Can Non-Causal Explanations Answer the Leibniz Question?

: Leibniz is often cited as an authority when it comes to the formulation and answer strategy of the question “Why is there something rather than nothing?” Yet much current research assumes that Leibniz advocates an unambiguous question and strategy for the answer. In this respect, one repeatedly finds the argument in the literature that alternative explanatory approaches to this question violate Leibniz’s intention, since he derives the question from the principle of sufficient reason and also demands a causal explanation to the question. In particular, the new research on non-causal explanatory strategies to the Leibniz question seems to concern this counter-argument. In this paper, however, I will argue that while Leibniz raises the question by means of the principle of sufficient reason, he even favours a non-causal explanatory strategy to the question. Thus, a more accurate Leibniz interpretation seems not only to legitimise but also to support non-causal explanations to the Leibniz question.


Introduction
The so-called Leibniz Question (=LQ) "Why is there anything rather than nothing" was long considered the ultimate why question or even super-ultimate why question, demanding a causal explanation. In current research, however, several tendencies are emerging that herald a change of direction with regard to the question's answering strategy: (T1) First, it must be noted that current research on LQ is pursuing an increasingly modest goal, as it focuses more and more on answer strategies and is less and less concerned with concrete answers. Thus, the question "What is the concrete answer to LQ?" is discussed less and less, but rather the question "What can an answer to LQ be like at all?" (T2) Moreover, Leibniz is still regarded today as a kind of authority that is often cited to legitimise the question and the answer strategy. The concrete answer Leibniz gave to LQ is still discussed in historically oriented Leibniz research, but rarely, if ever, are these results connected to the current debate on LQ. (T3) Modern research on LQ up to 2013 has often attempted to provide concrete answers or answer strategies to reformulations of LQ, most of which have also demanded a causal explanation. Since 2013, however, a new trend has emerged that dispenses with reformulations and instead discusses non-causal explanations for LQ. (T4) However, a sceptical strategy is known from the debate on reformulations of LQ, which also runs the risk of being applied to the modern non-causal explanatory approaches: Philosophers repeatedly invoke Leibniz and argue against their predecessors that their answers either are not compliant with the question Leibniz posed or with his answer strategy. I call this point, T4, "the sceptical objection" because it invokes T2 to argue against T3's research, even if it only pursues the modest goals of T1.
The sceptical objection has so far been raised mainly against reformulation approaches. In the course of the increase in non-causal explanatory approaches, however, current research on non-causal explanation is in danger of also being affected by the sceptical objection. For this reason, my aim in this paper is to pre-empt the sceptical objection and discuss the question of whether or not noncausal explanations can answer LQ at all. As described under T2, the authority that must be questioned about non-causal explanations in order to pre-empt the sceptical objection is Leibniz himself. Our question can therefore also be described as follows: Do non-causal explanations are compliant at all with Leibniz's answer strategy or does LQ necessarily demand only a causal explanation?
The paper proceeds in four steps and first introduces the classical LQ and the causal interpretation that has dominated until recently (Section 2). I then outline the research on LQ in more detail and explain what relevance the question dealt with here has for the further research programme for non-causal explanations of LQ (Section 3). In the next step, I show what non-causal explanatory approaches to LQ are in current debate, using two relevant approaches from the philosophy of science and metaphysics (Section 4). Finally, I come to the main argument of this paper, which provides an answer to how current research on non-causal explanations can respond to a looming sceptical objection: In doing so, I will argue for the fact that Leibniz explicitly separates the question from the answer strategy, in such a way that he justifies the question by causal explanation, based on the principle of sufficient reason, but demands a non-causal explanation as the only possible answer strategy (Section 5). This will show how especially modern philosophy on LQ benefits from the results of historically oriented Leibniz research (Section 6).

