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Single Idea 11086

[filed under theme 10. Modality / A. Necessity / 5. Metaphysical Necessity ]

Full Idea

Weak metaphysical necessity is either over the set of all logically possible worlds (in which case it is the same as logical necessity), or it is of a smaller set of worlds, and is determined by the underlying essence or nature of the actual world.

Gist of Idea

Metaphysical necessity can be 'weak' (same as logical) and 'strong' (based on essences)

Source

Robert Hanna (Rationality and Logic [2006], 6.6)

Book Ref

Hanna,Robert: 'Rationality and Logic' [MIT 2006], p.196

A Reaction

I take the first to be of no interest, as I have no interest in a world which is somehow rated as logically possible, but is not naturally possible. The second type should the principle aim of all human cognitive enquiry. The strong version is synthetic.

The 28 ideas from 'Rationality and Logic'

11046 Kantian principled rationality is recognition of a priori universal truths [Hanna]
11048 Humean Instrumental rationality is the capacity to seek contingent truths [Hanna]
11047 Hegelian holistic rationality is the capacity to seek coherence [Hanna]
11045 Most psychologists are now cognitivists [Hanna]
11053 Explanatory reduction is stronger than ontological reduction [Hanna]
11051 Frege's logical approach dominates the analytical tradition [Hanna]
11054 Scientism says most knowledge comes from the exact sciences [Hanna]
11055 Supervenience can add covariation, upward dependence, and nomological connection [Hanna]
11058 Logic is explanatorily and ontologically dependent on rational animals [Hanna]
11059 Circular arguments are formally valid, though informally inadmissible [Hanna]
11061 Intensional consequence is based on the content of the concepts [Hanna]
11063 Logicism struggles because there is no decent theory of analyticity [Hanna]
11067 Rational animals have a normative concept of necessity [Hanna]
11068 One tradition says talking is the essence of rationality; the other says the essence is logic [Hanna]
11071 'Affirming the consequent' fallacy: φ→ψ, ψ, so φ [Hanna]
11070 'Denying the antecedent' fallacy: φ→ψ, ¬φ, so ¬ψ [Hanna]
11072 Logic is personal and variable, but it has a universal core [Hanna]
11078 Intuition is only outside the 'space of reasons' if all reasons are inferential [Hanna]
11077 Intuition includes apriority, clarity, modality, authority, fallibility and no inferences [Hanna]
11080 Intuition is more like memory, imagination or understanding, than like perception [Hanna]
11081 Imagination grasps abstracta, generates images, and has its own correctness conditions [Hanna]
11083 A sentence is necessary if it is true in a set of worlds, and nonfalse in the other worlds [Hanna]
11082 Should we take the 'depictivist' or the 'descriptivist/propositionalist' view of mental imagery? [Hanna]
11084 Logical necessity is truth in all logically possible worlds, because of laws and concepts [Hanna]
11086 Metaphysical necessity can be 'weak' (same as logical) and 'strong' (based on essences) [Hanna]
11085 Nomological necessity is truth in all logically possible worlds with our laws [Hanna]
11089 Formally, composition and division fallacies occur in mereology [Hanna]
11088 We can list at least fourteen informal fallacies [Hanna]