Is it ok to use the irregular past tense of a verb as it were a regular one?

Let's say I say / write catched instead of caught or buyed instead of bought, etc.

I know this is grammatically incorrect, but is it incorrect or perfectly fine to use it in every-day life ? English is not my first language so I am a little bit curious about this. Some people say it is correct and understandable, while others say it is incorrect and ridiculous.

Solution 1:

You answered your own question when you said it was grammatically incorrect. It is usually understandable but is considered wrong.

That said, there are some verbs which have multiple forms. An interesting one is sneak which has both sneaked and snuck as past participles. Many people consider "snuck" to be incorrect. Indeed my spell check doesn't even recognize it. Yet for many others it is correct, if perhaps informal.

There used to be many more irregular verbs in English and over time a good number of them have become regularized. However, the most commonly used verbs are the most resistant to regularization because everyone already knows the irregular forms and they use them often.

As a non-native speaker you will probably be forgiven if you slip up and use a regularized form of an irregular verb. But, like my three-year-old son who also uses regular forms of plurals and past participles where fluent speakers would use an irregular form, you will be expected to correct them, especially if writing/speaking formally.

Solution 2:

As with many things, "it depends". It depends on what you mean by "incorrect" and it depends on the specific verb.

To generalise hugely, there is a phenomenon whereby children acquiring the language overgeneralise regular patterns while in the fairly stages of acquisition. So a 4 year old child may well say "He catched it". But a normally developed adult native speaker would probably never in their wildest dreams of a slip of the tongue use the form "catched" (unless they were deliberately mimicking child language, or for some other humoristic effect). The same generally goes for common irregular verbs. So in these cases, by pretty much any useful definition of the word, you would say that "catched" and "buyed" are "incorrect".

However, this doesn't hold for all irregular verbs. There are a few verbs 'on the fringe' where for a variety of reasons even in the adult language, there will be variation. This includes regional or ideolectal variation: e.g. "treat" can be irregular in Yorkshire English, whereas it is regular in standard English; "sneak" is generally regular in British English, but typically irregular in US English. You can even get cases where a verb is considered irregular, but there is uncertainty about the actual irregular form (e.g. "He span" vs "He spun"; "He rode it" vs "He rid it", though the latter would generally be considered non-standard). In these cases, whether e.g. "he treat [trEt] them well", "he snuck in", "He rid it fast" are "incorrect" or "correct" depends on what you decide your measure of "correctness" is.

In the case of some relatively rare verbs, it may be that many adult native speakers are simply never explicitly exposed to the 'standard' irregular form, so that they will tend to regularise. The most common past tense of "broadcast" is irregular, but there are a number of tangible instances with the regular form (e.g. "They never broadcast[ed] it"). Indeed, you're unlikely to get much of a consensus about the precise cases where "cast" is regular vs irregular ("They cast[ed] him as the hero"). These are all cases where the variants are probably all used sufficiently in adult, educated usage that you'd be generally hard pushed to say that one is "incorrect" by most definitions.