THE NORMATIVE POWER OF NECESSITY. MAKING SENSE OF POLITICAL REALISM

Abstract In this thesis I tackle the question of what the normative logic of political realism is. Thus, I have two goals to accomplish. First, and foremost, I want to offer an account of what it means to be a political realist. Secondly, I want to inquire why one should be a political realist. As, for the first question, what are the defining features of a realistic political philosopher? Given that realists tend to defend a variety of positions and that they are not often systematic in their arguments, this question is not as simple as it might seem. Thus, in the first three methodological chapters I develop a possible systematic account for political realism. While I am evidently sympathetic with the tradition of political realism, my aim here is merely reconstructive. However, such rational reconstruction aims to fix a significant flaw in this tradition: a lack of clarity and structure. In the first chapter, I argue that realists rely on a specific account of reality, in the second that from this account they derive a particular view of possibility and necessity and in the third one that the most important necessities in politics are the recurrence of conflicts and the need for order. My aim here is to provide a rational reconstruction of political realism by outlining a possible consistent interpretation of its basic commitments. More specifically, Chapter 1 focuses on the notion of reality adopted by political realists. I open the chapter by introducing a preliminary discussion of the commitments a realistic political philosophy seems bound to subscribe. I then argue that a metaphysical view matching these commitments is one that links reality with causality. This view, which I call \u2018effectual realism\u2019, is partially drawn from Alexander\u2019s dictum and the \u2018ad lapidem\u2019 argument in metaphysics, and claims that something is real if and only if it causally interacts with the world in some way. I close this chapter by observing that this view of reality is a form of metaphysical realism, because it satisfies three conditions: reality is knowable, independent from desires and independent from beliefs. These conditions, I conclude, fit very well with the idea common throughout the literature of political realism, that reality is something that resists our actions. From this causal account of reality, Chapter 2 draws a causal account of possibility and necessity. While political idealists focus on conceivability or compatibility with the world as criteria for possibility, a more realistic criterion would be one that links possibility and causality. I call this relation of realistic possibility \u2018trackability\u2019: a state of affairs is trackable if and only if there is some causal chain to move there from the actual world. I debate the implications of this view, and conclude that it allows to account for the contextual importance of the starting point, the inclination to prudence, and the focus on action. From this conception, I can derive a symmetric notion of necessity, whereby something is necessary, if there is no causal chain to avoid it. By the same argument, something is impossible, if no causal chain allows us to realize it. These two arguments can be neatly derived from effectual realism and the additional assumption that we are not omnipotent. Given that reality is independent from our beliefs and desires, and assuming that our power is limited, some states of affairs will lay beyond our ability to change. Among these necessary states of affairs, I argue in Chapter 3 that there are two, which are particularly relevant in the political sphere: the inevitability of conflict and the need for order. Conflicts, in my definition, emerge among actors with different views when one wants to impose his will against the resistance of others. Given that there is no causal chain to consistently avoid neither the different views nor the will to prevail, conflict appears a necessary feature in the sense specified in the previous chapter. The second necessary element is the need for order. As men need to feed, whether or not they want to, so they need a cooperative order, whether or not they want to. This is a weaker necessity compared to that of conflict, because it holds only conditionally. While conflicts are always inevitable and therefore necessary, order is necessary only provided that we want to survive. I conclude the chapter by suggesting that these two necessities of politics can be used as a criterion to determine whether a political theory is realistic or not. Clearly not every political realist would recognize himself in this reconstruction. \u2018Isms\u2019 are always more discordant than their adversaries believe them to be, and political realists are particularly diverse in their reflections. Thus, any unified account is likely to leave some disagreeing. This is inevitable, and thus one cannot realistically be blamed for it. Nevertheless, I think it is important to try to develop a consistent positive view of political realism. To summarize, in the first three chapters I defended the following conception of political realism: 1. Realism \uf0e0 Reality 2. Reality \uf0e0 Possibility and Necessity 3. Political Necessity \uf0e0 Conflict and Order Being realist means, in this view, paying attention to reality. Paying attention to reality means identifying accurately what is possible and what is necessary. Thus, being realist means that we should acknowledge that conflict and order are the two cardinal necessities of politics. The fourth and last chapter is intended to tackle the question of why one ought to be a realist and, thus, to turn the results of the first three chapters from reconstructive into normative claims. Political realism, I argue here, offers a set of hypothetical imperatives based on the conditional assumption that one wants to realize one's own preferences. This, I maintain, provides the driving force behind normative political realism. In fact, if it is true that one wants to realize one's own preferences, then, contrary to idealism, one ought not to choose between end-states, but among courses of action. I suggest that a more realistic account of rationality is one that tempers the value of a desired state of affairs with the costs or benefits of the best available means to reach it, their likelihood of success, and the unintended consequences of one\u2019s action. If this is how a realistically rational deliberation works, than the distinctive features of political realism I reconstructed in the first three chapters are shown to have an important normative force, as they are revealed to be the path realists point at in order for political actors to realize their preferences. In short, if you want to realize your preferences, you ought to be a realist. Differently from what I do in the previous chapters, here I try to put forward a justificatory argument for political realism. Notwithstanding this difference between the first three chapters and the last one, they all combine to provide a possible answer to my research question. If we put together the first three chapters with the conditional assumption that you want to realize your preferences, we get the following hypothetical imperatives: 1) You ought to be rational, and for realists this means that when you deliberate what is best you should not limit yourself to consider the value or disvalue of the ideal that you want to realize. Along with this, you ought to ponder the costs of the best means available to you, their likelihood of success, and the cost of their consequences. 2) You ought to acknowledge reality. This means that any descriptive theory of the world is normative for the agent, insofar as it sets the background conditions of his action. Reality determines the means he has at his disposal, his likelihood of success in reaching what he desires, and the consequences of his action. It thus gives him reasons to do something instead of something else. 3) You ought to pinpoint possibilities and necessities accurately. Reality sets the conditions of what is possible and what is necessary. Necessary states of affairs are of paramount importance for action, and political realism rightly emphasizes them. A necessary state of affairs is a state of affairs whose avoidance is impossible and thus any desire that requires that this be abandoned is unrealistic. This does not mean that there is nothing we can do in such cases. Rather, realists claim that necessities give us reasons to contain their negative consequences instead than eliminate them at their root, and to reallocate our efforts in alternative goals which can actually be reached. 4) You ought to acknowledge that the recurrence of conflicts and the need for order are necessary features of the political sphere. This is the substantive and defining claim of political realism. Any desire that requires one to be done with conflict or the need for order is unrealistic, whatever one wants. Moreover, any political theory that pays insufficient attention to this fact is bound to be of inadequate guidance in political matters. Any actor who does not satisfy these requirements risks being irrational insofar as he would be self-undermines his own preferences, whatever they are. Thus, we end up with the following claims: 0. If you want to realize your preferences, then you ought to: 1. Evaluate courses of action instead of states of affairs 2. Pay attention to reality 3. Individuate its possibilities and necessities 4. In politics, consider specifically the inevitability of conflict and the need for order In synthesis, political realism as an affirmative, analytical, normative theory would be, in my opinion, committed to these claims

