creative
process; not just taking descriptions of Nibbana literally at face value as
something easy to understand, then asking whether it qualifies as a transcendent
Good. (All easy-to-understand concepts are ambiguous with respect
to pure Goodness). But creatively formulating a description
of Nibbana (not easy to understand) which we can know to represent transcendent
Goodness;
If Nibbana is a specific kind of Goodness at the top of
Plato's ladder, what specific kinds of concrete examples of this goodness
form the bottom rungs of this ladder? (I will suggest, for example, that
Nibbana can be understood as something like the perfection of more familiar
concepts like self-confidence, independence, and flexible adaptation.)
No pure goodness can be described in terms of visible external behavior. Nibbana as transcendent Goodness can only be described in terms of things internal to a person (fundamental attitudes, motivations, capacities). Buddhist spirituality is in full accord with the Platonist idea that pure and perfect goodness can only be described as something internal to a person, not in terms of rules or guidelines for external behavior. This marks the difference between Buddhist "religion" (focused on visible externals, easily understood by the general public), and Buddhist "spirituality" entirely focused on radical internal psychological restructuring of a person's motivations, attitudes, and fundamental ways of relating to the world. But this also means that Buddhist spirituality needs to be separated from the specific visible way of life of monks and nuns practicing Buddhist spirituality.
For example, the Pali Canon insists that "true seclusion" does not consist in literal, visible withdrawal from society and social interaction. "True seclusion" is internal freedom and independence from deep and inflexible psychological dependencies on other people's approval (causing deep dukkha/distress if it is absent). Such internal/psychological freedom and independence is compatible with social interaction, but would cause a person to interact with others on a different basis. And on the other hand, if a monk literally secludes himself, but is unable to re-enter society and interact on the basis of this kind of freedom and independence, his literal seclusion will have failed to achieve its essential goal.
Participation describes the function of the Nibbana-ideal in the concrete life of the ideal Platonist. Rationally speaking, a Buddhist becomes a more admirable person to the degree that her life approximates or "participates in" the Nibbana-ideal, whether or not she actually fully "reaches" Nibbana. (For critical reasoning, it is unimportant whether anyone has ever fully reached Nibbana, that Nibbana "exists" in this sense -- it is an ideal to be striven towards.)