Non-physical thought processes

Image from the American Heart Association Blog



An argument for the non-physical intellect and the possibility that it can survive the death of the body (based on a recent Facebook discussion and also roughly on James F. Ross’s Immaterial Aspects of Thought)1:

D1) For all x, (x is a semantically determinate process ≝ there exists a y such that x contains y, and y is a set of operations that have a fixed and well-defined syntax and are semantically unique in their referents).
P1) For all x, (if x is a physical process, it is not the case that x is a semantically determinate process).
P2) There exists an x and there exists a y, such that {x is a formal thought process in my intellect, [x contains y, and (y = Modus Ponens)]}
P3) For all y, [ if (y = Modus Ponens), y is a set of operations that have a fixed and well-defined syntax and is semantically unique in its referents].
C1) There exists an x such that (x is a formal thought process in my intellect and it is not the case that x is a physical process). [From D1 and P1-P3]
P4) For all x, [if (x is a formal thought process in my intellect, and the mode of being of my intellect is physical), then x is a physical process].
P5) For all x, (if it is not the case that the mode of being of x is physical, then x is non-physical).
C2) My intellect is non-physical. [From C1, P4 and P5]
P6) For all x, if x is non-physical, then x cannot be physically destroyed.
P7) For all x and all y, if x cannot be physically destroyed and y can be physically destroyed, x can survive the physical destruction of y.
P8) My body can be physically destroyed.
C3) My intellect can survive the physical destruction of my body. [From C2 and P6-P8]

The point of the argument is essentially this: A physical process can be mapped onto a language, as we have computers do. But that physical process is only simulating the use of language and the way it computes symbols is only insofar as we tether symbols to physical states undergoing various processes. But the physical process itself does not fix the semantic content or the syntax, we do. And so we say that a computer might fail to “add” properly because of a hardware malfunction. But there is no telos intrinsic to the physical process that distinguishes functioning from malfunctioning, so it is merely our attempt to simulate adding that can, at times, be frustrated by a computer functioning in ways we did not anticipate or intend.

This is why no physical process can be semantically determinate. You can have a physical process that is given semantic content by a mind, and then it will be semantic, in a sense, but indeterminate in that the process doesn’t have to fix upon the syntax or semantics assigned to it.

However, a mental process like reasoning according to Modus Ponens is a syntactically well-defined operation that a mind can do. When the mind is doing this operation, it is preserving truth values. A mind cannot “do Modus Ponens” and “not do Modus Ponens” at the same time and in the same way. But a physical process “programmed” to track “Modus Ponens-like inferences” can run a program that makes “Modus Ponens-like inferences” while never actually doing Modus Ponens. It might be doing some other operation all together that is indistinguishable from Modus Ponens up to any given point in time, but in the next run of the program, the hardware catches on fire and it spits out on its display “if p, q/ p// not-q”. You can’t say that catching on fire and displaying an invalid argument on a screen was not part of the process, since the process just is however the hardware happens to function.

Given this, and given that the thing known is in the knower according to the mode of the knower, the rest follows from relatively uncontroversial premises.

Deduction: Let,
Px ≝ x is a physical process
Cxy ≝ x contains y
Ox ≝ x is a set of operations
Tx ≝ x has a well-defined syntax
Sx ≝ x is semantically unique in its referents
Fxy ≝ x is a formal thought process in y
Mx ≝ x has a mode of being that is physical
Nx ≝ x is non-physical
Rx ≝ x is physically destroyed
Vxy ≝ x survives the destruction of y
Dx ≝ (∃y){Cxy & [Oy & (Ty & Sy)]}
m ≝ Modus Ponens
i ≝ my intellect
b ≝ my body

1. (∀x)(Px ⊃ ~Dx) (premise)
2. (∃x)(∃y){Fxi & [Cxy & (y = m)]} (premise)
3. (∀y){(y = m) ⊃ [Oy & (Ty & Sy)]} (premise)
4. (∀x)[(Fxi & Mi) ⊃ Px] (premise)
5. (∀x)(~Mx ⊃ Nx) (premise)
6. (∀x)(Nx ⊃ ~◊Rx) (premise)
7. (∀x)(∀y)[(~◊Rx & ◊Ry) ⊃ ◊Vxy] (premise)
8. ◊Rb (premise)
9. (∃y){Fμi & [Cμy & (y = m)]} (2 EI)
10. Fμi & [Cμν & (ν = m)] (9 EI)
11. (ν = m) ⊃ [Oν & (Tν & Sν)] (3 UI)
12. Cμν & (ν = m) (10 Simp)
13.(ν = m) (12 Simp)
14. Oν & (Tν & Sν) (11,13 MP)
15. Cμν (12 Simp)
16. Cμν & [Oν & (Tν & Sν)] (14,15 Conj)
17. (∃y){Cμy & [Oy & (Ty & Sy)]} (16 EG)
18. Dμ (17 Def “Dx”)
19. ~~Dμ (18 DN)
20. Pμ ⊃ ~Dμ (1 UI)
21. ~Pμ (19,20 MT)
22. (Fμi & Mi) ⊃ Pμ (4 UI)
23. ~(Fμi & Mi) (21,22 MT)
24. ~Fμi ∨ ~Mi (23 DeM)
25. Fμi (10 Simp)
26. ~~Fμi (25 DN)
27. ~Mi (24,26 DS)
28. ~Mi ⊃ Ni (5 UI)
29. Ni (27,28 MP)
30. Ni ⊃ ~◊Ri (6 UI)
31. ~◊Ri (29,30 MP)
32. (∀y)[(~◊Ri & ◊Ry) ⊃ ◊Viy] (7 UI)
33. (~◊Ri & ◊Rb) ⊃ ◊Vib (32 UI)
34. ~◊Ri & ◊Rb (8,31 Conj)
35. ◊Vib (33,34 MP)
36. Fμi & ~Pμ (21,25 Conj)
37. (∃x)(Fxi & ~Px) (36 EG)
38. (∃x)(Fxi & ~Px) & Ni (29,37 Conj)
39.[(∃x)(Fxi & ~Px) & Ni] & ◊Vib (35,38 Conj, which is C1-C3)
QED

J.F. Ross. 1992. “Immaterial Aspects of Thought.” In The Journal of Philosophy. Vol. 89. No. 3. 136-150
I. Niiniluto. 1987. “Verisimilitude with Indefinite Truth.” What is Closer-to-the-truth: A Parade of Approaches to Truthlikeness. Ed. T.A.F. Kuipers. Amsterdam: Rodopi. pp. 187-188
(P4) is based upon the principle that a thing known is in the knower according to the mode of the knower. See, for example, Thomas Aquinas Summa Theologiae I.14.1.

Posted on October 23, 2015, in Philosophy of Mind and tagged , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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