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Good evidence, bad decisions #421

In an era obsessed with data dashboards and measurable outcomes, Andreas Matthias revives a dangerous philosophical question: what if the very act of demanding evidence is what blinds us to the truth? This piece is not a rejection of facts, but a warning that our rigid adherence to "evidence-based" mantras may be systematically filtering out the most critical, unquantifiable aspects of human expertise and decision-making.

The Trap of Measurable Truth

Matthias introduces the piece by highlighting a paradox that feels increasingly urgent in our algorithmic age. He writes, "Having evidence (usually in the form of some measurable quantity) does not guarantee that one will make good decisions — and the other way round." This observation cuts through the modern assumption that more data automatically equals better judgment. The author frames this not as a minor technical glitch, but as a fundamental flaw in how institutions—from universities to hospitals—approach complex problems.

Good evidence, bad decisions #421

The commentary leans heavily on the work of philosopher Hubert Dreyfus to bolster this claim. Matthias notes that Dreyfus, drawing on Heideggerian ideas, argued that "calculative rationality" misses all that is essential to true expertise. This is a crucial distinction. It suggests that when we reduce teaching, medicine, or leadership to a set of metrics, we are not refining our understanding; we are discarding the very intuition that makes those fields work. Matthias points out the irony in how this plays out in higher education: "Given what our universities are doing with outcomes-based education, measurable markers of teaching quality, and other such nonsense, it is particularly important to emphasise these points."

If one is determined to base truth, judgement, and decisions based on evidence, then one limits these to all to only that for which evidence may be gathered -- leaving those features which fail to qualify as evidence neglected.

This limitation is the core of the argument. Matthias explains that the "evidence-based" mantra creates a self-fulfilling prophecy where we only pay attention to what we can measure. If a factor cannot be pinned down in a spreadsheet, it is treated as irrelevant. This echoes the historical concept of Goodhart's law, which states that when a measure becomes a target, it ceases to be a good measure. By chasing the measurable, we inevitably ignore the messy, unquantifiable variables that often determine success or failure.

The Exclusion of the Unarticulatable

The piece argues that this bias toward the quantifiable actively harms decision-making by excluding vital context. Matthias writes, "The dangerous tendency then is that a tight or rigorous notion of evidence will put out of consideration as not-really-evidence factors that cannot be rigorously articulated, but which might be more relevant to determining well truth, judgement, and decisions." He illustrates this with the example of a teacher or lecturer, whose effectiveness may rely on a "heuristic gestalt view" that cannot be easily codified into an algorithm.

Critics might argue that without rigorous evidence, decision-making becomes arbitrary or prone to bias. However, Matthias counters that the alternative—ignoring the unmeasurable—is far more catastrophic. He suggests that the current obsession with evidence leads to "decisions being poorer than they need to be" because we are operating with a deliberately incomplete map of reality. As he puts it, "If one skews decisions so that they are based only on what counts as measurable evidence, the decision will be the poorer, as relevant features that do not count as measurable evidence will not be included in the decision making process."

The author also touches on the normative trap within evidence-based decisions. Even when data is clear, the interpretation often relies on value judgments that data cannot provide. Matthias notes, "Many of these get assumed, when they may be opened up reasonably or even unreasonably, to disagreement. In which case the decision that a certain treatment is beneficial in a normative sense cannot follow from the factual evidence alone, no matter how strongly it may appear to." This is a vital reminder that data can tell us what is happening, but rarely what we should do about it.

The Atrophy of Human Judgment

Perhaps the most striking claim in the commentary is the long-term psychological impact of this mindset. Matthias suggests that over-reliance on gatherable evidence leads to a degradation of our innate ability to judge complex situations. He writes, "There is a further a bolder claim one may make: that over consideration of gatherable features of a situation that may count as 'evidence' leads to the atrophy and perhaps moribundity of those faculties and habits of mind that lead one to understand a situation in a heuristic gestalt way."

