When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.

If it looks like a duck, and quacks like a duck, we have at least to consider the possibility that we have a small aquatic bird of the family anatidae on our hands.

It is the natural tendency of the ignorant to believe what is not true. In order to overcome that tendency it is not sufficient to exhibit the true; it is also necessary to expose and denounce the false. To admit that the false has any standing in court, that it ought to be handled gently because millions of morons cherish it and thousands of quacks make their livings propagating it-to admit this, as the more fatuous of the reconcilers of science and religion inevitably do, is to abandon a just cause to its enemies, cravenly and without excuse.

When I see a bird that walks like a duck and swims like a duck and quacks like a duck I call that bird a duck.

If it looks like a duck and quacks like a duck we have at least to consider the possibility that we have a small aquatic bird of the family anatidae on our hands.