DAY 166: Updating Your Priors

DAY 166

Faith in the Midst of a Pandemic    

A series of daily reflections for people of faith

by Rev. Robert Bayley, Interim Pastor

Patuxent Presbyterian Church, California, Maryland

pastorrobert@paxpres.org

Week Twenty-four Thursday 27 August 2020

Updating Your Priors

Thinking Like an Epidemiologist: 

A Rule to Update Your Prior Beliefs

 and Uncertainties Based on Observed Evidence

  

“There is a statistician’s rejoinder – sometimes offered as a wry criticism, sometimes as advice – that could hardly be a better motto for our times: ‘Update your priors!’…In the early pandemic era, for instance, airborne transmission of COVID-19 was not considered likely, but in early July the World Health Organization, with mounting evidence, conceded that it is a factor, especially indoors. The W.H.O. updated its priors and changed its advice. This is the heart of Bayesian analysis, named after Thomas Bayes, an 18^th-century Presbyterian minister who did math on the side. It captures uncertainty in terms of probability: Bayes’ theorem, or rule, is a device for rationally updating your prior beliefs and uncertainties based on observed evidence.” - From a recent newspaper article – “Thinking Like an Epidemiologist”

We are watching this Presbyterian minister’s theorem applied in an ongoing way by the CDC and others in the current pandemic, as new evidence shifts beliefs and alters perceptions about this unseen virus. And as it is with the whole health and scientific communities dealing with an amorphous unseen world of viruses, so it is also I believe with another realm of unseen and amorphous things, the realm of faith. Doctrinal statements and bulging books of confessions notwithstanding, it defies reduction to something objective. Indeed, its very definition mitigates against all such attempts. And while it is sufficient for all we need, the only objective resource we have is the Bible, God’s trustworthy Word, and even there we find ourselves at the end of the day “seeing but a poor reflection” of the reality to which it points us, 1 Corinthians 13:12.   

My core convictions regarding the Bible, the Triune God, the nature of creation, the necessity of salvation in Jesus Christ alone, God’s sovereignty and providence, and the security of my relationship with the Triune God have not changed during this time of multiple health, climate political and economic upheaval, but they have been visited and tweaked, my priors needing to reflect what I believe in the light of my current context, within which He still faithfully leads.  

Reflective question: How have your beliefs, your ‘priors,’ been affected by this pandemic?

Reflective Scripture: James 1:2 – “…the testing of your faith produces perseverance.”

Reflective hymn:

“He Leadeth Me” - Joseph Gilmore (1834-1918)

Sometimes mid scenes of deepest gloom, sometimes where Eden’s flowers bloom,

By waters calm, o’er troubled sea, still ‘tis God’s hand that leadeth me.