Abstract
Evidence can be complex in various ways: e.g., it may exhibit structural complexity, containing information about causal, hierarchical or logical structure as well as empirical data, or it may exhibit combinatorial complexity, containing a complex combination of kinds of information. This paper examines evidential complexity from the point of view of Bayesian epistemology, asking: how should complex evidence impact on an agent’s degrees of belief? The paper presents a high-level overview of an objective Bayesian answer: it presents the objective Bayesian norms concerning the relation between evidence and degrees of belief, and goes on to show how evidence of causal, hierarchical and logical structure lead to natural constraints on degrees of belief. The objective Bayesian network formalism is presented, and it is shown how this formalism can be used to handle both kinds of evidential complexity – structural complexity combinatorial complexity.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
- 2.
This norm is typically justified on the grounds that degrees of belief are used to make predictions, and calibrated degrees of belief lead to optimal predictions in the long run (Howson and Urbach, 1989, §13.e). Strictly speaking \({P}_{\mathcal{E}}\) depends on \(\mathcal{L}\) as well as \(\mathcal{E}\); we will write \({P}_{\mathcal{E}}^{\mathcal{L}}\) where we need to emphasise this dependence, but drop reference to \(\mathcal{L}\) and \(\mathcal{E}\) where the context permits. Williamson (2005, Chapter 12) discusses language change in the context of objective Bayesianism.
- 3.
This norm may be justified on the grounds that degrees of belief are used as a basis for action, extreme degrees of belief lead to riskier actions, and one should only take on risk to the extent that evidence demands – see Williamson (2007).
- 4.
Ontological or semantic evidence may be understood in terms of influence relations, just as can causal, hierarchical and logical evidence – see Williamson (2005, §11.4).
References
Fridlyand J, Snijders A, Ylstra B, Li H, Olshen A, Segraves R, Dairkee S, Tokuyasu T, Ljung B, Jain A, McLennan J, Ziegler J, Chin K, Devries S, Feiler H, Gray J, Waldman F, Pinkel D, Albertson D (2006) Breast tumor copy number aberration phenotypes and genomic instability. BMC Cancer 6:96
Haenni R, Romeijn J-W, Wheeler G, Williamson J (2010) Probabilistic logic and probabilistic networks. Springer
Howson C, Urbach P (1989) Scientific reasoning: The Bayesian approach, 2nd edn. Open Court, Chicago, IL
Nagl S, Williams M, Williamson J (2008) Objective Bayesian nets for systems modelling and prognosis in breast cancer. In: Holmes D, Jain L, (eds) Innovations in Bayesian networks: Theory and applications. Springer, Berlin
Paris JB (1994) The uncertain reasoner’s companion. Cambridge University Press, Cambridge
Williamson J (2005) Bayesian nets and causality: Philosophical and computational foundations. Oxford University Press, Oxford
Williamson J (2007) Motivating objective Bayesianism: From empirical constraints to objective probabilities. In: Harper WL, Wheeler GR (eds) Probability and inference: Essays in honour of Henry E. Kyburg Jr., College Publications, London, 151–179
Williamson J (2008) Objective Bayesianism, Bayesian conditionalisation and voluntarism Synthese DOI 10.1007/s11229-009-9515-7
Williamson J (2009) Aggregating judgements by merging evidence. J Logic Comput 19(3): 461–473
Acknowledgment
This research was carried out as a part of the project progicnet: Probabilistic logic and probabilistic networks, supported by the Leverhulme Trust.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2010 Springer Science+Business Media B.V.
About this paper
Cite this paper
Williamson, J. (2010). Epistemic Complexity from an Objective Bayesian Perspective. In: Carsetti, A. (eds) Causality, Meaningful Complexity and Embodied Cognition. Theory and Decision Library A:, vol 46. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-3529-5_13
Download citation
DOI: https://doi.org/10.1007/978-90-481-3529-5_13
Published:
Publisher Name: Springer, Dordrecht
Print ISBN: 978-90-481-3528-8
Online ISBN: 978-90-481-3529-5
eBook Packages: Humanities, Social Sciences and LawPhilosophy and Religion (R0)