Key Moments

Michael Kearns: Algorithmic Fairness, Privacy & Ethics | Lex Fridman Podcast #50

Lex FridmanLex Fridman
Science & Technology4 min read109 min video
Nov 19, 2019|51,891 views|1,267|83
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TL;DR

Michael Kearns on "Ethical Algorithms," fairness, privacy, and game theory.

Key Insights

1

Algorithmic fairness is a complex, multifaceted problem with inherent tensions between different fairness definitions.

2

Differential privacy offers a robust framework for data privacy, overcoming limitations of traditional anonymization techniques.

3

The "ethical algorithm" is not one that decides ethics itself, but one that can encode societal values agreed upon by stakeholders.

4

Group-based fairness definitions can be insufficient, and achieving individual fairness is a more challenging goal.

5

Algorithmic game theory provides tools to understand and design systems with interacting agents, relevant to platforms and markets.

6

The financial sector has seen a significant shift towards algorithmic trading, especially in execution and high-frequency trading.

THE CHALLENGE OF DEFINING AND IMPLEMENTING FAIRNESS

Michael Kearns discusses the complexities of algorithmic fairness, distinguishing it from privacy. Unlike privacy, for which differential privacy offers a relatively settled definition, algorithmic fairness is an area with inherent trade-offs. Kearns highlights theorems showing that desirable notions of fairness can be mutually exclusive, making it a significantly harder problem. The realization that algorithms inherently amplify existing societal biases, especially when trained on historical data, necessitates careful consideration. Furthermore, the definition of who or what constitutes 'harm' and which groups require protection is a crucial, non-technical decision that must precede algorithmic design.

GROUP VERSUS INDIVIDUAL FAIRNESS AND FAIRNESS GERRYMANDERING

Kearns elaborates on the spectrum between group and individual fairness. While group fairness metrics, like ensuring equal false rejection rates across racial groups, are a starting point, they can mask discrimination against intersectional subgroups. This phenomenon, termed 'fairness gerrymandering,' occurs when fairness is achieved at a broad group level but specific combinations of attributes lead to disparate outcomes. Achieving true individual fairness, where each person's unique attributes are considered, is a much more ambitious and complex algorithmic challenge that the field is still exploring, often requiring more refined subgroup analysis.

THE ROLE OF HUMAN VALUES AND THE PARETO FRONTIER

Kearns emphasizes that ethical algorithms do not self-determine ethical principles; rather, they are tools to encode human-defined values. The process of defining fairness requires societal agreement on who to protect and what constitutes harm, which can be politically charged and involve deeply unresolved debates like affirmative action. For understanding the trade-offs, Kearns introduces the concept of the Pareto curve, illustrating the numerical relationship between system error and unfairness. This curve serves as a crucial interface for stakeholders to make informed decisions about where to position a system on this spectrum, a decision that should not be made by computer scientists alone.

DIFFERENTIAL PRIVACY: A STRONGER FRAMEWORK FOR DATA PRIVACY

In contrast to fairness, algorithmic privacy has a more mature technical definition in differential privacy. This framework ensures that the outcome of an analysis is nearly identical whether an individual's data is included or excluded. The mechanism for achieving this is by carefully adding calibrated noise to computations. This approach overcomes the fundamental flaw of traditional anonymization techniques, which can be vulnerable to re-identification by combining datasets. Differential privacy allows for robust statistical and machine learning analyses while providing strong privacy guarantees for individuals.

ALGORITHMIC GAME THEORY AND COLLECTIVE OUTCOMES

Kearns discusses algorithmic game theory as a mathematical framework for analyzing systems of interacting individuals, particularly relevant for large-scale platforms and markets. Principles like Nash equilibrium help predict stability in systems where individuals act in their self-interest. The field explores how machine learning, especially 'no regret' learning, can drive these systems towards equilibria. Even when systems optimize for individual users (like navigation apps or social media feeds), the resulting 'competitive equilibrium' might not be the best for the collective, highlighting the need for careful design beyond simple engagement optimization.

THE EVOLUTION OF ALGORITHMIC TRADING AND FINANCIAL MARKETS

Reflecting on his work in algorithmic trading, Kearns notes a clear progression where computers first excel at tasks they are demonstrably better at than humans. This began with optimizing trade execution for large volumes and has extended to high-frequency trading, which exploits minute price discrepancies. While machines dominate these areas, Kearns posits that long-term, value-based investing, like that practiced by Warren Buffett, still requires human intuition, understanding of macroeconomic cycles, and broader contextual risks. Currently, machines are not well-equipped for the nuanced, multi-year predictions and risk assessments central to such investment strategies.

NAVIGATING THE ETHICAL LANDSCAPE IN A DIVISIVE CULTURE

Kearns acknowledges the difficulty of building ethical algorithms in a polarized society. He stresses that computer scientists' role is not to dictate societal values but to provide tools to implement agreed-upon principles. However, he also notes that technology has fundamentally altered society, sometimes in unforeseen negative ways. The challenge lies in balancing the economic models of platforms, which often optimize for engagement, with broader societal well-being. Solutions may involve user controls and experimenting with algorithms that expose users to diverse viewpoints, moving away from purely optimizing for user retention.

THE INTERPLAY OF DATA, PRIVACY, AND ECONOMIC MODELS

The discussion touches upon the economic underpinnings of the internet, where users' data is often the product, with advertisers as the customers. Kearns suggests that achieving greater individual control over data and privacy could necessitate a shift in these economic models, potentially leading to new market structures where individuals are compensated for their data. While this presents significant economic challenges, he remains optimistic about finding a better compromise between data utilization and robust privacy guarantees, likely requiring a combination of technological solutions and regulatory frameworks.

Common Questions

'The Ethical Algorithm' is a book co-authored by Michael Kearns that explores algorithmic fairness, privacy, and ethics. It delves into how to encode societal norms into algorithms from a technical perspective, addressing issues like bias and data protection.

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