The Classical LQ and its Causal Interpretation
The question of why there is something rather than nothing is considered in today's research to be the question that Leibniz raised and which has not been answered satisfactorily to date. In view of historical research, the phrase "Leibniz question" or LQ is difficult to justify for two reasons: (1) according to current knowledge, the question was not first posed by Leibniz at all, but first by Siger of Brabant in the 13th century (cf. Lemanski (2013)), and (2) at least six relevant text passages are known to Leibniz scholars today, in which Leibniz explicates LQ, sometimes in different wording (cf. (Busche (2013)).
Since Leibniz (1) was not the inventor of this question and (2) provided no exact wording, the notion of the one single LQ is just as problematic and should be treated with caution as the use of textual material from Leibniz's oeuvre to establish a fixed and definite question or answer strategy. Yet this is precisely what often happens in the research of the last 30 years on the so-called LQ. Philosophers and physicists in particular refer almost exclusively to §7 of Principes de la nature et de la grâce fondés en raison written in 1714 when determining the question and the answer strategy. So from this paragraph they often take the interpretation, (3) what the wording of LQ is, what LQ means and (4) according to which principle LQ must be answered.
In concrete terms, LQ is defined by the wording "Why is there something rather than nothing" (3) and LQ demands a causal explanation (4). Indeed, the relevant paragraph of Principes de la nature et de la grâce fondés en raison suggests this suspicion. In this text, Leibniz lists many classical principles of physics up to §6 and then comes to the rational principles of metaphysics from §7 onwards. It is at this transition point from physics to metaphysics that (3) LQ and (4) the relevant principle are named. Leibniz writes: Up to this time we have spoken as simple physicists: now we must advance to metaphysics by making use of the great principle, little employed in general, which teaches that nothing happens without a sufficient reason; that is to say, that nothing happens without its being possible for him who should sufficiently under stand things, to give a reason sufficient to determine why it is so and not otherwise. This principle laid down, the first question which should rightly be asked, would be, Why is there something rather than nothing? [Leibniz 1890a, p. 212f.] The first sentence of the quotation shows the transition from physics to metaphysics concerning the principles of reason. Leibniz emphasises the importance of the principle of sufficient reason (=PSR), namely that nothing happens without there being a reason for this happening. In his subsequent definition of PSR, several text fragments have elements of modern explanatory theory. For example, many modern explanatory theories emphasise that knowing-that (factual knowledge) precedes knowing-why (explanatory knowledge) (cf. Lawler (2019)). Leibniz also emphasises that we must first know things sufficiently before we can give reasons. Moreover, theories of explanatory knowledge, especially in the case of why-questions, traditionally assume that the known causes are a sufficient condition of the explanation. Leibniz also agrees with this here, since he declares that to determine or explain, it is sufficient to give a reason. (As we will see in Section 2, for Leibniz all causes are also reasons). Afterwards, the last sentence presents the classical formulation of LQ. Moreover, a dependency relation between PSR and LQ is implied, which, according to a weak interpretation, could be interpreted as a simple conditional statement: (5) If PSR, then LQ.
However, current philosophers in particular, who only receive this section of the text (and sometimes perhaps take an isolated look at a few subsequent sentences of the paragraph), interpret the last sentence of the quotation much more strongly. They often read a strong relationship of dependence between PSR and LQ, which should be interpreted as a biconditional such as: 1 (6) Iff PSR, then LQ.
This interpretation of Theorem 6 includes, of course, not only Theorem 5, but also the following inversion (Theorem 7), which elucidates the strong interpretation of the sentence in question: (7) If LQ, then PSR.
1 PSR is a sentence, while LQ refers to a question. First of all, I note that I am not setting up a formal system here, but only trying to show the relationships clearly. Now, however, one might ask how a sentence can entail a question (or vice versa). Our answer would refer to everyday language, because we all know examples of a relationship between a question and a sentence. An example would be: If the waiter asks me, "What would you like to drink?", one could answer, "A glass of mineral water". This strong interpretation in the sense of Theorem 6 and 7 is favoured by the fact that Leibniz is regarded as the author for whom PSR applies as a universal law of thought (cf. e.g. [Lin 2014, p. 188]). With this strong interpretation (7) (or 6) at the latest, it is clear why LQ was long regarded as a question demanding a causal explanation (cf. e.g. Oppy (2013), [Meixner 2016, sect. 3]) even if there were always approaches to circumvent or mask them. Whether the last sentence of the above quotation should be interpreted as a conditional at all, as the weak interpretation (5) suggests, can be questioned. However, I do not want to go into this in detail here. For our purposes, it is sufficient to have shown what the classical formulation of LQ is, that it is related to PSR and how causal explanations can tie in with this paragraph.