Fast Evolutionary Adaptation for Monte Carlo Tree Search

This paper describes a new adaptive Monte Carlo Tree Search (MCTS) algorithm that uses evolution to rapidly optimise its performance. An evolutionary algorithm is used as a source of control parameters to modify the behaviour of each iteration (i.e. each simulation or roll-out) of the MCTS algorithm; in this paper we largely restrict this to modifying the behaviour of the random default policy, though it can also be applied to modify the tree policy

Long-term multi-wavelength study of 1ES 0647+250

The BL Lac object 1ES 0647+250 is one of the few distant $\gamma$-ray emitting blazars detected at very high energies (VHE, $\gtrsim$100 GeV) during a non-flaring state. It was detected with the MAGIC telescopes during its low activity in the years 2009-2011, as well as during three flaring activities in the years 2014, 2019 and 2020, with the highest VHE flux in the latter epoch. An extensive multi-instrument data set was collected within several coordinated observing campaigns throughout these years. We aim to characterise the long-term multi-band flux variability of 1ES 0647+250, as well as its broadband spectral energy distribution (SED) during four distinct activity states selected in four different epochs, in order to constrain the physical parameters of the blazar emission region under certain assumptions. We evaluate the variability and correlation of the emission in the different energy bands with the fractional variability and the Z-transformed Discrete Correlation Function, as well as its spectral evolution in X-rays and $\gamma$ rays. Owing to the controversy in the redshift measurements of 1ES 0647+250 reported in the literature, we also estimate its distance in an indirect manner through the comparison of the GeV and TeV spectra from simultaneous observations with Fermi-LAT and MAGIC during the strongest flaring activity detected to date. Moreover, we interpret the SEDs from the four distinct activity states within the framework of one-component and two-component leptonic models, proposing specific scenarios that are able to reproduce the available multi-instrument data.Comment: 20 pages, 7 figures. Accepted in A&A. Corresponding authors: Jorge Otero-Santos; Daniel Morcuende; Vandad Fallah Ramazani; Daniela Dorner; David Paneque (mailto: [email protected]

