70 Education through Nature 



3. THE INDUCTIVE-DEDUCTIVE METHOD is, as the 

 name implies, a combination of the two methods 

 already described. This is probably the method used 

 by all those who achieve success in science. Indeed 

 it is difficult to conceive of true scientific work with 

 either of those methods used alone. This method 

 consists in first gathering the material of knowledge by 

 observation. From this a general idea is formed and 

 assumed tentatively to be true. Deductions are then 

 made from this general hypothesis, and induction 

 again employed to verify the truth of those deductive 

 inferences. Thus, careful observation shows that 

 plants grown in sunlight are usually green; the infer- 

 ence is that all plants influenced by sunlight develop 

 chlorophyll. This assumption, is held tentatively 

 till further induction, as to the effect of sunlight in 

 producing various pigments, as tanning the skin, is 

 secured. It being found that sunlight has this effect, 

 further observations are made, which reveal the fact 

 that plants grown in darkness do not develop chloro- 

 phyll, etc., from which the soundness of the original 

 inference, having been tested, is pronounced true. 



The advantage of this combined method is that the 

 benefits of each of the other methods are secured, but 

 the disadvantages eliminated. Far more, too, can 

 be accomplished by this combination. The inductive 

 method is used for the accumulation of material for 

 the general idea; and, this knowledge being gained, 

 is again employed in the discovery of new truths. 



General Considerations. Observation and experi- 

 ment, the method of science, naturally results from 

 this inductive-deductive method of reasoning. The 

 successful man of science is (a) a good observer, (b) a 

 good thinker, (c) a good worker. Many students 

 observe well and reason well; but, as they put no 

 energy into their work, accomplish but little. Others 

 work, but do not observe well; and still others work 



