My goal was to compare deductive and inductive methods of accumulating reliable knowledge in wildlife science. Under the hypothetico-deductive (H-D) method, observations are used to formulate explanatory or causal hypotheses, which serve as the basis for deductions (predictions) of expected events. Field experiments are designed to determine whether the deductions hold, in which case hypotheses are tentatively accepted or otherwise rejected. The H-D method provides the only way to test research hypotheses, but in field ecology it can lead to ambiguity and error. The method: 1) does not preclude confusion of correlation and cause, 2) might perform deceptively in multiple-cause venues, 3) is algorithmically blind to the fact that different hypotheses can lead to the same deduction, and 4) lacks an impartial means of determining whether a deduction has been observed and, therefore, whether a hypothesis is meritorious. Under the process of induction, the results of a study are presumed to hold generally and taken as knowledge accordingly. Induction is much maligned by logicians and philosophers, and wildlife scientists have built false knowledge inductively. However, wildlife scientists have auxiliary knowledge such as facts of natural history to screen inductions for validity. Both the H-D method and induction have important roles in the accumulation of reliable knowledge in wildlife science.