The Epistemology of Second Best

34 Pages Posted: 5 Feb 2021 Last revised: 10 Mar 2021

See all articles by Gary Lawson

Gary Lawson

Boston University School of Law

Date Written: February 2021


Second best theory “holds that where it is not possible to satisfy all the conditions necessary for a[] . . . system to reach an overall optimum, it is not generally desirable to satisfy as many of those conditions as possible.” Adrian Vermeule, Foreword: System Effects and the Constitution, 123 HARV. L. REV. 4, 17 (2009). In other words, if you are not moving all the way to the ideal state of affairs, it is unclear whether partial moves that seem to go in the direction of the ideal make the world “better” or “worse” – with “better” or “worse” defined by the same criteria, whatever they may be, that defined your ideal. This article shows how second best theory is even more important and even more (for want of a better word) subversive than its most familiar applications suggest. Second best considerations lurk at the core of all processes of acquiring or pursuing knowledge, including but not at all limited to legal knowledge. Put simply, even assuming away the costs of acquiring and processing new information, more knowledge will not necessarily lead to better decisions than will less knowledge, with “better” meaning “more likely to lead to accomplishment of a defined goal,” whether that goal is pursuing a substantive conception of justice, obtaining an economic equilibrium, or acquiring truth. The capacity of additional information to lead to better decisions depends on (1) the shape of the path towards full or ideal knowledge. (2) one’s location on that path at a particular moment of decision, and (3) the likelihood that one will be able to follow that path to its end. All three of these factors are highly contingent and often difficult, and perhaps impossible, to ascertain. The bottom line is that knowing less can lead to better decisions than knowing more. That will not always be the case. But it might sometimes be the case. There is an optimum amount of knowledge for any particular decision, and supra-optimal knowledge can be just as bad, from the standpoint of decisional accuracy, as sub-optimal knowledge. This has potential implications for, among other things, the role of expertise in administrative law and evidence law.

Suggested Citation

Lawson, Gary, The Epistemology of Second Best (February 2021). Boston Univ. School of Law, Public Law Research Paper No. 21-03, Available at SSRN: or

Gary Lawson (Contact Author)

Boston University School of Law ( email )

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