Thinking For A Living: A Philosopher’s Notebook 4 — Realistic Idealism: Ten Theses About Mind-Dependence.

By Robert Hanna

“Diogenes Sheltering in His Barrel,” by John William Waterhouse

61. Realistic idealism: ten theses about mind-dependence. I strongly believe that some or another version of metaphysical idealism is true; but I also strongly believe that the true version of metaphysical idealism must be substantively realistic.

How can this be so?

To show how, I’ll present ten theses about mind-dependence that add up to a realistic idealism.

62. I’ll start with some background notions.

By a veridical appearance I mean anything X that appears as F, or appears F-ly, or appears to be F, to any or all rational human cognizers, just insofar as, and precisely because, X really and truly is F.

For example, if I say “It appears that Sweetpea the cat, who lives at my daughter’s place in Los Angeles, is looking at me from her cat-cave,” like this:

or “It appears that 2 + 2 = 4,” or “It appears that The Minimal Law of Non-Contradiction[i] applies universally,” and what I say is literally correct, then all the things I am talking about are veridical appearances.

By the manifestly real world, I mean the world as it veridically appears to any or all rational human cognizers or agents.

By logical possibility, I mean analytic or weak metaphysical possibility; and by real possibility, I mean synthetic or strong metaphysical possibility.

Real possibility entails logical possibility, but logical possibility does not entail real possibility.

For example, 10,000 year old human animals are really possible and also logically possible; immortal human animals are logically possible but not really possible; and mortal immortal human animals are logically impossible and really impossible.

Now for the ten theses.

63. Thesis 1: A world that cannot veridically appear, a world “in itself,” a noumenal world, is logically possible but not really possible. (The Real Impossibility of a Noumenal World)

64. Thesis 2: Necessarily, if the manifestly real world exists, then the specific characters of its basic structures systematically correspond to the specific characters of the innate structures of the rational human cognitive and practical capacities. (World-to-Mind Conformity)

65. Thesis 3: Necessarily, if the manifestly real world exists, then if rational human cognizers/agents had been/were differently constituted as to their innate cognitive or practical capacities, the manifestly real world would have been/be correspondingly differently constituted as to its basic structures. (World-to-Mind Covariance)

66. Thesis 4: Necessarily, if the manifestly real world exists, then if some rational human cognizers/agents were to exist, they would be able to know or change that manifestly real world to some salient extent, by means of the normal operations of their innate cognitive or practical capacities. (Mind-to-World Access)

67. Thesis 5: Even if any or all rational human cognizers/agents were to go out of existence, nevertheless it is really possible for the manifestly real world not only to remain in existence but also to retain all the specific characters of its basic structures. (The Mind-Independence of the Manifestly Real World)

68. Thesis 6: Necessarily, if the manifestly real world exists, then if some rational human cognizers/agents were to exist, they would all be able to know or change that world in essentially the same ways. (The Objectivity of the Manifestly Real World)

69. Thesis 7: Necessarily, if the manifestly real world exists, then for some but not all spacetime locations L in the manifestly real world, if any given rational human cognizer/agent — call it Bob — were to have been/be actually present, cognizant, and active at L, then the manifestly real world would have been/be differently constituted at L than it would have been/be had Bob not been present, cognizant, and active at L. (The Observer-Dependence of Some Proper Parts of the Manifestly Real World — for example, Heisenberg-style quantum mechanical effects.)

70. Thesis 8: Necessarily, if the manifestly real world exists, then rational human cognizers/agents are not only logically (analytically, weakly metaphysically) possible but also really (synthetically, strongly metaphysically) possible. (Anthropocentricity 1)

71. Thesis 9: Necessarily, if rational human cognizers/agents had not been really possible, then the manifestly real world would not have existed. (Anthropocentricity 2)

72. Thesis 10: It cannot be the case that

both (i) the manifestly real world exists, and

also (ii) rational human cognizers/agents are really impossible.

(Anthropcentricity 3)

73. If theses 1–10 are all true, then the manifestly real world is non-trivially mind-dependent even though subjective idealism and irrealism are both false — that is, realistic idealism is true.