“More than that: you say that then science itself will teach man (though this, to my mind, is already a luxury) that he really does not possess, and never did possess, either a will or a whim of his own; that he is, in fact, no more than a kind of piano key or organ stop; and that, besides, there is such a thing in the world as the laws of nature; so that everything that is done by man isn’t in the least a matter of his own will, but happens itself, according to these laws. Consequently, all that is needed is to discover the laws of nature; then man will no longer be answerable for his actions …”
In the prefatory quotation, Underground Man reflects on the philosophical naturalism affirmed by many in his time. He notes that on naturalism: (a) science teaches us everything there is to know about human beings; (b) human actions are like piano keys played by the laws of physics and chemistry; and (c) human beings are not morally responsible for their actions. In sum, naturalism and free will are incompatible. Let us consider his claim.
Naturalism entails causal determinism (CD). If CD is true, then human beings lack libertarian free will (LFW). A causal determinist might be inclined to believe that we have freedom in the compatibilist sense; however, if CD is the case, we lack freedom in the libertarian sense. For Underground Man, this is bad news. He will have no truck with CD; on his view, neither hard nor soft determinism provide genuine freedom. For him, the desideratum is LFW. Without it, we are mere instruments of nature. I suspect that Underground Man would agree with Kant that the compatibilistic sense of freedom is “the freedom of a turnspit,” an attempt at “subterfuge” and “word-jugglery.” In short, CD is incompatible with free will. Is he right?
The Consequence Argument
If the Consequence Argument is sound, he is right. The argument has been developed and advocated by Peter van Inwagen, among others. It can be articulated in different ways. Peter van Inwagen has expressed it as follows: “If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us.”
Here is another way to express the argument. Let us begin with a working definition of CD.
CD = Df for any event E, the conjunction of l (the laws of nature) and h (the complete history of the universe prior to E) are jointly sufficient for E to occur.
Now, it seems that if the conjunction of l and h are sufficient to bring about E, then we humans have no control over E. If this is the case, we are wholly passive concerning E. (Let us call this proposition ‘P’ for “passivity.”) To see this, note that no human being is free to change the existence or the causal efficacy of l. (Let us call this proposition ‘L’ for “laws.”) And no human being can control h. (Call this ‘H’ for “history.”) Moreover, no human being can do anything to prevent the conjunction of l and h. (Call this ‘C’ for “conjunction.”) Further, if CD is the case, the fact that this conjunction is sufficient to bring about E is not up to us human beings. (Call this ‘B’ for “bring about.”) If L, H, C, and B are true, no human being is free to control the occurrence or the non-occurrence of any event whatsoever, including those occurrences which are his own actions. We are wholly passive and we do only what we are causally determined to do; i.e., P is the case. And if P, then we are not free in any meaningful sense.
Let as assume arguendo that CD is the case. As such, l and h are sufficient to bring about E. Thus, P is true. And P entails that we are not free. (Call this ‘~HF’ for “humans are not free.”) Notice that the assumption of CD logically leads to ~HF. Hence, CD is incompatible with human freedom. (Call this ‘CDIF’ for “causal determinism is incompatible with freedom.”) Moreover, if CDIF is true and we are nevertheless free, then we have LFW and CD is false. But, arguably, we are free. Thus, plausibly, we have LFW and CD is false.
The Consequence Argument can be summarized formally, using the Conditional Proof (CP), as follows:
- CD –> ((l & h) –> E) (The definition of CD given above)
- ((l & h) –> E) –> P
- P –> ~HF (i.e., human beings are not free)
- CD (Assumption)
- (l & h) –> E (1, 4 MP)
- P (2, 5 MP)
- ~HF (3, 6 MP)
- CD –> ~HF (4 – 7, CP)
In addition, one can argue:
- (CD –> ~HF) –> CDIF
- CDIF (8, 9 MP)
- HF (i.e., human beings are free)
- CDIF & HF (10, 11 CONJ)
- (CDIF & HF) –> LFW
- LFW (12, 13 MP)
- ~CD (8, 11 MT)
Why accept (2)? The conjunction of the untouchable propositions L, H, C, and B seem to show that P. In other words, the conjunction seems to indicate that we are wholly passive regarding the occurrence or non-occurrence of any event whatsoever – including all of our behaviors, actions, and choices. On CD, these events are caused by l and h; the events happen as a result of things completely beyond our control. As such, we are not active agents; rather, we are passive instruments moved by nature and the events of the past. What about (3)? If it is the case that we are passive, causally determined instruments of nature, there seems to be no room whatsoever for us to exert any freedom or influence at all.