Let us now turn to the causal interpretation, which is closely connected with the strong interpretation. This causal interpretation of LQ can be seen in the following scheme: Since Sober has used such a scheme to explain causal explanations that are also relevant with regard to LQ, I will call Theorem 8 the Sober scheme [Sober 1991, Chap. 7]. In this Sober scheme, E is the abbreviation of event and the index indicates the order within time. E 1 represents the present, so that all events E n+1 > E 1 are in the past and E n−1 < E 1 are the events in the future. Now, in order to explain an event E n , the conditions (C) mentioned by Leibniz must be fulfilled: (C1) if E n is the explanandum, then E n+1 is the explanans, (C2) which is factually known by the explainer p, so that (C3) p can represent E n+1 as the cause of E n . Let E 2 be the cause of E 1 , and let E 2 and E 1 be known by p, so p can state E 2 as the explanation of E 1 . Let E 3 be also the cause of E 2 and let E 3 , E 2 and E 1 be known by p, then p can state E 3 as a direct explanation of E 2 and as an indirect explanation of E 1 . Causal explanations according to this scheme are thus irreflexive, anti-symmetrical, but transitive.
With reference to the Sober scheme, many prominent explanatory strategies and possible interpretations (P) of LQ can now be described (cf. Weidemann (2013)) especially with reference to an obvious or hidden causality assumption. I highlight only two: (P1) The Sober scheme (Theorem 8) takes advantage of the transitivity property to explain the answer strategy for LQ: If the events E n+1 explains the event E n and transitivity holds, then there must also be an explanation for E n+1 . This pushes the series of explanations further and further into the past, raising the question of whether there is a first explanatory instance, let us call it E x .
If there is an E x that is the cause of all events that follow it in time, then Theorem 8 must be supplemented as follows: Since especially transitivity can also demand an explanation for E x , but according to the limitation given by Theorem 9 a further explanation by using E x+1 cannot be given, LQ results as follows: why is there E x rather than ¬E x ? Thus Theorem 9 can be seen as an interpretation of the PSR, from which LQ follows after Theorem 5. The strategy associated with (P1) is then to explain E x and all the events that depend on it.
(P2) If there is no E x that is the cause of all events that follow it in time, then there is an infinite series of events E indicated by the ellipses in Theorem 8.
Theorem 8 thus becomes the scheme for an infinite sum of events Σ, giving LQ as follows: Why is there Σ rather than ¬Σ? Consequently, the strategy would be to give an explanation for every single event to explain its existence (cf. e.g. [Meixner 2016, sect. 2]).

Modern Research on LQ
Whereas many authors after 1960 initially pursued the causal interpretation of LQ and its answer strategy presented in Section 2, between the mid-1980s and the mid-2010s it was mainly reformulation approaches that prevailed as answer strategies of LQ (cf. Goldschmidt (2013)). Many philosophers have proceeded in such a way that they have reformulated the causally interpreted question, then argued for an answer strategy or a concrete answer to the reformulation question, which should finally answer LQ. The critics' strategy was as follows: Often the solutions to the reformulated questions of the predecessors were accepted, but not the reformulation or the answer strategy. Thus, although argumentative concessions were often made concerning the answer, they either criticised that the answered question was no longer in the sense of LQ or that the answer strategy did not contain a causal explanation, i.e. PSR. (The last point often follows from the above interpretation in terms of Theorem 6). I give here as examples only a few worth reading and recent papers that emphasise such a sceptical objection: [Rodriguez-Pereyra 2018, p. 15], [Schnieder 2019, p. 73]. In the literature before the 2010s, one finds the sceptical objection even more frequently.
