Understanding Epistemic Humility and The Principle of Sufficient Reason (Research Paper Sample)

Epistemic Humility and The Principle of Sufficient Reason
ABSTRACT: According to the unrestricted version of the Principle of Sufficient Reason, every truth has an explanation. I argue that there is defeasible methodological justification for belief in an unrestricted PSR. The argument is based on considerations about epistemic humility and complete explanatory knowledge as a basic goal of reasoning. We have reason to expect that there are truths we can now represent whose explanations are at present cognitively inaccessible for us. They call for the introduction of new concepts. I call this the Principle of Epistemic Humility about Cognitive Accessibility (PH-CA). I argue that considerations about PH-CA allow the construction of a non-circular argument for the PSR, according to which some explanatory truths can only be known if we accept that all truths which are apt for explanation have an explanation.
1.Introduction
The Principle of Sufficient Reason (PSR) is readily recognized as the centrepiece of early modern rationalism. Historically prominent in the works of Spinoza and Leibniz, the PSR has also received renewed contemporary interest by metaphysical neo-rationalists, among others. Various versions of the PSR have been formulated and its complex relationships with necessitarianism and contemporary accounts of metaphysical explanation and grounding have been explored (Della Rocca 2003, 2010, 2021; Pruss 2006, 2017; Pruss and Koons 2020; Dasgupta 2016; Smith 1995; Lin 2012, Amijee 2020, 2021; Raven 2020; Schnieder and Steinberg 2015; McDaniel 2019). My goal in this paper is to articulate and defend a novel argument for an unrestricted version of the PSR. The intent of the paper is not to settle the question of PSR’s validity but to uncover an additional source of justification for the PSR, which has so far been overlooked.[One possible exception is Kant’s discussion of the PSR as a regulative ideal of human reasoning. See Kant (1787/1998). He accords a central role to the idea of completely unified knowledge as a necessary goal of human reasoning. Kant, however, arguably took epistemic humility to pull in the opposite direction, i.e., cast doubt on the validity of the PSR. For recent discussion of Kant’s views on the PSR, see Longuenesse (2005); Lu-Adler (2021).]
The argument is based on considerations about epistemic humility and complete explanatory knowledge as a basic aim of reasoning. We have reason to expect that there are truths we can now represent whose explanations are at present cognitively inaccessible for us. They call for the introduction of new concepts. This is the case in two different ways. Truths we can now represent have an explanation we cannot yet formulate and we know this. But there may also be truths which have an explanation we cannot yet formulate but we do not know this. Call this the Principle of Epistemic Humility about Cognitive Accessibility (PH-CA). I argue that considerations about PH-CA allow the construction of a non-circular argument for the PSR, according to which some explanatory truths can only be known if we accept that all truths which are apt for explanation have an explanation. This provides defeasible methodological justification for belief in an unrestricted PSR on the basis of considerations about epistemic humility and complete explanatory knowledge as a basic goal of reason.
My discussion will proceed as follows. In sec. 2, I articulate the version of the PSR which the argument of this paper is meant to support and then present the argument in detail. In sec. 3, I address some key objections. In sec. 4, I conclude my discussion by comparing and contrasting the argument of the paper with some recent defences of the PSR.
2. PSR and Epistemic Humility
The following discussion motivates the unrestricted version of the PSR which is my main focus. I assume that there is a coherent distinction between truths in a language which are apt for explanation and truths which are not apt for explanation, following Dasgupta’s recent discussion on the PSR and metaphysical grounding (Dasgupta 2016). This is different from admitting the possibility of truths which are apt for explanation but simply have none, as supporters of brute facts maintain. The goal of this paper is to argue that we are justified in rejecting such brute facts. In sec. 2.2., I set out the argument of the paper.[Della Rocca has recently questioned the coherence of this distinction. See Della Rocca (2021). According to Della Rocca, the distinction between propositions apt for explanation and those not apt for explanation really amounts to a restriction of the PSR. I do not think introducing this distinction amounts to a restriction of the PSR. I agree that it is often difficult to determine objectively whether one is giving reasons to think some proposition in L is not apt for explanation as opposed to giving reasons to think that it has no explanation, even though it is apt for explanation. Nonetheless, the difficulty is dialectical and does not stem from lack of intelligibility in the distinction itself. One can get a grip on the distinction by reflecting on uncontroversial cases of propositions which are not apt for explanation, and I think some of the examples that I give in the text are uncontroversial.]