A lower bound on intergalactic magnetic fields from time variability of 1ES 0229+200 from MAGIC and Fermi/LAT observations

Extended and delayed emission around distant TeV sources induced by the effects of propagation of gamma rays through the intergalactic medium can be used for the measurement of the intergalactic magnetic field (IGMF). We search for delayed GeV emission from the hard-spectrum TeV blazar 1ES 0229+200 with the goal to detect or constrain the IGMF-dependent secondary flux generated during the propagation of TeV gamma rays through the intergalactic medium. We analyze the most recent MAGIC observations over a 5 year time span and complement them with historic data of the H.E.S.S. and VERITAS telescopes along with a 12-year long exposure of the Fermi/LAT telescope. We use them to trace source evolution in the GeV-TeV band over one-and-a-half decade in time. We use Monte Carlo simulations to predict the delayed secondary gamma-ray flux, modulated by the source variability, as revealed by TeV-band observations. We then compare these predictions for various assumed IGMF strengths to all available measurements of the gamma-ray flux evolution. We find that the source flux in the energy range above 200 GeV experiences variations around its average on the 14 years time span of observations. No evidence for the flux variability is found in 1-100 GeV energy range accessible to Fermi/LAT. Non-detection of variability due to delayed emission from electromagnetic cascade developing in the intergalactic medium imposes a lower bound of B>1.8e-17 G for long correlation length IGMF and B>1e-14 G for an IGMF of the cosmological origin. Though weaker than the one previously derived from the analysis of Fermi/LAT data, this bound is more robust, being based on a conservative intrinsic source spectrum estimate and accounting for the details of source variability in the TeV energy band. We discuss implications of this bound for cosmological magnetic fields which might explain the baryon asymmetry of the Universe.Comment: 10 pages, 5 figures, accepted to A&A. Corresponding authors: Ievgen Vovk, Paolo Da Vela (mailto:[email protected]) and Andrii Neronov (mailto:[email protected]

Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) 3-rays. A significant correlation (>3σ) between X-rays and VHE 3-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy 3-rays and radio, with the radio lagging by more than 100 days, placing the 3-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE 3-rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock. © 2023. The Author(s). Published by the American Astronomical Society

Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514

The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy $\nu_{synch,p}$ above 1keV). While those extreme states were so far observed only during high flux levels, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to VHE performed so far, focusing on a systematic characterisation of the intermittent extreme states. While our results confirm that 1ES 2344+514 typically exhibits $\nu_{synch,p}>$1keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase of the electron acceleration efficiency without a change in the electron injection luminosity. We also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of $\nu_{synch,p}$. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. During a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions contribute significantly to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3-2keV band. Using a time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model.Comment: Accepted for publication in Astronomy & Astrophysic

MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7

Context. Certain types of supernova remnants (SNRs) in our Galaxy are assumed to be PeVatrons, capable of accelerating cosmic rays (CRs) to ∼ PeV energies. However, conclusive observational evidence for this has not yet been found. The SNR G106.3+2.7, detected at 1- 100 TeV energies by different γ-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape, which can be divided into a head and a tail region with different physical conditions. However, in which region the 100 TeV emission is produced has not yet been identified because of the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear as to whether the origin of the γ-ray emission is leptonic or hadronic. Aims. With the better angular resolution provided by new MAGIC data compared to earlier γ-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1 resolution at TeV energies. Methods. We observed the SNR G106.3+2.7 using the MAGIC telescopes for 121.7 h in total - after quality cuts - between May 2017 and August 2019. The analysis energy threshold is ∼0.2 TeV, and the angular resolution is 0.07-0.1. We examined the γ-ray spectra of different parts of the emission, whilst benefitting from the unprecedented statistics and angular resolution at these energies provided by our new data. We also used measurements at other wavelengths such as radio, X-rays, GeV γ-rays, and 10 TeV γ-rays to model the emission mechanism precisely. Results. We detect extended γ-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detect a significant γ-ray emission with energies above 6.0 TeV from only the tail region suggests that the emissions above 10 TeV detected with air shower experiments (Milagro, HAWC, Tibet ASγ and LHAASO) are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of ∼1 PeV for that region. Such high-energy emission in this middle-aged SNR (4-10 kyr) can be explained by considering a scenario where protons escaping from the SNR in the past interact with surrounding dense gases at present. Conclusions. The γ-ray emission region detected with the MAGIC telescopes in the SNR G106.3+2.7 is extended and spatially coincident with the radio continuum morphology. The multi-wavelength spectrum of the emission from the tail region suggests proton acceleration up to ∼PeV, while the emission mechanism of the head region could either be hadronic or leptonic