Arguments for LFW
But why (11)? First, consider the following variation of Tim Stratton’s Free-Thinking Argument: (i) if humans do not possess LFW, then humans do not possess the ability freely to gain knowledge (or at least justified belief) via rational thought; however, (ii) humans possess the ability freely to gain knowledge (or at least justified belief) via rational thought; therefore, (iii) humans possess LFW; but (iv) if humans possess LFW, then CD is false; hence, (v) CD is false. This argument is valid by modus tollens and modus ponens.
Second, consider the phenomenological experience of libertarian freedom. Arguably, we are directly aware of our libertarianly free choices. For example, suppose you go to the store to buy cereal, your options are wheat flakes or corn flakes, and you select the former. In this situation, you are directly aware of your ability to choose without being determined by external factors (such as physical laws) or internal factors (such as your own desires or beliefs). Moreover, you are aware that it is in your power to refrain from choosing wheat flakes and to choose corn flakes instead, or to opt for neither. And you are aware that the choice is up to you such that you make it and are responsible for making it. You have rational control over your decision. This awareness does not conclusively prove that we have LFW, but it justifies the belief that we have LFW.
Third, plausibly, LFW is necessary for moral responsibility. Since we are morally responsible agents, we have LFW. Fourth, we all assume as a matter of daily life that we are free and rational agents rather than causally determined tools of nature. Thus, we have a practical reason to believe that we are in fact free agents. Moreover, we have an epistemic right to believe that we are free unless and until there is an argument sufficient to prove conclusively that we are not free. No such argument has been provided. Fifth, I refer the reader to We’re All NPCs by Timothy Fox.
I ended the Introduction by inviting the reader to consider whether or not Underground Man is right that naturalism (and hence CD) entails the absence of human free will. Are we humans nothing but instruments of physics? If the Consequence Argument is sound, then CD is indeed incompatible with human freedom. In this case, Underground Man is correct that if naturalism and thus CD is true, we are like piano keys moved by the laws of nature. But if we are free, then CD is false. Again, Dostoyevsky helps us to see the bleak implications of naturalism.
 See Fyodor Dostoyevsky, Notes from Underground, (New York: Bantam Dell, 2005), 23-24. Notice that Underground Man considers the claim “science teaches man” to be a “luxury” for the naturalist. In other words, given the ontology of naturalism, it is intellectually extravagant for a naturalist to make such a claim. Could it be that Mr. Underground sees that if naturalism is true, consciousness does not exist and thus human beings neither practice science, nor teach anything, nor learn anything?
 Dostoyevsky satirically refers to this worldview as the “Crystal Palace.” See Notes from Underground, 24.
 See Kant’s Critique of Practical Reason, (New York: Dover Publications, 2004), Book I, Ch. 3, 101-103.
 See Peter van Inwagen, “The Consequence Argument,” in Metaphysics: the big questions, Second Edition, eds. Peter van Inwagen and Dean W. Zimmerman, (Oxford: Blackwell Publishing, 2008).
 For more information about Stratton’s argument, go to freethinkingministries.com and search “free thinking argument.”
 As Roderick Chisholm has noted, we should be guided in philosophy by those propositions we all presuppose in our ordinary activity. We have a right to believe these propositions until there is a sufficient reason to reject them. Moreover, the burden of proof is on the one who rejects them. See Person and Object: A Metaphysical Study, Second Edition, (Chicago: Open Court Publishing Company, 1979), 15-16, 18.
 See https://freethinkingministries.com/were-all-npcs/. Fox writes that if philosophical naturalism is the case, “humans are blindly-programmed biological machines who have no free will and no consciousness.” Technically, if humans lack consciousness, the term “who” does not apply to us. This term is a pronoun used to refer to persons (i.e., individual subjects of a rational, and thus conscious, nature). On philosophical naturalism, arguably, a human being is an it but not a who. Nevertheless, Fox succinctly and vividly addresses the implications of naturalism. For more information on the implications of naturalism, see Philosophical Notes on the Underground: One at https://freethinkingministries.com/philosophical-notes-on-the-underground-one/ and Philosophical Notes on the Underground: Two at https://freethinkingministries.com/philosophical-notes-on-the-underground-two/