2.1. Unrestricted PSR and explanation-aptness
According to the fully unrestricted version of the PSR, every truth, whether necessary or contingent, has an explanation. Arguably, not all truths one can state in a given background language L with sufficient expressive power to support explanatory relations are apt for explanation. Some necessary truths in L may be apt for explanation. Reductive philosophical accounts of identity presuppose that one could give explanations for facts about numerical identity. If it is a fact that a = b and that a ≠ c, then there is an explanation of why a = b and a ≠ c. Similarly, it may be metaphysically necessary that space and time exist. But it would still make sense for one to ask for explanation of this fact, especially in light of a salient alternative, e.g., that the actual world consists only of abstract objects.
According to a number of recent discussions on mathematical explanation, it is also an established practice to ask for explanations of mathematical theorems, which are clear examples of necessary truths (Lange 2016; Mancosu 2008). On the other hand, not all theorems of mathematics and logic are apt for explanation and one could argue that not all distinctively philosophical truths are apt for explanation. Essentialist truths might not be. I want to remain neutral on the question of where the boundary between the necessary truths which are apt for explanation and those which are not apt for explanation should be drawn. This a live and open debate. I only make the assumption that the distinction is real and, at the beginning of philosophical debate, substantive. If it turns out that all necessary truths are apt for explanation, then one can interpret the scope of the PSR I defend in accordance with this result.[Discussion on explanation of necessary truths and specifically mathematical ones can also be found in Pruss (2006, Ch. 1).] [Dasgupta (2016) argues that essentialist facts are not apt for explanation. For an opposing view, see Raven (2020).]
The same observations also apply to contingent truths in L. Within the class of contingent truths, one can also draw a distinction between those which are apt for explanation and those which are not. Perhaps some contingent truths which seem to call for explanation turn out to involve presupposition failure. Their explanation would require there to be an intelligible connection between facts which we have a priori reason to think that there cannot be. For example, one might naively ask for an explanation of why John closed the door to his apartment exactly at the moment of time when James sits on his desk in an office in Kuala Lumpur. John and James have led completely disconnected lives. There is no connection between these facts. At the relevant level of description, which the call for explanation here presupposes, i.e., psychological/sociological or historical, this conjunction of facts is not apt for explanation. There is no intelligible connection between the relevant facts of the kind the question seems to presuppose. At any other level of description, the questioner can insist, the conjunction of facts is not really intelligible and not what they were wondering about.
Similarly, if one asks for an explanation of why neural gamma oscillations in the visual cortex in John’s brain occur three minutes after some unknown gardener finishes work on a flower design on Dec. 15th, 1903, the same response can be given. The call for explanation involves a presupposition failure. This time, one could also give further principled reasons for invoking this response. Supporters of anomalous monism such as Davidson are sceptical of the prospect of any law-like intelligible connections between events couched in psychological vocabulary and events couched in physical vocabulary, metaphysical commitment to physicalism notwithstanding. There is no hope for drawing a connection between neural events in John’s brain and the working habits of an unknown gardener from 1903.[There is no hope except perhaps for Leibniz and for those who support something like the Principle of Pre-established Harmony. Only one has to be satisfied with the same explanation each time there is a conjunction of contingent truths to explain: appeal to God’s providence in setting up the complete individual concepts of monads, their harmonious interactions and each monad’s mind-body interaction. The same response can apply to a Spinozist necessitarian explanation if...