Evidence, philosophy of science, information

1. An informational approach
to evidence
Federica Russo
Philosophy & ILLC | Amsterdam
russofederica.wordpress.com |
@federicarusso

3. Overview
The ‘evidence turn’ in philosophy of science
What evidence is
Formal approaches
Evidential pluralism
Evidence as information
What it means
Why it matters
Outlook and perspective
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4. THE EVIDENCE TURN
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5. Questions at the core of phil sci
What do we know?
A question about scientific knowledge, about
the claims the sciences make
And how do we know what we claim we
know?
A question about the concepts and methods
that allow us to establish scientific knowledge
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6. Traditional strategies
to the core questions
Debates in the fields of scientific realism and
modelling
Science aims to establish truth
There is a true reality out there to be discovered
Our models improve and approximate to this
truth
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7. The ‘practice turn’ in phil sci
Models are part of scientific practices
These, and other practices, allow us to
gather evidence
It is on the basis of evidence that we
establish scientific claims
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8. Evidence is ubiquitous
In the sciences
Because ultimately any scientific practice is about
gathering, processing, and assessing evidence
But also in phil sci
Many debates now about evidence
Evidence-based medicine
Evidence of mechanisms
Data and evidence
…
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9. … and yet largely undefined
Many of these debates try to discuss
Whether evidence comes into categories
How evidence supports scientific claims
How evidence is gathered
What to do with missing/poor evidence
But what is evidence?
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10. WHAT EVIDENCE IS
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11. Formal approaches /1
Evidence is what allows certain formal
(probabilistic) relations to hold, especially
with respect to (scientific) hypotheses
Example questions
How does the p(H) change given some E?
When is H confirmed by E?
When is belief in H justified by E?
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12. Formal approaches /2
An established tradition in analytic phil sci
Achiestein’s The Book of Evidence
Rooted in eminent work of e.g. Carnap and Hempel
In dialogue with important contributions of e.g.
Glymour, Williamson, Bovens&Hartmann
Still alive and active
Bandyopadhyay, Brittan, and Taper’s Belief,
Evidence, and Uncertainty
They attempt to reassess the debate, and take a
fresh look at ‘evidence’ and ‘confirmation’
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13. Evidential pluralism /1
Evidence is what allows one to establish
(causal) claims (in medicine, and
elsewhere).
Causal claims are to be established based
on multiple sources of evidence
Evidence of difference-making and of
mechanisms label the most important
categories of what we seek evidence of
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14. Evidential pluralism /2
A debate mostly applied to the biomedical
sciences
Trying to establish relevance of phil sci to
the practice of science
See EBM+ and the tools for assessing evidence
of mechanisms
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15. In sum:
Formal approaches are … formal and leave
largely unspecified what ‘E’ is
Evidential pluralism fixes what ‘E’ is in a
rather specific way
We are stuck between <no> or <too much>
specification of what E is
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16. EVIDENCE: AN INFORMATIONAL
APPROACH
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17. Sketch of an idea
Evidence is ubiquitous
Evidence means different things in different
research contexts
How best to account for
Generality?
Variety?
Evidence is information
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18. Brief interlude:
Why going informational?

19. PI: a sub-field within philosophy
Information’ is a central notion, to be
investigated in its ontological, epistemological,
methodological significance
Making ‘information’ central to philosophy
allows us to re-design our conceptual
apparatus
Knowledge, Truth, Modelling, … All require
redesigning
All this is (partly) motivated by the digital
revolution
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20. PI: a philosophical methodology
The ‘method of the levels of abstraction’ (LoA)
Borrowed from computer science to analyse
systems and their models
Applied to philosophical questions: specify the
‘level’ at which a question is asked, and an answer
given
Avoid ambiguity, enhance rigour, facilitate comparison
Constructionism
A general approach to describe the relations
between us epistemic agents and the outside world
It is in between realism and constructivism; we “in-scribe”
reality, not just de-scribe or pre-scribe
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21. In some more detail:
Evidence is information – of what kind?
General Definition of Information:
p is semantic information if
(i) it consists of data,
(ii) data is well-formed,
(iii) well-formed data is meaningful, and
(iv) the meaningful well-formed data is truthful.
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22. Semantic information
It is about interpreted data,
unlike mathematical theories of information
They abstract from the contents;
Data is un-interpreted (e.g. Shannon’s)
It is weakly constrained by mathematical
theories
Highly flexible and applicable to several
contexts
Here: evidence and modelling!
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23. Evidence is information –
what does it imply?
Modelling practices generate evidence
Information, in these modelling practices,
comes from data – it must comply with GDI
We can check formal properties of modelling
practices:
Well conducted? Biased data? Inappropriate modelling
approach? Etc.
The kind of data is not fixed
Experimental, statistical data; expert opinion;
surveys; narratives …
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24. Evidence as information
provides a most general
account of what
evidence is
A semantic approach to
information allows is to
specify factual or
instructional content of
evidence
Formal approaches and
evidential pluralism hold
at different LoAs 24
Evidence as
information
Formal
approaches
Analyse formal
relations
between H and
E
Evidential
pluralism
Describe
contents of
evidence in
specific sci
contexts

25. Why does it matter?
What payoffs?

26. Model validation
Establishing the validity of a model is
question of adopting the correct LoA
Don’t compare pears with apples (or, against
rigid hierarchies)
Check the whole consistency of the modelling
practice (or, models are not just stats, but also
justification of modelling choices, etc.)
Consider models’ usefulness (rather than
absolute truth)
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27. TO SUM UP
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28. Evidence is central to phil sci debates
In mainstream, analytic-oriented phil sci
They look at formal relations
In practice-oriented phil sci
They give very specific account of the contents
But what is evidence, in more general terms?
An informational approach
Evidence is (semantic) information
General and flexible, the account also helps
with model validation
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29. OUTLOOK AND PERSPECTIVE
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30. Why going informational?
To explore prospects of ‘information’ beyond
narrow construction of ‘mathematical
information’
An opportunity to redesign phil sci concepts
after the information revolution
Make sense of the practice of science
Make sense of a techno-scientific practice [not
explored here]
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Techno-scientific practices
An informational approach
Coming soon at Rowman &
Littlefield