Before we take a closer look at this sceptical objection, however, I should make clear what role Leibniz has played in research since the mid-1980s: (1) To our knowledge, there are no analytic philosophers who attempt to represent the Leibnizian answer (in the current discussion on LQ), as Leibniz researchers have worked it out. Some philosophers do claim to argue in Leibniz's sense, but none of these authors meets the Leibnizian answer spectrum as found in historical research on Leibniz (cf. e.g. Busche 2013; Liske 2019). Thus, Leibniz's own answer to LQ remains limited to Leibnizian research, and Leibniz is no longer considered an authority regarding the concrete answer to LQ.
(2) Many current philosophers, however, make particular use of the quotation from Leibniz presented in Section 2 to instrumentalise either the question or the answer strategy in Leibniz: As also mentioned in Section 2, the last sentence of the cited quotation from Principes de la nature et de la grâce fondés en raison is especially emphasised as the authoritative LQ (cf. e.g. Schnieder (2019)). PSR, especially in the sense of Theorems 6-9, is often used for an answer strategy.
In modern research, the authority of Leibniz in the sense of the question and the answer strategy is then often used as a corrective to check to what extent the questions posed and the answers considered conform to Leibniz at all. One can refer to this requirement as L-compliance as follows: (10) Author X, if she wants to give an answer A to LQ, must indicate to what extent her reformulated question Q is compliant with LQ or to what extent A is compliant with Leibniz's explanation strategy.
From the requirement of L-compliance (Theorem 10), a clearer idea of the sceptical objection can now be gained. In particular, reformulation approaches are quickly criticised in the sense of the following counter-argument: (11) Author X argues convincingly for an answer A to the reformulated question Q, but Q does not correspond to Leibniz's question (LQ) or does not agree with Leibniz's causal explanation strategy (PSR). For this reason, A is not L-compliant and thus not a valid answer to LQ.
Since 2013, however, a new answering strategy has emerged in research that strongly argues for the original LQ in terms of Leibniz's wording, on the one hand, but deliberately seeks non-causal answering strategies, on the other hand (e.g. Brenner 2022; Lange 2013; Lange 2019; Pearce 2017; Schnieder 2019). As a result, this new answer strategy obviously runs the risk of being invalidated by the sceptical objection given in Theorem 11, as opponents of this answer strategy could easily dismis non-causal approaches as not L-compliant. If it could be established that Theorem 6 or 7 are L-compliant, the entire answer strategy of non-causal explanations for LQ would be invalid. One can imagine the criticism to non-causal answer strategies as follows: (12) Author X argues for a non-causal explanation strategy NCA to answer LQ. But since Leibniz demands a causal explanation (PSR) for LQ, NCA is not L-compliant and thus not a valid answer to LQ.
Before we come to the question of whether non-causal explanations are Lcompliant or not, and thus discuss whether non-causal explanations can respond to LQ at all (Section 5), I would like to introduce what non-causal explanations are to LQ by means of two examples (Section 4).

Non-causal Answer Strategies to LQ
Explanatory approaches are divided into two types in current research: causal and non-causal explanatory approaches. Whereas causal explanations have already been presented in Section 2 based on LQ, non-causal explanations will be presented here. For in order to understand what the alternative answer strategy to LQ is in contrast to causal explanations (be they a direct answer to LQ or a reformulation of LQ), two approaches can be presented in this section. The first approach is a nomological one and comes from the field of philosophy of science, the second approach favours grounding explanations and comes from the field of metaphysics. Non-causal explanations are not usually presented as opposing causal explanations. According to the prevailing opinion, they complement causal explanations. Representatives of explanatory pluralism or monism not only distinguish between causal and non-causal explanations, but also differentiate between various types of non-causal explanations, e.g. grounding explanations, identity explanations, statistical explanations, etc. (cf. Reutlinger, Colyvan, and Krzyżanowska (2022)). Only proponents of causal reductionism try to invalidate non-causal explanations and thus reduce them to causal explanations (cf. Skow (2013)). Inherent in all non-causal explanations as an answer strategy to LQ is that they must reject Theorem 7 (and thus also Theorem 6): LQ, according to them, thus does not require a causal explanation.
