I am interested in a reasoning problem, which recurs repeatedly across multiple areas of my interest, and would like the members of this board’s thinking on this issue.
It is a standard requirement, widely accepted by those who are "reasonable", that one should only hold by beliefs that are sufficiently justified. This is the Principle of Sufficient Reason. What is sufficient per the PSR is not specified, but it is generally taken as less rigorous than logical proofs. Anti-rationalists, and anti-realists, have taken aim at the PSR, and challenged that it is ever satisfiable even at levels well below proofs. One of the problems that justifications of beliefs runs into is that there appears to be no valid way to terminate justifications. The name for this critique is the Munchhausen Trilemma, or sometimes the Agrippa Trilemma.
The core problem for justifications is that one can always ask how the justification itself is justified. There are three basic answers identified in the Trilemma – an infinite series of justifications, circular justifications, or holding that some claims or information do not need justification. Because an infinite series of justifications has never been, and never could be done by anyone – this solution is not achievable by anyone making a claim, and if needed, then nothing satisfies the PSR. Declaring that some data or statements are undeniable and basic, and do not need to satisfy the PSR – is to abandon the PSR. And circularity is considered a definitive refutation of reasoning, per formal logic. The name of the trilemma critiques circularity, as Baron von Munchhausen was fabled to have pulled himself and his horse out of a quagmire by lifting up on his own hair.
While the Trilemma does not generally play a major role in politics or biology, it has regularly appeared as a problem bedeviling the advocates of one POV or another in some related fields that are discussed on this board: Cosmology; Theology (particularly Cosmological arguments); Morality; and the basis of science, knowledge in general, and reasoning. I will offer a few examples of “solutions” that have been proposed.
Most theology tends to treat deities as a Special Pleading exemption to the PSR – that they have some special feature that makes their existence unquestionable – IE a basic truth or fact. This sort of argument, of course, is not convincing at all to those who do not accept that particular theology. Another approach is to hold that a deity is eternal – hence basically satisfies the infinite logic chain. That one can reasonably ask “why should one believe this exemption”, or “why did that particular eternal entity exist”, is a problem for theologians. Theologians often at least give SOME reasons for these assumptions – Aquinas’s 5 proofs of God for example is an effort to at least partially satisfy the PSR.
Cosmologists have generally taken the same approaches as theologians – some postulating that the universe is an infinite series (bouncing universe, steady state universe, and eternal inflation) thus satisfying the infinite regression, some holding that existence of A universe is a basic and undeniable fact (special pleading exemption from the PSR).
Hawking in various writings offered a variety of alternative claims – putting a lot of effort into trying to find ways around the trilemma. A few examples: in A Brief History of Time – he argued that a closed object in space-time need not have a cause (IE if the universe winked out of existence after existing for 60 billion years, not having anything there at the 62 billion year point, its transitory 60 billion year existence would basically have a “no harm, no foul” exemption). In this argument, he was drawing on the analogy of virtual particles -- which both exist and don't -- as they wink out of existence before they can do anything. However, the analogy does not work, in that the asserted existence of virtual particles itself requires justification (and has been justified), and one can ask for the justifications for the appearance, sustained existence, and then disappearance of his universe, AND for the justification of his exemption.
In Black Holes and Baby Universes, he argued that at its origin the universe was so small that time and space dimensions became commingled, hence the exact time of the universe’s origin is slightly indeterminate – and then claimed that anything with an indeterminate origin in time need not have a specified cause (exemption to the PSR). WHY this would be a valid exemption – is not clear, at least to me. And why it would not apply generally to everything (as per the Heisenberg uncertainly principle, the exact time of all events, including all origins, is somewhat indeterminate), and would therefore be a wholesale repudiation of the PSR in all applications – is unclear to me as well.
Many of the Greek thinkers considered geometry, mathematics, and reasoning to be unquestionable, and the rationalist program in philosophy has sought to ground all knowledge in these sort of rational truths. This is to hold that some basic logic facts are unquestionable, and need not satisfy the PSR. Following them, Frege, then Russell and Whitehead, tried to derive all knowledge from formal logic and mathematics. They each failed, and Godel showed why, with his incompleteness theorem. Meanwhile, the development of non-Euclidian geometry, and of non-standard logics, has undercut any claim that a particular logic or mathematics is “basic” or undeniable. Not only has other knowledge not been shown to be derivable from logic, but by my understanding of the state of the field, logic itself is now subject to the trilemma.
Science has also struggled with the Trilemma. A number of approaches are summarized: Descartes famously declared his selfhood, his reasoning, and God to be undeniable, and built up a worldview from these three foundational exceptions to the PSR. Phenomenalism treated sensation as an undeniable basic. And the Logical Positivists treated reasoning as undeniable, and scientific induction as a close enough approximation to reasoning. Naïve Realism holds that the external world is undeniable.
In opposition to these exemptions to the PSR, which were primarily from the first half of the 20th century, most philosophy of science in the last half century plus has taken a primarily circularity approach to justification. Quine argued for a radical wholism in which all of science is self-supporting. The latter Wittgenstein agreed all scientific propositions are questionable – but that one can’t question all of them at the same time. EO Wilson’s criteria of consilience to accept a claim is wholistic. And the ultimate justification to accept science and empiricism as a truth method is a circular empiricist argument that empiricism works well to gain knowledge!
The principle behind all of these is that if one makes the circle of a circular argument large enough, then at some point it is no longer a refuting fallacy to be circular. The baron may not have been able to pull on his own hair to get himself out of the mud, but if he pulled on his horses mane, the horse lifted its head and pushed against the baron, lifting him in the stirrups, then by gripping the horse with his thighs the baron may have been able to lift them out. All it took was a four step circle, not a two-step one ;-).
I am not convinced that any of these efforts to evade the Trilemma, in any of these fields, have been successful.
B&B orig: 4/7/19
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