This aligns with the Dreyfus model of skill acquisition, which posits that true mastery involves moving beyond rigid rules to a fluid, intuitive understanding of the environment. By forcing every decision back into a box of measurable evidence, we risk stunting the development of this higher-level expertise. Matthias warns that this isn't just a theoretical risk; it is a practical one where "the evidence will shift the focus on decisions being based on truths that may be determined by evidence crowding out other considerations which are not part of the assembled evidence one has."

The power of the evidence outweighs matters one might otherwise consider, but which strictly speaking do not count as evidence as what they are has not been pinned down in a way that is transparent in its factual precision.

Bottom Line

Matthias delivers a compelling critique of the uncritical worship of data, arguing that the most dangerous decisions are often those made with the most confidence in their evidence. The piece's greatest strength is its ability to reframe "evidence-based" from a virtue into a potential blind spot, forcing readers to question what they are ignoring in their own data-driven strategies. Its vulnerability lies in the difficulty of operationalizing this insight; without clear metrics, how do institutions avoid sliding into pure subjectivity? The answer, Matthias implies, is not to abandon evidence, but to stop pretending it tells the whole story.

Deep Dives

Explore these related deep dives:

  • Being and Time Amazon · Better World Books by Martin Heidegger

  • The Tyranny of Metrics Amazon · Better World Books by Jerry Z. Muller

  • Goodhart's law

    This economic principle explains the specific mechanism by which the 'measurable markers' of teaching quality mentioned in the text become counterproductive when turned into targets, validating the author's critique of outcomes-based education.

  • Dreyfus model of skill acquisition

    While the article references Dreyfus's general argument, this specific model details the five stages of expertise where 'calculative rationality' is explicitly replaced by intuitive grasp, providing the technical framework for why evidence fails in true mastery.

  • Criticism of technology

    The article invokes Heideggerian ideas to challenge data-driven decisions; this topic reveals the specific concept of 'enframing' (Gestell) that reduces complex human realities to mere 'standing reserve' of data, illuminating the philosophical root of the 'bad decisions' described.

Sources

Good evidence, bad decisions #421

by Andreas Matthias · Daily Philosophy · Read full article

Dear friends of Daily Philosophy,

We’re back from the holidays, and things are starting to normalise again. Over the summer, I received a great number of fascinating articles, and I am excited to share them with you over the coming months.

One of them is the article below, by John Shand. What I found immediately relatable is the argument that having evidence (usually in the form of some measurable quantity) does not guarantee that one will make good decisions — and the other way round. It reminded me of an argument by Hubert Dreyfus, who had argued, based on Heideggerian ideas, that “calculative rationality” (as he called it) misses all that is essential to true expertise. Given what our universities are doing with outcomes-based education, measurable markers of teaching quality, and other such nonsense, it is particularly important to emphasise these points. Feel free to forward this article to your local learning success measuring and optimisation authority.

And now, enjoy the article and have a great weekend (or what is left of it)! — Andy

Good Evidence, Bad Decisions #421.

By John Shand

Evidence and decisions.

This paper sets out to challenge the uncritical claim, presented as a mantra implying a virtual truism, that we should aim for ‘evidence-based decisions’. It is often claimed, for example, that most medicine is now ‘evidence-based’, with the implication that that is a ‘good thing’. On the face of it, it looks obvious that the best way of going about things is surely to base decisions, or judgements that lead to decisions, on the evidence. This will if accepted without nuance and unquestioningly, it is argued here, lead to poor decisions, even catastrophic decisions, or at the very least decisions being poorer than they need to be.

Evidence may not be appropriate.

Of course, the mantra is not applied to all decisions, and it’s important to get that out of the way at the start, as otherwise it will be said that the claim addresses a straw man. If someone close to you -- a partner or offspring -- asks you if you love them, it’s going to go all wrong if you ask them to hang on a minute while you check or gather the evidence. So we set aside, for the sake of argument, those areas where no-one has ever seriously held that decisions should be evidence-based.

Assumptions about evidence.

There is ...