The nomological approach, advocated above all by Lange (Lange 2013;Lange 2019), assumes that causal explanations are problematic precisely when (1) they only explain contingent events from other contingent events and (2) the events in the Sober scheme are too similar to offer a satisfactory explanation. Let us imagine the problem using the following scenario: I call the sentence you are yet reading E 2 . And the sentence you are now reading we call E 1 . Let us assume that you have not skimmed the text and have therefore read sentence E 2 first and sentence E 1 afterwards. Both sentences can be understood as an event, namely that you have read the respective sentence. If someone asks you why you read sentence E 1 and you answer with, for example, "I read the entire text word for word and sentence E 1 came after E 2 ", then this explanation is probably rather unsatisfactory. Because (1) you could have simply stopped reading after E 2 (e.g. because this paper was too boring or because you were interrupted and could not or did not want to continue reading afterwards) and (2) E 2 and E 1 are so similar that there was no good reason for distinguishing between E 2 and E 1 (both sentences had almost the same syntax).
For Lange, however, this problem already results in a solution by contradiction: explanations should (1) not explain contingent events from other contingent events, but look for necessities, and (2) the events in the Sober scheme should (to a certain degree) be dissimilar. Both points can be further specified: (1) Since LQ asks for events or objects in nature, it is natural to look for necessities of nature.
(2) Since only contingent events occur in the Sober scheme and it is obvious that every contingent cause is similar to the following contingent effect, it is also obvious to look outside the Sober scheme for an instance that explains E x or Σ (see Section 2).
Lange's overall aim is very modest: He only searches for an answer strategy on how to respond to LQ. For this reason, he is looking for an explanatory instance that circumvents the two problems mentioned above and satisfies the two possible solutions: This instance, in his opinion, is the laws of nature. Natural laws are (1) natural necessities, and (2) they are distinct from contingent events or objects per se. Lange summarises the role of natural laws in the following quotation: I understand laws as standing outside of space and time (as God is supposed to do) and as able to supply noncausal explanations, not merely explanations that describe causal processes; laws can noncausally account for the existence of the things that form the framework (whether space and time or something else) in which all natural processes must operate. [Lange 2013, p. 247] It can be said that the aim, namely to show how a non-causal answer strategy to LQ might be constituted, has been achieved. Nevertheless, several questions and criticisms remain open: For example, physicists describe that the fundamental forces of nature only differentiate after the crucial GUT era, i.e. shortly after the Big Bang. This makes a physical recourse to nomological necessities including the laws of nature or proto-laws physically problematic. Although Hempel and Oppenheim had not ruled out inferences with pure laws for their model; and today there are representatives of causal reductionism who argue against substituting natural laws for contingent events, e.g. Skow (2013). Since Lange's approach ultimately demands a concrete naming of natural laws and a physical verification that cannot be fulfilled under the conditions of current physics, this explanation will remain a pure answer strategy for the foreseeable future.
The metaphysical approach presented by Brenner (2022) is different. Brenner follows Lange in criticising causal explanations of LQ and in favouring noncausal answer strategies. Nevertheless, this approach takes a different route, invoking non-causal grounding strategies. This approach is also accompanied by the modest aim of showing that non-causal grounding explanations do not conceptually disqualify themselves as answers to LQ. Grounding explanations, especially in the field of metaphysics, have a habit of breaking with some of the characteristics for causal explanations explicated in the Sober scheme. For example, causal explanations always have a temporal component that is not relevant for grounding explanations.
Let me explain this with the following example: Imagine an author sitting in front of a wooden Brenner goes on to give two grounding explanations in order to show how such an explanation could be conceptualised as an answer to LQ. The first grounding explanation is axiological in nature, while the second is phenomenalistic. In the axiological grounding explanation, the good is invoked as the grounding of the something or being in LQ: There is something rather than nothing because it is good that there is something rather than nothing. In the phenomenalistic grounding explanation, sense data are given as the foundation of something or being in LQ: There is something rather than nothing because we have sense data that prove something rather than nothing.
