Does the presumption of liberty withstand scrutiny?
Perhaps, but it's probably more complicated than your average trolley problem
The presumption of liberty stands as a cornerstone of the liberal tradition, positing that liberty itself does not require defense; instead, it is the imposition of limits that necessitates justification. Essentially all credible interpretations of liberalism prioritize liberty, albeit to varying degrees. Some views regard liberty as paramount, often superseding other concerns, aligning with John Stuart Mill's harm principle, which contends that societal authority should only restrict liberty to prevent tangible harm to others. In contrast, more moderate perspectives advocate for a balance between liberty and values such as equality and beneficence.
Viewing liberty as a natural moral default is a fundamental tenet for liberal intellectuals, public liberals, and liberal-leaning politicians, significantly shaping their theoretical frameworks and ultimately guiding them toward liberty-centric positions. With this presumption in place, the challenge of establishing coercive collective rules becomes arguably more complex than it would be under alternative foundational premises. If values such as equality, beneficence, or desert were to take precedence, the theoretical considerations and resulting political demands would likely differ substantially, necessitating, at the very least, more robust justifications for individual freedoms and civil liberties.
Given that intellectual and political liberalism is grounded in a strong a priori presumption in favor of freedom, one might expect a robust justification for this stance. However, as Jason Brennan and Christopher Freiman argue in a recent paper, a common strategy to defend the presumption of liberty—specifically, an appeal to commonsense moral intuitions about the presumptive wrongness of interference—fails to substantiate this principle in any meaningful way that truly advances liberalism. This reliance on commonsense and moral intuitions, often illustrated through apparently trivial thought experiments, seems to be a natural move for many proponents of liberal political philosophy. In A Theory of Freedom, Stanley Benn offers a thought experiment that elicits a widely shared and deeply held intuition: that it is fundamentally wrong to interfere with an individual's actions unless one has a valid reason to do so.
"[I]magine Alan sitting on a public beach, a pebble in each hand, splitting one pebble by striking it with another. Betty, a casual observer, asks him what he is doing. She can see, of course, that he is splitting pebbles; what she is asking him to do is to explain it, to redescribe it as an activity with an intelligible point, something he could have a reason for doing. There is nothing untoward about her question, but Alan is not bound to answer it unless he likes. Suppose, however, that Betty had asked Alan to justify what he was doing or to give an excuse for doing it. Unlike explanations, justifications and excuses presume at least prima facie fault, a charge to be rebutted, and what can be wrong with splitting pebbles on a public beach? Besides, so far as we can tell, Alan is not obliged to account to Betty for his actions.
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Suppose Betty were to prevent Alan from splitting pebbles by handcuffing him or removing all the pebbles within reach. Alan could now quite properly demand a justification from Betty, and a tu quoque reply from her that he, on his side, had not offered her a justification for splitting pebbles, would not meet the case, for Alan's pebble splitting had done nothing to interfere with Betty's actions. The burden of justification falls on the interferer, not on the person interfered with. So while Alan might properly resent Betty's interference, Betty has no ground for complaint against Alan."
This text might prompt readers to instinctively align with the liberal notion that individuals should have the freedom to act as they wish. But does it truly do so? Enter Brennan and Freiman, who introduce a series of modified 'pebble' examples that, while highly entertaining and worth reading for that alone, also challenge one's initial intuitive response to the pebble case, prompting reconsideration. Here is a glimpse of their curious-to-absurd variations:
1. Alf is smashing pebbles on Betty's beach. She doesn't know who he is or why he's on her beach.
4. Alf is smashing pebbles, but making lots of loud noises doing so, which bothers others.
8. Alf is smashing a baby instead of pebbles.
9. Alf is smashing pebbles. He pays no attention to the toddler drowning nearby.
26. Alf is smashing the pebbles with what he thinks is a toy hand grenade, but which Betty knows is a live grenade.
34. Betty is Alf's guru, helping him to achieve eudaimonia. She tells him the phronimos would find something more virtuous to do.
