In Grades of Significance, G. N. M. Tyrrell addresses one of the central problems of psychical research: how to judge the strength and meaning of evidence for paranormal phenomena.
Rather than focusing on sensational cases, Tyrrell develops a careful framework for evaluating different kinds of data, including:
Testimony, coincidence, and probability
Experimental results versus spontaneous cases
The role of bias, expectation, and interpretation
Degrees of evidential strength rather than all-or-nothing conclusions
How anomalous evidence challenges conventional scientific assumptions
Measured, lucid, and intellectually rigorous, this book exemplifies the balanced approach of the Society for Psychical Research, encouraging open-minded inquiry without abandoning critical standards. It remains a foundational text for anyone interested in how extraordinary claims can be responsibly evaluated.
 
Brown Binding