Here, too, it can be said that the modest goal, namely to show that noncausal grounding explanations conceptually fit LQ, has been achieved. However, numerous problems arise, which Brenner himself sees, so that he allows the phenomenalist approach to stand as evidence for the answer strategy, but not as a concrete answer. The axiological approach also has its difficulties, since we are again forced to ask of why there is something good in the first place or why there is the one who finds something to be good. If we transfer this explanatory strategy for LQ back to the table example given above, the problems might become clearer: We admit that the table is grounded by the wood, but without the carpenter who shaped the wood in various temporal steps, there would also be no table for which we ask for a reason.
However, despite all the criticism, both approaches show that the non-causal answer strategy can be a useful alternative to the previously prevailing reformulation approaches to LQ or to causal explanations. Moreover, unlike reformulation approaches, both non-causal answer strategies have the advantage that they can concretely respond to LQ without transferring the question to another field of research. In order to circumvent the sceptical objection (Theorem 11), however, it must finally be clarified whether the answer strategy corresponds to Leibniz's intention or whether Leibniz (as shown by the strict interpretation through Theorem 6 and 7) demanded a causal explanation. If the latter were the case, non-causal answer strategies and at some point also concrete non-causal explanations on LQ run the risk of being invalidated by the sceptical objection due to Theorem 12.

Leibniz's Answer Strategy
The intergenerational project of the Leibniz Edition is far from complete. In this respect, a definitive statement on the number and formulations of LQ variants is far from possible. According to Theorem 2, however, six relevant formulations of LQ are known to current Leibniz research. These six texts show that Leibniz wrote down the question at the age of 25 at the latest and dealt with it until shortly before his death. The six relevant formulations have been intensively quoted, analysed and discussed in detail in Busche (2013), insofar I only give excerpts and translations of these six formulations here: LQ1 "it is not possible to have a cause (since nothing is without a cause) why things, which could not be, are something" (Errichtung einer Societät in Deutschland, 1669). LQ2 "A reason must be given why contingent things exist rather than do not exist" (Specimen inventorum, 1688). LQ3 "That reason which causes these things to exist rather than others also causes something to exist rather than nothing." (De Ratione cur haec existant potius quam alia, 1689) LQ4 "so we must first acknowledge how by that something exists rather than does not exist" (De Rerum Originatione Radicali, 1697). LQ5 "There is a reason in nature for something to exist rather than nothing to exist" (Ratio est in Natura, 1698).
LQ6 "This principle laid down, the first question which should rightly be asked, would be, why is there something rather than nothing?" (Principes de la nature et de la grâce fondés en raison, 1714) In Section 2, we have already dealt with LQ6. As can be seen, this is the last formulation of LQ found so far in Leibniz's work. LQ1-6 show that Leibniz did not always pose the formulation of LQ as a question. Sometimes the formulation simply appears as a relative clause in the text without being announced as a question. Moreover, the language in which Leibniz formulates the question also changes. The first version was written in German, most of the text in Latin and finally one in French.
In any case, what is crucial here is not the precise examination of the variants of LQ, but the fact that the identification of variants brings us to the text passages in which we can find explicit answer strategies of Leibniz to LQ. This gives us a way to test the L-compliance (Theorem 10) of the texts discussed in Section 4. Indeed, answer strategies can be found in the context of LQ2-5. Since current research on LQ is particularly oriented towards Principes de la nature et de la grâce fondés en raison, let us mainly look at the later writings. In doing so, it can be seen that Leibniz pursues a single answer strategy to the question in these late texts. Since the last two texts cited (LQ5, LQ6) were written 15 years apart and also contain similar formulations to LQ and PSR, we can assume that Leibniz reconsidered his answer strategy several times, but did not really revise it, but rather consolidated it. The answer strategies in Leibniz's late work are thus very similar overall.