These examples may indeed challenge the initial approval stemming from the implicit parameters of the original thought experiment, or even question whether the presumption of natural liberty is the most plausible explanation for our intuitions in the original example. However, Brennan and Freiman argue that these amendments can 'easily defeat' the presumption of liberty, bordering on tautology à la "people must treat known-to-be-permissible actions as permissible." This conclusion may be somewhat overstated; while the pebble cases demonstrate that additional information can override a liberty-by-default stance, all the presented examples align with even staunch liberals' concession that freedom has contextual limitations. Ultimately, the justification for interfering with liberties appears self-evident only in rare pebble cases, such as baby-smashing.
Brennan and Freiman present a more compelling argument against inferring natural liberty from pebble-case-driven intuitions. Specifically, they challenge the presumption of any moral duty derived in this manner—freedom included—by highlighting how easy it is to construct thought experiments where a particular moral reason is made salient, with no competing considerations. This approach renders the presumption of any moral duty trivial; if a specific moral concern is designated as the only relevant factor, then naturally, that concern prevails. In other words, it "turns out, trivially, that when some moral consideration C is specified to be the only relevant consideration, then C 'wins'." Consider the following examples:
Betty is very sick, but touching the intact magic pebble on the public beach will heal her. Alf knows this, but smashes the pebble anyway.
Alf and Betty come across an apple tree in the unowned, uninhabited forest. They are both equally hungry, equally needy, and so on. The tree has two apples.
These new thought experiments now seem to suggest a presumption of beneficence or potentially the primacy of equality. However, they simplify complex moral situations by isolating beneficence or equality as the only relevant factors, overlooking considerations like familial duties, reciprocity, or unintended consequences. Perhaps, for example, Alf "learned that Betty would plan to use her newfound health to go on a murdering spree, which is why he smashed the pebble." At most, these cases illustrate a nothing-else-considered reason to prioritize beneficence or equality. Intuitively, there is a presumptive duty to act on these reasons, yet they remain vulnerable to potential overriding factors that these simplified scenarios fail to account for.
This objection calls into question the validity of deriving the primacy of liberty or other natural duties from thought experiments. It is straightforward to concur with the authors that "a presumption of liberty cannot be defended by citing the intuitions such cases elicit but will instead require a genuinely robust philosophical defense." That said, Brennan and Freiman's critique would have been more persuasive had they situated the pebble cases within the broader philosophical framework—the more robust philosophical defense—that grounds the presumption of liberty or the public justification principle. As they themselves concede, liberal theorists present far more comprehensive defenses that reach beyond simple appeals to commonsense intuitions; however, they repeatedly emphasize that this remains outside the scope of their analysis.
Public reason liberals, the focus of Brennan and Freiman's critique, agree that public justification serves as the rationale for exercising power. However, this idea is far from unified. There are debates about whether public justifications must rely on shared or accessible reasons, or if diverse, unshared reasons can be valid. Additionally, theorists differ on how reasons are attributed to citizens and which social processes, such as discursive, universalizing, bargaining, or evolutionary, are best suited to establish public justification. The justifications for liberalism are indeed more profound than mere pebble cases or Brennan and Freiman's assertion that "the presumption of liberty plus the public justification principle yields public reason liberalism." Public justification is traditionally rooted in respect for individuals as free and equal, preserving moral relations by ensuring coercion is based on reasons that others can reasonably accept. Coercing someone without such justification undermines their status as moral agents. Public reason serves to align coercion with respect for others as ends in themselves. The presumption of liberty does not result from the equation presented in the paper but rather follows from a specific theory of moral agency.
While Brennan and Freiman convincingly argue that pebble cases and similar thought experiments cannot fully justify these principles and may be overused as intuition pumps, these experiments still serve important roles in conceptual analysis, exploration, and theory development. In fact, they remain valuable tools for testing intuitions about the appropriateness of coercive measures or imposed limits. Furthermore, the authors clarify that their analysis is not intended to dismantle liberalism or the presumption of liberty; by avoiding engagement with deeper justifications, such as moral agency, they essentially sidestep this issue. So, does the presumption of liberty hold up under scrutiny? Perhaps. But Brennan and Freiman remind us that, whether you lean liberal, utilitarian, egalitarian, or anything in between, your arguments should strive to better transcend the limitations of your standard trolley problem.