The first text of the late Leibniz on the answer strategy of LQ, i.e. Ratio est in Natura, begins right at the beginning with the formulation of PSR and LQ: §1 There is a reason in nature why something exists rather than nothing is. This is a consequence of the great principle that nothing happens without a cause, just as there must be a cause for this to exist rather than that. §2 This reason must exist in a real being, that is, in a cause. For a cause is nothing other than a real reason [...]. §3 But this being must be a necessary one; otherwise a cause would again have to be sought from within it, why it exists rather than does not exist, which would be contrary to the presupposition. ( [Leibniz 1890b, p. 289], our transl.) The text is relevant insofar as it begins directly with a variant of LQ in the first sentence. LQ is not formulated as a question here, but as a relative clause, which however clearly close to the famous LQ6 wording. One could say that the first sentence could directly answer a possible question, which could be something like: Is there a reason why there is something rather than nothing? Moreover, it can also be seen from §1 how similar this text is to §7 of Principes de la nature et de la grâce fondés en raison. Leibniz also speaks here of a "great principle" and this principle is -as in §7 -PSR. The second paragraph then presents the connection between PSR and today's causal explanatory strategies. For Leibniz, "reason" is the broader term, "cause" the narrower. After all, the sentence suggests that while all causes are reasons, only some reasons are also causes. In the case that reasons are also causes, we must speak of a real reason, which also requires a real being.
The third paragraph takes up the notion of a real being again and also clarifies Leibniz's answer strategy. The cause or the real reason, which was announced in §1 as an answer to LQ, must be necessary. How Leibniz arrives at this thesis and why this thesis can be understood as an answer strategy to LQ only becomes clear from the last sentence. One could say -somewhat exaggeratedly -that Leibniz here provides a kind of apagogic proof for his assertion in order to set the cause in something necessary: If this cause were not necessary, we would be dealing with an infinite regress of causes due to PSR. That is, we would go on and on demanding reasons for previously stated reasons and would never come to an end of asking. Question, question context and answer strategy can be clearly differentiated in Leibniz's Ratio est in Natura: PSR is responsible for LQ, but PSR cannot answer LQ. The question is thus raised by a principle, but cannot be answered by the same principle. On the contrary, Leibniz argues, the question can only be answered by avoiding PSR, otherwise we end up in an infinite regress of questioning and explaining. The only explanatory strategy Leibniz sees as an alternative to using PSR is to look for something necessary in nature. The explanation for LQ can therefore only be non-causal and Theorems 6 and 7 do not hold.
Let us see if Leibniz sticks to this explanatory strategy for LQ. As described above, many researchers instrumentalise §7 of Principes de la nature et de la grâce fondés en raison to argue against predecessors. If many researchers had read a little more of the text, however, they would have realised that the sceptical objection does not hold here either. For already in §8 of Principes de la nature et de la grâce fondés en raison, Leibniz comes up with the same answer strategy as in Ratio est in Natura. And this answer strategy is also non-causal: §8 And although the present motion which is in matter, comes from the preceding motion, and that from still another preceding, yet in this way we should never make any progress, go as far as we might; for the same question would always remain. Therefore it must be that the sufficient reason which has no need of another reason, be outside this series of contingent things and be found in a substance which is its cause, or which is a necessary being, carrying the reason of its existence within itself; otherwise we should still not have a sufficient reason in which we could rest. [Leibniz 1890a, p. 213] These sentences of paragraph 8 confirm the answer strategy we elaborated in Ratio est in Natura. The first sentence illustrates that Leibniz again sees the problem of an infinite regress when PSR is chosen as the explanatory strategy for LQ. Leibniz seems to have something similar to a Sober scheme in mind: If E 2 serves as a causal explanation for E 1 , then E 3 must also be sought to explain E 2 . Since one can now make the same claim for every E n+1 > E 3 (thanks to the transitivity of PSR), one never arrives at E x . In this respect, a non-causal strategy must be pursued in order to explain the series of E's. Thus §8 confirms that Theorems 6 and 7 cannot hold. The second sentence reveals that Leibniz is pursuing a strategy that is outside the Sober scheme. There must be a reason that is non-contingent. In doing so, Leibniz even specifies his non-causal explanatory strategy given in Ratio est in Natura: The answer strategy seeks (1) a necessary being and (2) a being that grounds itself. Point 1 must be understood as a demand for an ens necessarium. However, one must be careful not to overinterpret this demand as necessitarianism. Often such a position is attributed to Spinoza and understood as meaning that all events or things (in the Sober scheme) are necessary (cf. Huenemann (2018)). But that is not the case here. Leibniz is only concerned with a single necessary being that grounds all contingent things or events. (2) Can be understood as a variant of classical aseity, perhaps in modern terminology one can also speak of self-grounding (cf. Kovacs (2018)). No matter how this demand can be located by name, it remains decisive that the ens necessarium grounds its being from itself and does not receive it from another. In this way, (2) can be understood as an extension of (1), since it explains how something can be necessary at all and why the series of contingent causal explanations is broken with this ens necessarium.
If one asks what the reason of the ens necessarium is, one can ultimately point to self-grounding. Thus Leibniz is very close to Siger (Theorem 1), as analysed in Lemanski (2013), not only in terms of LQ, but also in terms of response strategy. But this is a topic that needs to be discussed somewhere else.

Conclusion
In this paper, I have shown that LQ has traditionally been understood as the question of ultimate causal explanation. For several decades, however, one has encountered reformulation approaches in research that attempt to transfer LQ to another question. These reformulation approaches, however, are often subject to a sceptical objection that the reformulated questions are not compliant with LQ or to Leibniz's demand for PSR. Many authors therefore argue that certain explanations cannot answer LQ because they are not L-compliant.
In recent years, non-causal explanations for LQ have increasingly emerged in research: As an example, a nomological explanatory approach was presented here. This approach looks for something necessary that explains the series of contingent things and events. It was argued that only laws of nature come into question for this, since on the one hand they are supposed to be a natural necessity, but on the other hand they can also be distinguished from contingent things or events and therefore represent a good explanatory strategy. Another answer attempt, on the other hand, had chosen a non-causal grounding explanation as a strategy. This strategy was illustrated by two examples, each of which asks what grounds the something or the events that are implicitly confirmed in LQ. On the one hand, 'the good' can serve as a grounding element (axiological approach), on the other hand, sense data can also ground 'the something' as mentioned in LQ (phenomenalist approach).
In order to immunise these new explanatory strategies in relation to LQ against expected sceptical objection, we have investigated whether these approaches are L-compliant. The interpretation of Leibniz's historical texts is an important epistemological step in that Leibniz is often invoked as an authority on the question and answer strategy by those philosophers who wish to formulate a sceptical objection to predecessors. However, when interrogating Leibnizian texts, it has become apparent that many sceptical objections invoke Leibniz for no reason, since Leibniz explicitly favours non-causal or alternative explanatory approaches to solving LQ. Leibniz raises LQ through PSR, but does not believe that PSR can provide an answer to LQ. On the contrary, he even argues that we get into an infinite regress if we favour PSR as an answer strategy for LQ. We would then be forced by PSR to keep asking for reasons and would never arrive at an instance that can function as the ultimate justification. Leibniz therefore separates PSR from LQ in the explanatory strategy and instead calls for a non-causal solution: the ultimate reason of things must (1) be necessary and (2) justify itself. In this way, Leibniz not only legitimises current research on LQ, but seems to virtually promote it with his explanatory approaches.
The question, which I wanted to answer in this paper, was therefore: Can non-causal explanations answer LQ? And we can state that this is the case in the sense of Leibniz. The non-causal explanations we find in current research are fully L-compliant in terms of question and answer strategy. It should be clear, however, that today's concrete answers are likely to be different from Leibniz's more theological answer. Nevertheless, today's research agrees with Leibniz in its answer strategy. It remains questionable, however, whether this also makes them more convincing with regard to a concrete non-causal explanation on LQ that can be expected in the future.